Hi everyone,

I’m installing a new 22mm tongue and groove subfloor for an engineered wood floor. The room was previously two rooms that have been knocked together, and there is a height difference of around 22mm between the two. The first layer of subfloor is down and I plan to sheet over the lower of the two to create an underlayment to bring it up to level, and would appreciate advice on suitable materials: my current thoughts are some 8x4 sheets of 18mm OSB3 and then a layer of 4mm ply or hardboard, but would like to hear what other people think. Given that this is in a kitchen would some sort of membrane on top of the underlayment be a good idea to protect against spills, or would a good quality underlay handle this?

Many thanks,


Stu

 

Why not use the same 22mm thick material throughout instead of trying to make up the thickness with two sheets of other materials?

I would not install a waterproof membrane. Your floor isn't going to be waterproof so I don't see any benefit. If there is a water leak the membrane will trap the water and cause it to spread.

 

Thanks that sounds a much better suggestion: I’m not sure why I’d not considered just using 22mm sheet originally.