OK, so our ‘shed’ has a concrete floor that has a screed finish which is now breaking up for one reason or another. I have patched it a couple of times but it’s not really satisfactory as the repair is harder than the screen which then breaks up around the repaired patch.
90% of the time the floor is only walked on with bare feet (it’s a beach hut) so it’s not exactly hard traffic.
I was thinking that maybe a self-levelling compound floated over the whole floor might do the trick or is this not really up to the job? Another option was a rubberised paint that might hold everything together.
The other option is obviously to fit a wooden floor over the top but that might be a bit pricey.
Anyone got other solutions?

Flooring screed breaking up – options?

Sleep with the screed’s sister

Oops, sorry, wrong thread

If its not a big area to cover, and the shed is dry, then I’d put tongue and groove chipboard over it. A layer of dry sand can be be packed into areas where the screed has come away. The boards would be nice and warm under foot too.

Set the damaged areas with PVA Glue and then use self levelling stuff to fill holes?

+1

Set the damaged areas with PVA Glue and then use self levelling stuff to fill holes?

From what I understand, no repair will work. As the screed sets it contracts causing surface tension which gives it the hardness. Now, if it breaks up, then that is because it actually pulls itself apart because it isn’t bonded to the floor below properly. Moisture can cause it to debond from the floor if you don’t have a damp proof membrane or it isn’t a moisture tolerant screed. Alternativley if the floor below hasn’t been prepared properly then the screed won’t bond either. By prepared proeprly I mean clean of surface contaminants and free from dust, same as for any surface you want to stick something to.

Your options are to put a wood floor over it and let it continue to break up below until you are forced to do something about it which could well take many many years. Or, pull the entire screed up now and re-do it properly.

As price seems to be a factor for you, I’d suggest wooden floor.

If you have any warranty from when the shed was built, you can claim as it is clearly a latent defect.

Hmmm. I’m leaning towards putting a wooden floor over the top as it will be warmer underfoot and non-slip for wet/sandy feet.
Using PVA glue to set the damaged areas sounds interesting though.

Odd situation and on paper its hard to explain why. Screed can be laid bonded or debonded / floating over the concrete. If its debonded it will be thicker than a bonded screed and reinforced.

Based on your OP I suspect the screed has a very weak cement content. Hence the break up of the mix and your repairs being stronger.

The only real way would be to remove the whole screed and do a complete repair. Alternatively the sand / board option. Although with this I would go belt and braces and cut a pocket or pockets through the screed to get your battens back on to the concrete floor and or stronger repair patches.

It’ll be the frost thats made it crack during the winter. The whole idea of a latex screed it to self level, thats its purpose when laid, however, in the thinnest areas it will break up in very cold temps. It happens even when floor tiles are laid on top, leading the floor tiles to crack if any weight is applied to them. With the combination of frost, sand and water I would think carefully about your repairs…..Good luck!!!!

Should have just Googled it and saved the time writing post above

Taken from the Concrete Society’s website.

Question on screed durability
Description: What has caused my sand cement screed to break-up?

Answer

There are two aspects; is failure due to cracking or crumbling?

Crumbling is caused by a lack of compaction or low cement content. A screed tester (in accordance with BS 8204) is likely to show that the screed falls short of the lowest Category C (indentation of 5 mm). An analysis to assess the proportion of sand to cement might indicate a low cement content. Visual inspection and density check of the screed may suggest poor compaction.

Cracking is expected in all sand cement screeds (Clause 6.9.1 BS 8204) unless sufficient joints are provided. Cracks are not considered a problem under thin floorings e.g. vinyl sheet/tiles or carpet, unless the screed has curled at the crack. See clause 8.4 in BS 8204-1

The general recommendation would be that unsound areas of screed should be cut out and replaced. Proprietary systems can be used to upgrade an unsound screed, which may be by impregnation with a low viscosity resin or by laying a fibre-reinforced, flowing cementitious screed. Trials of repair systems should be undertaken using test methods such as the BRE Screed tester.

If the overall quality of the existing screed is found to be similar to the areas tested, it may prove more cost effective to remove and replace.

Acknowledgement: The Concrete Society