Checked it today - and despite all the major efforts to rail the room with battens to allow the tamping bars to have a point of reference, we got some lumps.
I think it was because the screed was a lot dryer than I was expecting (no capacity to flow) although the mix was absolutely by the book.
Luckily I checked today, before the screed has fully cured and dried to cast-iron mode, so we managed to knock the high spots off with a bit of scraping and light use of an SDS + scutch comb.
On the plus side, the screed is *extremely* well attached to the base. It's not falling off, ever.
The guide rails did at least prevent overall errors in the level. We now have a generally flat and level floor with some hollows (2mm).
Oh well - referring to the Latex screed thread, time to bang a bag of F Ball over it.
Decided I don't like subfloor work - it's crappy and difficult.
Get the Stopgap 300, they have many other types, but that's the most self-levelling. Use the max amount of water (5.675l from memory) - the water is critical, it sounds faintly ridiculous but the difference between the standard amount (5.5l) and the max is very obvious. It levels better if you go for a bit more than the min 3mm layer on average, as 3mm on average will be thin on the high spots.
A pin leveller or wiper blade will help spread the stuff evenly if it is a big area, but are a bit of an investment (=A350-70) for a one off (try Refina tools if you want to go that route) - I made a pin leveller from a plaster's darby - drilled and tapped the stiffening braces on the back of it to take some M5 bolts, which set the height above screed to 4mm, and screwed a handle to it. That spreads about the right amount roughly evenly around the floor as you go, from where it will level. You'll need a trowel to push it into corners.
Speed is everything - being two people will help, one mixing and pouring, the other spreading. Don't try and mix it all first, there isn't enough time (unless it's only two bags or something).
Oh and shade the room if it is hot, I think I said that before.
snipped-for-privacy@mailbolt.com coughed up some electrons that declared:
Hiya,
Already done :)
BTW it was 5.75 l max water. I'm encouraged to hear that it makes a big difference :) Yes I will be precise - already have a plaster mixer doobrey for an SDS.
4 bags of Stopgap 300 on order and a bottle of Stopgap P131 primer. Wasn't sure whether to use P121 (anhydrite screed) or P131 (random substrates) - a call to F Ball's tech dept said use P131 for SBR screed, which is handy as it's a more universal primer.
That's an idea. The room dimensions are small (3m2 and 7m2) so I reckon a bit of straight wood batten with 3-4 roundhead screws will work for me. I ordered a pin roller too.
Indeed - 20-30 mins working time - I read the datasheet. As it happens, if I mix exactly one bag for the 3m2 room and 2 bags for the 7m2 room, I'll be spot on where I want to be and I can mix 2 bags in one (big) bucket.
I ordered on extra spare bag for the end of the hall too.
Good tip. Luckily, these rooms are round the north side.
We're doing the cempolatex in the front room too soon, that's on the south side, so might be time to hang sheets on the windows...
Thanks for your detailed advice. Will get photos afterwards - either of a nice floor, or me dangling by the neck off a tree, depending on how it goes!
If you get it right... which I didn't first time round.
Which is the reason for the advice, I'd rather my second-time lucky gives you a first time lucky!
Fill 4 buckets with the right amount of mix water in advance. Cut all the bags open first - they have built in spouty bits which pull out like a nozzle so you add it steadily to the water - didn't work for me as I was trying to empty while holding the other end of the bag between my legs and sds in the other hand, but if you have both hands as a bag pourer it might work better. Then pourer can go and spread while mixer mixes for the rest of the 2 mins. Some of the advice I've seena round suggests leaving the mix for 5 mins and remixing - I had better results not doing that and just pouring it straight after the first mix.
snipped-for-privacy@mailbolt.com coughed up some electrons that declared:
Did it today. Bloody hell - that stuff is *good*.
Bathroom (3m2) one bag. Nearly perfect. One high spot in the original screed means I need a second layer (if I'd know I'd have done a 2 bag mix obviously). But a quick call to F Ball technical told me how to add a 2nd coat correctly. Will do that tomorrow. Really was a 20 minute job, having prepared well.
P131 primer is probably essential IMO - certainly prevented the 300 getting sucked dry. At 16C I got a good 20 mins plus working time - no rush at all.
I made a TEE bar out of 2 bits of 18x30ish wood. The tee was about 50cm long and I set 3 roundhead screws into the corner on the edge - one middle, one each end to give a similar rake to the one you made.
It worked well enough - I slopped the 300 down in batches, pushed into the sides and corners with the rake then pulled it back roughly level. Repeat until room done...
I was lucky - the other room (7m2) was a two bag mix - that had a 40l bucket nearly brim full. That room worked very well save two slight oversights:
a) I had to "dam" an opening to stop the 300 buggering off into another area - used a bit of wood wrapped in masking tape. Good idea so far. However, next time I will pack play-doh underneath - the 300 found the 2mm gap underneath and buggered off anyway, leaving a sq ft hollow behind it. Minor and easily filled with tile adhesive.
b) Slight wibble in level near the door - 2 sq ft area couple of mm off. Suspect either I did not rake well there or there was a high spot in the underlying screed that stopped it moving freely. Might drop a little bit of
300 in from tomorrows batch and trowell in - or fix with tile adhesive - it's fairly minor.
However, 90% did look like a billiard table. For first go, I was totally impressed. It's done the job better than I expected with a lot less fuss.
I think the main mistake was underestimating the amount by a bag, but I did run a level over it all first, so the mis-estimation wasn't for want of trying.
Anyway, an extra bag tomorrow will make the bathroom perfect (I'm sure of that). The other room has such localised problems it would be a waster to repour the whole room when I should be able to patch correct it.
Yeah - 16C was a very optimal pour temperature. The spikey roller helped too (I could see it knocking air bubbles out) but I dare say one could get a pretty good result without it.
Anyway - I;m sold. Reckon I might bang 3 bags down the hall later...
Thanks for the spot on advice.
Wish me luck next week with the Cempolatex and the slopey new kitchen floor. Somehow I think that none of my hard earned experience will count for anything there! And it's a south facing room...
And it did. The high spot must have been quite high, as it still pokes its little head up a bit, but only to the tune of a couple of mm over about
4x4". If I cared, I'd grind it back with an angle grinder - but the tile adhesive will have no trouble with such a minor bump. Having a generally flat floor is what counts.
And the rest of the floor is mm perfect.
Where I had some let-by through an opening - this time I siliconed the wooden dam in place and filled the hollow and feathered it in. That worked.
I'm tempted to throw 3-4 bags of this stuff down the hall as it will sort of the area where a wall was removed and it changes from screed to quarry tiles, the latter of which have a slump in one corner. Have to dam 5 doors though!
Yes. The only issues I seemed to have were if there was a pronounced lump in the surface being covered. In a couple of places, the Stopgap seemed to ride up over the lump and stay there. We're only talking 1-2mm bulges in
*very* small localised areas. Probably the effect of the stickiness and viscosity of the liquid - once it was up there, it couldn't flow down well enough.
Is there a stock solution to this? One might be to use twice as much Stopgap in a single pour. Another might be to not push it over the high bits but let it creep up the sides as far as it wants...
No - that's next week, hopefully. This week was putting bricks in all the holes in daughter's bedroom (old kitchen, *many* vents), prepping to install door frames, plumbing and making a brick pit for the water joint outside.
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