Plasterboard

[miah]

Thank you Mosona,

How much lime would you use in quantity i.e less than cement?

Many Thanks

 

[miah]

Thank you Mosona,

How much lime would you use in quantity i.e less than cement?

 

[DavidH]

You can get some nice results using a technique called "bagging" or "sponging" where the render applied with a trowel and then sponged over to get a rougher more traditional finish. Although it needs a little practice it can be done by the amateur (honest). The render is made from a mixture of plasterers sand, cement and lime in something like a 9 2 1 mix (9 sand, 2 cement, 1 lime). The walls do need a good clean and wetting before hand.

If you are after a perfectly square straight finish then the render (traditionally) was applied as a base coat to give a nice flat surface allowing for even suction when the plaster was applied and hence helping to stop any cracking. This is important if you have a mixture of background material, i.e different mixtures of brick or blockwork.

 

[masona]

1 part cement
1 part lime
6 parts sand

We also use lime for Glass Blocks laying for elasticity to stop shrinkage and cracking.

 

[DavidH]

I was following the techniques in a groovy little book called Plastering and Rendering (basic repairs and skills) by Kim Kennerson (bargain at 2.99)

He suggests a 9 2 1 mix, which is what Ive used but I appreciate a weaker mix may be appropriate for different backgrounds.

He even goes so far to suggest a 6 2 1 if the sand is not of good quality.

However I am quite willing to bow to the voice of experience .........

 

[masona]

I've found this website ,for more info.

In the old days it used to be 1:2:9 is okay but found 1:1:6 ratio is most common used for anything and easy to remember

Quoted from the website above,

The Smeaton Project, a research programme commenced by English Heritage, concluded that a 1:1:6 (cement:lime:sand) mix is unlikely to segregate, while a 1:2:9 mix will almost certainly fail. As the cement proportion is reduced further, the mortar will certainly fail.

Now chuck that book in your next car boot sale

 

[DavidH]

Looks like I will be sitting back and waiting for all my render to crack and fall off

Not wanting to waste my 2.99, I think I will amend the offending page!

 

[miah]

Thank you all.

I have another question though, recently we had our front bay windows replaced, when they took the frame off some of the plaster had come off.

It was patched with sand/cement i believe they did only 1 coat.

Shall I get some one to to 2nd coat but this time using Lime because I read in the weblink by Mosonan and it says......

lime has benefits because of its flexibility and its porosity; it helps moisture that has penetrated a wall to evaporate.

Appreciate your advise.

 

[masona]

Looks like I will be sitting back and waiting for all my render to crack and fall off

Don't worry about it too much,it won't happen unless your property was built many years ago when they used to use lime in the bricks mortar walls when they was a lot of movement plus footing not being deep enough etc.

Shall I get some one to to 2nd coat but this time using Lime because I read in the weblink by Masona and it says......

lime has benefits because of its flexibility and its porosity; it helps moisture that has penetrated a wall to evaporate.

I think this will be pointless now as the sand/cement will stop the lime penetrating into the wall to evaporate.Sand/cement is ideal around windows for strenghten,just smooth it off with finish plaster.But having said this there's nothing stoping you using lime if you want,sometime we go over the top

 

[miah]

Hi,

When rendering using sand/cement for internal walls in side the house, how many coat do you have to put?

Thank You.

 

[masona]

Normally 2 coats would give you approx 1/2" or 12mm then your finishing plaster on top.

 

[miah]

Thanks Mosonan,

I wanted to take off old ceiling down for re-plastering.

Can I go ahead and do this - is there any thing I need to know before hand apart from wearing safely goggles, mask, etc.....

The reason I want to do this is obviously to save some money from the my plasterer.

Thanks

 

[masona]

I wanted to take off old ceiling down for re-plastering.

If the old ceiling not too bad and you don't fancy the mess you can put plasterboards over the old ceiling with plasterboards screws but would need to know where the joists & wire cables are.

If you do take the old ceiling down most people have accident on step ladder after losing balance,I find it easier with a small tower or step ladder platform type.

Also this would be the chance to put in extra electric wiring or inspection if need be...........

 

[miah]

Plasterer also said the same thing.

The ceiling is extremely bad, after taken the tiles off we've noticed a lot of patch on the ceiling, plus there were a lot of cracks in some area as well.

And furthermore, in some areas it looks like its going to fall off!

2ND QUESTION - on the internally wall we've also noticed that there are lot of cracks on them but the condition is sound, we were just thing of skimming it it, is that OK?

The plasterer said it should be fine but I just wanted a second opinion.

Many Thanks

 

[masona]

2ND QUESTION - on the internally wall we've also noticed that there are lot of cracks on them but the condition is sound, we were just thing of skimming it it, is that OK?

Yes,that's okay

Regarding the plasterboards I always take down old ceiling,it's messy but easier putting plasterboards back up.If you're going to do the plasterboards you can hire a plasterboard props which hold the sheet up while you're fixing it.