Extension - builder economic with truth - regs breached imo - what do I do?

After glass was installed in our new sun room I saw it had paper labels saying U value was 2.8 (The doors are labeled 1.8 and the one opening window is 1.4 - don't know about the velux). I would choose much better and had originally asked about reflective glass which all my neighbours have because of heat - was battered back (builder tends to ignore me because I am female and ask difficult questions).

Spoke to building control (his private firm). Builder had told them it was an exempt conservatory but they agreed when I asked them to look at the plans that it is NOT EXEMPT - so windows should be 1.6. (Year round use, Solid roof with <25% glass lantern, under-floor heating separate from rest of house, new walls about 2/3 glass, existing wall has 2 large sets of patio doors to much-used rooms).

Builder now says the windows were probably mislabeled !?! and therefore no need to worry ...
I'm worrying. I think we'll boil in summer and freeze in winter (in our adjacent living rooms).

I will ask for documentation of the windows' U value as I'm ultimately responsible for meeting building regs.

As building control is a private company paid by him, can I influence them? My preference would be to replace the windows. Other options might be film on the windows and/or very good internal doors (which causes issues re thresholds...)

What do I do next? I can see it will cost quite a lot for him to put right (remove and replace windows and make good exterior clam shell window fitting). We never discussed the windows spec except for me asking about reflective, low-emissivity glass and being ignored. Most items we are asked to spec to minute detail (including very technical stuff for insulation and electrics - spend hours online researching). But imo it's his fault for cutting corners (I'm paying 120K, if he'd said reflective glass was a few K more we could have had a conversation - but we had no conversation.

Same builder is also rebuilding most of my house after a flood so we have an extensive relationship... he's getting even more money for that.

It's a permitted development under the "temporary" rules on size - 7.5m x 3.5m footprint). No architect except for initial plans.

thanks - it helps - gives me something new to learn about

I wish now I'd used an architect but we're both unemployed right now
and we thought we could manage the project -- how hard could it be : -) ... really, really wish we'd had someone to help but the architect who drew up the plans was pretty useless really - if we'd liked him we'd have used him.

Theres a few things here.

If the sunroom is exempt, it doesnt need to comply.
In general it could be exempt if its separated from the house by external quality doors and separate geating controls.
The glass area is not relevant since current buildkng regs just say 'substantially glazed'.

If the sunroom is open to the house, then it must all comply with building regs, so it would need full indpection from foundations onwards.

It is possible for an extension to have lots of glass (ignoring 25% rule for elements of an extension), because it can be classed as having 'excess glazing' - in that case a heat loss calulation for the whole house is needed and any additional heat loss over the 25% allowed for the glazing element needs to be made up elsewhere (you mightve had a new boiler in the house, or replaced all, the lights with LED). A SAPs test costs is needed to prove it and costs around £300

In terms of the glass -modern double glazing with low e coating should achieve a 1.6 u value for the whole window. 2.8u sounds more like glass without low e.

Solar reflective glass is always tinted so its only generally used in roof glass not side frames. These days solar control glass includes self clean coating and the inner pane can have low e as well. The extra cost is negligable.
See ambi glass for a range of solar glass options.

If the glass is wrong it could be changed. Personally I always specify solar control neutral, soft coat low e, warm edge spacer, argon gas fill.

Quite simply, get the glass tested by a third party independent firm.

Permitted development and building regualtions are different. The post does not make it clear what will apply.

@Notch7 - thanks, v helpful. Your recommendation on spec sounds spot on (and I assumed we'd get to discuss it but it would be on those lines, possibly with extra cost if we wanted something fancy - but there was no discussion).

The builder's private BC company says the extension isn't exempt but I think they're pretty poor from our chat. They also spoke specifically about % glazed etc rather than "substantially" although I guess previous requirements would be a reasonable guide to the meaning of "substantially".

The doors are yet to be replaced, so he could up the spec on those to external - but we want round the year use.
The heating is separate because under-floor and we chose not to add a radiator just because we want the two solid walls for furniture & pictures.

We are improving insulation elsewhere by adding 10cm insulation where we can during renovations, but that is all in an almost completely separate building (connected by a single storey corridor, L shaped house) - so in practice makes no difference to this part of the house). This might help with an overall calc.

But tbh I want to use the regs to make the builder give us good spec windows!

^woody^ said:

Quite simply, get the glass tested by a third party independent firm.

Permitted development and building regualtions are different. The post does not make it clear what will apply.

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Sorry not to be clear. We need both Permitted dev and building regs approval. I applied for the permitted dev and that has been fine.

Building regs the builder is handling by appointing a private firm (with whom I've spoken). I believe he has not met regs - his first story was that the build was exempt as a conservatory, which he has now agreed was an error. His next story was that the glass is in fact ok but was mislabeled. So I've asked for documentation of the glass but shall be surprised if it is ok. Also as you say, we might need to get it tested to be sure (how do I arrange that?)

thanks!

mashie said:

Sorry not to be clear. We need both Permitted dev and building regs approval. I applied for the permitted dev and that has been fine.

Building regs the builder is handling by appointing a private firm (with whom I've spoken). I believe he has not met regs - his first story was that the build was exempt as a conservatory, which he has now agreed was an error. His next story was that the glass is in fact ok but was mislabeled. So I've asked for documentation of the glass but shall be surprised if it is ok. Also as you say, we might need to get it tested to be sure (how do I arrange that?)

thanks!

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But what are you actually having built that requires building regulations?

If this is an extension that you are having built then it's subject to building regulations, and the glass installed in it needs to conform.

If you are having something else built, which is being inspected along with a "sunroom" then its a case of whether the sunroom is being built distinct from building regulations and so does not need to comply, or whether the builders have made mistakes and what should be an exempt sunroom becomes a controlled extension which brings in building regulations inspections of it.

Again, sorry if that's not clear. It's one building, an extension, we're calling it a sun room as it has a lot of glass. It's not a conservatory.

It is subject to building control as I understand it, the builder is definitely responsible for building control and he appointed a private company at the outset to advise him and provide the certificate at the end - there have been no inspections afaik but the company he appointed know about it, I spoke to them and they confirmed it is not exempt (but they didn't realise that til I spoke to them, based on what he told them it was exempt but they have been sent the plans and when they looked at those they decided it wasn't exempt).

My understanding of the situation is much as Notch7 said... SAPS test might be the way to go for the builder.

Local council have given permitted dev approval and viewed the site just to check the foundations were as proposed - they aren't interested in the building control aspect because another company is due to certify it.

Hope that is clearer.

mashie said:

SAPS test might be the way to go for the builder.

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No it's not. It's no good getting an overall energy rating for the house and compensate elsewhere (more roof insualtion of a new boiler etc) to acheive a complaint rating that leaves you with crap glass in a room that is highly glazed and for which the whole point is to have lots of glass that is thermally efficient, in what will be a too cold/too hot extension.

You need the glass to perform as it should do, as you have paid for, and as you have specified/implied as being a "sunroom" attached to the house for use all year round.

Be very wary of builders and inspectors in a close relationship.

@woody you're quite right ... I'm trying to focus on where I have leverage through regulations to make something happen - builder is trying to find a low cost fix to the fact I spotted the issue.

Fighting builders has filled my life every day for 18 months with no end in sight; these are the second builders renovating the house. Husband and I are both knackered from full time trying to manage people far more manipulative than we are,
thanks again
Mashie

mashie said:

@woody you're quite right ... I'm trying to focus on where I have leverage through regulations to make something happen - builder is trying to find a low cost fix to the fact I spotted the issue.

Fighting builders has filled my life every day for 18 months with no end in sight; these are the second builders renovating the house. Husband and I are both knackered from full time trying to manage people far more manipulative than we are,
thanks again
Mashie

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What glass is it that had the label 2.8?

Are you sure it referred to u value? Could it have said 28mm? I only ask because glass labels never usually mention u value. Double glazing labels usually state the construction detail: ie 4/20/4 soft coat black spacer toughened argon and the label is usually says 'this face to inside'.

I cant imagine and door, window or velux coming with anything but low e as a standard option these days and I cant imagine the builder actually specifying non low e glass.

The difference in price of different types of glass is pretty negligible between low e and clear

@Notch7 I thought that was a great thought - but they clearly say "U=2.8" - and on the opening window it says U=1.4
So I think it's U value. But I may be leaping to conclusions.

The builder now assured me he has checked with the supplier and the labels are wrong, so everything is ok. But he still wants to switch to external doors on the inside and do a calculation. Which seems contradictory

Here’s the label.. Can anyone interpret it for me, please?

I phoned the manufacturer who said for this order, there is U value 1.6, unrated for g value, air filled
they can't tell me about emissivity as "that depends on the frame" (the last comment was after they realised I wasn't a company).

This appears to be a 24mm ‘Low E’, argon-filled, double-glazed unit. I agree the labelling is very confusing, but I actually think you're fine.

I suppose their software could be set up wrong, but if the label is correct then what you have is:

4mm tough clear
4mm tough clear

24mm double glazed unit with 4mm toughened clear glass in and out
that would have a u value of around 2.7 to 2.8

-I would expect it to say:

4mm Tough clear
4mm Tough soft coat

the centre pane u value should be between 1.1 and 1.4 (1.1 is soft coat+warm edge spacer+argon gas fill).

emissivity coating is either hard (pilkington K glass) or soft coat (Saint Gobain planitherm total)

emissivity coatings can be tested.......it needs a specialist laser checking tool.