old house leveling floor

[danielmthomas]

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I have an "off grade" house and would like to pour self leveling compound over the existing 1.25" plywood subfloor. The floor is stable with no visable movement when walking, although you can hear the stove vibrate when jumping up and down.
Some books say use roofing felt under the metal lath. Others say prime the plywood, then lay the lath, then pour the compound.
Which is right?

Should I be trying this at all.

I got mapei novaplan2 for the self leveling compound.

I'd like to stain it and leave it as is... good idea? bad idea?

[hookknife]

Daniel, I am not familiar with mapeis SLC, but for ardex you would not use any felt or anything that might break the bond of your self leveler Im sure you will need a 2 part primer and lath like you said, but you might also need a special additive to mix in with your SLC one that will add some flexibility to your leveler, in ardex's case it would be e-25 added in place of some water, but not sure with Mapei's leveler.
The one thing I will strongly advise is to absolutely follow the manufacturers instructions to the T, it is more important than you might think especially with self leveling compounds

[danielmthomas]

hooknife,

Thanks for the reply... I'll look for something like that. Haven't seen the Ardex brand in my area. (Pensacola, FL)

What about the floor stability... I just put three jacks under the house but there's still a slight vibration. But I'd say it's fairly stable. How forgiving are these SLCs?

[danielmthomas]

Also... what about using the self leveler as my finished floor... just staining and etching it too look nice??? Any problems there?

[H Scott]

Hello.
I am very familiar with Mapei's products.
Mapei has a tendency to spider web under strain due to its high tensil strength.
It has a 4200 psi rating while this good for floor leveling it makes it very brittle.
It does require a primer and the primer is expensive.
What type of floor are you installing over this.
If it is tile, Ditra may be your answer.
H Scott

[danielmthomas]

I'd like to just have a stained concrete floor... is mapei's novoplan2 slc going to work?

[H Scott]

No Mapei would be not work as finished floor.
If you want stained concrete you may have to screed the floor out then over lay it with a slip sheet membrane and then think about a slc or whatever.
This application is not practical for a concrete floor.I am not saying it cannot be done I am saying it will cost more than it is worth.

[danielmthomas]

H Scott,

What does it mean to screed the floor? Metal lath?

If the Mapei isn't going to work, what will?

[Floorguy]

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[Tandy Reeves]

If the stove rattles when jumping up and down, you have too much deflection for any concrete type product to work. I would suggest you check and see how much deflection you have and estimate how much more weight you are going to add to the floor with your overlayment. I would then recommend Mapei two part epoxy primer covered with sand and then use Mapei M20 Plus self leveling overlayment. If you want a blotchy look in your floor, use dry powder coloring. If you want a solid color then use liquid coloring. Be sure the colors you use has very little or no iron oxide in them. Excessive iron oxide will cause spider cracks. Follow the directions to the letter. No shortcuts. If you think you need more help in your area, pm me and I will get the phone number for the Mapei in your area. With this material you can leave as is or it can be polished to a mirrow sheen if you wish.

[danielmthomas]

Tandy,

How do I measure the deflection?
You're suggesting sand... I assume "play" sand?
What about metal lath?
and what are your suggestions for firming up the floor... should I tie the joists together? I've already put a 10' 4x4 with 3 floor jacks under the joists... they're 20" on center. and the stove only slightly rattles.

[Tandy Reeves]

Deflection--pull a string line across the floor perpendicular to the floor joists. Go the the center of the room and measure the distance the string is from the floor. Next place at least 300 pounds in the center and measure again. Now take the measurement of the room the direction the string is stretched. Now take that measurement and divide it by 360 and you will know how much the floor is deflecting (sagging).

Yes you use clean play sand and scatter it over the primer before it dries. If it dries before the sand is applied, the primer is then a bond breaker and nothing will stick to it. You walk the sand into the primer and when the primer is dry, sweep off the excessive sand.

The joist must be cross braced at a minimum. Then if there is still movement, bracing must be applied.

Give us the demintions of the rooms you are working with so we can help you with the weight measuremants. What is the size of the joist and what is the span they cover. We want no rattle in the stove, not even a little. We know you can do it and we will help.

[H Scott]

So the sand is going to give body to the slc shrinkage,to prevent spider webbing?

Very inventive concept, one I have never used or even thought of.
I will pack this in my bag of tricks.

Still learning after 25 years....

[Tandy Reeves]

Mr. Scott this is for the two part epoxy primer. Without the sand the M20 Plus or for that matter any other SLC would not bond to the primer. I don't think it has anything to do with shrinkage, but I will find out for sure and let you know.

[Peter Kodner]

20" centers... are these preformed 2X4 truss type joists or Engineered I beams? If so, aren't they designed to stiffen under load and have a need to deflect a certain amount to perform?