Sand & cement or hard wall?

[macadonald]

Hi guys,

About to get a plasterer in to do most of our internal rooms in the house. I've already removed all the plaster right down to bare bricks. 2 plasterers have given quotes. one quoted using sand and cement as the base coat/scratch coat and the other suggested using hard wall. Is there a preferred material for the scratch coat. I would imagine hard wall would be easier and possibly cheaper.

Thanks

 

[Richard C]

Sand and cement base/scratch coat is traditional & the best IMO. Hardwall will be also be fine, I use it over new block work but prefer sand/cement render over old brick/block walls. Hardwall will certainly be a lot easier for some to work with but it won’t be cheaper & is not an advisable option on solid brick external walls.


PS: don’t tell Building Control you removed all the internal plaster from external walls & don’t have any inspections on any other work you’ve notified before you’ve re-plastered & made it look like it’s not just been done or you could get an expensive shock!

 

[macadonald]

Mr C

Can I ask why hardwall is not an advisable option on solid brick external walls? This is exactly what I have. Double skin brick, but with no cavity...

 

[Richard C]

Solid brick walls tend to hold moisture & the original traditional plaster finish would have allowed the wall to “breath”. If you get the slightest hint of moisture in the wall, Gypsum based plasters will fester & eventually fall off as they will not tolerate damp.

You may like to consider lining the external walls something like Thermaline with an integral vapour barrier which will also upgrade the insulation & prevent condensation due to relatively cold, solid walls; Building Control will probably insist on this if they find out you’ve stripped the walls right back.

 

[roughcaster]

Solid brick walls tend to hold moisture & the original traditional plaster finish would have allowed the wall to “breath”. If you get the slightest hint of moisture in the wall, Gypsum based plasters will fester & eventually fall off as they will not tolerate damp.

Absolutely spot on advice above from Rich'.
To you Mr Mac,, go with the plasterer who suggested a sand/cement scratch coat first,, that's always the correct material for scratch coating onto old, suspect, brickwork. This would normally have a waterproofer in the mix,,, it's essential. You can then use Gypsum Hardwall with no problems. It's not any easier though, whether using either Hardwall or cement render,, both require similar skills, and the cost wouldn't be much different in the long run. There are no cheap options when having a job done properly.