Varnish plywood before laying vinyl a good idea?

[DundeeDancer]

I'm getting ready for the carpet fitters to come deck out the property.

 

In the kitchen and bathroom the floors have been prepared by putting down sheet plywood that has been untreated.

 

The intended floor covering is standard vinyl off a roll.

 

Wondering if it would be a good plan to put down a layer of varnish on the plywood to make it more robust against dampness before laying the vinyl on top.

 

Any thoughts?  Thanks, DD

[Nickfromwales]

You need to find out what adhesive the layers will use to see if they'll react to each other. 

I don't see you needing to do much more than mastic all around the wall / ply junctions to seal up the gaps. Sealing the vinyl to the wall afterwards is a no brainer. Will there be skirtings sitting on this junction or tiles / other ? 

[DundeeDancer]

Vinyl installer thoroughly recommends against varnishing the ply so going to go with no varnish.