Notice of Rejection Building Plans - Insulation / Boundary

[AllNewTo Me]

Hi,
Just been directed to this forum and looking for help / Ideas

We are building a timber frame 2 storey property that is just over 1 metre from our boundary. Building Control has rejected our wall make-up.
The timber frame has 70mm PIR in the frame with another 50 of PIR on the innerside of the frame, then followed by service batten and plasterboard.

To the other side of the frame is MultiPro XS, then battens and finally wood cladding.
The wood cladding is a planning requirement and there is no option to change this.

Due to being close to our boundary, BCO has asked for a certificate for fire test covering the overall wall solution for fire from inside and outside. This seems an impossible request as no manufacturer has conducted this test.

It is not clear if it is the PIR causing the problem or whatever solution is used a test is required, all we get is 'it does not meet building regs, we don't offer solutions' no help or guidance at all, so go away and find a solution.

This is the BCO's comment ' The importance of the system as a whole is to ensure it provides the required fire resistance in relation to parts B3 and B4 of the Building Regulations 2010.'

Has anyone else run into this problem and found a solution or has anyone else built close to a boundary and had a solution passed.

It would be great if a BCO or qualified person could explain how to resolve this.

Thank you in advance

Colin

 

[A_Novice]

We did similar and had to use another product on the outside that had a certain fire resistance. I can't remember the product we used but the one in the BC plans was Supalux.

This was only because we built to the boundary so were within 1m of it.

Surely the person doing your BC plans should know all this?

An expert though will be along shortly

 

[^woody^]

You need a BCO who has done this hundreds of times before. Wait ...... as if by magic ......

 

[mrrusty]

I think I would try changing the planning requirement and use a different cladding. Is it flat panel or planks? if it's planks you could use a timber embossed cement plank in a timber colour.

 

[AllNewTo Me]

I think I would try changing the planning requirement and use a different cladding. Is it flat panel or planks? if it's planks you could use a timber embossed cement plank in a timber colour.

Wish I could use cement board but planners do not allow its use on the Norfolk Broads.

It is so frustrating as I know someone who built a house close to a boundary and used Celotex and had no problems with the same BCO that is refusing us and it was only a year ago, have things changed in that time.

 

[mikeey84]

have things changed in that time.

If you are following the Grenfell Enquiry, then whilst the regulations haven't changed, I think BCOs are probably paying another closer attention to the fire safety, and how combinations of materials need testing

 

[tony1851]

It appears that Kingspan and Celotex might have been covering up/ignoring test results.
The BRE and BBA also come under a negative spotlight.

https://www.constructionmanagermagazine.com/grenfell-manufacturers-exploited-ignorance-for-c

 

[mikeey84]

It appears that Kingspan and Celotex might have been covering up/ignoring test results.
The BRE and BBA also come under a negative spotlight.

https://www.constructionmanagermagazine.com/grenfell-manufacturers-exploited-ignorance-for-c

I don't think any party is going to come out of the enquiry looking good

 

[tony1851]

@op

1. If you can compartment the building horizontally (assuming two-storey?) that helps.

2. The Approved Document gives 2 methods for calculating the limits of unprotected areas if the building is >1m from the boundary, both of which are conservative. But the small print also allows you to use the method in BRE Report 'External Fire Spread:Building separation and boundary distances' 1991. This can give more refined results if you follow the examples step-by-step.

Did your architect/plan drawer not raise this issue with you?

 

[JohnD]

Due to being close to our boundary, BCO has asked for a certificate for fire test covering the overall wall solution for fire from inside and outside. This seems an impossible request as no manufacturer has conducted this test.

From previously-concealed documents now disclosed to the Grenfell inquiry, the truth may be worse than that.

 

[Diver Fred]

Umm...

In Suffolk Coastal we just seen 2 wood framed building projects completed.
First finishes 900mm from neighbours has 200mm of (loft insulation style) matting between the frames (350 centres) with chipboard outer skin, breathable membrane, battens and cement planking. internally plasterboard and skimmed.
Second has 150mm PIR between the framing (400mm) OSB skin, vapour barrier, batterns and cement planking. Internally plasterboard (with air gap) and skimmed.
Both passed planning.

Really don't know what to suggest except possibly get an (registered) architect to calculate it out.

 

[Old Salt]

I know nothing of building regs but what about cement boards to meet the fire test aspect and then cover with your wooden boards.

 

[JP_]

If planning is only interested in fire proofing and external appearance, why not do a block wall with rockwool insulation and clad it?

 

[wessex101]

Everyone is extremely nervous of anything to do with fire post Grenfell and a lot of insurers now exclude it from PI cover or massively increase premiums so it is understandable that the local building control are being rather reticent.
You will either need a certified construction method or a fire engineer's report. How about the basic timber stud 60 minute construction with mineral fibre batts but dryline internally to achieve the required U value. If building control are being super pedantic they could say the timber cladding might adversely affect the overall fire resistance of the wall but it might be worth a go. We do something similar here but they are only single storey holiday lodges although often a lot closer than 1 metre from the boundary.
As Tony said what the hell was your designer doing? Certainly took his eye off the ball.

 

[frutbunn]

2. The Approved Document gives 2 methods for calculating the limits of unprotected areas if the building is >1m from the boundary, both of which are conservative. But the small print also allows you to use the method in BRE Report 'External Fire Spread:Building separation and boundary distances' 1991. This can give more refined results if you follow the examples step-by-step.

Its actual to do with surface spread of flame, the area of a lower surface spread of flame (ie untreated timber) is double the allowed unprotected area, however, as it is the external surface internal compartmentation is ignored.