Wrong insulation used, Small claims court or not ?

[GaryM]

Hi All,

 

I can't believed how stressful my build has been, so much for a nice relaxed retirement.

 

I employed a main contractor to remodel my house, which including raising the roof level and adding a second story over a old flat roof. The full set of detailed drawings was produced by a local architect.

 

There was a few issues but the build continued, back in jan 2020 the roof insulation was going in, the builders were putting glass mineral wool, I never thought anything off it, I wasn't the project managing the job and hadn't studied the drawings.

 

Anyway a few months later, May time, we had a few problems with plaster finish, so had a meeting with builder and architect (who at this time was hands off), due to this problem I had started studying the drawings more and seen PIR insulation was specified.   In the meeting this was raised, the architect said the mineral insulation would still be above building reg requirement, so the build continued...

 

Since then, the builders and us have departed ways and we are now trying to get building regulations signed off, all is good but Building control want letter from architect to say insulation in roof is above spec. Unfortunately the architect is now saying he can't provide letter as he can't be sure it does meet spec.  I believe the builders changed the insulation without consulting the architect, using 200mm of glass mineral wool instead of 200mm of PIR.  but the problem was compounded 4 months later by the architect saying it was still above spec. (this was only in passing in a conversation).

 

In retrospect we  should have insisted on new calcs being done, but this was my first build, I employed a main contractor who were following detailed drawings, why should I know what should be done?

 

So I'm trying to get letter from architect who is reluctant to supply as it was not built to spec by builders. Me, I just want relax and enjoy retirement, but now may have a 5 - 10k spend on getting my roof up to spec. What do I do? take builders to court? what options do I have?

 

Thanks for any advise.

 

 

 

 

 

Edited September 29, 2022 by GaryM
typos

[markc]

Definitely take up with builder first, regardless of conversations they have not built to spec and drawings supplied so it is their job to get sign off.

write to them explaining the situation and ask them to provide all information and agreement with architect to get sign off.

 

[GaryM]

3 minutes ago, markc said:

Definitely take up with builder first, regardless of conversations they have not built to spec and drawings supplied so it is their job to get sign off.

write to them explaining the situation and ask them to provide all information and agreement with architect to get sign off.

 

Thanks for reply.

 

I should clarify we did not split with builder on good terms. His last words to us after departing ways was don't worry we will get the building signed off, we never heard from them again.

[Temp]

32 minutes ago, GaryM said:

Since then, the builders and us have departed ways and we are now trying to get building regulations signed off, all is good but Building control want letter from architect to say insulation in roof is above spec. Unfortunately the architect is now saying he can't provide letter as he can't be sure it does meet spec.  I believe the builders changed the insulation without consulting the architect, using 200mm of glass mineral wool instead of 200mm of PIR.  but the problem was compounded 4 months later by the architect saying it was still above spec. (this was only in passing in a conversation).

 

Do you know what U-Value was specified for the roof? 

 

What U-Value would be needed to meet the Building Regulations? 

 

I assume the insulation between the rafters behind plasterboard rather than on the floor of the loft, so not easy to top up.

 

 

 

 

Edited September 29, 2022 by Temp

[Happy Valley]

Find out from the manufacturer of the glass mineral wool what specifications their material has for 200mm

[Conor]

Best option might be a couple hundred quid on an independent EPC. Because ultimately that's what building control need to prove that you've met that part of the regs. Give him/her the drawings and explain the actual build up in the roof so they can assess the buildings overall performance.

 

Personally, I'd be asking the builder to add 75mm PIR under the joists and renboard, which should get you close to what was specced.

 

You have to remember that you'll be paying for this cockup for years and years to come through higher energy bills.

[GaryM]

7 minutes ago, Temp said:

 

Do you know what U-Value was specified for the roof? 

 

What U-Value would be needed to meet the Building Regulations? 

 

I assume the insulation between the rafters behind plasterboard rather than on the floor of the loft, so not easy to top up.

 

 I don't have them at hand, but architect is saying it's very close.  We have a vaulted ceiling, using open web joists, from the architects point of view he is saying the insulation and joist manufactures are being very cagey on how there product will perform with each other

 

[Carrerahill]

33 minutes ago, GaryM said:

Hi All,

 

I can't believed how stressful my build has been, so much for a nice relaxed retirement.

 

I employed a main contractor to remodel my house, which including raising the roof level and adding a second story over a old flat roof. The full set of detailed drawings was produced by a local architect.

 

There was a few issues but the build continued, back in jan 2020 the roof insulation was going in, the builders were putting glass mineral wool, I never thought anything off it, I wasn't the project managing the job and hadn't studied the drawings.

 

Anyway a few months later, May time, we had a few problems with plaster finish, so had a meeting with builder and architect (who at this time was hands off), due to this problem I had started studying the drawings more and seen PIR insulation was specified.   In the meeting this was raised, the architect said the mineral insulation would still be above building reg requirement, so the build continued...

 

Since then, the builders and us have departed ways and we are now trying to get building regulations signed off, all is good but Building control want letter from architect to say insulation in roof is above spec. Unfortunately the architect is now saying he can't provide letter as he can't be sure it does meet spec.  I believe the builders changed the insulation without consulting the architect, using 200mm of glass mineral wool instead of 200mm of PIR.  but the problem was compounded 4 months later by the architect saying it was still above spec. (this was only in passing in a conversation).

 

In retrospect we  should have insisted on new calcs being done, but this was my first build, I employed a main contractor who were following detailed drawings, why should I know what should be done?

 

So I'm trying to get letter from architect who is reluctant to supply as it was not built to spec by builders. Me, I just want relax and enjoy retirement, but now may have a 5 - 10k spend on getting my roof up to spec. What do I do? take builders to court? what options do I have?

 

Thanks for any advise.

 

 

 

 

 

200mm of mineral wool could never match the U-value of 200mm PIR - if 200mm was what is required then it will not be enough, if however, it was calculated that it would work at 100-110mm PIR, which equates to a U-value of 200mm mineral wool, but 200mm PIR was spec'ed to get a really well insulated envelope, then there is a chance a good 200mm mineral wool will work. 

 

If you can find your original insulation calcs, you can probably work it out and submit your rational, there is a chance they will accept it. If there is 200mm mineral up there, and we say that is comparable to the 110mm PIR, then you may be able to get it to work, if it came to it, with 40mm insulated plasterboard on top of what you have - not ideal by any stretch but better than ripping it all apart. Or you might be able to do notional calcs and get other areas to work better than others thus balancing it all out. 

 

 

 

 

[GaryM]

3 minutes ago, Happy Valley said:

Find out from the manufacturer of the glass mineral wool what specifications their material has for 200mm

now that's the problem, apparently they will not supply it when put in conjunction with open web joist, the figures are only for timber joist. The architect has phoned a few and currently no one will give figures.

 

All seems very odd to me

[GaryM]

3 minutes ago, Carrerahill said:

200mm of mineral wool could never match the U-value of 200mm PIR - if 200mm was what is required then it will not be enough, if however, it was calculated that it would work at 100-110mm PIR, which equates to a U-value of 200mm mineral wool, but 200mm PIR was spec'ed to get a really well insulated envelope, then there is a chance a good 200mm mineral wool will work. 

 

If you can find your original insulation calcs, you can probably work it out and submit your rational, there is a chance they will accept it. If there is 200mm mineral up there, and we say that is comparable to the 110mm PIR, then you may be able to get it to work, if it came to it, with 40mm insulated plasterboard on top of what you have - not ideal by any stretch but better than ripping it all apart. Or you might be able to do notional calcs and get other areas to work better than others thus balancing it all out. 

 

 

The added complication I should add above is the build is the build, a vaulted ceiling using open web joists, the insulation manufactures are reluctant to supply figures for the performance of there products with open web joists, so i am told

[Chanmenie]

If 200mm PIR was specified was that what you paid for ?
I believe 200mm PIR would be considerably more expensive and take much longer to fit, therefore the builder has made quite a bit more money by using mineral wool 

Edited September 29, 2022 by Chanmenie

[GaryM]

9 minutes ago, Conor said:

Best option might be a couple hundred quid on an independent EPC. Because ultimately that's what building control need to prove that you've met that part of the regs. Give him/her the drawings and explain the actual build up in the roof so they can assess the buildings overall performance.

 

Personally, I'd be asking the builder to add 75mm PIR under the joists and renboard, which should get you close to what was specced.

 

You have to remember that you'll be paying for this cockup for years and years to come through higher energy bills.

This is one of the suggestions from the architect, he said getting a SAP calc done for the whole house and not just the roof.

 

But as you said, the real problem is the poorer insulation.  We can't do 75mm as it will be below window frame level, but perhaps 37.5mm insulated plasterboard may be enough

 

[Andehh]

200mm PIR spec'd in roof is really significantly more then regs, especially on a refurb.... That alone doesn't seem right to me!! 

 

Get 40mm (ish) Insulated plasterboard over boarded and get on with life!! 

Edited September 29, 2022 by Andehh

[GaryM]

3 minutes ago, Chanmenie said:

If 200mm PIR was specified was that what you paid for ?
I believe 200mm PIR would be considerably more expensive and take much longer to fit, therefore the builder has made quite a bit more money by using mineral wool 

so 4 months afterwards when it become apparent they had a use mineral wall they did reduce the price, but i was still given the impression it was still way above spec. If we had not said anything they would have charged for PIR

[GaryM]

3 minutes ago, Andehh said:

200mm PIR spec'd in roof is really significantly more then regs, especially on a refurb.... That alone doesn't seem right to me!! 

 

We wanted it well speced, it's a large vaulted ceiling with a huge gable end window, hence the need for good insulation.

 

5 minutes ago, Andehh said:

Get 40mm (ish) Insulated plasterboard over boarded and get on with life!! 

 

Yep, that's what I want to do, but In still want to yell, shout, kick the dog (we don't have a dog) Grrrr and all that, but life is to short

[Temp]

33 minutes ago, GaryM said:

now that's the problem, apparently they will not supply it when put in conjunction with open web joist, the figures are only for timber joist. The architect has phoned a few and currently no one will give figures.

 

All seems very odd to me

 

I'm pretty sure open web joists would have better thermal properties than solid (eg less thermal bridging). I'm sure the makers would answer that question asked on its own.  Might even be on their Web site somewhere. 

 

So perhaps see if the calculation for solid timber rafters is OK and add a comment that open web will be better.

[Temp]

Appears metal open web rafters are similar to solid wood..

 

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16357

 

Quote

Apparently metal web joists are pretty much equivalent to solid timber joists thermally. 

 

Quote

Wao. I can't believe easy joists are the same (fractionally worse actually), for thermal bridging as solid timber. I've read they Wolf Easy-joist tech guide, and that's what they say. So must be true.

 

[Andehh]

38 minutes ago, GaryM said:

We wanted it well speced, it's a large vaulted ceiling with a huge gable end window, hence the need for good insulation.

 

 

Yep, that's what I want to do, but In still want to yell, shout, kick the dog (we don't have a dog) Grrrr and all that, but life is to short

 

Listen to this guy, he gets it. Life is too short to worry about this....!!!

 

Overboard, and within a couple of weeks all is forgotten. 

[Radian]

1 hour ago, GaryM said:

I believe the builders changed the insulation without consulting the architect, using 200mm of glass mineral wool instead of 200mm of PIR.

It's quite common to mitigate cold bridging by having another layer of PIR (e.g. 50mm) over-boarding the underside of the joists. Was this not on the drawing?

[Temp]

5 minutes ago, Andehh said:

 

Listen to this guy, he gets it. Life is too short to worry about this....!!!

 

Overboard, and within a couple of weeks all is forgotten. 

 

BCO may still want figures to prove it though.

[Andehh]

Oh yeah, but £150 on a new epc calculator will resolve that. Likely to take a couple of weeks, they're all busy with the new regs changes....

[TonyT]

 

Just make up some bullshit to keep the BCO happy. 

a signature is all they are looking for to pass the blame elsewhere.

just make sure you do the remedial works like the overboarding. 

 

 

[Adsibob]

2 hours ago, Andehh said:

 

Listen to this guy, he gets it. Life is too short to worry about this....!!!

 

Overboard, and within a couple of weeks all is forgotten. 

I agree with this.

 But as an aside, your architect is just as liable as your builder. They both (expletive deleted)ed up, although I think your builder has the excuse that he is not the designer, and the architect okayed it at the time. Your architect should not have said it would be okay to use 200mm of mineral wool, because by answering that question he took on a duty of care to you to get it right. If he would have said “I don’t know, I would need to run a new set of calculations and that will cost you £x” and you decided not to pay that, and proceed without the u value calculations, then it is on you, but unless that’s how it happened, your architect is liable.

[Kelvin]

Just to add to this reference who is liable. My father in law was an architect. Several years ago he did some drawings for a new house and got it through planning etc. A builder then did the work and it was signed off. 2 years after completion there was a structural failure that was down to an installation problem by the builder. However the builder had gone out of business. The warranty insurance company went after my father in law and his insurance paid out. 

[SuperPav]

I'd stick 25+12.5 insulated plasterboard underneath and stop worrying about it personally. I would've expected some underboarding with PIR anyway, so the 200mm full fill PIR with nothing underneath (if that's what was originally specified) is not a great design to start with! 

 

What's your build up within the roof (or rather above the roof)? Do you also know the spec of the wool, is it 32, 35, 40? - I can run you some basic U-value and CRA via Ubakus but done through my Ltd company's commercial license and on a proper letterhead - could satisfy BCO without having to get a full SAP/energy calc.

 

I also agree that your architect is liable and shouldn't be let off the hook if they said "oh it's fine".  At the very least they should pay for the energy calc.