cracking levelling compound

T

theflyingpig

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thought I'd done a reasonable job of levelling my 25 square metre floor - mixed 200kg of the compound (water based) by hand, and all looked good. now all cracking underfoot!! its not crumbling, but makes nasty cracking noices when walked on. . . arrrrahhhhh! thinking it'll be OK when underlay and floor floating on it as the weight will be dispersed, but am worried!!
where did I go wrong? And is it a disaster that needs re-doing (please NO!)

thanks

Huey
 
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did you read the sticky at the top and follow instructions? Whos primer did you use? what product is it? is the subfloor dry? And yes it needs to come back up!
 
It sounds like you laid it on a dusty floor. Remember how your mum used to put flour down on the bench when she rolled pastry to stop it sticking? Same principle in action. 20 kilos isn't a lot to get up.
 
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Hi guys - what a nightmare! and yes - it was more like 250 kilos. The subfloor was definitly dry - been there 40 years! And I primed with diluted PVA as reccomended by the builders merchant. I can't remember the name of the product, but it was water based and bought at Abbey Rose. The cracking is getting worse all the time, and its like 'snap, crackle, pop' when I walk on it. The one place its not cracking is where I planed a really high spot down with a concrete planer so that certainly gives weight to the primer theory. Why oh why didn't i prime it???? Its going to be a mammoth job getting it back up, and bang goes my new floor in time for new year . . .. . . .

NIGHTMARE!
 
It sounds far too thick to me. You usually only go up to 3mm but 250 kilos at that thickness would level a Tesco car park!. If I'm going a bit thicker I always add sand to help bulk it out for the thicker stuff.
 
i dont get it. You say you primed as directed by the supplier, but then you say why o why didn't i prime it? Did you prime or not?
Let me give you a list of why water based compound fails-

1- Damp floor ( above 75 % rh ) Because your floor is 40 years old does not mean it is dry! Your on the boarder line of when a dpm was used and not used.

2- If you dont prime it will fail. Also you need to use the correct primer for the subfloor or it will also fail! Pva is not the best primer, ALWAYS use the primer recommened on the product bag!

3- incorrect mixing, to much water or even to little water can cause problems. A maximum of 1/2 a litre difference or this can cause it to fail!

4- incorrect mixing of product. You should always use a electric whisk. Mixind by hand is not correct. you can not mix the product properly in the time it takes to start setting. ( but i dont THINK this is your problem here)

5- To thick or not thick enough with cheap compounds ( wickes seems to be the worst for this ) On a good quality compound like balls or uzin you can get away with double the thickness they say! But i didn't say that ;)

6- out of date compound! Yes really, If the product has gone off it will not work correct. May only be a month out of date and it can fail. Normally 6 months shelf life on water based.

What size area did you lay the compound over? And if i knew whos product it is i could tell you if its crap or not. One of the sheds sells a product that fails every time. Cant belive they are allowed to sell it!
 
thanks for exhaustive list. apologies for confusion re primin - I primed using diluted PVA, and then was regretting not using the primer you reccomend in the sticky . . .

the product was (water based) Sealocrete which according to the builders merchants used to be Bostik . . From memory there was no advice regarding primer on the bags.

going to start taking it all out tomorrow, be interesting to see if its stuck to the floor at all - if not I guess thats my problem . . :(

its moved into top place on my disaster list during the current flat rennovation (12 mths and counting!)
 
what is the subfloor ? and i would suggest you make sure there is no moister. A safer and more forgiving compound is acrylic is any damp etc.
 
apologies - that last post was just plain stoopid . . having read a few older posts I can see some 20 quid meter is not going to take a reading of my floor!

a question however . . . I was planning on using a dpm underlay underneath my floating floor - in this case is the mositure reading necessary? (assuming I can get the levelling compond to stick to sub floor on my second attempt)

cheers
 
if your sub floor is wet then you wont be able to use a water based compound. ( it will always fail ). You could use acrylic or latex tho. (Acrylic is a much better product than latex ) But you will find that these other compounds wont flow as good as water based compound. The meter your on about is only a indicator and far from reliable! You could just go a head with the dpm underlay if you want, but not technically correct.
 
hi again mattysupra - just wanted to run the advice I've just been given (by two seperate local flooring people). both say not to bother measuring for moisture - stating that if there is no obvious damp . . .?? they said to 'key' the floor and use sand and cement to fill up to from 5 mm level, then use stopgap green bag 2 part (which I understand is latex?) to do final 5mm.

in your opinion would this work, and last the distance? bearing in mind I will be using the combined dpm/underlay under the bamboo as well . . . .

thanks!

Huey
 
the advice was to use sand and cement where more than 5mm of material is required to make the floor level, then the 'green bag' for last 5 mm.

what I'm wondering is whether the underlay/dpm I am planning on using under the wood is a sufficient dpm . . . . .because if so I could potentially avoid having to test the subfloor? . . . . .testing accuratly does not seem available to DIYers?

thanks
 
D

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