Hello, newbie to the forum here. I’m just a weekend warrior DIY’er. I have laid solid hardwood floors for my homes and have approximately 8,000 sqft laid under my belt.

I’ve come across a situation where my kitchen subfloor is .125” lower than the matting family room. I have experience with uneven floors before but with a thicker difference like .250” and great which I just laid the appropriate thickness plywood on top. But for this scenario it seems I can’t find any decent sheets of wood at .125” thick.

My question is, what would some of you recommend in building up the thickness. I’ve looked a roofing felt paper, compressed flooring felt underpayment, 1/8” peg board, etc...

What would be these best practice for my situation.

Thank you for any feedback.

Is the whole room an eighth inch lower than your kitchen? Have you a 10 foot straight-edge so you can check flatness across both rooms?
90 pound roll roofing, with the tiny gravel on one side may be the best solution.
An eighth inch is not out of acceptance for a sub-floor. You may be a blessing to add thinner 30 pound tarpaper to even out the two floors in a doorway over a few feet, so there is a gentle slope to make them more even.
I use a sharp painters putty knife to score the back of the roll roofing, then bend it back on itself to separate a piece, instead of trying to cut through with a utility knife. Putty knives are made with tough, hard steel.

Thank you for the reply and input.

Yes, the kitchen subfloor is an 1/8” lower throughout compared to the family room. This is because the kitchen had 3/4” solid oak floors and the family room had 5/8” parquet floors (what a comb, lol) that builder installed in the early 80’s.

I like the idea of transitioning 3 to 4 feet into the kitchen creating a gentle slope. I think transitioning this way would be perfect since the floors are being laid length wise into the kitchen versus right to left.