Porotherm clay blocks

[Russell griffiths]

Hi 

in 2006 I built our old house using timber frame with a brick outer skin, so now we are putting in an application for a new build I thought I was 100% going down this route again, that is until I passed a site a couple of miles down the road from us and they are using the clay blocks with the thin joint system, just wanted to know if anybody has any good or bad things to say about them. 

Cheers russ. 

[AliG]

I am currently building with these, so maybe a little early to say.

 

Negatives

 

Whilst they go up very fast in theory, that is only if you have a flat wall with no doors windows etc. The measuring and cutting takes pretty much the same time as with any other block work.

 

They are somewhat more expensive than standard blocks. As I didn't price up the job with standard block work though I cannot be sure of the comparison. I would guess around 1/3 more per square metre of wall.

 

When I look at the Celotex U-Value calculator, despite being advertised as having better insulation properties due to being hollow, it actually makes negligible difference, they are still blocks. The U-Value is 0.01 better using these or indeed aerated blocks rather than standard blocks.

 

Positives

 

The thin joint system produces a much neater job with very little mortar overspill etc compared to conventional blocks.

 

The system doesn't require any ventilation in the cavity avoiding ugly perpend vents in the outer skin that are required with timber frame.

 

They allow you to have concrete upper floors.

 

They should perform much better in terms of sound transmission than timber frame.

 

You can work as long as the temperature is above freezing.

 

You can just build the inner skin and put the upper floors on to get watertight and then build the outer skin whilst work continues inside.

 

 

 

[jfb]

i've never used them but I have heard that your bricky needs to be very accurate in laying them down as there isn't so much room for error.

[thomas]

I've also heard they are very bad for air tightness and you need to parge both sides