Render question

[paulb33]

Me again. So, the previous owners hacked off the roughcast render before fixing plastic to the gable. Picture attached.

Any ideas on what to re-render this with? Elsewhere, the original render is blown in places, but mostly intact. It looks like an early cement render on a metal lattice (imprint can be seen on the timbers), with small pebbles and covered with lime wash. The render was painted with modern plastic paint in the 90s.

I spoke with Ty Mawr and they were unclear on the merits of lime here, but particularly recommended use of a flexible board. They said avoid 'EML'.

I assume breathability isn't a huge issue. But, movement and frost damage might be. The gable faces the sea. I may also need to render in the winter, which may be a factor when using lime. I will need to render the entire gable from the second floor to the apex.

Value folks' suggestions on this.

Regards,

Paul

 

[Zebra]

Ah! I've already replied to your other, similar post. Now I see what you mean by "plastic on the gables"! You have plenty of overhang, you certainly could use a woodfibre board, it would keep the house warmer, and it would be breathable too.

 

[paulb33]

Yeah: site crashed and forced me to repost. Now I can't delete the duplicate.

Anyhow, wood fibre board is flexible I assume? Any thoughts on the render system?

 

[Zebra]

Woodfibre is flexible to a point. It's quite dense and firm, but not hard or brittle. Interlocking boards, which you screw through to the frame with special oversized washers. If you really had a lot of movement in the frame, of course the boards would move and you'd get cracks in the render; anything would crack if you really had a lot of movement. I can't say as I haven't lived with mine for a full year yet, but apart from a few hairline cracks, probably due to shrinkage, it hasn't moved.
Different brands of woodfibre boards have their own special render systems which are sold with them. Some of these render systems are made from an all-lime mix, the top coat of which can be coloured if you like. Some of them have cement in them, although are still breathable. Some of them are a very thin layer of a type of acrylic, almost like a very thick paint.
I remember I had a conversation with Ty Mawr when I was deciding on the system to use for mine, and they said that it is possible to use woodfibre boards with a standard lime render which you can mix yourself, instead of the system sold with the boards - did they say NHL2 or fat lime render, I can't remember. Or you could use woodwool boards - a different type of boards, which are still breathable but less thermally effective. I'm not sure whether they come as tongue-and-groove interlocking or not.

 

[paulb33]

Dare I ask what building regs might apply to a repair like this?

 

[Zebra]

Dare I ask what building regs might apply to a repair like this?

Well........
I've not put in a notice for the extensive thermal upgrading I've carried out on the old part of the house. I did enquire about doing so, and the helpful BC officer said that instead of the usual U-value required for renovations, I could work to a less stringent U-value (which I have easily exceeded on the upstairs, not met at all on the downstairs). He said that if I put in a notice then they would enforce it, implying that if I didn't..... they wouldn't.
When the inspectors have been to look at other works which I have notified, they've cast a curious eye over my EWI, and said "Oh, you're using that, are you?" and said no more.
If I don't make them look into what I'm doing, they're happy to let me carry on.
Now, that seems to be a reaction which is peculiar to my circumstances, my council, even my BC officer, and clearly, similar results cannot be guaranteed!
However, if the area in question is less than - don't quote me on this, but if I remember correctly - 25% of the area of the house, or perhaps of the external wall surface area, then you wouldn't have to put in a notice for it anyway. I think.

 

[paulb33]

Dare I ask what building regs might apply to a repair like this?

However, if the area in question is less than - don't quote me on this, but if I remember correctly - 25% of the area of the house, or perhaps of the external wall surface area, then you wouldn't have to put in a notice for it anyway. I think.

That'll do for me. You've earned your stripes, Zebra.. 8)

 

[Zebra]

I see from your blog the reason you're saying you might have to do this in winter. Scaffolding.
I didn't do the lime rendering on mine until late October last year. It fared fine, although I don't suppose I would have wanted to leave it any later.
Don't know the answer to that....

 

[paulb33]

I see from your blog the reason you're saying you might have to do this in winter. Scaffolding.
I didn't do the lime rendering on mine until late October last year. It fared fine, although I don't suppose I would have wanted to leave it any later.
Don't know the answer to that....

Good to know. I was disappointed that there was no render at all under the plastic. I hoped it would need patching, but hadn't counted on this full re-render.

If pushed, I could screen off the over-hang and leave the large oriel windows open. I assume this would keep the gable somewhat warmed. British Gas will be happy too…..

Some folks thinkI should be true to the Edwardian experimental cement render. So, I'm still scratching my head about what's best.

Thanks for your interest!

Paul

 

[plasticpigeon]

I'm not sure why lime would be superior to cement in this case.

 

[88v8]

I'm not sure why lime would be superior to cement in this case.

Nor me. At the top of the house, breathability is not really an issue. I'd use two-coat cement. Or if you want something Period, what about one coat plus Tyrolean?
Like this ...
http://www.netweber.co.uk/renders-decorative-finishes/products/decorative-finishes/cullamix-tyrolean.html
Featuring a nice 1920s(?) house from which nearly all character has been carefully removed.

Ivor