Cavity Bead Insulation natural stone finish

HoofRocks

Hi all

Recently visited the self build show in city west to try and find out about insulation for our dormer bungalow.

We had hoped to have a six inch cavity with bead insulation. We have a natural stone finish on the two end gables.

We spoke to a supplier rep about the bead insulation and he advised us that it may not work well with the natural stone finish as natural stone is permeable and may effect the bead. (I dont know if I can name the supplier on this page)

I have spoken to alot of people who have got the bead insulation and are delighted with it but I never heard of this complaint before. We also spoke to our stone supplier who couldn't understand how the water would penetrate and 7 inch natural stone and then a 4 inch solid however we were concerned because this was raised by the rep.

I'd just like to find out has anyone in a similar situation had any issues with the bead insulation? or ever heard of this issue before and in general how do you find the bead insulation in your new home?

muffler

Moved to C & P

sydthebeat

HoofRocks wrote: »

Hi all

Recently visited the self build show in city west to try and find out about insulation for our dormer bungalow.

We had hoped to have a six inch cavity with bead insulation. We have a natural stone finish on the two end gables.

We spoke to a supplier rep about the bead insulation and he advised us that it may not work well with the natural stone finish as natural stone is permeable and may effect the bead. (I dont know if I can name the supplier on this page)

I have spoken to alot of people who have got the bead insulation and are delighted with it but I never heard of this complaint before. We also spoke to our stone supplier who couldn't understand how the water would penetrate and 7 inch natural stone and then a 4 inch solid however we were concerned because this was raised by the rep.

I'd just like to find out has anyone in a similar situation had any issues with the bead insulation? or ever heard of this issue before and in general how do you find the bead insulation in your new home?

i suppose his worry is that there is more of a possibility of moisture entering the cavity where there is natural porous stone (i assume sandstone?) and then an unrendered outer block leaf.... than a rendered outer block leaf. I suppose a solution would be render the gables before applying the natural stone.... or ensure a good mortar coat between the stone and cladding when applied.
are you applying a mortar-free stone course ??

HoofRocks

we are using a natural stone granite finish and it wont be mortar free. i did ask him if we rendered the wall before putting the natural stone on would it work and he said it would. would water penetrate through the natural stone and the outer leaf but wouldn't through a rendered finish?

sydthebeat

the sand and cement render finish that you get on a typical house is the weather proofing layer.

kieranhr

This is a similar situation to pumping a cavity wall with a brickwork outer face. If you look at the Agrement cert for the particular bonded bead insulation (available on the NSAI website), there is usually a site exposure map, showing what areas of the country are suitable for a brick outer leaf, and what areas you'll need a rendered finish if you want to pump the cavity.
Two things in your favour - a 150 mm cavity will stop more moisture ingress than the 100 mm cavity assumed in the Agrement cert, and a natural stone finish with 100 mm blockwork is more weathertight than 100 mm brick.

BarneyMc

I just want to bring up this topic for my own house - the construction plans will be ready next week. I'll be pumping a 250mm cavity and using natural stone on the front. Should I allow for a sand & cement render finish before placing the outer stone finish or is normally done anyway as the stone work is bening built?

sydthebeat

kieranhr wrote: »

..... If you look at the Agrement cert for the particular bonded bead insulation (available on the NSAI website), there is usually a site exposure map, showing what areas of the country are suitable for a brick outer leaf, and what areas you'll need a rendered finish if you want to pump the cavity.
....

barney, as kieranhr says above, refer to the nsai cert of the product you wish to sue and see what it recommends.

personally id apply a sand and cement render coat to not only weather proof the construction but also to add to the air tightness aspect. be careful with the mesh ties though.

BarneyMc

Thanks Syd, I assume this coat can be applied as the stone is being built rather than separately and before it?

BarneyMc

sydthebeat wrote: »

barney, as kieranhr says above, refer to the nsai cert of the product you wish to sue and see what it recommends.

personally id apply a sand and cement render coat to not only weather proof the construction but also to add to the air tightness aspect. be careful with the mesh ties though.

I'll have my walls finished in a few weeks and will be using field stone on the front of the house. Does the sand and cement render have be applied in one go before the stone is built or can it be applied between the blockwork and stone as the stone is built?

kieranhr

BarneyMc wrote: »

I'll have my walls finished in a few weeks and will be using field stone on the front of the house. Does the sand and cement render have be applied in one go before the stone is built or can it be applied between the blockwork and stone as the stone is built?

The only problem with doing both at the same time IMO, is that you'll get spots where there is no layer of sand-cement render because a large or protruding stone will touch the blockwork. Unless you're very careful.

rampantbunny

More questions than answers for you Barney but for what it's worth...

Would there not be a continuity issue with a stop-start plastering approach?
I'm probably way off, but in my mind I imagine piecemeal bits of plaster more at risk of having air pockets or such between each swipe of the trowel when trying to join fresh plaster to plaster that was previously applied and has set.
If there were gaps behind the surface of the plaster, then more permeable and prone to water ingress. But maybe that's just not possible at all.

Sounds like you are maybe considering getting the stone mason to apply plaster as he is building up the stone work?

I'll face the same situation myself later. Architect has specified a bituminous layer behind the stone, but I'm having the wall plastered in any case (in one fell swoop).

BarneyMc

rampantbunny wrote: »

Architect has specified a bituminous layer behind the stone, but I'm having the wall plastered in any case (in one fell swoop).

Does anyone know what products could be used for this bituminous layer and if it's a job anyone could do? It might work out cheaper than plastering, especially if it's a DIY job.

rampantbunny

BarneyMc wrote: »

Does anyone know what products could be used for this bituminous layer and if it's a job anyone could do? It might work out cheaper than plastering, especially if it's a DIY job.

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