Advice needed - should we change building control approver?!

[ARC Guitars]

Hi all - first proper post on here so apologies if the answers to this question are out there and I’ve failed to find them!!

 

I’m trying to work out if we should change our building control officer as the one we’ve got hasn't been super helpful. But then I’ve not done a self build before so worry it might be me not understanding what they're allowed to do!

 

Backing up a bit: we’re nearing the end of the detailed design phase of a self-build house, and appointed a registered building control approval firm (one of the fairly big ones) a while ago. They moved us from their original chap (who was quite helpful) to a new guy about 6 months ago, as the original was too busy and they’d changed the areas they cover.

 

The new guy’s completed a plan check for us and there are a couple of areas we need to address, but he says he can't offer any advice on how to address them. Is this right?! I’d always understood that your BCO should be able to advise you on what they want to see / how to comply.

 

An example: the plan check report said “Part B… The following details do not appear to achieve compliance: Alternative exits; Inner rooms.” We went through the regs and concluded it was just our proposed snug that wasn’t compliant, so we asked if that was the case (it was) and if he could offer any advice on achieving compliance, to which he said he wasn’t allowed.

 

(We think we’ve now got a solution to this issue, although we’ve only got a one word answer from him as to whether it now meets the regs so I’m not totally confident!).

 

Similarly, he’s asked for evidence that the external walls meet the required fire resistance (they should as it’s a standard construction), but when I asked for advice on how to demonstrate this, he again said he’s not allowed to help. 

 

I’m worried we’re stuck in this cycle where he says something cryptic about a thing not being compliant, then we spend ages working out what he means, then we have to propose loads of solutions until we stumble on one that he’s ok with. Seems pretty inefficient and likely to leave us with some solutions that aren’t the most sensible / cost effective. It’s worth saying he’s also quite slow to respond on emails if he replies at all, and when we rang to chase him, his reply was “I’ll try to squeeze you in” which I find a little annoying since we’re paying for this service!!!

 

So have I misunderstood how much help / advice a BCO can give? Or is it worth us sucking up the cost of switching to another firm before we start the build?

 

Grateful for any advice!!

[kandgmitchell]

This has all come about after the Building Safety Act. These guys are individually registered building inspectors now with the emphasis on "inspector". They are being told they are not designers as that path leads to liabilities.......

 

I would agree that doesn't help you but to be fair the regulations now expect a designer to be competant so you should be leaning on a design professional if you are unsure about the regulations. When you say your walls are of a standard construction - what is "standard"? It's difficult to judge what level of information you are giving this person, if it's little more than planning drawings then a plans check does result in some fairly vague queries I'm afraid because there's not much to go on. In the past I've seen some house photo's and a land registry location plan submitted as an application for converting the loft of a listed, converted barn to a habitable room. The plan check response was suitably sparse in response I can tell you.....

[ARC Guitars]

Ah that's helpful - thank you. We wondered if the rules change was behind this. 

 

On the drawings - the level of detail is pretty high. There are now over a hundred drawings right down to the specifics of all the build ups and junctions so there's no ambiguity about what we're proposing. It's a timber frame from one of the big factory framers with 140mm studs and 9mm OSB sheathing, mineral wool fill and 50mm PIR on the inside. There's a 35mm service cavity then plasterboard and plaster inside. Outside is 50mm cavity then 20mm timber cladding on two elevations, and a 145mm cavity with corrugated box profile steel sheets on the other two. (The cavity's so big on the steel sides because we've got hidden gutters at the top and the framers recommended making the cavity bigger rather than notching out the top corner of their frame.)

Edited Wednesday at 11:26 by ARC Guitars

[kandgmitchell]

So how close to the boundaries are those walls?

[ARC Guitars]

North 4m

South 2.1m

East about 44m

West 6.1m

 

We're under the protected areas allowed on the North and South so long as it's just the glazing that counts. It's the North and South elevations that have the steel cladding.

 

[kandgmitchell]

Unprotected areas - they don't have the required fire resistance. No hope of either the north or south walls facing a road, river, canal or like? The relevant boundary then moves out to the centre of that feature and you may find the whole face may be UA. Wishful thinking probably. 

 

First stop would be the steel cladding manufacturer (or at least the one with the most technical stuff on their website). Look to see if they have any fire test reports for boundary wall situations, go to your timber frame supplier and ask them, - usually with a bit of hunting around you can find a certified detail that you can wave under BC's nose even if you have to add say a mineral cement board behind the steel to get a match.

[ARC Guitars]

That's good advice - thank you!

[Gordo]

Don’t quote me but I think you need 1/2 hour fire resistance both sides of external wall. I assume that % windows are within that allowed relative to the distances from relevant boundary. Otherwise the BC officer would have mentioned concerns about % unprotected areas. So you just need to demonstrate that your makeup achieve 1/2 hr FR on both sides using manufacturers declarations such as the British Gypsum whit book

Edited 23 hours ago by Gordo

[Alan Ambrose]

I’ve seen this mentioned a few times before, but don’t get how anyone builds a timber frame and timber clad house? Like a Scottish long house, for example, or anything from Heb Homes.

[Gordo]

51 minutes ago, Alan Ambrose said:

but don’t get how anyone builds a timber frame and timber clad house?

It’s not an issue if the wall is far enough away from boundaries and not supporting a fire resistant element.

Edited 21 hours ago by Gordo

[Gus Potter]

On 08/01/2025 at 10:02, ARC Guitars said:

Hi all - first proper post on here so apologies if the answers to this question are out there and I’ve failed to find them!!

Welcome to the land of BH!

 

34 minutes ago, Alan Ambrose said:

I’ve seen this mentioned a few times before, but don’t get how anyone builds a timber frame and timber clad house? Like a Scottish long house, for example, or anything from Heb Homes.

It's doable!

 

On 08/01/2025 at 10:02, ARC Guitars said:

I’m worried we’re stuck in this cycle where he says something cryptic about a thing not being compliant, then we spend ages working out what he means,

Ah! If it's any help I do this as a day job. The poor performance, basic lack of knowledge about the construction / design industry, professional standards in terms of communication from say Planners and BC is astounding at times. In mitigation they are starved of funds so there is no time for them to learn these basic skills.

 

On 08/01/2025 at 10:49, kandgmitchell said:

This has all come about after the Building Safety Act. These guys are individually registered building inspectors now with the emphasis on "inspector". They are being told they are not designers as that path leads to liabilities....

And the liabilities are big! My PI (Professional Indemnity)  insurer has a  long list of questions about just what I'm designing in terms of fire protection. They need to understand how much risk I'm taking on and their exposure. In general BC officers just don't hold the required PI cover these days. Many Architect's are nervious.. and rightly so as fire protection is linked to structural design.

 

56 minutes ago, Alan Ambrose said:

I’ve seen this mentioned a few times before, but don’t get how anyone builds a timber frame and timber clad house? Like a Scottish long house, for example, or anything from Heb Homes.

It might kind of work like this for Heb Homes. But they may be able to shed more light on this. It works for me. Here is a rough summary of the things we need to think about when building something near a boundary.

 

In Scotland / kind of rest of UK. If something is closer than 1.0m from the boundary we need to stop flames and sparks from jumping over the boundary and setting light to the house next door. We call this fire integrity. For example if you have steel cladding then if the seams of the panels come apart then sparks and flames come out which can jump the boundary.

 

Another part is what we call "fire resistance. Here we want to stop the wall from heating up so it radiates heat, like an electric fire too close to the bed.

 

The fire intergrity and resistance are then combined to give you the overall fire rating of say a wall. That's a rough summary. If more than 1.0 m it gets easier in terms of complaince.

 

Some structural design stuff relating to fire:

 

The easy way to explain (laymans terms) this is that we need to make sure the structure is protected enough so you can get out if a fire starts. Hence the 15 min and 30 min you see. But we also need to make sure the structure does not fall on the Fire Brigade. Many of these folk have lost their lives trying to protect badly designed properties and industrial buildings.

 

On 08/01/2025 at 11:03, ARC Guitars said:

and a 145mm cavity with corrugated box profile steel sheets on the other two. (The cavity's so big on the steel sides because we've got hidden gutters at the top and the framers recommended making the cavity bigger rather than notching out the top corner of their frame.)

Here lies one big issue. There is no standard detail for this. I do a lot of refurbs / conversions etc and and many of these are timber frame / light weight construction. I adopt this approach as often I get to reuse existing founds and so on. When adding an extra storey to a building I often look at how much load I can remove first and then see what I can add back in without having to say strengthen the existing founds.  But this leads to odd sized cavities (we are building off an old cavity wall maybe) that we need to ventilate. But we also need to fire protect the wall panels.. often called fire stopping.

 

It the cavity is fairly normal 50 - 60mm I may use an intumescent fire stop strip like say TENMAT which gives me the ventilation but also stops fire spread. But this has limitations. If the cavity is say 145mm then we need to block a bit of that off ( say with good solid timber ) but still keep enough ventilation for day to day perfomance.

 

I'm just touching on some of the complexity. BC just can't give you this kind of advice / take liability for the amount of money you are probably paying them.

 

 

[LnP]

@Gus Potter since it's timber frame, what are your thoughts about needing to have the structure assessed against the STA Design guide to separating distances during construction? 

[saveasteading]

@LnP thanks for that link. I was not aware of this document so will read it thoroughly later.

It's a great example of what I was going to say which is basically...it is complicated and ultra important.

 

i have designed and built buildings for decades. Hundreds. I thought I was expert on fire risk. One of our steel buildings was exposed to extreme fire and the fire chief said he'd never seen such good resistance.

And yet, when I went on a 3 day intensive course I learnt much more.

Professors study nothing else, and what we see in the regulations is a summary.

 

Building inspectors rightly want to see proven constructions as any variation creates a risk. That can be frustrating when you have a special circumstance of a 'great idea' but safety must come first. Why should they accept a variation. Even so, we find that kingspan and celotex  ( do i say allegedly still?) cheated their fire tests.

 

@ARC GuitarsWhat are  you paying the bco? Typically about £1000 for the whole project. That is what 4 days of a tradesperson will cost, or 1 day max of a professional designer. The bco is not your designer.

 

On the positive side. A timber housing estate here won't burn like in Los Angeles. Timber needs air flow if it is to blaze and spread. Working to the regulations prevents that.