Floating over thermalite blockwork

[essexandy]

Sand and cement wins hands down every time why we have change a winning formula is beyond me.
Oh I know knauf,larfarge and Bg lobbying ministers hence dab and dot which is fecking shite and still cracks.

I totally agree Henry, S&C almost every time as material of choice.
Speaking to a BG rep a while back he said that BG wanted to re-establish wet plastering as the "way" most jobs were done. Although he agreed that the level of skill within the trade was a problem.

But not on lightweight blocks I suspect.

I would and in fact have.

 

[bubbles65]

I totally agree Henry, S&C almost every time as material of choice.
Speaking to a BG rep a while back he said that BG wanted to re-establish wet plastering as the "way" most jobs were done.

Seeing as you can produce plasterboards with a synthetic gypsum and BG are sitting on huge deposits of the natural stuff, they would do wouldn't they :RpS_thumbup:

 

[nickelarse]

for currier who mentioned it a bit earlier and anyone else getting into knauf products, for some reason mp75 doesnt pull in quick on high suction blocks or bricks. so personally, if the job will let you use a one coat plaster then its ideal, if not then if you can get it a good price, which if you speak very nicely to a rep you should be able to, then its nice gear to float with and skim up the same day

 

[nickelarse]

I totally agree Henry, S&C almost every time as material of choice.
Speaking to a BG rep a while back he said that BG wanted to re-establish wet plastering as the "way" most jobs were done. Although he agreed that the level of skill within the trade was a problem.

my favourite gear to use by far but has an annoying tendancy to crack more than gypsum

 

[Curry]

for currier who mentioned it a bit earlier and anyone else getting into knauf products, for some reason mp75 doesnt pull in quick on high suction blocks or bricks. so personally, if the job will let you use a one coat plaster then its ideal, if not then if you can get it a good price, which if you speak very nicely to a rep you should be able to, then its nice gear to float with and skim up the same day

so you dont need to prime celcons first? we have been using gypprime when using MP75 but are you saying we dont need to?

 

[jamesthefirst]

Any high suction backgrounds need to be controlled so as to get a good flat level finish on your floating before being able to comfortably skim it. As I work on my own and have to labour too I sometimes dab boards but prefer a solid job.
used BG one coat plaster for about 5 years until I discovered floating with Knauf one coat and skimming with FP90. I know this is expensive way of doing it but the one coat does not pull in too fast and also sticks to anything.
thistle dri coat is again nice to use and skim but bloody expensive.

 

[essexandy]

my favourite gear to use by far but has an annoying tendancy to crack more than gypsum

Not if you keep the S&C nice and weak

Any high suction backgrounds need to be controlled so as to get a good flat level finish on your floating before being able to comfortably skim it. As I work on my own and have to labour too I sometimes dab boards but prefer a solid job.

Sorry James but that just isn't true. I've never primed a Celcon, Thermalite or Durox wall before floating with S&C, as I've said many times if you use box screeds there's no need to worry about suction. It's only those that rule freehand that have issues with floating these blocks.
And if you work on your own as I have many many times using screeds means that you can even stop part way down a wall to mix more gear if necessary.

 

[jamesthefirst]

Not if you keep the S&C nice and weak



Sorry James but that just isn't true. I've never primed a Celcon, Thermalite or Durox wall before floating with S&C, as I've said many times if you use box screeds there's no need to worry about suction. It's only those that rule freehand that have issues with floating these blocks.
And if you work on your own as I have many many times using screeds means that you can even stop part way down a wall to mix more gear if necessary.

So what is in your S&C mix that stops shrinkage, cracks etc and controls the suction when skimming onto it?

 

[Nico69]

Sorry , i do think the woman of the house is a lot fussier than your average foreman ..

 

[essexandy]

So what is in your S&C mix that stops shrinkage, cracks etc and controls the suction when skimming onto it?

I use good quality sand with Feb DH and a single capful of Everbuild 3:1 in it. The Everbuild 3:1 is not there to waterproof it but because it's a great plasticiser even at very low dosages.
If you seal up the substrate before floating with S&C it will create suction when skimming not lessen it. If you just float Celcons as I've said, without primer or soaking them and then allow the S&C to cure as you should then you won't get a fierce suction. Think about it, where do you get the most suction from when skimming on cured S&C?
It's always on the lintel where there's no suction at all when floating.
Sorry for babbling on, as being a spread you'll already know all that.

 

[jamesthefirst]

Sorry Andy you've already answered that. Keep it nice and weak. Thanks

 

[essexandy]

Also if they're using those all steel type Catnic lintels I'll go ahead filling as many lintels in with a stronger S&C mix to still give a bit of suction when floating. I don't mean just going ahead on the day but on a one off house I'll try to get there as soon as the roof is on and flooring down or on bigger jobs I've filled them out in twenty plus houses ahead of myself so they're nice and dry to float over.

 

[jamesthefirst]

I use good quality sand with Feb DH and a single capful of Everbuild 3:1 in it. The Everbuild 3:1 is not there to waterproof it but because it's a great plasticiser even at very low dosages.
If you seal up the substrate before floating with S&C it will create suction when skimming not lessen it. If you just float Celcons as I've said, without primer or soaking them and then allow the S&C to cure as you should then you won't get a fierce suction. Think about it, where do you get the most suction from when skimming on cured S&C?
It's always on the lintel where there's no suction at all when floating.
Sorry for babbling on, as being a spread you'll already know all that.

Yes I agree with all of the above, you are not babbling just being polite. and I assume unlike me you are constantly covering large areas so you use S&C for cost or you just love the stuff?

 

[Arti]

Andy. on the pics on ya website of the internal stuff when ya floating the room with S&C are you using box screeds marra?

 

[malc]

to control suction weather it be sand and cement or hardwall, i would apply in two coats so that i could rule in easy. i usually rule in freehand

 

[nickelarse]

so you dont need to prime celcons first? we have been using gypprime when using MP75 but are you saying we dont need to?

that is what i am saying yes

if you use mp75 over high suction blocks or bricks and use it as a one coat then it still takes 3-3.5 hours to finish, which is almost the same as blocks. its just a bit less greasy when troweling.

 

[nickelarse]

Not if you keep the S&C nice and weak

we used to do 6-1 by hand, cpi more recently by pump. i believe cpi is 6-1-1. ceiling lines more than anything. and occasionally along conduits, but i think thats more to do with them being left too loose

 

[essexandy]

Yes I agree with all of the above, you are not babbling just being polite. and I assume unlike me you are constantly covering large areas so you use S&C for cost or you just love the stuff?

Nowadays I'm not covering the metreage a year that I used to but I'll persuade clients wherever possible (full new build house) to let me quote for S&C, knowing I'll be able to undercut anyone using D&D and skim. Plus I prefer using it to any other material.

Andy. on the pics on ya website of the internal stuff when ya floating the room with S&C are you using box screeds marra?

Yes mate the only time I rule freehand is on tiny little walls, say up to 1.2m wide.

we used to do 6-1 by hand, cpi more recently by pump. i believe cpi is 6-1-1. ceiling lines more than anything. and occasionally along conduits, but i think thats more to do with them being left too loose

Yeah cappings can be a pain and do really need at least 3mm coverage, I don't find the ceiling lines to bad as long as they are cut out nice and deeply so the ceiling and wall are separated.

 

[Curry]

that is what i am saying yes

if you use mp75 over high suction blocks or bricks and use it as a one coat then it still takes 3-3.5 hours to finish, which is almost the same as blocks. its just a bit less greasy when troweling.

thanks ill give it a try some time

 

[plasterman2]

Has anyone used one coat plaster on thermos and is a couple of coats of Pva enough for this aswell

 

[malc]

Has anyone used one coat plaster on thermos and is a couple of coats of Pva enough for this aswell

if you are talking about thistle universal why would you want to kill the suction?

 

[plasterman2]

havent used it before only for a few chases

 

[nickelarse]

Has anyone used one coat plaster on thermos and is a couple of coats of Pva enough for this aswell

im pretty sure we just discussed that??

 

[quinns]

Guys, there is an alternative sytem for use with Celcon, Durox and Thermalite light Aircrete Blocks, Knauf Plano as a backing coat and Knauf Deco as a finishing coat, no primers or bonding agents required, applied to 5-6mm, or MP75 to 11-13mm, hose the wall with water first. visit www.knaufdrywall.co.uk/projection_plasters

 

[essexandy]

Not being funny Quinns but I've never worked on a new build with blockwork good enough to only use a 3-5mm backing coat. Roughly how much does it cost per m2 to use MP75? I'd like to be able to compare it with S&C.

 

[nickelarse]

mp75 works out about the same as hardwall and set, £2.50 a meter ish

 

[Curry]

mp75 works out about the same as hardwall and set, £2.50 a meter ish

Tis quicker though :RpS_thumbsup:

 

[spunky]

And shitter

 

[essexandy]

Tis quicker though :RpS_thumbsup:

But tis it as good? If not then I'm out.

 

[nickelarse]

depends what you call good. if its flat with no holes which i would say is a good finish then its as good. if you want it smooth to touch and shiny then no its not

 

[Curry]

depends what you call good. if its flat with no holes which i would say is a good finish then its as good. if you want it smooth to touch and shiny then no its not

When they are painted they look just as good as a end product. I dont understand the UK's obbsesion with having smooth shiney walls which we then cover in paint which is left slightly mottled.

I am however float and setting with hardwall today because its only a smallish room and you cant just got mp75 in small amounts (except at wickes for £12 a bag)

 

[nickelarse]

i used to get sheffins to order me in a pallet at a time and i used to pick it up when i wanted

 

[00paul]

Gyp prime use 4 hard wall I tend to not uses it unless it is supplied . I pulls tight coat over the wall first then apply another coat which will then hold of a bit gives u time to rule

 

[keirongriffin]

gyprime is by far the best.for best results make sure you seal the walls the day before floating.

 

[SpankySouthport]

Not being funny mate but you must be "only" a domestic type spread to do that, you couldn't survive doing that on site/new build work.

Haha like wtf is pva on site