Looking for Subfloor advice also

[luc1976]

I've been reading this board and lots of great help around here so I thought I would join and post to pick the brains of many at once.

I am laying down 10mm Richmond laminate in three rooms. I have taken up all the existing flooring and have a 3/4" plywood subfloor that I have screwed down with #8 1-3/4 subfloor screws. There are a few creaks that I am working out from the basement as it is not finished and I can access the joists and subfloor easily. Here's where I have some questions:

1- The manufacturer says to level/fill any spots that are 3mm (1/8th). It does not say over six feet, but I assume this means over six feet. In some sections I have almost a 1/4" over six feet.

The floors are level width wise but the 1/4" over six feet is over the length of the room. I'd like to use self leveling compound (Mapei Novoplan Easy) to bring it up to the specs I don't need much of it and was wondering if there's a risk of bringing up the floor too much? I just want the floors FLAT. If I only have 1/4" over six feet is it necessary to get it up to the 1/8" that the manufacturer recommended or is this overkill?

2- As long as I prime can I use SLC on a plywood subfloor. I plan on using latex caulking on the seams of the plywood and blocking off the vents and cold air returns.

3- Has anyone used Mapei novoplan easy and had success/concerns?

4- I am floating the floor and read that it is o.k. if it is not perpendicular to the joist. That a floating laminate floor and be laid down parallel to the joist? Is this true?

Thanks for reading and I hope someone can lend a helping hand.....luc.

[hookknife]

Too much movement can ruin a laminate floor, So do get as close as possible to the manufacturers specs. Remember level and flat are two different things. You are usually looking for flat in most cases. A 1/4" in 6 feet is significant and should be addressed. The SLC you choose to use will have to be approved for wood floors, Not all of them are.

A floating floor can be run any direction you choose.

[Kman]

From the Mapei website, technical data sheet for Novoplan:

RECOMMENDED SUBSTRATES
• Plywood subfloors with a total thickness of at least 1-1/4" (3,2 cm).
Subfloors must be properly prepared, bonded, and free from dirt and dust
(see Section 1, “Surface Preparation,” for details).
• Do not install Novoplan 2 over particleboard, chipboard, oriented strand
board (OSB), Masonite, Lauan, metal, asbestos, gypsum-based patching
materials or any other nondimensionally stable materials.

I don't know if any of the second part applies in your situation, but it certainly looks like you need, at the least, a layer of 1/2" plywood to use Novoplan. Laticrete's leveling compound has the same requirements, if I read them correctly.

Henry 555 Level Pro is the only one I found that is supposed to work over 3/4" ply only. There may be others, but I've used Level Pro several times and had good luck with it. I buy it at the local Home Depot. I used to buy Novoplan at Lowe's many years ago, but they quit stocking the primer for it , and no SLC should be used without a recommended primer.

http://www.ardex.com/cms%5CAssets%5C...-tech-us-e.pdf

[Rain Man]

Overkill is when you gotta eat a job.

[cproader]

Just layer felt to flatten areas under a floater. Slc is not a good idea.

[Mike Sahli]

cproader said Just layer felt to flatten areas under a floater. Slc is not a good idea.

Listen to CP, slc is way harder to use than the way they make it sound at the box stores.

You can make a big expensive mess in a hurry.

[cproader]

msahli said Listen to CP, :

..............

[Kman]

luc1976 said In some sections I have almost a 1/4" over six feet. The floors are level width wise but the 1/4" over six feet is over the length of the room.

This part kind of confused me after I re-read your post. How can it be flat in one direction, but not another? Unless we're confusing 'flat' and 'level' here.

[hookknife]

Sorry but layering felt is not proper floor prep.

Sorry I forgot my smiley

[cproader]

hookknife said Sorry but layering felt is not proper floor prep.

........

[Mike Sahli]

hookknife said Sorry but layering felt is not proper floor prep.

I have had good luck with 15 lb felt for years, works for me.

[luc1976]

Kman said This part kind of confused me after I re-read your post. How can it be flat in one direction, but not another? Unless we're confusing 'flat' and 'level' here.

The floor is Flat width wise and not Flat length wise as there is a slight slope over a six foot span from Flat to an eventual 3/8" gap.

I haven't heard of using Felt before. Seems to be two schools of thought on using FELT vs. SLC. Can anyone point out the advantages/Disadvantages of both and where does one purchase 15 lb felt? Thanks again for all the responses!!

[Daris Mulkin]

15 lb. felt is tar paper for roofing. Can be purchased at a local lumber yard such as Home Depot or Lowe's.

Daris

[hookknife]

The difference is one is meant to fix floors, the other to put under roofing.

You don't want a floating floor to move too much or it can begin to show problems, that is why the manufacturers have a guideline as to the floors flatness. I agree that an SLC can be a problem for a DIYer and would be safer for a DIYer to use some other form of patching the floors low spots, some sort of hand trowelable patching compund, or even something you could screed out. On that same note though, CP and Msahli also have had success with roofing felt evidently, and I for one do not doubt their abilities or the quality of their work. Its JMO but felt would not be an option under a floor I install.

[Mike Sahli]

hookknife said The difference is one is meant to fix floors, the other to put under roofing. You don't want a floating floor to move too much or it can begin to show problems, that is why the manufacturers have a guideline as to the floors flatness. I agree that an SLC can be a problem for a DIYer and would be safer for a DIYer to use some other form of patching the floors low spots, some sort of hand trowelable patching compund, or even something you could screed out. On that same note though, CP and Msahli also have had success with roofing felt evidently, and I for one do not doubt their abilities or the quality of their work. Its JMO but felt would not be an option under a floor I install.

I understand what you are saying Hook,

The trick with using felt is knowing how much you can use and how you attach it to the floor so you don't have a problem down the road. If you do it right it works like floor patch.

Most of my customers are repeat or referral so i don't take chances on slip shod practices. For leveling wood floors I like to use a power planer to knock down the ridges where the sub floor T and G comes together and then float up the low spots with cement floor patch and a screed board.

Felt is just another product to help me do the best job possible.