So, I'm goig to show ya'll the steps I went through before installing the cork flooring and explain why I did things this way. Basically, the cork is only about 1/2" thick and I intend to run it through the kitchen and out to where it will meet the hardwood flooring in the dining area. Although the cork seems to be rather resilient, I believe that traditional hardwood will be more durable, for me and my work boots, in the living room and dining area. Anyway, hardwood is 3/4" thick and I didn't want to have this 1/4" discrepancy between floor heights. Also, adding a layer of cement board would just help provide a very smooth and clean surface on which to run the cork. My plywood floors, having been down so long with no other flooring over them, are a little rough in some areas.
Using a 1/8" notched trowel I spread a layer of water based glue that is used to adhere vinyl tile, wood and/ or base trim. This stuff has a relatively short working time so I only spread enough for one piece of cement board at a time. I picked this glue up off a job a while back, not knowing if I would ever use it but seems it came in handy after all! They were going to throw it out even though it had never been opened. So, making sure I was staggering the cement board joints over the plywood subfloor joints, I just started laying in one corner, working my way out. These sheets come in 3' x 5' sizes, btw.
Make sure to stagger the joints of the cement board also. I then screwed the cement board down using 1" coarse threaded drywall screws, 12" on center both ways. Make sure that the screws sink beneath the surface well. You don't want to feel those screw heads because they can cause problems in your finish flooring later.
As you can see, the cement board makes a lot of dust, so I try not to even cut it in the basement, although I have on occasion. I continued to run the cement board up to the threshold of the pantry door. You could use 1/4" luan plywood I guess but the cement board will never delaminate on you and is very resistant to moisture.
After getting everything glued and screwed real good, I installed the plastic underlayment that the cork manufacturer recommends for a moisture barrier. It is basically 6 mil black poly. I shouldn't ever have a moisture issue, considering this floor is elevated and not on grade, but you do what they call for, for warranty sake. The red, moisture resistant tape they recommended was basically crap however. It wouldn't even stick to anything. The plastic has one sticky edge though, so it sticks itself together anyway. I lapped the pieces about 3 or 4 inches.
It wasn't too terribly bad to put all this down and after stopping to eat lunch, I then proceeded to install the flooring. Which I will show in the next post.