Is modern breathable render a scam

[Spadez88]

Hi,

There seems to be a lot of conflicting information online. There doesn’t seem to be any doubt that putting sand and cement on a solid wall Victorian is a dumb idea but is it really the case that you have to resort to lime render?

A lot of companies quote that their render is breathable. Krend, Parex, Weber, Vimark, Baumit etc then refuse to publish any stats about the breathability of their product. It seems like it’s a positive quality you want in your render for older properties but none of these guys can back up their claims.

Modern breathable render. Does it exist or is traditional lime rendering the only serious option for Victorian properties even today.

[dewaltdisney]

I think these days the most common used render is Monocouche. But like all renders it depends on the stability of the substrate wall as any degree of movement will cause cracks which in turn will allow moisture in to cause delamination and more cracks. Victorian houses tend to move as the bonded brickwork walls, although strong will hold more moisture than a cavity wall which vents both sides of the outer skin. I think that is where the problem is in that a coat of render will trap in any moisture and wet bases renders will add to the problem perhaps. The Monocouche comes in premixed tubs with the colour already added and it is not wet just a strange lumpy mix. It gets towelled on and levelled and cures to a hard shell. Most rendered new build houses all have this. It is expensive though and a detached house will be £15K up, much of the costs is the necessary scaffold.

I always bang on about Marley Cedral. This is the cement board siding that will allow an air movement behind but protect against weather. Considerably cheaper than Monocouche it will give a pleasing finish although it might not suit the Victorian style of building. Have a look at this to get an idea https://www.cedral.world/en-gb/cladding/

I hope this helps

DWD