Help needed with vinly floor tiles

[RALLYPUG]

My small bathroom floor has had the original broken floor boards
over-layed with the type of weatherboard that is normally used for external work such as boarding up damaged windows.I have purchased vinyl floor tiles from Wickes and have used a varnish to paint the weatherboard.
As you will know this seals the surface but it is not perfectly smooth.My question is will the tiles stay down if fitted on this varnished surface?

[thedoctor]

The timber needs to be smooth plywood which can then be painted with the varnish although it is much more usual, cheaper and easier to do this with PVA adhesive (see the projects on PVA and laying floor tiles). Laying tiles on what we assume is Stirling Board, which has a rough face, will not make a succesfull base for vinyl tiles.

[renovationman]

Retired ex-plastics industry which included industrials vinyls for buses, aircraft etc etc.

Vinyl whether tiles or sheet will 'telegraph' any uneven surface and will be visible on the vinyl surface.

A smooth surface is essential and adhering hardboard for example [having first allowing it to stabilise to the humidity level of the room in which it will be installed] is a low cost to acheiving this. Edges of the hb should be sanded flush and any dust vacuumed away, then go over with a 'tacky cloth' to remove any remaining dust particles.

Check out the vinyl manufacturers recommended adhesive type and use it.
Manufacturers are not stupid and are glad to advise to help you get the best from the product.

In my experience, up to 90% of floor laying trademen have not updated their thinking concerning correct use of adhesives. (Too many times I had to right their wrongs)

Good luck