Advice for rendering a part masonry, part timber dormer

Share this page

H

Homeowner2022

New Member
I need to get a new dormer rendered (Weber monocouche), however I'm after some advice on how to prevent cracking where two different materials meet.

The front of the dormer is medium density block, but the cheeks are timber frame with OSB board. How do I prevent cracking at the corner where it meets. And any cracking generally due to the differing expansion/movement of the two materials?

I've uploaded a photo for clarity. Thanks.
 

Attachments

  • Advice for rendering a part masonry, part timber dormer
    Screenshot_20221012-073709-418.png
    2.9 MB · Views: 289
What a crappy fix. Yes to a carrier board, but I think better to batten and tile it with an vertical edge flashing over the rendered blockwork.
 
Might need to sort Lead out ....
wrong on dormer .
@ should be soakers ...@ any lap on lead no nails ( @ expansion.) .
 
First battens to OSB, 16" centres, secondly building paper ,staple to battens, thirdly fix expanding metal lath to battens, 2 coat render to finish.leave first coat render overnight to ensure good fix to EML.
 
Quinny said:
First battens to OSB, 16" centres, secondly building paper ,staple to battens, thirdly fix expanding metal lath to battens, 2 coat render to finish.leave first coat render overnight to ensure good fix to EML.
Click to expand...
It is 2022 not 1970. your method it years out of date.
 
Homeowner2022 said:
I need to get a new dormer rendered (Weber monocouche), however I'm after some advice on how to prevent cracking where two different materials meet.

The front of the dormer is medium density block, but the cheeks are timber frame with OSB board. How do I prevent cracking at the corner where it meets. And any cracking generally due to the differing expansion/movement of the two materials?

I've uploaded a photo for clarity. Thanks.
Click to expand...
That metal strap needs to go as well, it'll expand and force off the remder that's over it. Whole thing looks like it has been designed and built by people lacking knowledge.
 
Seems like everyone has a different opinion!

Renderer has told me the OSB section will be covered with roofing felt, with EML mesh over the top and wrapped round the corner. The whole thing will then have a layer of glass fibre reinforcement render mesh installed.

Anything majorly wrong with that?
 
Homeowner2022 said:
Seems like everyone has a different opinion!

Renderer has told me the OSB section will be covered with roofing felt, with EML mesh over the top and wrapped round the corner. The whole thing will then have a layer of glass fibre reinforcement render mesh installed.

Anything majorly wrong with that?
Click to expand...
Yes
You can’t render onto osb even if it’s covered in roof felt.
The osb needs removing, breather membrane. Batten out,Cavity drain at the bottom of the battens to allow moisture to drain. Render carrier board mesh the joints with a thin coat of render, then render & mesh the whole carrier board and block work, primer and finish with a silicone top coat.
Your renderer knows fcuk all and probably gone in cheap to do the job when in the long run it will fail and he’s long gone leaving you to find someone to do what I’ve just told you. This advice will most likely fall on deaf ears and you’ll be posting pics on here in a few weeks asking what’s gone wrong. Ffs
Now @Danny I’ve given a proper answer can you reinstall my previous posts please?
 
Homeowner2022 said:
Seems like everyone has a different opinion!

Renderer has told me the OSB section will be covered with roofing felt, with EML mesh over the top and wrapped round the corner. The whole thing will then have a layer of glass fibre reinforcement render mesh installed.

Anything majorly wrong with that?
Click to expand...
Sounds good to me,best wishes.
 
Homeowner2022 said:
Is that sarcasm or a genuine reply?

Its quite confusing when you come on a dedicated plastering forum and there's a whole range of conflicting replies on how to approach something.
Click to expand...
Understandable there’s more than 1 way to skin a cat,but there’s the right way and wrong way,plus your seeking advice on here that tells me your not to confident with the renderer in question take on board what @themucky1 and @Elite exteriors are telling you and you will be alreet
 
Homeowner2022 said:
Is that sarcasm or a genuine reply?

Its quite confusing when you come on a dedicated plastering forum and there's a whole range of conflicting replies on how to approach something.
Click to expand...
Do what I’ve said and you’ll be fine, and stewie touched on something that if you’re asking on here you’re not very confident in what the “renderer” is telling you so while you’re at it sack the c**t.
 
themucky1 said:
Do what I’ve said and you’ll be fine, and stewie touched on something that if you’re asking on here you’re not very confident in what the “renderer” is telling you so while you’re at it sack the c**t.
Click to expand...
Charming, what have I ever done to upset you?
 
essexandy said:
That metal strap needs to go as well, it'll expand and force off the remder that's over it. Whole thing looks like it has been designed and built by people lacking knowledge.
Click to expand...
Well spotted, so someone has poked a hole thru to fix a strap to the inside, presumably to stabilise the studs holding the osb? WTF?
Homeowner2022 said:
There are soakers under the tiles, the lead on top is additional.
Click to expand...
You sure? I don't think so, that lead is dressed too tight and is too small to get soakers under it.
 
Brimstone said:
Well spotted, so someone has poked a hole thru to fix a strap to the inside, presumably to stabilise the studs holding the osb? WTF?

You sure? I don't think so, that lead is dressed too tight and is too small to get soakers under it.
Click to expand...
Hi yes here are the soakers, installed beforehand.
 

Attachments

  • Advice for rendering a part masonry, part timber dormer
    Screenshot_20221018-200531.png
    5.4 MB · Views: 167
You must log in or register to reply here.
Top