Becoming rendered

[paulb33]

Hmmm - it'll be interesting to see how well the pebbledash stays on that timber, as time goes on. Given timber's propensity to expand and contract, I'd be inclined to keep an eye open for cracks.

I share your concern, Penners. It's sitting on a suspended timber frame. I suspect the original finish was an early cement based render. Considering this, using lime was somewhat overkill. But I hope it will be somewhat flexible and resist cracking. Its sitting on a flexible fibre-board and we also used an embedded plastic mesh.

Time will tell..

 

[88v8]

On our previous house, the outside of a rendered gable was stud and lathe, did we add chicken wire can't recall it was 30 years ago, anyway the render
never came off. However, there was no bare junction with brick, because it abutted bogus half-timbering on the front and the valley gutter at the back.

I reckon your overhang will certainly crack at the junction of timber & brick. Whether it matters depends.... to know whether it will matter, spray the wall above with water so as to saturate it, and watch how it drips off the edge of that overhang. Does it drip off the outside angle - good - or does it cling and run beneath the overhang onto the inner wall - bad.
If the latter, while the scaffold and the renderers are there, you could form a drip?

Ivor

 

[Zebra]

Its sitting on a flexible fibre-board

What type did you use, out of interest, and how thick?

 

[paulb33]

Its sitting on a flexible fibre-board

What type did you use, out of interest, and how thick?

I believe it was a 25mm Celenit Wood Wool board from Ty Mawr. http://www.lime.org.uk/products/boards-and-backgrounds/buildingwood-wool-board/buildingwood-wool-boards/
This was fixed on to marine ply, which itself was screwed on to the structural timbers.

 

[paulb33]

I reckon your overhang will certainly crack at the junction of timber & brick. Whether it matters depends.... to know whether it will matter, spray the wall above with water so as to saturate it, and watch how it drips off the edge of that overhang. Does it drip off the outside angle - good - or does it cling and run beneath the overhang onto the inner wall - bad.
If the latter, while the scaffold and the renderers are there, you could form a drip?

Ivor

Thanks, Ivor. So, I went out with a hose this afternoon. The roughcast is so "granular' (or "stony") that the water drips off regardless off the run off angle. Thousands of pebbly undulations serve as millions of drip planes. I guess its doing what its designed to do - impeding flow back and presenting a vast surface area for evaporation?

Without doubt, the corners and joints (including to old render) are vulnerable points.

 

[Zebra]

The ply will give a lot of structural stability and prevent cracking, I should think, especially if the edges of the woodwool boards are staggered from the edges of the ply. Looks like a good system.

 

[88v8]

I reckon your overhang will certainly crack at the junction of timber & brick. Whether it matters depends.... to know whether it will matter, spray the wall above with water so as to saturate it, and watch how it drips off the edge of that overhang. Does it drip off the outside angle - good - or does it cling and run beneath the overhang onto the inner wall - bad.
If the latter, while the scaffold and the renderers are there, you could form a drip?

Ivor

Thanks, Ivor. So, I went out with a hose this afternoon. The roughcast is so "granular' (or "stony") that the water drips off regardless off the run off angle. Thousands of pebbly undulations serve as millions of drip planes. I guess its doing what its designed to do - impeding flow back and presenting a vast surface area for evaporation?

Without doubt, the corners and joints (including to old render) are vulnerable points.

Good. So, hard to see how one could improve on what's being done.
Someone in a hundred years should be very grateful for the way you're going about this job.

Ivor

 

[paulb33]

Someone in a hundred years should be very grateful for the way you're going about this job.
Ivor

Unless someone in a few weeks finds me hanging from the scaffold... :wink: