should I use waterproofer in my cement mix

colbags · 11 Sep 2009

Hi all

I am building a dwarf wall for a conservatory and have worked out from browsing other posts that I need a mix of 5-1 for my mortar & 4-1 for pointing (building sand - cement). 1 post said that they add waterproofer to the mix. Is this necessary and if so how much should be used with each mix.

Also

How much plasticiser should be added to each mix of mortar?

thanks for Any advice

mater · 11 Sep 2009

you can point your bricks as you are going with the same mix 5-1 , just a splash off plasticiser is fine in a small mix, if a cavity wall there is no need for waterproofer

^woody^ · 11 Sep 2009

Do you plan on adding waterproofer to the clay for the bricks too?

If no, then what good waterproofing the mortar?

Use plasticiser as directed on the container. Too much and you will be using sticky blancmange to lay the bricks with.

Typically a table spoon of concentrated fairy liquid per mixer load, or a teaspoon per barrow load.

But it does depend on the sand - you may not actually need any plasticiser

And your mortar mix is the same for laying and jointing. You don't use two separate mixes - what other posts have you been reading?

spread9264 · 14 Sep 2009

personally i always add waterproofer to my mixes.it costs about the same as febmix.it says on the instructions hows much you need to add.but it is usaully about half a cup to a cup full.have used fairy before makes a nice fluffy mix.but is supposed to kill the cement. simon the builder

^woody^ · 14 Sep 2009

spread9264 said:
personally i always add waterproofer to my mixes.

Why?

What about the bricks - are they waterproof?

You can increase the chances of effloresence with inappropriate use of waterproofing admixes.

But above all, waterproofing admixes are intended for RENDER not bricklaying

stuart45 · 14 Sep 2009

Generally mortar joints in brickwork should allow moisture to escape from the wall, and shouldn't have waterproofer added. The main problem with washing liquid is that there is not really a set measure to add, and often too much is put into the mix. With plaz it is easier to add the required amount.

spread9264 · 15 Sep 2009

never had any problems before.but i can see what your saying.if bricks are blue brindle or hard engineering bricks it could run so then i would use febmix.otherwise i use rendamix which can be used for sand&cement mixes its a sort of febmix/waterproofer in one.on site work we had to hide the fairy as this was not allowed but makes a nice mix all the same.the mixing is let the mixer knock it in slowly.do not add loads of water first as it will not be fluffy. simon the builder

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should I use waterproofer in my cement mix

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