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What is minimum Subfloor thickness for Hardwoods or engineered floors 3/8"

What is minimum Subfloor thickness for Hardwoods or engineered floors 3/8"


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Old 02-28-07, 08:25 AM
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What is minimum Subfloor thickness for Hardwoods or engineered floors 3/8"

What is the required subfloor thickness for a 10X13 room w/inaccessable crawlspace. Not sure about the joist spacing. I'd like to install 3/4" hardwoods but only have a 1/2" ply down. Is that enough?

Also, any thoughts on 3/8" hardwood floors? I could add more subfloor and arrive at the same total height. Would that be better?
Currently there is 1/2"ply w/a 1/2" particle board.

Lastly, does the particle board give any strength to the floor because I'll remove it if it doesn't as there is a little bounce to itand I'm not sure it'll hold nails for the floor very well.
thanks
 
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Old 02-28-07, 10:05 AM
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When all else fails......

I would find the floor you want to install and read the manufacturer's directions. They will tell you the recommended subfloor thickness.
 
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Old 02-28-07, 03:03 PM
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1/2" subflooring is definitely not enough. You would be better off applying a layer of 3/4" Advantech, then installing your flooring. The 3/8" laminate flooring such as the click lock produced by many manufacturers is a fine floor. I plan on installing some in a cabin I have here in the mountains, and have decided on a brand that has the foam underlayment attached to the flooring itself, saving one step and an additional cost.
 
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Old 02-28-07, 04:29 PM
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Another trick when height is a problem is to glue and screw cleats onto the sides of the floor joists, then glue and screw 3/4 plywood between the joists, flush with the top of the joists. Then glue and screw the 1/2" over the top of everything. It's a lot of work and you end up using a ton of glue and a ton of screws, but sometimes when height is a problem, that's one way to cope with it. You'll see that technique used sometimes with tile floors that get reinforced cement poured on top.
 
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Old 03-01-07, 06:13 AM
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What do you guys think about if I Screwed and glued 3/8" plywood on top of the existing 1/2" before adding the 3/8" engineered floor>?

Would that be sufficient?
 
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Old 03-01-07, 11:34 AM
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Particle board is garbage as floor underlayment (popular underlayment in the 70's that doesnt hold nails or screws well, and expands and contracts too much with changes in temperature and humidity) and 3/8 plywood has very little strength. If you want a stiff floor IMO all you need to do is remove your particle board subfloor and lay down 3/4" tongue & groove plywood or OSB. That would be perfect.
 
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Old 03-01-07, 02:52 PM
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I wouldn't have suggested the 3/4" T&G Advantech if anything less would have done as well. It has a wax impregnation that repels water, so we use it almost exclusively on subflooring on new construction. Let it rain, sweep it off, and keep on going.
 
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Old 03-01-07, 06:51 PM
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Are you sure the sub is only 1/2" ply? I don't think it meets code anywhere in the U.S.
 
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Old 03-02-07, 06:16 AM
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I think the current subfloor is actually 5/8".

But there is a single low step down in that entry room from the kitchen and I want to make the floor very very solid. My wife walks so...... heavily the house shakes (yet she is small)? Drives me nuts..

Problem really has arisen from the working around the entry door and slider door height.

Does a 5/8" with a 1/2" screwed and glued on top equal the strength and stiffness of a single 3/4" Ply? That's the question at this point.
 
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Old 03-02-07, 06:17 AM
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that low step I mentioned is along one entire wall of that room 10'. not just a little area.
 
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Old 03-04-07, 05:43 PM
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Cool Another Question on Advantech flooring

Originally Posted by chandler View Post
I wouldn't have suggested the 3/4" T&G Advantech if anything less would have done as well. It has a wax impregnation that repels water, so we use it almost exclusively on subflooring on new construction. Let it rain, sweep it off, and keep on going.

I am in the process of having a new home built, and I believe the builder uses 5/8" subflooring. I have heard about the 3/4" t&g Advantech that you mentioned above. How much more expensive is it? Is it worth the additional cost?
 
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Old 03-04-07, 06:25 PM
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66Tiger, welcome to the forums! It is not expensive at all in relation to other sheet goods. Here in the South they run about $21 per sheet, but the advantages outweigh the price, as, like I said, the wax impregnation is a real boon if it rains prior to getting it dried in.
 
 

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