Gluing plywood to concrete

GDiak · 11-27-2010, 01:32 PM

Hello ! I am in the process of building a house , and you should all know that all the floors are from concrete. I have bought my bamboo flooring so we can install. I would like to lay down plywood and then glue the planks to that, do you think I will have a problem with the plywood over time, and should I glue the plywood to the concrete, or screw it in, or just leave it floating? And should I lay some kind of sealant on the concrete to block the moisture?

KarlJay · 11-27-2010, 02:11 PM

I too have concrete floors and the original floor has some tar stuff then tiles, I plan on doing about the same with the new floor then laydown plywood. I don't think you have to glue the plywood down, but the correct glue would have the moisture block built in. Might want to concider tar paper under the plywood.

http://server.iad.liveperson.net/hc/...63&action=view

rusty baker · 11-27-2010, 06:06 PM

Plywood on concrete=failure.

KCB · 11-28-2010, 06:58 AM

By a calcium chloride kit to test moisture level.A high moisture level is a bad thing .You may even consult a professional to do the test and install.
You can do this but it will be at a high risk for failure.
To many things working against you (moisture) being the biggest.
You would have to use a water resistance glue that also acts as a vapor barrier.Id prep the floor so the glue bonds better.I would also nail or screw down the subfloor as well.

If i were to do this myself i would use enginneered bamboo and install it as a floating floor.All you would need then is a 6-8 mill vapor barrier on the concrete.Alot more cost efficient with a low risk of failure.

GDiak · 11-28-2010, 08:29 AM

I've been told that the planks have to be glued down onto wood. So I figured I wood have to lay down some kind of plywood. Do you think it would be better to screw it down? Thanks for your your help, it's starting to make me understand.

rusty baker · 11-28-2010, 11:18 AM

I have been in the flooring business almost 40 years and have never seen wood/plywood fastened or glued to concrete that did not fail. It is just a bad idea. A floating floor will allow the moisture to evaporate and ALL concrete has some moisture.

GDiak · 11-28-2010, 01:44 PM

So then how do you suggest that i do this? I'm sorry but this is my first time and I have no clue as to what is the best way. Thanks again for your help. Should I not glue the planks together? And what do I lay in between the wood and concrete?

warnerww · 11-28-2010, 04:30 PM

This is what I have heard of people doing. I have never done it though http://www.woodweb.com/knowledge_base/Installing_Hardwood_Floors.html

KarlJay · 11-29-2010, 12:48 PM

I wonder where you buy the asphalt mastic? Seems like that would work, but I wonder if this would be a DIY type project or something you have to hire out.

rusty baker · 11-29-2010, 01:39 PM

As far as I know, they quit selling that mastic years ago. Cutback contained asbestos.

Bud Cline · 11-29-2010, 01:45 PM

This information appears at the abovementioned "woodweb" website.

Quote:

Install the plywood after the vapor barrier is in place. Loosely lay a nailing surface of 3/4" 4' x 8' exterior plywood panels over the entire area, leaving a 3/4" space at the wall line and 1/4" to 1/2" between panels. Cut plywood to fit within 1/8" near door jambs and other obstructions where finish trim will not be used. Lay plywood diagonally across the direction of the finished floor to help prevent cracks along panel edges. Fasten plywood to the slab with power-actuated fasteners, securing the center of the panel first, then the edges, using nine or more fasteners.

ARE YA KIDDIN' ME ??? That idea is just plain asking for trouble. It appears the author of that suggestion has absolutely no practical field experience with the subject-matter. Some of the crap that shows up on the Internet is unbelievable. LMAO!

warnerww · 11-29-2010, 02:25 PM

Quote:

Originally Posted by Bud Cline

This information appears at the abovementioned "woodweb" website.

ARE YA KIDDIN' ME ??? That idea is just plain asking for trouble. It appears the author of that suggestion has absolutely no practical field experience with the subject-matter. Some of the crap that shows up on the Internet is unbelievable. LMAO!

Nope as a I stated before I have never done this procedure but I have heard of it done and was in one house several years back that was installing it this way. Looked like a lot of work but since you guys would never do it, it must not be right (and it may not be the best way to go). I am not a hardwood expert but I did not Know you had to be one to offer ideas in this forum ( which is what I thought the poster was looking for). Now it is up to them to decide what they want to do. I never researched this procedure I did not think that was my job. Now the poster can do the research and decide what they think is best for them.

GDiak · 11-29-2010, 03:05 PM

Ok, but what is the best way to do this? Nobody has really told me !!!! Anybody that knows, please let me know !!

KCB · 11-29-2010, 06:34 PM

Sure we did

If i were to do this myself i would use enginneered bamboo and install it as a floating floor.All you would need then is a 6-8 mill vapor barrier on the concrete.Alot more cost efficient with a low risk of failure.

Absolutely the best way to do your floor over concrete.
Check your floor for level you dont want a bunch of dips(low/high spots) in the concrete.It doesnt have to be perfect , laminate is very forgiving the flatter the better tho.Use self leveling floor filler/compound to level low spots out.
Hopefully you wont have any high spots that you have to grind down.
Use a very good vapor barrier /overlap the barrier 3 feet/tape your seems
with a vapor resistant tape/ Use a strong quality insulating cushion underlayment.Alow your floor room to expand and contract(recomended expansion gap is in the instructions ).And you wont have any problems.The directions are included in your floor packaging.
A very simple way to test for high levels of moisture cut a piece of the vapor barrier say 4x4 , lay it over the floor and check it for sweating in a few hours or overnight.The moisture will be under the plastic.Very little is a good thing.

KarlJay · 11-30-2010, 12:17 AM

Found a few sites that may have a solution for you. I don't know if LL has a good enuff rep to be followed, but worth looking at.
http://video.bobvila.com/m/21320495/...r-concrete.htm

I wonder if you could just put the floating floor closed cell foam under some 3/4" plywood and nail the hardwood to that.

My house was built in 1937 and has some kinda tar and then some tile (looks like asbestos tile), the problem is that I've replaced some of the foundation and that's an area that I want hardwood over.

If these options don't work well, then what is the solution? (other than going with a floating enginered floor)