Subfloor above concrete thoughts?


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Old 01-21-12, 07:06 AM
T
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Subfloor above concrete thoughts?

Hi All

I'm planning on finishing in my garage and need to put in a subfloor. It needs to raise the floor a minimum of 4 inches so I can run a dryer duct and a couple other things under it.

Here is my current plan. Someone let me know if I'm way off base or where I could make improvements/save money.

I'm going to tar paper the whole floor #15. lay down 1 inch strips of 1/2 ply Pressure treated. Drill small holes every couple feet insert thin wire and nail into that. Then construction adhesive vertical 2X4 to the plywood strips and side nail the 2X4 to plywood. All lengthwise boards will be 16 in centers. For horizontal pieces I'm not sure how far they can be spaced. I was told the install them flat so there is a 2 inch air gap in on the bottom. Then 5/8 plywood on everything. screwed and glued.


THANKS!
 
  #2  
Old 01-21-12, 07:57 AM
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Here is a link to get you started. At the bottom you will find "related links" and more reading. Much of the decision process depends upon your flood, how it was constructed, your soils, moisture, and temperatures. IMO, I would be installing a min of 2" rigid foam without the tar paper. If you end up running that dryer duct under their, which you need to check code for approval, it definitely needs to be air sealed with access so it can be cleaned. There is a limit on how far you should make those runs.

Garage floors usually don't have a vapor barrier under them, so no VB on top allows the moisture to escape into the room. But again that is specific to your application. Hacve fun reading.
BSI-003: Concrete Floor Problems — Building Science Information

Bud
 
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Old 01-22-12, 05:59 AM
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hey thanks for the link.

It looks like they have a similar setup to what I'm planning except they eliminate the tar paper and seal the floor with epoxy instead. I didn't see any specifics about insulation but it makes sense to install the rigid foam so the floor isn't always cold.

I checked into the dryer vent and I should be good. Has to be under 35ft at least 4 inches and it has to be solid pipe. Not flex. I was going to use solid anyways. That way you can use a brush like a chimney sweeper to clean it out.

Thanks!
 
 

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