Thread: Curling screed
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Mathew Newton[_2_] Mathew Newton[_2_] is offline
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Default Curling screed

I am currently being an extension to increase the size of our lounge and have had tradesmen in to the job, which included laying an unbonded 60-80mm fibre-reinforcedÂ*sand and cement screed to finish flush with the existing lounge floor and a concrete threshold running along a set of doors. Here it is:

http://www.newtonnet.co.uk/permanent/screed1.jpg

This was done 6 weeks ago and, as per the screeder's instructions, it was left covered with a polythene sheet for a week to help the initial cure and has been left uncovered since at a room temperature of ~16c - not for any particular reason; although I was mindful that the slower it dries the less issues I would likely have.

Unfortunately I noticed today that the slab has risen ~7mm along the join with the door threshold as seen he

http://www.newtonnet.co.uk/permanent/screed2.jpg

(The black sheet on the right isÂ*the separating barrier between the screed and the concrete slab underneath but it is very thin and so not affecting the measurement as much as it might appear).


From what I have read, unbonded screeds can be prone to curling as a result of the top surface drying out quicker than the bottom and soÂ*whilst it might not be that surprisng that this has happened I am keen to get it sorted. It's not just the height differential that concerns me (some self-levelling compound to bring the lower levels up could likely sort that) but moreÂ*the fact that you can feel movement in screed if you jump up and down there. There's no cracking (yet!) but it is definitely flexing.

The screeder is coming out on Thursday to have a look but I would welcome anyone's thought on what options I have, noting that I'll be covering it with a 15-18mm engineering wood floorÂ*eventually.

Thinking aloud I thought I/we could:

1. Do nothing - not really a viable option (for me at least!) as it'll obviously compromise the final floor covering
2. Bring the threshold height up with some form of self-levelling compound - this still leaves a poorly supported screed in the affected areas which may cause issues a later date (although I imagine engineered wood flooring itself provides some strength?)
3. Drill holes and force some sort of resin in/under the screed and then bring the threshold height as required - don't know anything about this as a technique; it just sounds like a possibility to me.
4. Try and get the screed to settle back down by jumping on it and fill what I assume would be a resulting crack
5. Cut and remove/replace the screed as required

I did read that sometimes the curl can be reversed by putting a polythene sheet back overÂ*the affected areas for a week to move the residual water balance. I am surprised that this could work but I've seen a few mentions of it in what appear reputable places. Does anyone know anything more about this? I suppose it's got to be worth a try before Thursday just to see if anything changes.

Grateful for any thoughts!