Hi all!
New to the forums here, but been reading them awhile.
I have a 3/4" Brazillian Redwood (BR111) to install in a highrise condo.
I've laid down 1/4" cork with mastic, 3/8" cdx with mastic, and a second
layer of 3/8" cdx glued & screwed at 90 degree to first layer.
Ready to start nailing in a coulpe days but wanted to run this by you pro's first.
I have 2 exterior walls that have floor to ceiling windows, so here's my plan.
I won't have enough clearance to put in any trim piece by these windows
so I thought I could leave a smaller gap for expansion and caulk it and
paint it to match, then leave small spaces maybe 1/64" between my first
6 or 7 rows to allow for expansion that way.
Is this ok? or is there another way to work this?
Also,
I'm concerned about using 2" nails, I'm afraid they will penetrate the cork
and thus defeat it's purpose of insulating sound. I'm planning on using
1 1/2" nails will this be ok?
Or will 2" nails not penetrate the cork?

Thank You in advance for your help.
Ray

Hi Ray,

Welcome! Sounds as if you have concerns so I tell you what I think.
First, I hope you used the same adhesive for the cork as you did for the 1st layer of ply. I hear about how the cork can lose it's bond to the subfloor (I guess it's concrete) if the adhesive is not as strong. Assuming that's not a problem, you are concerned about the flooring to the glass. Is the floor boards running paralell or into the glass? I would be way more concerned about a paralell install. It sounds as if you are taking expansion into consideration. I can't tell what will work other than to adequately plan for expansion and it sounds like you are. You most certainly can use the 1&1/2" nails/staples/cleats/fasteners. In fact, with a 3/4" CDX subfloor over concrete, you should. Be careful where you need to facenail. You may want to use a 1&1/4" finish nail for facenailing. Also, use a caulk that will not get hard and lose it's ability to compress. A paintable silicone type or urethane. Some of the latex bath caulkings get real brittle in a few months.