Movement joint

[Jaxta1]

Would a movement joint be required at all on a 3m x 8m extension made on concrete blocks?

Cavity wall, both internal and external with blocks and external rendered.

 

[themiddleagedun]

I can't recall ever seeing one on a domestic extension. So, no.

 

[tony1851]

As above, prob. not. But if your outer skin is built in aac block, and the mortar is a little too strong, you might get a narrow crack.

Manufacturers recommend movement joints for those blocks at 6m intervals, but that's probably to cover themselves. Rarely see them in domestic work.

 

[Jaxta1]

Thanks Tony,

Don't think I'll bother, like you say I don't see them on similar extensions I've looked at.

What type of blocks would you recommend? I'm trying to keep wall to 300mm max width? I need to learn about u values but it seems daunting!