OSB timber framed extension

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richspread87

New Member
Hello.

I have recently rendered a timber framed extension.

It had been clad in OSB and the builder had done the prep work.

Membrane fixed to the OSB and the metal lathe fixed over the top of that.

Then rendered. Application and finish was fine but it has in a very short amount of time cracked like crazy paving.

Any input as to why and how to rectify the issue would be really appreciated. Really scratching my head over this one. Something must have gone a miss in the prep before rendering but I've no idea what??

Cheers
 
basically.... its all got to come off.

timber and sand cement doesnt go.

timber will swell at a different rate to metal lath and sand cement as i guess is what youve used doesnt move atall im.afraid.

correct build up.
osb
membrane.
25mm battens creating a cavity.
rendercarrierboard
light weight flexible render.

hope this helps
 
basically.... its all got to come off.

timber and sand cement doesnt go.

timber will swell at a different rate to metal lath and sand cement as i guess is what youve used doesnt move atall im.afraid.

correct build up.
osb
membrane.
25mm battens creating a cavity.
rendercarrierboard
light weight flexible render.

hope this helps
Is the cavity not just for air flow then? I suppose it keeps the s and c away from the OSB in the event of swelling and contracting?

Also, if the laths are in place would it be possible to use EML across the lath instead of boards? I've seen a lot of that mentioned. Can't quite get my head around how the render is suitably stable using EML with a 25mm cavity behind it?

Thanks for your reply
 
Is the cavity not just for air flow then? I suppose it keeps the s and c away from the OSB in the event of swelling and contracting?

Also, if the laths are in place would it be possible to use EML across the lath instead of boards? I've seen a lot of that mentioned. Can't quite get my head around how the render is suitably stable using EML with a 25mm cavity behind it?

Thanks for your reply
the cavity is for airflow yes. and prevents vapour build up.

forget using eml and laths.. as above us a render carrierboard and a thincoat render system.
 
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