Smoothing over Ashpalt Sub- Floors?

[Rexion]

If I overlay an ashpalt sub-floor in my kitchen with 6mm plywood drilled and pluged at 300mm centres {100 x 1" screws per 8`x 4` sheeet of plywood am I creating future problems -

Will screws `pop` out due to foot traffic?
Will plywood warp and twist?
Will drilling ashalpt cause damp problems {as ashalpt is a Damp proof membrane}

My intensions are to fit sheet vinyl cushion floor as a floorcovering over this. Incidently, selflevelling flooring compound appears to expensive and would take a lot to reach 6mm height.

Appreciate contributions from Building Surveyors and Floorlayers

 

[mattysupra]

You will damage the sub floor. Only way to go is smoothing compound with primer. Treat as impervious floor when following instructions on what ever compound you use. Try to get hold of acrylic based compound. Will take two coats if trying to raise 6mm.

 

[Rexion]

Hi! Mattysupra,

Thanks for your response. My asphalt sub floor is in without cracks, but not level and when I removed old vinyl floor tiles there is some minor surface damage. I had intended to overlay with plywood as it`s inexpensive at around £50., by comparison to leveling compound. But from your post you advice against this - is this because I may suffer damp problems? Do you know of a cheaper alternative? looking forward to hearing from you soon!

 

[mattysupra]

basicaly plywood is designed to go over another wooden sub floor( not concrete, asphalt, etc) The type of subfloor you have can also be easily damaged. So drilling hundreds of holes in it will not be good for it! If you count the cost of all the plywood , screws , plugs and drill bits you use , you might find your not far of the price of doing it the correct way. Also when your floor does fail down to moister or damaged base etc you will of wasted all the money you already spent by not doing it correct in the first place.

 

[Rexion]

Hi! Mattysupra,

Thanks for your response highlighting the drawbacks of plying over asphalt, I now have a much clearer view of the situation than I ever did before.

Cheers!
laser