My brother and I plan on putting down some laminate flooring but the existing sub floor very uneven. We are hoping to get out of replacing as much as we can and use some of that leveling material.

So my question is how much is the max suggested? Is it 1/4" or ?

Thanks for the help.

They vary from about 1/4' up to 2" depending on what type you use. Remember that with laminate, you can go the heavier pad that will give you a bit more lee-way as far as how perfectly flat the floor is below it.

Is your current floor wood or concrete? If wood, is it plywood or lauan? Is the un-evenness due to bad seams, or is it damaged wood?

It's doubtful that you'll use the pour in type; you'll probably want one you trowel in.

Here are some various floor levelers you can look at - and learn a little about as far as their recommended applications go:
http://www.google.com/search?num=100&hl=en&lr=&safe=off&q=floor+leveler+OR+leveling&btnG=Search

... or check out the couple different ones they carry at Lowes/HomeDepot. All will tell on the packaging what the maximum thickness is.

A few years ago I put tile and laminate flooring in my home. Upon pulling up the carpet and sheet vinyl, I found the concrete slab to me a mess. The guys who poured it must have been drunk at the time. There were high spots that I took down with an air chisel. After cleaning through mechanical and chemical means, any glue and residue, I used Level Quick. It is fairly expensive (about $25 per bag at that time). It is imperative to put their latex primer on the concrete prior to the Level Quick, to avoid separation. I was happy with the results. Good luck.

Thanks for the help guys. The sub floor is OSB plywood. We found dips and high spots as much as 1 1/2" all over the three story home. It's only five years old so maybe that same drunk crew worked on this one too Dr D.

So if I use the leveling compound how will I manage the doorways if the center of the room has a high spot of 1 1/2"? The entire floor in the whole house is so bad, someone suggested lidting up the whole sub floor and replacing it!

Any ideas on how to proceed?

Higher a sober contractor and get him to draw up a plan and run with it.

If you have an 1 1/2" settling/sagging in a 5 year old home, you should be getting a structural engineer and not worrying yet about floor leveling compound. You may have some structural issues that need addressing first.

Thank you gents, all good data to take into consideration.