I am installing 3/4 inch hardwood in a high rise. I put in a cork sound barrier and I am wondering how to do the expansion gap. The cork has an isolation barrier and I need to know if I can just butt the wood up to that since it gives a slight amount or do I need to put a gap between it and my floor.

Thanks
Tony

I'm missing some information...

What is under the cork?

What method of installation are you planning on, with the ¾" solid wood. Nail down?

no, its glue down actually. the nails would ruin the integrity of the soundproofing (cork). The cork is glued to the concrete slab... the wood is glued to the cork

You really ought to be using an engineered type hardwood for this purpose. A solid, glued down, is very risky.

In what way is it risky? I do not really have a choice, she already bought all the wood.

Solids are much more prone to movement than engineered products. I'm not so sure being glued to cork is wise. If the solid wood wanted to move it could end up tearing the cork apart.

I know you don't want to hear this, but I would not feel comfortable with this type of install.

I agree with Jerry here, I wouldn't feel comfortable with that method of install. I would be worried for the same eason, some movement of the hardwood could tear the cork from the floor.

well that sucks... haha

the floor has already been started so there is no going back, can you help me out with the expansion question?

Expensive firewood!!!

That is why I asked the question above, in my last post. Your headed down the road to a failure.

Too late you have already started??? Do you have time and money, to do it all over again?

I don't know what you mean by isolation barrier Tony. Solids are supposed to have an expansion gap around the entire perimeter. More so on the width than the length. At exposed openings cover the gap with a trim or use a flexible color matched caulk/filler.

When installing a cork sound barrier, you are supposed to cut two inch strips and place them vertically around the walls. After installing the floor, you go and cut the wall strips down to be flush with or under the top of the floor. This install is on the 15th floor of a high rise condo. I figured since the climate is so controlled that this installation could be done. On top of this, it is the only way you are allowed to install any type of floor because of the noise issue. Reading up on the cork isolation barrier, I never came across any warning against using solid hardwood on top of the cork. In fact it is important that you do not nail through the cork since this will ruin the sound control characteristics.

http://www.ecobydesign.com/shop/cork/un ... stall.html

Check with the condo association. They should have specs. I've seen quartered solid glued in this scenerio, but yet to see a plain sawn 3/4" solid. Although it's done in very high end stuff like one would see in $ 20M Manhatten apartments.

The condo association claims to have had this method "developed" by a local flooring store. In actuality, they simply asked what to do for sound and the store answered with a simple solution... cork underlayment. The association is acting as if they had cork underlayment invented for them specifically, it is actually pretty funny. I assumed since the owner had gone through all the red tape with the condo association and various suppliers that she would have been warned against this install. It really is my only option to install this wood, and it is the only wood she wants.

thanks
tony