Chipped back a lower render to a dashed wall (this was a 2nd coat - left is a scratched 1st coat) I understand a 5 to 1 mix is about right. I understand that I might need a lime mix (what is the substitute for lime - I have only about 5 yards to cover to complete this job. The important ? is mixes and do I need a water proofer, how much and a substitute for lime. I will take a pic of the area to give you an idea
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Render mix and additives ?
- Thread starter johnscts
- Start date
Chipped back a lower render to a dashed wall (this was a 2nd coat - left is a scratched 1st coat) I understand a 5 to 1 mix is about right. I understand that I might need a lime mix (what is the substitute for lime - I have only about 5 yards to cover to complete this job. The important ? is mixes and do I need a water proofer, how much and a substitute for lime. I will take a pic of the area to give you an ideaAny help please on this project I have; would like this done before the winterises in. I understand from the past - 2 x cement. 4 and half builders sand. 2 Lime (what is the substitute for that, and is it needed) 4 & half sharp. This again is for the render in the picture. Many thanks in advance
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dontbelieveawordofit
you intend plastering it flat?
if so the surface looks as if the finish will be proud of the dash.
this isn’t good and will transport rainwater into the wall.
ideally you need to remove the scratch coat too and redo the section in one coat, so the finish level is not proud of the dash.
builders sand with a ratio of 4 1/2 sand 1 cement and 1/2 lime.
or 4 1/2 sand 1 cement and waterproofer in the mix.
if so the surface looks as if the finish will be proud of the dash.
this isn’t good and will transport rainwater into the wall.
ideally you need to remove the scratch coat too and redo the section in one coat, so the finish level is not proud of the dash.
builders sand with a ratio of 4 1/2 sand 1 cement and 1/2 lime.
or 4 1/2 sand 1 cement and waterproofer in the mix.
OP,
Your dash should have stopped with a plastic BellCast, and all below the BellCast hacked off back to masonry.
What you have will be wicking up water to bridge the DPC and cause possible damp issues inside the room.
Fwiw: using cement in render is an older discredited method of rendering. S&L render is the way forward.
Your dash should have stopped with a plastic BellCast, and all below the BellCast hacked off back to masonry.
What you have will be wicking up water to bridge the DPC and cause possible damp issues inside the room.
Fwiw: using cement in render is an older discredited method of rendering. S&L render is the way forward.
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