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Plastering & Rendering

Correct mix for sand cement render?

Anonymous user 23/02/2024 - 3.04 PM

Hello folks, I have stripped my 1890s property back to brick work on the inside. The walls are in decent shape but uneven. Before any plaster goes on, I'd like to apply a layer of render on the inside. Is the right way to do it? 1. Clean wall with brush to ensure no dust / debris 2. Knock up render: 4 parts sharp sand + 1 part cement + 0.3 parts Cementone SBR (this will waterproof it and ensure no moisture comes from the outside) 3. Apply a layer maximum 2cm thick to the wall, scratch it 4. Let it settle and dry out 5. Leave overnight to dry, check back in morning, hopefully still on wall, apply a second layer where necessary (wall is very uneven and some places might need more than 1 layer) Is that about right right?

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3 Answers

ADR Property Maintenance

Rating: 5 out of 5

Boston

on this type & age of property applying a cement render is the worst thing you can do. especially with a water proofer , this age of building need to breathe not be sealed. good luck Alex

Answered3 August 2016

BuildWorks

Rating: 5 out of 5

Ringwood

As stated by the other tradesmen, in all probability your mortar in the brickwork will be sand lime and horsehair, lime mortar allows the buildinfb to breath and therefore if you render with cement based mix you will not allow the walls to breath and will create damp problems which will result in your render and plaster blowing off the wall or worse damaging the brickwork. If you want to render you will need to do so with lime render mix, which requires mich greater set time in between coats and plastering, as the render actually hardens by carbonation as opposed to a chemical set as with cement. You will need to use lime putty mixed with coarse sharp sand for base coat and lime putty with washed sand for subsequent coats. You may also want to add synthetic fibres to the base mix to aid flexibilty and strength.

Answered10 August 2016

Greenstreet plastering

Rating: 5 out of 5

Dover

No cement whatsoever Sand and lime is all that's needed

Answered18 June 2022