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Hey Guys , I have worked with wood for 30 years and would like to try making some guitars. I am currently insulating my shop and I know if I want to get serious about making guitars I need to keep humidity under control. So a few questions -
As far as humidity, should I keep my concrete floor or build an insulated wood floor on the concrete?
Shop is 24x36 , would you try and control the whole shop or build something like an 8 x 12 room to store the wood?
Any of you use wood heat?

Seal the concrete with epoxy paint. This will minimize moisture infiltration.

I'm controlling an area of about 15 x 22 feet. My shop is insulated (standard brick structure with drywall, etc.). I have a concrete floor and have a few of those thick rubber mats on it mostly to make it comfortable to stand on and to protect tools if I drop them. If I still had the larger shop I had when working with furniture (about 40 x 28) then I think I would build an assembly/wood-storage area and just control that. I would also set up a spray booth and a closet for the dust collector. I'd keep the stationary machines, sanders, down-draft table and such in the uncontrolled main shop. On the other hand, I don't have to worry about rust anymore since I maintain 40 - 45% humidity.

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Steve Smith
"Music is what feelings sound like"

You didn't mention where you are located or what the RH tends to be in that area. I am in a very dry area so I kept the concrete floor. When I am doing an important glue-up I can adjust the humidity by throwing water on the floor the day before to get it up to the 50-60% range if it is low.

Alan D.

Also depends on if there is a vapor barrier and/or a continuous source of moisture under the slab. My slab is on top of a lot of pea gravel and there's a vapor barrier. It took awhile to dry it out but now it stays dry.

If you have poor drainage around the shop, then you may want to use epoxy or a vapor barrier under a wood floor.

And yes, a small assembly room can work quite well and save on energy costs.

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http://www.chassonguitars.com

A shop of 24x36 I would separate the rooms and make a parts/assembly room of about 15x24 (that's twice the size of my entire shop...) that would certainly save you $$ on humidity/heat control. I would certainly seal the concrete floor (I did...) that way you can control the environment more accurately.

Man what I would give for a shop that size. I'd get lost for sure in it but boy it would nice to set up several work stations specific to a task.

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"There's really no wrong way, as long as the results are what's desired." Charles Fox

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"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

This begs the question: what would you give for a shop like that, Rod???

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I guess about $25,000 all said and done. Now I just need the $25,000

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"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

I have faith in myself. If my shop was that size, I'd be excited about how much more stuff I could put in it, and I wouldn't have any more room than I have now!

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Phil

http://www.oleninstruments.com

"Those who tilt at windmills are only considered insane by those who can't see the dragon."

The shop is actually 72x36 but it is to big. Concrete floor part is 24x36. When I was building cabinets it was just the right size. I quit building cabinets a few years ago and now most of it has turned into junk storage and empty space.
Thanks for all the input. I cant wait until I can get setup. I will post pictures when I get something made.

My shop is smaller (about 17 x 33), and it is divided into one "dusty" heavy wood processing room and one "clean" bench / assembly room. Only the bench room is humidity controlled, but I store most of the wood in the other, non controlled part. The theory is that exposing wood to varying degrees of RH over time will help it become more stable, so I only bring it into the bench room so it will reach its equilibrium moisture content there, some time prior to building with it. How long before depends on its dimension and to some degree the species, but once I bring it into the assembly room it stays there until the instrument is ready for finishing. Another good reason for keeping the heavy machinery in a separate room is dust control.

The best way to seal a concrete floor is from the outside, with proper drainage and external vapor barrier, as Kent mentions. Lacking that, epoxy paint or a similar vapor diffusion coating will help somewhat, but as with guitar finishes, most of these are only moisture retarders as they have varying degrees of permeability. A wooden floor can be built directly on a properly built and dry concrete slab, but you will certainly need a moisture barrier if there is a high moisture transmission rate. Various plate materials or pressure treated sleepers can be used as a sub floor.

A wood stove for heating is nice, but in order to keep a constant RH it is better to use more stable heat source.

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Rian Gitar og Mandolin

my floor is a slab (basement) built over pea gravel with a vapor barrier.
When I built my shop I installed a padding/vapor barrier on the slab and then some laminate flooring. The laminate flooring can always be found on sale or clearance at the box stores, Borg, or flooring stores. It was an easy and fun project and made my shop comfortable, clean, and with less humidity.

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My shop is a converted 40 x 60 pole barn with a concrete slab and no vapor barrier. The walls and ceiling are thoroughly insulated and vapor sealed. The moisture coming up through the floor keeps the temps quite moderate in the summer. I've had visitors compliment my 'air conditioning' as they enter the shop on a hot day. I'm not entirely sure epoxying the floor would be better in this case. I use a small dehumidifier to keep the place at 40-45% but it really doesn't get too high without it. Mainly, I have to add humidity in the winter which I do by heating big, aluminum lasagna pans of water on a homemade hotplate.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

My shop temperature would max out around 81 degrees on the 100 degree days as long as I kept the doors closed. I poured the floor in the late 80's and just used a layer of gravel.