Self Leveling over timber

[ricardo100671]

We are considering leveling out our joisted timber floors with Setcreet Latex Self Leveling compound to 7mm avg. thickness.

The deck is ProWarm UFH routed boards with 6mm over ply.

Some people have said tis is a waste of money as it will eventually crack and crumble over time due to vertical flexion form walking. We can see a bit of movement when we walk but wondered if concrete would weight this down and give a more sturdy base.

Has anyone has success/Issues with this ?

Thank you 

[BotusBuild]

Any self levelling screed is best laid on an already stable surface. If things are moving now, they will afterwards. Get the ply fixed to be as inflexible as possible.

 

May be better to lift the ply and have a screed poured directly over the pipe and insulation. 

[Nickfromwales]

53 minutes ago, ricardo100671 said:

We are considering leveling out our joisted timber floors with Setcreet Latex Self Leveling compound to 7mm avg. thickness.

The deck is ProWarm UFH routed boards with 6mm over ply.

Some people have said tis is a waste of money as it will eventually crack and crumble over time due to vertical flexion form walking. We can see a bit of movement when we walk but wondered if concrete would weight this down and give a more sturdy base.

Has anyone has success/Issues with this ?

Thank you 

What is the purpose of using the self leveller exactly? Joists (and therefore flooring) a bit out of whack?

Whats going over this as the finished flooring? 

[ricardo100671]

20 minutes ago, Nickfromwales said:

What is the purpose of using the self leveller exactly? Joists (and therefore flooring) a bit out of whack?

Whats going over this as the finished flooring? 

Floors undulate cross joists about 7mm and dip down by one wall to 10mm over about 800.

 

Planning 12mm laminate over, which brings up another question of whether I still have to use underlay if I do pour leveling.

 

Also its about 74sqrm into four connected rooms

[Nickfromwales]

6 hours ago, ricardo100671 said:

Floors undulate cross joists about 7mm and dip down by one wall to 10mm over about 800.

Ah, ok. Just make sure you mop and clean the floors aggressively, I use a janitors mop. Soak the floors (and I mean soak) with 75% water 25% primer (not PVA) and repeat a couple of times. This will rid the surface of dust / contaminants, and size it prior to levelling.
 

The self leveller will need fibres ideally, so go for the Mapei builders screed (20kg bags) and mix to the exact detail on the package.

 

2 person job so ones pouring a bucketload out whilst the others mixing the next, this isn’t a job where you can break off for a cup of tea as this needs to be laid wet on wet so it flows and levels.

 

Use the same mop and prime the floors immediately prior to laying, repeating as you go. Don’t worry about standing pools / puddles just avoid as best you can, but you can’t have this too wet imo and it makes a huge difference to how the leveller will settle and blend.

 

After mixing as instructed, you then put 1/2 pint of extra water in and give it one final good whisk, and literally get it onto the floor whilst it’s still spinning. The extra bit of water will further promote it levelling out and flowing very well, plus it extends the ‘open’ time between bucketloads going down to guarantee that wet on wet application.

 

You’ll need a spiked roller too. 

 

Have you levelled before? If not, do one room at a time, and choose the easiest one first for a practice run.

[Nickfromwales]

Underlay is for impact / noise more than anything, so just use whichever you want. Some have a foil for an vapour barrier, and some insulate, etc.  

 

If it’s over a suspended, cold ventilated sub floor then you’ll need to control vapour, so look for one that offers that functionality.