Tried using the search function to help answer my question, but I only found some of the answers.

I'll be installing 3/4" X 5" Bruce hand scraped T&G planks throughout my entire 1st floor w/ 2" cleats. Most of the 5/8" plywood subfloor is level and flat, but at one end of the rooms, the subfloor dips down about 1/2" to 3/4" over 4 (ish) feet to the end of the room...up until that point the subfloor is OK enough to work with as-is. This area will have base cabinets on top.

I was thinking of using shingles/felt to build up the area, but seems to me that many layers would be required. How many layers can/should I go? Could I use a combination of layers of 1/4" ply and shingles/felt to build it up, feathering off as needed? Any other suggestions for building this area up correctly?

Thanks!

KG:

You're on the right trail with plywood but think about starting with 3/4 inch near the far side then tapering back with 1/2 and 1/4". Too much felt will not make for a solid sub floor to nail to. If you do go with more than a layer or two of felt #30 is going to work better as #15 compresses too easily.

Yeah - that's what I was thinking...use as big of a singular piece of wood as I can at the deepest end, then taper back to a smaller one and fill w/ felt. Thanks Ken!