sand & cement plastering

[b21playa]

What are peoples opinion to this?

Whats the workability of it and is it harder to apply?

Also what should the ratio of plastering sand to cement be?

 

[b21playa]

anyone?

 

[Micilin]

What are peoples opinion to this?

Whats the workability of it and is it harder to apply?

Also what should the ratio of plastering sand to cement be?

I prefer s/c because it is cleaner work, You can go to your tea and leave a bit on the spotboard too, unlike hardwall etc. If skimming it, you can add waterproofer.

This allows you to float for a full day, or float out a house before you turn around and skim it.

Rendering outside is my favoured work, be it traditional render or monocouche.


It is a bit heavier than your lightweight gypsums like hardwall , but when you are using it for a while, you take no notice.

Wrkability depends on the sand and how it is mixed. You can get a lovely , lively bit of gear or some really dead, greedy sand. I don't really know how to answer if it is 'harder to apply'. You need to get used to it, but it's the same with any material , I suppose.


If you are floating upstairs, you need to get the mixed gear up to you, which takes a bit more work than carrying a few bags of hardwall up and filling your water upstairs.

Where do you intend using it might be a better place to start answering your questions?

And generally, floating is 4:1 or 5:1, but it depends on the application and how many coats etc.

 

[b21playa]

If you are floating upstairs, you need to get the mixed gear up to you, which takes a bit more work than carrying a few bags of hardwall up and filling your water upstairs.

Where do you intend using it might be a better place to start answering your questions?

And generally, floating is 4:1 or 5:1, but it depends on the application and how many coats etc.

It is going to be used on the whole house, its all back to bare brick - will hopefully work out cheaper then browning/bonding.

First step is to apply it to all rooms upstairs, i was told one application.

Would be skimmed a week later.

 

[Micilin]

Presumably old brick, not new build block?

 

[b21playa]

Presumably old brick, not new build block?

correct

 

[Micilin]

Presumably old brick, not new build block?

correct

Okay, hacked off to bare brick.

Day before plastering, brush down with wet brush to get all dust off, getting into any chases or old switch box holes etc. Fill with s/c holes, loose beicks chases etc.

To render, use 5:1 mix with waterproofer (check drum for waterproofer mix).

You can brush down the wall with water to kill the suction, or a weak PVA or SBR solution, 5 :1 just before you render. You should be able to get then walls in one coat, but you may find it easier to give the wall or two a tight scratch coat and then come straight back on to it with a float coat.

The waterproofer will do three things:

keep out damp

kill suction for easier skimming

improve workability.

Don't use lime with waterproofer.

You will need to keep the stuff in the mixer for a while to get it nice, but be careful not to leave it in too long or it will get too runny and have no body. It should sit up nice on your hawk, and hold a pattern if you pull a trowel through the spot board.


Depending on your experience, coat teh wall in sections and rule off, or pull screeds first and then infill. If right handed , always apply floating from right to left . Rub up with devil float, and clean off ceiling lines etc.

Flatten with trowel when gone off a bit to leave nice for skimming.

Skim after 24 hrs

 

[b21playa]

Cheers

before skimming does pva need to be applied?

 

[Micilin]

"before skimming does pva need to be applied?"

Not if you have waterproofer in it.

You will have a key if it is devilled up, and there will be no bad suction, you can skim it from next day or leave it as long as you like.

Even s/c without waterproffer is okay suction wise for a day or two, especially this time of year , depends really on backgound and humiidity etc.

You can alway test with a splash of water, or throw on a small return or back of a cupboard first to see how it pulls in.

 

[Tozzy]

What are peoples opinion to this?

Whats the workability of it and is it harder to apply?

Also what should the ratio of plastering sand to cement be?

Well here is my result:

I messed up a couple of times though because you see the problem with sand and cement, is that it's quite heavy and tricky to apply. You have to erm, what I call, 'have your way with the cement' if you know what I mean lol. Show the mortar that YOU are in control. Slap it on the wall and do exactly what you want it to do. If you aren't confident about it, then don't do it. It'll go everywhere. And yes, there were quite a few occasions where the whole lot slipped off my hawk and onto the floor , but that's normal anyway .

Another problem, is that with it being heavy, it can sag; not too much much though, but a little noticeable. What I did though is just leave it about 5 minutes, get a cuppa and go back and spread it so it's even again. By this time, the mortar has had a chance to dry out a little bit.

I would say that workabilty is very good. I got it nice and smooth .

My ratio was 3:1, but you can probably get away with 4:1 and maybe even 5:1.

 

[Micilin]

just finished a 430 sq mtr two coat lime based finish from prep to gone in 3 weeks. 15 days for whole job. Now thats rendering. just done a you tube thingy at decopierre II

How many of you in the gang? - were the rates any good?