# Any Woodworkers Here Have a Shop Building Over a Crawl Space?



## gerrym526 (Dec 22, 2007)

Guys,

I'm designing my free standing wood shop building, and considering having it built like my house was-i.e. perimeter foundation and crawl space. This gives me the advantage of an insulated wood (OSB) warm floor, space for the mechanicals, and possibly the dust collection as well.

Anyone have a shop building designed with a crawlspace? Can you share the pros and cons of doing it that way. I don't need a basement, but can't have a concrete slab floor building because I live in the mountains with a sloping acreage and lots of snow melt in the spring, and a "slab on grade" building will flood.

Thanks in advance for the advice/feedback.
Gerry


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## CaptainKlutz (Apr 23, 2014)

Works well.
Make sure you talk to an architect or licensed engineer about your use plans. When using raised floors for heavy tools, often need to increase the floor joist load handling capacity .vs. normal home.

Machines are heavier than house furniture, and vibrate during operation. Especially if you plan to have any of the typical 400lb+ industrial tools with 3HP-5HP motors in shop. For heavy tools, will likely need to reduce joist spacing, maybe increase height, or use glulam beams if long span.

Additionally, floor loading is typically calculated as average per sqft. If you attempt to use mobile base under a 1000lb tool and fail to use enough contact points to floor, it can/will dent a basic OSB wood floor (or worse case cause floor sag). Commercial buildings that are designed for heavy floor loading typically have 2-4" concrete sub-floor on top of wood/steel beams to support higher loading. This is overkill for home based amateur workshop, only mention it so you understand floor loading is not a trivial subject.

Best Luck.


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## wormil (Nov 19, 2011)

Not exactly but my shop is elevated. The front is about 18" off the ground which allows air to flow underneath. And despite living in a humid climate, rust problems are almost nonexistent. Wish my floor was beefier. If I build another shop I'll probably use 2×10 joists, 12" OC, for a rock solid floor; and 2 layers for the subfloor.


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## rustfever (May 3, 2009)

I've found OSB does not respond well to point loads. 
Try using 2x joist at close centers, topped with 1-1/8" ply underlayment [aka, 2.4.1 ply] which is much superior than multiple layers of OSB [Oriented Strand Board/chip board] subfloor.
Yes, I'm a retired contractor. 40 plus years.


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## jonah (May 15, 2009)

OSB just isn't all that strong, so I'm not surprised it doesn't handle point loads well.

+1 for plywood underlayment.

2×10 joists 16" on center with 1.125" plywood should be plenty strong, so long as the span of the shop isn't really really long. If it is, you'll likely need beefier joists or a beam in the center.

Whatever you do, insulate the hell out of it. A dollar spent on insulation now will save you big money later on energy costs.


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## BlueRidgeDog (Jan 2, 2019)

Just design it based on the static load tables using your table saw as the basis and you should be fine. You will want a vapor barrier on the ground and then some rocks so you can stash wood under there.


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## Gene01 (Jan 5, 2009)

+1 on the vapor barrier and, I'd enclose the crawl space, with a couple access doors.


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## shipwright (Sep 27, 2010)

Easier on the legs, back, and feet, dust collection and electrical under the floor, storage space, ... what's not to like. I built mine with about four feet of space in 2004 and I love it. The big thing is to carefully plan the floor layout for efficient work before you start. Once the DC and electrics are in it gets hard to change.
There are some good shots of my crawl space here. https://www.lumberjocks.com/shipwright/blog/31966
The next segment in that series shows the floor from the top with the access lids to the receptacles.


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