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John Page

The Birth of a Workshop

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Over the last 8 years (shocked that it's already been that long) I've worked out of and visited somewhere in the range of 30 shops in all manner of buildings and scale, from the basement welding room that I started in to the likes of Baltimore Knife & Sword in MD and Jim and Jeff's shop out in Oakland. Since then I have a fairly good idea of what I want out of a workshop, but there are a few questions I have for the hivemind.

Before getting into that, I want to share the plan that I currently have going, evolved from plans I started drafting a few years ago. The ultimate motivation behind the design in creating a space that inspires further creation. Although a bit nebulous to try and describe, it is a combination of aesthetic, function, and the culmination of design choices that establish the basis for inspired design.

The shop I currently work out of, in historic Old Town State Park, a recreation of a Californian colonial era blacksmith and wood shop, does a fantastic job at portraying what I am after for the sheer fact of the weight contained in its history and the contribution of smiths for the better part of 150 years. However, the things that fill the space do not replace certain design pieces when applied to the space itself.

What I currently have the general design worked out for is a 9 sided building dedicated to hotwork and other metalworking apparatus, a clean room attached to one end, and a woodshop above it and looking down into the metal shop. In and around the forge area will be a stone hearth for the obvious fire prevention reasons, as well as a contained portion where the quench tank will be. Ideally, I'd like to segregate the tools based on function, having a power hammer and press near the forge but not against the wall, allowing them to be accessed from a wider variety of angles. Underneath a slight overhang from the woodshop floor would be the grinding area, the thought being that extra bit of coverage would help contain the inevitable dust that comes from it, although with a few additional containment measures and fire-proofing in place. In the metalworking shop, having a large welding table in the middle of the room for layout, welding, etc. provides a valuable hot-metal-resistant surface to work on, while also allowing it to be used from other areas around the shop unhindered. Along another of the walls will (eventually) be a lathe, mill, and drill press. That leaves, accounting for doors and whatnot, two additional walls open for workbenches and storage.

I won't go into too much detail on the wood shop and clean room, although the layout for those is reasonably organized at this point. Once I am able to upload a few cad drawings of what I am talking about, it will probably make a little more sense.

 

The questions I have are this:

For anyone who has recently built a shop or is in the process of building a shop, how did you decide on the overall square footage? Is it based on what tools you currently have with room for projected growth? Layout for tools is always open for change, but how did you account for any future acquisitions? On the logistics side of things, did you do anything to certify the plans for the space prior to building? I know building code varies considerably depending on where you are located and proximity to urban environments (what can be built as a 'barn' with no strings attached vice having to get special permits to put up a 10x5 garden shed) but what sort of complications did you encounter that you wish you would have been better prepared for prior to commencing the build?

For anyone who is currently well established, what things work well in your shop that cannot be fixed by a simple rearrangement of equipment? Any issues with utilities (distribution of power, ventilation, lighting, etc...) that a little more planning could have solved?

 

The building of a workshop that stands on its own as a place of craftsmanship is something that I have been putting a considerable amount of thought into lately, and, although constructing it almost entirely by hand (including the tools to build it) will take a tremendous amount of time, I am nearing the phase of developing a final set of plans for construction. I have a few imminent opportunities for substantial changes in life direction, this being the forefront of them.

I'd love to hear from the collective experience represented here and draw from anything that can contribute to the success of it. I intend to keep using this thread as a long term exploration and documentation of the process, from now in the design phase, until the ultimate completion of the space.

 

As always, thanks for reading

John

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To better illustrate what I'm talking about and for an initial approximation of size, here are a few pieces of the design-

Floor Dimensions.PNG

Ignoring the angles in there, the length of each side was based off of an inscribed circle that has an equivalent area to a square 45 feet across. That gives a final area of ~2100 square feet for the metal shop, which looks huge on paper but when filled full of tools, forges, and heavy equipment fills up fast. Other considerations used when coming up with those dimensions are the length of beams required for various supports and roof timbers. I went through a few iterations of the above shape based on distribution of negative space. Those 3 overlaid triangles represent the joists at the top of the walls that transpose radial force of the roof's weight into tensile force distributed to the walls. Having the greatest distance between the joints/intersections of those beams and the angles of the beam terminus will theoretically give the greatest amount of strength.

Joist and Roof.PNG

And the above shows the addition of the floor space of the wood shop/clean room. I initially went through two iterations of width for that space, based on the projection of the northmost corner of the hotwork shop into that space. For structural purposes, the ceiling beam needs to pass through the wood shop to the top of that wall. To help prevent the space from being wasted, I plan on building a long bench in that space using the ceiling beam where it enters the woodshop's south wall as the bench height. (difficult to explain but I'll grab a drawing of that at some point)

Describing the layout of machinery in the first post, the forge and heat treating equipment would go against the east two walls with press/power hammer towards the centre from there. On the southernmost wall will be a bench and storage, with additional layout equipment on the wall to the right between it and the hot work. To the left of the door on the southwest corner, more storage and bench space, aimed at housing bench mounted tools like an arbor press. The western two walls are reserved for lathe/mill/drill poress, etc. That leaves the northern two walls for the grinding area, sheltered by the 6 feet of overhang to help contain the debris and allow for a place to mount additional containment. On the eastern corner of the clean room/woodshop floorplan will be the entrance to the clean room. The exact situation for a stairwell up from the hotwork shop to the woodshop is yet to be determined, either straight from one room to the next, or from inside the clean room.

Hopefully that provides a bit more sense into what I'm thinking. I'd love to hear any criticism and suggestions you might have.

 

John

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One thing I truly miss is built in shelving / drawers for nuts bolts, cabinets for tools, etc. Cleans up the shop and rids of an eyesore of clutter / keeps grinding dust out. Instead of having my oxygen & acetylene tanks wandering about on a cart they were in the wall with the hose abe to be in or out of the door. 

Having your welder on an I-beam able to span the side of your shop. or on a pivot above head. 

Do you want a crane, hoist, gantry? best figure that out now. 

once you place electrical, wish there was another outlet, or dedicated 118 / 220/240 

never mentioned bathroom, a urinal / sink. Having a shop with no water ...

 

 

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First let me say that I think this is a cool and ambitious design, and i think it would look awesome as a workshop.

The more practical side of me however, can't help but wonder how much more space you would get for the same money if you would build it a more traditional rectangular shape.

I also often entertain myself with designing my ultimate workshop,  and a must for me would be to have a separate forging, grinding, woodworking and finishing space, separated by doors to keep dust from cross-contaminating. At the moment most of my shop is in one space, and I am sick of having to clean everything when I'm working with light wood or leather.

As Tim Jackson above me already said,  make sure you will get three-phase power and running water in your shop, and having an overhead crane in the hot shop is also a great thing to have.

Lastly, I would also put some thought in heating/cooling, a big shop with high ceilings will be a lot nicer when there is a woodstove or something placed strategically.

This are just my thoughts on the matter and you are free to do with them however you want ofcourse.;)

Anyhow, I will be following this thread and your shop build with great interest.

 

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I've also been wondering around my area looking at both big and small shops.  Everything from knife makers to very large architectural work shops.  But I tend to fall back on a layout from my local craft school I learn at either because It's just what I'm used to or that so many people have come through there and made the place what it is.  

With that I would say give yourself more space than what you think you need.  When I go off to my local open forge (smaller facility) and either work or just help out - for a one person shop the space would work, but it also gives you this feeling of being crammed due to people, tools everywhere and then it becomes hard to work comfortably.    So plan for a little extra space to keep that crammed feeling away, because more tools will come. 

A lot of your building layout, should come from the majority of work you expect to do. I am not 'established' or yet considering myself a 'professional' although I'm really attempting to take my hobby that way to a degree.  I just have some likewise experience in getting involved with getting into some workshops and seeing what kind of layouts they have. 

From the majority of what I have seen so far. Guys that are just producing knives or just tools in general like hammers can have smaller shops, people with architectural or even just consider themselves artist tend to have big shops.  Like an entire barn plus the need for another one.  

In regards to electrical having a phase converter is a good idea for just about any business facility as so many old and even new motors run on three phase.  But maybe look into that when that tool comes in that you need it for.

Ultimately building code, will dictate a lot of things if your going to be doing this by the book. 

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Hi John. One practical consideration....run through a check list of all the power tools you would like to have at some point and map out enough electrical service to handle everything with ease, then double that!!! You still wont have enough power in the long run but doubling what you think you need to start will put you a little further down the road. I would also consider separating the grinding area completely from the woodwork area, meaning they don't even share the same air handling equipment. Un-sealed motors on woodworking tools do not like metal dust! If you plan on having a big shop compressor you will want an isolated compressor room with a good sound proofing too. I'm on my fourth shop in thirty plus years and those are my biggest concerns for layout.

1) More Power!

2)  Isolating airborne nasties, i.e. metal dust silicates etc.

3) Not having to hear the compressor!

As to building code requirements I am blessed to live and work in a place where I can do whatever I want. I have worked in areas where everything was coded and required inspection. The time to find out all the ins outs and requirements for your area is Before! you break ground! Unforeseen code requirements can double or triple your budget once you're too far in to turn back! Get the facts up front. If you live in a densely developed area a dedicated fire suppression system in a hot work area may pay for itself in insurance premiums. I'm sure I will think of something else after I log off but I stand by my number one.....More Power!

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Thanks for all the advice everyone!

Tim, I have thought a few times about the gantry situation, for both the wood and metal shops. When I was in upstate NY, one shop I was in had a large section of I-Beam from a collapsed skyscraper a few decades ago, and it had a system of wheels that travelled near the web. It was a surprisingly economical and robust design for its simplicity. I thought of doing something similar with a section of large rail track, rigging wheels to ride along the rail surface or flip it upside down to travel the corner of the web, depending on how I could mount it. In the wood shop, it would be easier with the ceiling timber layout, but I am still trying to devise a way to work it into the metal shop as well. Good to know that it's worth the effort, I'll do some figuring on how to make it work.

For electrical, I plan on having at least two dedicated junctions for each side of the shop, one 220v, another 120v. Having worked around some weird and convoluted electrical plants the last couple of years, being able to guarantee power and quickly isolate problems is hugely valuable. For running the cables, using the tops of the beams that connect the tops of the walls made the most sense initially, both to distribute lines to all the sides in an out-of-the-way place and to keep the walls clean aesthetically and practically. Having high amp breakers will be a must, especially with some of the larger equipment.

The bathroom situation is still in the works, for a single albeit strange reason. It is currently situated in the westernmost end of the clean room, having a sink, toilet, and shower. Aside from the septic field logistics, I am working through a design that uses waste heat from the forge flu to heat water, circulating it via natural convection/ heat pump rather than an electric pump. The idea is to reclaim as much of the forge exhaust heat as possible through a coil type heat exchanger wrapped around the chimney flu. Interfacing the two is where the dilemma lies. The two options I am seeing are having the coils be inside the chimney, where the rising air would have direct contact with the coils at the expense of higher rates of corrosion and therefore maintenance/failure. The second is to have it adjoining with but on the outside of some sort of thin walled flu/baffle and either soldered in place to increase the rate of heat exchange or use a thermal paste of some sort. That second option would make the apparatus last longer but harder to access, and then comes into question the materials selection and the efficiency. I suppose that the efficiency doesn't really matter considering it is waste heat to begin with, but being able to heat water with it instead of a gas or electric hot water heater (probably used supplementally anyway) is desirable. Inscribed Roof timber.PNG

Excribed Roof timber.PNG

 

The above four drawings show where the secondary layer of roof truss supports will fall. I have another diagram somewhere showing where it will be from a front facing (rather than top down) view, but it involves a similar distribution of force/stability rectifying solution for the ceiling load while also serving as a mount for an air movement system. Doing some research into old sail powered mills (i.e. historic Holland), there is an elegant solution to air circulation that involves suspending a mechanical fan from the centre of the secondary roof support. It would fit inside the inner circle radius of the horizontal timbers and move air up or down depending on the time of year. That whole system is intended to be a system of timber cogs and axles with large, slow moving blades moving a high volume of air. Depending on the later engineering of that, it may be simplified by a more commercial fan system, although I would rather avoid it due to looking down/at it from the woodshop vantage.

Daniel, I'm glad you mentioned the space/people consideration. While I am currently a solo operation, sharing the space with other creative types is one of my favorite things. Having hammer ins and possibly in some distant future teaching out of the space is a primary consideration for size. Having worked out of small shops more often than large ones, I could certainly downsize a fair amount and be perfectly content, but that's if it's only me working out of it. Out of curiosity, roughly how large is the open shop you go to? Is it mostly the people filling space which is a problem or the amount of tooling in there that makes it difficult to navigate? Probably a combination of the two...

Building code is a major concern, no doubt. Before finalizing anything or pursuing materials, I will be sending the drafts over to a collective who deals specifically in timber framed buildings and certifies/conducts stress analysis/validates these types of plans (churches, houses, barns, etc.). A few of the dimensions I have already come from the critical pieces of building code for heavy snow areas like roof pitch, but not being an architect I am sure there is a considerable amount I would never even think of. For the clean room, I am trying to build in such a way that the floor of it is below frost depth, with the floor of the wood shop being ground level. Complications aside, there will be a slight sunken foundation for the hot work shop, but the masonry and concrete work is another story altogether.

Isolating the wood shop will come from a series of windows on that outward facing wall to act as containment, but be able to open if needed for access/air movement/etc. I am still thinking of ways to further isolate the grinding area, which may ultimately come by sacrificing part of the clean room and dividing it (separate entrances) for use as a separate grinding room. What solutions have you all found to make dust containment easier? I've seen a lot of interesting things out there, but little consistency other than the classic bucket of water at the bottom of the wheel :D 

And for the air compressor, depending on the space availability and layout, I'm mixed between having a separate corner of the wood shop segregated for a compressor with noise insulation, or sticking it by the hot water heater. Having it on the top floor gives a more convenient excuse for plumbing a sink up there too, as I plan on having compressed air down in the clean room as well. Either way I suppose there would be a pass through of some sort connecting the spaces.

 

Thanks for all the feedback so far, it's greatly appreciated!!

John

 

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In regards to my local forge - a lot of their layout trouble in my opinion is that they just don't have the space for what it's become in the past 2 years I've gone there.  There are 4 open forges (two back to back) with about 6 anvils and 3 vises in a 25x40 space shared with power tools and a 50LB hammer which is basically facing a wall and partitioned off. When I go there which is pretty much for the hammer, I feel like I have to walk around the entire building to get to it.  The power tool area doesn't bother me as I don't use it, but it has in a way pushed everyone into the last 2/3rds of the building. 

The organization is doing all they can with the space to accommodate people who do come in, which can be up to 30 people a night wanting to hit some metal. 

Imagine, 30 people being 30 tools that you didn't expect to accumulate each one having its own needs, but knowing that you do need it. 

 

On the other hand, the craft school I go to, has 12 forges back to back, layout table in the center and both power hammers are off to the sides of it.  This building is large, and if they put out more anvils would easily accommodate 24-30 people. There are 4 treadle hammers, so much is just so easy to get to. Even when workshops are considered full at 12 people - I've never felt crammed.  My craft school is just the opposite of the local forge.  Not enough people and it's sad for the facility that's put together there.  I haven't been to Peters Valley although the thought crosses my mind, as it's one of the most heard of places.  My local school is just too close to justify going over there for the cost.     

The architectural smiths I've visited with, although their building rival the size of my local school, are just more personalized.  Their forging areas are usually the forge somewhat centered in the shop or at least in the middle of the floor the anvil and vise pretty close by, along with their hammer (yes they all have a hammer).  Layout tables seem to occupy a space of their own away from this area, but they normally have a floor space equal to their layout table open close to their forging area.  Mostly to toss all their big stuff once it's gone though the forging process.    The rest of their space is just dominated by other toys depending on how they do their work.  Fabricating or whatever else.

Architectural smiths are tool junkies! and if they don't have 2 of everything then they usually don't have 1.  everything, literally, everything . . . . . . finding these guys has been like finding a vein of gold.

Edited by Daniel W

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Thanks for the insight, appreciate it! 30 people in a space that size sounds like a rodeo! I think the most people we've had in the shop at the state park is around 16, and even that was way too many for the size in spite of having enough anvils and forges to (sort of) accommodate everyone. In my head, a space 25x40 sounds huge, but it's only 1000 sqft, and thinking about some of the apartments I have lived in, perspective shrinks it down pretty fast when that many people are in it at once! While I don't plan on having tooooo many seeming duplicates of heavy machinery, I guess having only one is just the start of the slippery slope :rolleyes:

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John,

First I need to apologize for not seeing this sooner. I think this is a very ambitious and worthwhile project. I am a builder and have erected more than a few buildings with big beams and this would be a framer's dream to build. I do have to ask, why are you set on timber framing? Is it just the look or the historical accuracy? I'm looking at what I think are beam spans and applying a live load for a second floor and I'm rapidly coming to think Glu-lam beams of extraordinary size.

Have you run this idea past a structural engineer yet?

Edited by Joshua States

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Glad to have you in the conversation Josh! The primary motivation for timber framing comes from a combination of historic construction, aesthetics, and intimacy in the building process. Those long beams over the main shop won't be supporting a second floor- they are there mainly to help distribute the weight of the roof into a tensile load. I've done a few scalings of the dimensions based on certain timber lengths, one of which limiting the maximum unsupported beam length. Depending on the viability of that construction and available timber sizes, I've thought about joining two smaller timbers with a lap joint and supporting the scarf with a vertical timber that runs from the floor to either the first layer of supports or all the way to the ceiling rafters to help distribute additional load.

Out of curiosity, do you know any concerns or complications that come from the joining of the wooden sills to stone foundations? The horizontal ones seem easier, but I haven't been able to work out a good solution to vertical posts meeting masonry. Having a clean room that is mostly insulated by piled earth/a hillside relies on having three sides being not-wooden, but the junction between the foundation walls and the wooden walls of the adjoining workshop give me enough concern that I've started making a few sets of plans which have a normal exposed first story for the clean shop  that continues the foundation of the hot shop in the same horizontal plane. While I'm not dead set on the hillside based construction, the primary reason for pursuing that is the availability of being able to drive up to a door in the wood shop for easy maneuvering of timber and machinery.

Haven't gotten anything looked at by the engineers yet- there are a few geometric details I want to sort out first, but I'm probably a few weeks out from finalizing everything on my level and sending it off to be finalized/validated/professionally drafted.

Cheers!

John

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For amplifying information, here's a side profile of the main shop and how the lower level clean room and upper level woodshop attach to it-

Clean Room.PNG

The 11 and 12 foot ceiling height for the lower level is arbitrary, and I've moved in the direction of lowering the foundation of that space slightly to allow for a taller east wall height of the woodshop. Based on snow loading codes, the standard roof pitch for heavy loads is between 6:12 and 7:12, which comes out to 27~30 degrees .The above roof pitch is set at 30 degrees, but there is an excess of unused space there existing for the purpose of introducing ventilation and other air moving apparatus. The width of the above space is 18ft, although as mentioned in the previous post I've been developing alternatives for the adjoining rooms based on wood-stone interface and the problem of pitch angle for intersecting roofs. One alternative is having the wood shop come out of the metal shop so the short wall is touching rather than overlapping the long wall, which gives much greater freedom in roof angles at the expense of dividing the clean shop with a separate piece for the grinding room...

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7 hours ago, John Page said:

Out of curiosity, do you know any concerns or complications that come from the joining of the wooden sills to stone foundations? The horizontal ones seem easier, but I haven't been able to work out a good solution to vertical posts meeting masonry.

Simpson Strong-Tie and Mitek Industries make construction connectors for every application under the sun. Both companies sell what we in the industry call "Listed products", which means they have been tested by third party nationally recognized agencies and are generally acceptable to any permit issuing jurisdiction. Both companies also have lines of "architectural"  or "ornamental" connectors. These are meant to be exposed and look like old-world ironwork. They don't actually get there, but they try.  This is where a good structural engineer can really help you out. Not only will the SE be able to analyze the beams and all the forces (both vertical and lateral) they will know the Simpson and Mitek connector libraries and know where the connectors have to go to manage those forces. They also can help you design and make your own connectors from welded plate steel. 

Generally speaking, post connections to foundations are managed by embedded straps or long bolts that attach a steel device to the foundation with an embedded hook or a long bolt, and to the post either with a lot of nails, or a couple of through-bolts. Some of them are a single piece, others are two parts, the anchor and the connector. Look through the Products and see if anything matches your needs. 

Once you start splitting the beams and reducing the beam spans with vertical posts, your loading becomes much easier, but your floor space gets interrupted with vertical elements. This is where engineered trusses really surpass conventional framing. The downside is you loose the aesthetics of exposed wood beams, unless you come in and do some purely decorative beam work under the truss system. (been there, done that too!)

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Great stuff, thanks Josh! Really appreciate the info. I ran some measurements with vertical supports, and I keep running into the floor space problem. From the walls to the support, the farthest distance I can get is about 10ft, which doesn't seem like that much when there are work benches and machinery taking up most of that space. The whole 40ft+ unsupported beam length is hefty, especially when there are notches and whatnot for the crossing interfaces. One solution I've been considering is using reinforcing plates on the top face (not visible from the ground) although that would only go so far. Another idea I'll be consulting on is the introduction of a hammer-beam type support that comes out from the walls to the weak points on the beams, although that too will be spanning a fair amount of distance. Having 15ft ceilings would alleviate the interference with head and machine space, but for the span and loading even that might not be enough.

One solution I've come up with for increasing the distance between walls and supports is to simply make the building larger, but the increase in circumference needs a dramatic enlargement to have the desired effects.

Going back to the gantry discussion, another possible means of rigidizing the transverse beams would be to use the rigidity of an I-beam or rail in key points, either above or below the beam, and anchoring them together. Seems like a sketchy solution though...

While researching large floor plans without interior supports, I saw a few truss designs which rely mostly on ironwork as reinforcing joinery. While I'm not necessarily opposed to the idea, the premise of timber framing or post-and-beam construction relies heavily on compressive strength rather than tensile strength. In principle, the type of loading these types of frames are built to withstand seem contrary to these large open spaces. Further investigation ensuing.

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One or two I-Beams in key locations across that 40 ft span might be enough to reduce the timber beam spans to lengths that do not require vertical supports by attaching the wood beams to the I-beams. The same is true for using a steel truss or two......this is an engineering problem that most structural engineers really love to wrestle with.

I could see the entire roof/ceiling structure supported by top-bearing steel trusses with the wood beams attached to the top chord of the truss. The steel truss would hang below the beams giving you a way to create the gantry system along the truss location lines. The strength of steel with the aesthetics of wood.

Another idea I had was building a large central masonry forge/chimney and using it to create a radial beam design. The beams are supported on one end at the chimney, the other end on the walls. The only floor space lost is the footprint of the forge. There's a ski lodge on Mt. Hood that is built this way.

Edited by Joshua States

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What are the two span lengths marked A & B?

InkedLayout 1_LI.jpg

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Josh, great ideas into the mix! I hadn't thought about putting the forge in the centre- that would also make for an awesome natural draft with the height of the chimney. Would using a central column have any effect on the overall transverse stability of the walls? Done right, it would take most of the weight of the roof and translate to compressive forces on the chimney and the walls, but I'd imagine there would still need some sort of auxiliary support structure on the rafters. Running some additional numbers, an (arbitrarily sized) 5ft diameter stack would still have the nearest timber be 10,25 ft away at the current scale.

The length of the above 'B' is 26ft for a centre-wall distance in the same plane, 31ft when looked at facing the building accounting for the pitch of the roof. 'A' is roughly 18,5 for the scaling. I have a few other constraint based scales that make each side length as short as 16,8ft.

Browsing a few pictures of the Mt Hood Timberline lodge, that place is something special! There is a lot of deliberate design taken in the joinery and complementary material layout, thanks for mentioning it, I'll be borrowing a bit from the aesthetics going on there.

I fiddled around with floor based supports, and the biggest problem I'm having is symmetry. Bracing equally on all intersections, the beams are extremely close together for convenience, but offsetting where they support gives two sets of three points, the distance between the post and wall still being about 10ft. Workable, but I think the truss/rail idea maximizes usable floorspace. The building not being rectangular makes the introduction of square/rectangular footprint benches/machines a bit more problematic when dividing space towards the centre.

I have a few more drawings that I'll upload this afternoon that hopefully explain it a little better

 

John

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I played with some rough and dirty load calculations using a radial roof beam design and a center bearing masonry column that is 6 feet in diameter. This reduces the clear horizontal span down to approximately 23 feet. Using 18 beams spread equally around the column (9 bearing at each wall corner and another 9 bisecting the resultant triangles formed by the first 9 beams). I get these triangle roof areas. Then I looked at jack rafters from walls to beams. The longest rafter span is roughly 21 feet. Spaced at 16" o.c. and an assumed ground snow load of 30 psf, a 2x12 Douglas Fir #2 rafter will make the longest span. So how big are the beams? Well, a really rough calculation looks something like this:

The area of the large triangles is ~248SF. Each beam will need to support half that total load. Using a dead load of 15 psf and a snow load of 30 psf (reduceable to 24 psf with the roof pitch you are quoting) I have a total load of 39 psf.  (248 x 39)/2 = 4836 psf divided along the length of the beam (uniform loading) gives us ~210 pounds per linear foot. A quick check on the AITC Glu-lam beam tables (roof loading) says, that this can be accommodated by any of the following beams: 3-1/8" x 12", 5-1/8" x 10-1/2", or 6-3/4" x 9".

These are rough and dirty calculations, NOT an engineered assessment. YRMV when a structural engineer does the clean and pretty calculations. My calculations tend to be conservative with loading, but I maty screw up from time to time.

If I got the snow load reduceable wrong and we use the full 30 psf snow load, the uniform loading is ~243 plf and the 2 smaller beams get 1-1/2" taller. The 6-3/4" GLB remains the same size. The rafters may be downsized as the span shortens. 

radial roof section.jpg

 

I just looked over my calcs and I have overstated the loading. The beam sizes will probably remain fairly large just because the span is so long though.

Edited by Joshua States

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Wow, the weight of snow adds up fast!! From what I understand, the snow load roof pitch codes that I found are based on the angle of repose for snow, but I'm not sure if that means the snow load will shed after building up a certain amount or something else. A 6-3/4" x 9" beam doesn't sound too bad, although I presume that is for an unbroken cross-section along its entire length. Any introduction of joinery would surely change those dimensions, although based on some of the documentation I read about static structural loading for notched beams suggests that if it's small enough and in the right places, they can be negligible. Not that I'd want to make those assumptions anyway, but that beam size is entirely reasonable. More likely than not, I'll probably try and find lumber in the range of 6x12s or 8x10s based on final loading configurations. Also some configuration of hammer beam trusses would help brace a portion of the span nearer the walls, but I haven't quite gotten there yet.

Thanks for all the info!!

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3 hours ago, John Page said:

A 6-3/4" x 9" beam doesn't sound too bad,

I have to apologize. It was late and I read across the wrong line on the beam chart. That beam cannot span 23 feet. It would have to add an additional lamination and be 10.5 inches deep. That 6-3/4" x 10-1/2" beam weighs 17.2 pounds per linear foot. Including 6" of bearing length on either end brings that beam weight to about 413 pounds.

AITC (American Institute of Timber Construction) beam charts are available free: http://www.aitc-glulam.org/capacity.asp Engineered beams are significantly stronger than sold wood beams. Lumber suppliers can create a "rough sawn" GLB if so desired. I admit, they do not look as good as real rough sawn timber, but they are way stronger.

The AITC standards are used by all building codes and design professionals, so it's a great resource for the DIYer.

Not sure why you would want create joinery through exposed notches in beams. (I know it looks cool, but it's so much stronger when that notch is supported vertically) Any reduction in the beam depth creates a weakness, and for Glu-lam beams (GLB), 1.5 inches of change in depth is appreciable. Take for instance, that 6-3/4" x 9 inch GLB that cannot achieve a 23 foot clear span under any load. Add an additional 1.5" to the depth and now that 10.5" beam can support a uniform load of 285 PLF at a 23 ft. clear span.

You are a blacksmith man! Create the beam joinery with steel plates! Google "Beam Hangers" and get some ideas of how these things join beams together. They can be exposed flange or concealed flange. You can have the engineer spec out the materials and design them for you to make. (if you are confident in your welding skills)

As for how loads are computed and adjusted in the International Building Code (IBC), a general rule of thumb is to use 10-15 pounds for Dead Load (weight of building materials) depending on what is in the roof/floor assembly. This is static load and does not move or create rapid deflections. The weight of people walking around is called the Live Load. This moves and causes intermittent deflections in the building materials.  In non-snow load areas, we use a live load of 20 PSF to account for people on the roof. Snow loading in the IBC for rafter spans is broken down into 2 separate tables, 30 PSF and 50 PSF, depending on where you are in the country. In the areas that have building codes, these values for live/snow load are applied to any structural support calculation. Your local jurisdiction may have adopted a different snow load than one of these two. You should inquire at the local building department as to what the design loads are in your area.

You use the greater of the two for live load, either the 20 PSF for people or the ground snow load for your area, not both. Add Live Load plus Dead load and you have the Total Load, or uniform loading for a diaphragm (roof or floor) on a structural member. Live loads are calculated for the horizontal projection, not across the entire beam length and can be reduce by a percentage when the roof pitch is 4:12 or greater and/or the tributary load area exceeds 200 SF (further reductions apply to tributary areas over 600 SF). I honestly do not remember if snow loads are reduceable the same as live loads. I'll have to check on that.

I have also attached a generic beam/header chart for solid beams and laminated box/sandwich headers.

Good Beam_tables.pdf

Edited by Joshua States

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Another thing to think about with regard to beam joinery is the concept of a "point load".

Up until now, I have been discussing "uniform loads". These are uniformly distributed across the length of a structural member, such as a beam. The total load is equal to the uniform load (pounds per linear foot, PLF) multiplied by the length of the beam. This total load is then evenly divided by 2 and half the load sits at one beam end and half at the other.

So when beam X carrying a uniform load is attached to beam Y, the beam X end load is applied to a centralized location along length of beam Y. This is called a concentrated load or a point load. Beams do not carry concentrated loads the same as uniform loads. How the beam's capacity handles a point load (PL) is a calculation that I am not qualified to run. I can tell you that under some circumstances the PL can exceed the uniform loading and sometimes it cannot. It depends on a bunch of factors that engineers keep as esoteric knowledge...…. it includes such things as distance from the end support and additional loading (uniform) on the beam. There are software packages out there that do these calculations, but they are expensive and generally only available to registered design professionals. (engineers and architects)

So, if you plan on doing a bunch of beam joinery (whether by notching or steel connections) plan on have a structural engineer do the design for you.

Edited by Joshua States

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Once again, really appreciate the info! That'll take a bit to fully digest, and I'm now seeing more and more of the secret wizardry done by structural engineers. The point loading is a substantial consideration, and I think that the radial translation of force out from the centre of the ceiling warrants investigation. Previously I was basing the design on the assumption that timbers connecting the walls across the top would be sufficient to mitigate the weight and loading of the roof, but now I'm not so sure. Thanks for the references, I'll do some perusing, and the approximate scale of timber helps immensely, especially knowing how substantial a difference there is between the solid wood and laminated alternative. I think I may be rapidly approaching the end of what I am able to design on my own :rolleyes:

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I sincerely hope that I have helped in some way. If you have any questions, or come up with a design idea that you want feedback on, just let me know and I'll take a look.

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Sorry for the delay, but thank you! You've added a considerable amount that I am much better off for having read. Due to extenuating computer circumstances, I haven't been able to get any additional screen captures over to the internet, but in the next few days I'm hoping to have a few additional considerations and scalings posted. I think the major design choices remaining mostly tailor towards how to adjoin the other rooms and approximate sizes, but I'll do a bit more drafting based on your previous info. Thanks again!

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All right! Finally able to get the latest revision uploaded. First is the various scalings of the building based on the constraint of a few of the different dimensions.

Scaled Dimensions.PNG

The first limits the side length to 18ft, which is the closest whole number to the original size. It reduces the overall footprint by about 200 sqft, and the longest unsupported span to just under 43ft. Similar, the third one lengthens the walls to 20ft, but the longest beams are now 47,5ft long, and without any supports there it would probably be unrealistic to have them free floating without the introduction of some metal. The second one limits the unsupported beam length to 40ft, and therefore the overall size of the building shrinks another 200 sqft or so. Even so, I'm of the mind that any of these lengths of beam would require additional support and reinforcing as previously discussed. Finally, the last one enlarges the building to have a 50ft diameter (not radius like labelled) inscribed circle. Sitting around in the desert currently looking at the standard size of the shipping container barricades (each one 40ft long for a full box and 20ft for a half box) it seems like a floorplan around the previously sized-without-visual-reference is about right for the size of space I'd like to have. 

Alternate Woodshop Junction.PNG

Next up are a few of the alternative adjoining rooms plans if the roof pitch joinery and angular relations don't work out. Each one assumes that the clean room foundation wall is in the same plane as the shop rather than having it rise up and enclose 3 full sides like the original designs. The only reason for this is solving part of the problem with building into a hillside. This allows for some additional covered space outside and ease of construction. That being said, the first of the two plans has the room oriented opposite the original plan, with the short end against the adjoining wall and extending outwards from there. The other two offset lines are an extension of the roofline, allowing for a covered area about 6ft deep running the length of the wood/clean shops. I figure it would leave outside storage space for wood and coal and other odds and ends. The shop oriented this way also makes it easier to run a gantry along the line of the ceiling, but it would be  necessary given the lack of hillside.  Then again, the orientation could still serve in that capacity so it is not limited in that way. Of course, if the terrain permits that, the roof extensions would not be feasible. 

Second has the wood shop occupy a space that is not rectangular. I'm not sure if I like this at all, but I thought I'd see what it looks like. The three options for the outside walls have it either 1) follow the line of the roof joists all the way out, which looks the worst from above but would probably be the strongest and easiest given the relationships of the angles. 2) a wall perpendicular to the face of the other two, making 90 degree corners. That leaves some weird geometry for the roof intersection, but would provide the most usable space inside. 3) having the outer walls extend straight out in the 'north' direction so that they are parallel to the centreline of the room. That makes the most sense aesthetically and holds closest to the original design of a rectangular room oriented with the long wall adjoining, but has the weirdest corners and most likely to have awkward or unusable space. In any event, I'll probably stop considering any of those ideas, but I thought I'd put it out there to more fully encompass the design process I'm going through. 

Side End view End Joined Woodshop.PNG

Focusing on the first one of those two with the rectangular room oriented with the short side connected to the metal shop. I particularly like this idea for the simplicity of roof junctions, the open wall looking down into the metal shop limiting the number of windows/containment needed, and the amount of wall/ceiling space for additional windows. I recently saw a picture of a woodshop which had more windows than non-windows, and the way the light interacts with the space is incredible. That stark dichotomy of wanting as much natural light as possible for a woodworking shop and relative darkness for a metalworking shop affords an interesting design challenge. Because of the geometry of the metal shop and window space, a lot of the usable natural light will probably come in through the woodshop windows, and this maximises on that opportunity. 

It's a bit difficult to tell what's going on, but I'm not quite knowledgeable enough in CAD to get a 3D model going. The floor of the clean room is a few feet below the level of the metal shop in order to bring the ceiling of the wood shop above it down farther. I'm still on the fence of how high of a ceiling I want in all of these places, but everywhere I've ever been, people say they either love their high ceilings or wish theirs were higher. 15ft seems excessive for the clean room given the type of work being done there, so I took it down to 12 and 11 feet to see what it does to the angles. 12 is looking like the better option, but I probably don't even need that much. For the woodshop ceiling, I measured 8ft from the floor to the shortest point on the ceiling (intersection with the walls) which gives the above proportions. I'm yet to be determined on if I like that or not. Most likely, the top of the roof would remain in place and I would adjust where the floor is/ceiling of the clean room. 

For a length of 30ft (might expand to 40 to accommodate for sacrificing part of the clean room to a contained grinding room, part for utilities/bathroom/air compressor) an even spacing of 4 columns on the roof extensions/covered walkway gives reasonable space for moving about, introduction of doors, and storage. If I extend the extra 10ft, I'd probably only add 1 more column so it doesn't get too close together to be useful.

Ceiling Joist Layout 6 Beam.PNG

Finally, here is a theoretical layout for supports on the ceiling tensile rafters. Symmetry was my biggest problem here, but I came up with a viable solution. Putting an upright post under each of the beam intersections, whichever of the 3 different joints it would be, the posts are spaced too closely together to be practical. Having every other one doesn't work because of the odd number of sides. So, I found the most ideal triangle of the three overlapping ones based on configuration of the door and location of the forge if it is against the north/east wall, and another triangle offset from the first by 120 degrees but placing the posts under the middle of the beams rather than under the intersections. That gives a hexagon of supports that are about 13,5ft apart, and at closest 10,5ft from the nearest wall (using the original scale of 18,5ft wall length). If the floor-to-beam height is 15ft, there is enough room to put branching supports from each of the posts to the critical joints nearby without sacrificing any working space. Any fewer than these 6 beams and it doesn't look like the additional supports would be effective. Any more, and there would be too much space absorbed by their proximity to one another. 

In any event, that's what I've come up with for now, but as previously mentioned, it's time to finalise what I am able to do on my own and begin consultation with the structural engineers to see if this is even workable...

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