# Prime subfloor or not?



## HandyPete (Mar 23, 2008)

DO NOT PRIME THE PLYWOOD!!!!

I'm assuming you've done your homework and your sub floor is strong enough for tile (1 1/4" plywood, cement board does not add sturdiness). Your right about the thinset, if you use a top quality product that is modified it will stick well to the plywood. 

You should always check the data sheets on the products you buy, go to the manufacturers web-site and check them out!

- pete


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## orson (Mar 18, 2008)

Whether you nail or screw the underlayment to the subfloor make sure your screws or nails are no longer than the thickness of the underlayment plus the subfloor.

You don't want to tie the underlayment into the framing beneathe the subfloor.

As far as priming, no way. Most flooring installers using any type of adhesive(in this case thinset) will throw a hissy fit if there is paint on the substrate.


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## Hobb3s (Apr 2, 2008)

Thanks for the responses guys. I've already laid the plywood and the cement board down on the floor. I didn't prime the plywood, just purchased a high quality mortar. I think I 'did it right'. 
Mortar was an interesting learning curve, I wasn't too tough to mix properly, but definitely trickier to spread well than I expected. But overall I would consider the laying of the floor and underlayment a success. Next it's on to the tub install and then the walls go up!


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