# External wall construction and fixings



## space.dandy (12 May 2022)

Hi all,

The house I've recently moved into has a newish (~2016) single-story extension. I want to fix some shelves to the inside of the external wall, but I'm a bit puzzled about the construction of the wall and therefore what fixings to use. Having taken a few measurements and drilled some small test holes, the construction seems to be ~150mm of rendered block/brick, 150mm of kingspan/celotex insulation and a layer of plasterboard on the inside. I've tapped around various places on the inside but can't hear any evidence of stud work, so I have no idea how the layers are fixed together. I do know that the extension was properly constructed and signed off, so is compliant with whatever regs were in place at the time.

Can anyone tell me what the actual construction is likely to be, and what sort of fixings would be appropriate for medium/heavy duty use?

Cheers,
Chris


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## Droogs (12 May 2022)

best bet would be to use butterfly fixings which spread the load over a wider area than rawlplugs etc and so lesson the likelyhood of pulling through the plasterboard.


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## space.dandy (12 May 2022)

I did consider butterfly fixings, but they are usually intended for hollow walls. I'm not sure the butterfly wings would be able to expand properly into the surrounding celotex?


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## Housey210 (12 May 2022)

local planning portal should have all the plans to view online. If so, details will be given as to construction. 150 blocks seems odd as too the 150mm ins.


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## space.dandy (12 May 2022)

Housey210 said:


> local planning portal should have all the plans to view online. If so, details will be given as to construction. 150 blocks seems odd as too the 150mm ins.


Thanks. I've tried the local planning portal but, while I can find the application, there is no facility to view/download plans.

The measurements I've given are pretty rough. The total wall thickness seems to be 300mm by measuring outside to the window and subtracting the internal reveal. The celotex thickness was estimated by shoving a thin stick into a test hole until it met something solid.


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## Housey210 (12 May 2022)

on the application, site address, are there any tabs saying associated documents, appeal, ward, etc? Typical construction would be lightweight blocks on inner leaf and 100mm brick outer. The slab celotex is butted up to back of inner leaf and held in place by wall ties the and grommets. 50mm air gap then outer leaf. Is your property conventional build or timber framed? Blocks, ordinary masonry plug and screw, timber frame, hollow wall fixings.


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## MikeJhn (13 May 2022)

If you thinking of heavy duty use of the shelves, support them off the floor, any fixings into plasterboard is not going to last.


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## Dave Moore (15 May 2022)

space.dandy said:


> Hi all,
> 
> The house I've recently moved into has a newish (~2016) single-story extension. I want to fix some shelves to the inside of the external wall, but I'm a bit puzzled about the construction of the wall and therefore what fixings to use. Having taken a few measurements and drilled some small test holes, the construction seems to be ~150mm of rendered block/brick, 150mm of kingspan/celotex insulation and a layer of plasterboard on the inside. I've tapped around various places on the inside but can't hear any evidence of stud work, so I have no idea how the layers are fixed together. I do know that the extension was properly constructed and signed off, so is compliant with whatever regs were in place at the time.
> 
> ...


Hi,
If you are going directly into the blocks I would recommend resin anchoring.
Regards,
Dave


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## PhilipL (19 Jun 2022)

Planning or building control plans cannnot be relied upon. Things change between planning and building, often with informal approval (or not).


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