Do I need to lay luan down?

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  #1  
Old 10-06-13, 11:17 AM
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Do I need to lay luan down?

We have a 1008 sq. ft. building. The floors consist of a sandwich of 5/8 plywood, 1 inch cement board and another layer of 5/8 plywood.
If we put a floating floor over the entire surface, is it necessary to put a layer of luan down first?
Thanks
 
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  #2  
Old 10-06-13, 11:26 AM
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Luan is not acceptable as an underlayment. If the surface layer of 5/8" is smooth enough, it is ready for the felt/foam cushion underlayment and then the new floor.
 
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Old 10-06-13, 11:28 AM
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Welcome to the forums! Is your floor a sort of prefab unit, in layers, or was it placed there piece by piece? If the latter, why? I don't understand the cement board, two layers in the middle of plywood. You definitely don't want to lay down luan as it is not a good substrate for any flooring. What type "floating" floor do you intend to install....laminate, engineered flooring, Allure??
 
  #4  
Old 10-06-13, 12:32 PM
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Thank you for the welcome!
We had the building built by the Amish. The original intent of the building would have been a 2 car garage, but we nixed the garage doors, added windows and french doors. Originally, the garage floor would have been nothing but 3/4 inch pressure treated plywood (I originally said 5/8, I was mistaken). We opted for their "insulated floors", which added the cement board and the extra plywood.
Once finished, the building with have weight equipment, a pool table, couches, a tv and wood burner. It's
We're looking for the most economic product to use on the floor, but something that will last "forever". I've really been thinking that hardwood flooring would be the best for the long run. My thought was that if we used a floating floor, it would "float" over the seams between the existing plywood flooring.
I can use all the advice I can get.

XSleeper, the surface is pretty smooth already, which is why I didn't think it would need yet another layer of wood (luan or otherwise) and also why I hoped a floating floor would be best
 
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Old 10-06-13, 01:02 PM
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Still not making a whole lot of since the way this floor was done.
Pressure treated should never be used inside a home except for the bottom plate where it makes contact with concrete.
Tile board has nothing to do with "insulation".
If this was a slab, and someone just laid plywood over it before the tile board, big mistake!
 
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Old 10-06-13, 01:08 PM
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I am guessing the OP means 1" foam board, not 1" cement board. Perhaps they misunderstood the construction method.
 
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Old 10-06-13, 01:34 PM
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Here's the description of how they build their garages:
"The buildings are constructed on a foundation of pressured treated 4x4s. The floor joists on the garage style buildings consist of 2x4s on 12" centers covered with pressure treated plywood." (We had them add the optional insulated floor.)

Maybe it is foam board and not cement board, it's been awhile since we discussed the building process.

This wasn't built as a home, it was built as a garage and will be used as a glorified man-cave.

Sorry this isn't making sense and I'm a bit confused as to why it makes a difference in the end, but that's why I'm "here". It was not a slab.
 
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Old 10-06-13, 06:02 PM
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The reason it could make a difference it insulative qualities and moisture movement. We are trying to visualize what you have, and concrete board in two layers just doesn't make sense. Foam, on the other hand gives a minimal insulative value.
So no luan if your plywood is in reasonably good shape. Now, we can't talk you into an engineered floating floor or naildown hardwood, as opposed to clacky laminate, can we???
 
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Old 10-06-13, 07:21 PM
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Thank you for explaining that to me, chandler.

The plywood is in great shape actually. You could very easily talk me into an engineered floating floor! Is it possible to have a floating hardwood floor? I was hoping that whatever we put down wouldn't need nailed or glued.
 
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Old 10-06-13, 10:07 PM
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Is there gravel under the 4x4's on their sides? Are they supported on concrete piers for a uniform load? Is insulation between the 4x4's? Is the first layer of subfloor fastened to the 4x4's? The second layer?

Foamboard helps, R-3.5---R-6.8 per inch depending on the type. The first 1" (R-3.6) reduces heat loss by 80%; http://www.google.com/url?sa=t&rct=j...,d.cGE&cad=rja

"Foam, on the other hand gives a minimal insulative value." ---- Chandler, you must mean backer board......?

Gary
 
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Old 10-07-13, 02:36 AM
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You are right, Gary, thanks for the catch. I still have to wrap my head around cement 1" thick.

Treeflower, a good 5/8" thick click lock engineered floor would be an excellent floor, which is stable and will feel more like a nail down floor. I do not glue down full 3/4" flooring that is made for nailing. It just doesn't seem right, when there are similar products (engineered) that will click lock in place and eliminate the need for any glue.
 
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Old 10-07-13, 04:42 AM
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Hi Gary, There is gravel under the 4x4, but no concrete pads or insulation between them. The site was leveled and then the gravel was brought in (this is how the builders wanted it).

It is my understanding that the first layer of subfloor was fastened to the 2x4s. The top layer is fastened well and the floor is very solid.

Chandler, I will look for the engineered flooring. I appreciate the recommendation.
 
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