Sand Cement Render

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blackbirdxx

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Hi,
I have a 1880’s house with solid brick construction which is sand cement roughcast rendered. The exposed walls all seem to suffer from damp problems on the inside where water has been allowed to enter through cracking and is now trapped. All the renderers who have come around to look at the problem have proposed taking all the render off and reapplying new sand and cement with waterproofer. I have my concerns over this proposal and don’t want to undertake all of this work only to have the damp problem reappear. Wondering what you experts feel about the use of sand and cement on solid brick walls….

Thanks in advance
 
You could consider lime render to help it breath. But this is far more expensive than sand and cement.

Sand and cement is normal practice in this situation. Post your location someone on here will be able to help.
 
blackbirdxx said:
Hi,
I have a 1880’s house with solid brick construction which is sand cement roughcast rendered. The exposed walls all seem to suffer from damp problems on the inside where water has been allowed to enter through cracking and is now trapped. All the renderers who have come around to look at the problem have proposed taking all the render off and reapplying new sand and cement with waterproofer. I have my concerns over this proposal and don’t want to undertake all of this work only to have the damp problem reappear. Wondering what you experts feel about the use of sand and cement on solid brick walls….

Thanks in advance
Click to expand...
Ewi ,depending on the property , i will post up some gumf
 
Sand and cement with a waterproofer is to an extent breathable as most renders are. The same would apply if you painted any render or the bricks.

You may still get damp issues with a breathable render because of the brick ties going from the outside skin to the inside skin. Condensation will settle on these bricks.

You will find that this house in the 1800's was drafty and would have needed some ventilation as every room would have an oxygen consuming coal fire. Chances are now this house is fully sealed up with no natural ventilation. Moisture being created with no where to go but settle on cold spots like above.

So I would not worry too much about a re-render, consider positive ventilation or keep the house sealed up tight and install an envirovent unit. About £500 plus installation. They work.

Better still as said install an insulated render system, you will save loads of energy and no more condensation problems but still fit an envirovent unit.
 
Where are you based? If it's the whole house Lime doesn't actually work out that much more expensive. The main thing is making sure that you eliminate any causes of the damp. If it appears to just be cracked render then hack off and use Lime. This will the allow the walls to breath. Putting Sand and Cement back on will just trap the moisture in the wall.
 
Hi,
Thanks to those who responded.....
Yes, the problem walls are south facing and are very exposed. I live in Croydon, south London.
I have been considering K-Rend to allow the walls to breathe but not sure if its worth the extra over S&C. The current render appears quite solid but there must be small cracks to allow the damp through.
 
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