I'm completing (with the aide of my contractor) an extensive renovation of the ground floor of my 100 year old home. We're about to install my 3/4 x 3 1/4" pre-finished jatoba in the next couple of days - which has been acclimating in the house for approximately 3 weeks - and I've identified with my contractor the following issues:

1. The subfloor (3/4" tongue and groove plywood over wood joists 24" on center - the joists are exposed as the basement is unfinished) is very uneven in a number of spots with a variance of up to approx 3/8" to 1/2"; and

2. My basement is wet in the spring and fall so moisture is a factor.

My contractor has suggested simply using a self-levelling compound but I don't feel comfortable with it as I'm concerned about a possible difference in feel between the areas with the compound and the plywood - the potential for crumbling as well as the need to control moisture.

Any help would be appreciated.

Self leveler is for concrete not plywood. The prefered way would be to use felt/ wood shims/ shingles. Now if you have a moisture problem in the basement I would consider having that fixed proir to instsalling the flooring. A solid wood installed in the hight of the heating season where a know moisture problem underneeth is present sping and summer is a problem waiting to happen.

Thank you for the reply, I'll take your advice regarding the felt, shims, shingles.

Regarding the moisture problem, I'm stuck doing it now as I've already started with the rest of the build out...is there any way to control moisture from underneath prior to the install? Does the fact that we've got radiant heating make any difference regarding moisture control?

Again many thanks for your reply.

p.s. radiant heat - meaning radiators not infloor.

A dehumidifer in the basement may become necessary in the spring/fall to keep the humidity level down. I dont have any idea of what to expect In Canada. I would try to talk to an installer who is a litttle more knowlegable to the local climate/conditions

In your situation I would try to work from underneath with some blocking between the joist and driving in shims on any low joist. You really need another layer of plywood underlayment if you want to do this right.

Don't use any kind of portland based leveler or patching compound.

The flooring will have to be installed perpendicular to the joist or diagonally.

The moisture issue will have to addressed or it could lead to cupping down the road.