Internal sand and cement float and set

Cornelius

Well-Known Member
Just curious at to what the correct procedure is? Sand cement floating has been pretty much obsolete in my time as a plasterer apart from damp proofing jobs. I learned with toughcoat and now hardwall but have used sand/cement on occasions. I’ve looked through some old threads and there was discussion whether you should put one coat on about 11mm or two coats? I do a tight first and then a tight second on hard wall. But with sand cement should you get two coats on? Or aim for one coat. Depends on background I guess. I’ve normally scratched over block work that’s been hacked off so scratch uneven surface and then top over. Also curing times before skimming? I’ve skimmed next day but seems this isn’t correct, five days was mentioned but doesn’t seem practical to wait that long? Lime or no lime? Feb plasticiser or waterproof in the floating? I’ve skimmed over sand cement and we used a blue damp proofing type waterproofer? I’ve also skimmed over work that just had plasticiser in and it pulled in rapidly fast and was hard to keep up with, you don’t get that problem when it has a waterproof in the float coat? Might seem quite basic questions but a lot of the guys on here in there 20’s and 30’s this practice is just not used anymore. What are the general guidelines for sand cement skimming?
 
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Just curious at to what the correct procedure is? Sand cement floating has been pretty much obsolete in my time as a plasterer apart from damp proofing jobs. I learned with toughcoat and now hardwall but have used sand/cement on occasions. I’ve looked through some old threads and there was discussion whether you should put one coat on about 11mm or two coats? I do a tight first and then a tight second on hard wall. But with sand cement should you get two coats on? Or aim for one coat. Depends on background I guess. I’ve normally scratched over block work that’s been hacked off so scratch uneven surface and then top over. Also curing times before skimming? I’ve skimmed next day but seems this isn’t correct, five days was mentioned but doesn’t seem practical to wait that long? Lime or no lime? Feb plasticiser or waterproof in the floating? I’ve skimmed over sand cement and we used a blue damp proofing type waterproofer? I’ve also skimmed over work that just had plasticiser in and it pulled in rapidly fast and was hard to keep up with, you don’t get that problem when it has a waterproof in the float coat? Might seem quite basic questions but a lot of the guys on here in there 20’s and 30’s this practice is just not used anymore. What are the general guidelines for sand cement skimming?
When I first started all we did was float and set 4 to 1 with waterproofed one coat skim next day
 
Leave s@c finishing 4 schools,hostels,drug dens etc and hospital corridoor..why do u need s@c finish in a house? It's out dated its 4 places wheres theres going to be alot of foot traffic etc..
 
Last time I did internal s@c it was a drug and alcoholics hostel,all party walls were scratched then topped and plain face finish..all other walls in room were hard wall then skimmed..made tons of money was about 12 years ago..theres no demand 4 it now..people dont care
 
Leave s@c finishing 4 schools,hostels,drug dens etc and hospital corridoor..why do u need s@c finish in a house? It's out dated its 4 places wheres theres going to be alot of foot traffic etc..

if customer wants solid wall. Order double the amount of dab lol.

Floatings like Renderering imo. Only 3 in 10 spreads can do it. Amount I’ve knocked back thats 5mm to 30mm all over the shop
 
I'm all for a week's delay and use lime in the mix , two coats
But was brought up one coat if it's a cupboard and skim next day was standard for my dad
 
Last time I did internal s@c it was a drug and alcoholics hostel,all party walls were scratched then topped and plain face finish..all other walls in room were hard wall then skimmed..made tons of money was about 12 years ago..theres no demand 4 it now..people dont care

Only way these days is spraying hardwall imo
 
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Leave s@c finishing 4 schools,hostels,drug dens etc and hospital corridoor..why do u need s@c finish in a house? It's out dated its 4 places wheres theres going to be alot of foot traffic etc..
Damp proofing aswell, plenty of places with damp problems. Definitely better materials to use but not always an option.
 
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Damp proofing aswell, plenty of places with damp problems. Definitely better materials to use but not always an option.
Ye can use limelight tho..wish is shite to use tho..are you wanting to do it as a option to your clients or your own house? Majority people just dont seem to care anymore..theres proper plasterboard fixings now you can buy etc,takes too long to dry out
 
Only way these days is spraying hardwall imo
You can make serious money doing 2 coat lurpy without a machine..if your getting £8m2 + you can easily rack up £350 and be done 4 2..but that's why I dont touch it anymore,was getting £8m2 about 12 years then in 2008 it went down to £4.50!!!! f**k that..its crept back up now to £7.50-£8 but I wont touch it as it should be £12 m2 as it's a specialist trade but there dont want to pay it
 
Ye can use limelight tho..wish is shite to use tho..are you wanting to do it as a option to your clients or your own house? Majority people just dont seem to care anymore..theres proper plasterboard fixings now you can buy etc,takes too long to dry out
I might be doing some work for a damp proofing company and although the technique of floating isn’t a problem or confusing my understanding of sand cement internal work is poor. With the drying times and additives etc? I’ll most likely be working off a spec but doesn’t harm to know what’s right and wrong.
 
I might be doing some work for a damp proofing company and although the technique of floating isn’t a problem or confusing my understanding of sand cement internal work is poor. With the drying times and additives etc? I’ll most likely be working off a spec but doesn’t harm to know what’s right and wrong.
Was looking for a new contractor and rang three different jobs , all were skim green and not reskimming whole walls
 
Was looking for a new contractor and rang three different jobs , all were skim green and not reskimming whole walls
Yeah I used to do insurance work and it was a hack off up to 1.2 high and float the bottom half and patch in. Lazy really but that’s what the surveyors would price for.
 
Most walls aren’t much thicker than 11 -14 mm but if it was say upto 27mm thick I’d do a scratch coat then go back and top it up upto 13mm Ish you should be fine in one go though mate
 
Most walls aren’t much thicker than 11 -14 mm but if it was say upto 27mm thick I’d do a scratch coat then go back and top it up upto 13mm Ish you should be fine in one go though mate
I’d be seriously worried if someone would float that depth in one coat! I think you’re on the wind up again ;) 27mm lol. What I meant was with hardwall you coat the blocks then go over it again and rule off. Do people do the same for sand cement etc?
 
5/1 sand .cement with wp to control suction for skimming . leave as long as you can but a minimum of three days should be ok otherwise you will get cracks as the float coat shrinks and cures . Needs a good rub up with a devil float to ensure that the finish does not shell . If doing a scratch coat first make sure that the following coats are weaker in mix that the preceding coat. Just a quick answer.
 
there is a local developer , Moody homes, that still wants float and set, traditional build they call it. more like a 60s build to me.
when we float sand and cement it does depend on the background suction from the different blocks. high / medium suction, a tight first coat, with a second coat then ruled off and ruled in. 1st coat kills the suction second coat will rule easy. 1 wall a time.
low suction , i may 1 coat, it depends on the area.
floating was a good earner for a plasterer.
 
Most walls aren’t much thicker than 11 -14 mm but if it was say upto 27mm thick I’d do a scratch coat then go back and top it up upto 13mm Ish you should be fine in one go though mate

the only time i have floated about 27mm was for fire proofing using Carlite Browning.
 
5/1 sand .cement with wp to control suction for skimming . leave as long as you can but a minimum of three days should be ok otherwise you will get cracks as the float coat shrinks and cures . Needs a good rub up with a devil float to ensure that the finish does not shell . If doing a scratch coat first make sure that the following coats are weaker in mix that the preceding coat. Just a quick answer.
Ok so you’ve floated your wall with waterproof in it and left it to cure for a few days minimum, does it need Pva to skim over to control suction and create a bond? Or skim straight over because the waterproof will slow the suction and the devil scratch creates a key?
 
Ok so you’ve floated your wall with waterproof in it and left it to cure for a few days minimum, does it need Pva to skim over to control suction and create a bond? Or skim straight over because the waterproof will slow the suction and the devil scratch creates a key?
Don’t pva will hang like f**k!
 
Ok so you’ve floated your wall with waterproof in it and left it to cure for a few days minimum, does it need Pva to skim over to control suction and create a bond? Or skim straight over because the waterproof will slow the suction and the devil scratch creates a key?
read what i wrote again......... :coffe:.
 
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Ok so you’ve floated your wall with waterproof in it and left it to cure for a few days minimum, does it need Pva to skim over to control suction and create a bond? Or skim straight over because the waterproof will slow the suction and the devil scratch creates a key?

i always devil float mine, but a lot of plasterers now float up smooth they say that multi keys to plasterboard . therefore why do you want to put a load of lines which will slow your skimming down ?
we where sharing a site with a gang from Southend,who floated up smooth, we floated a lot quicker then them but they came back on the skimming. overall about the same areas and same time.
 
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i always devil float mine, but a lot of plasterers now float up smooth they say that multi keys to plasterboard . therefore why do you want to put a load of lines which will slow your skimming down ?
we where sharing a site with a gang from Southend,who floated up smooth, we floated a lot quicker then them but they came back on the skimming. overall about the same areas and same time.
I don't devil float , I use neat sharp , leaves a course open surface
 
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