Taylor Wimpey "Net Zero" Chobham Manor houses use 3x expected energy

[Sparrowhawk]

Unsurprisingly the promise and the build quality don't match up. Thermal bridging, plasterboard tent.

 

If you can't view/access X (formerly Twitter) here's a readable link to the thread:

https://nitter.net/jimmybb/status/1733051913027949027

 

The image below is from a neighbour's survey. I have never seen dot and dab (with blower door running) highlighted so well.

Source: https://twitter.com/sav_ann/status/1733118128199020803 / https://nitter.net/sav_ann/status/1733118128199020803

 

The thermal imagery is excellent and I am coveting these £18k/£30k thermal cameras.

[joth]

As shocking is it is depressingly unsurprisingly.

 

Do they mention what the airtightness test result was? 

[ProDave]

It sounds like they ticked all the boxes except for the "attention to detail" one.  As above, not very surprising, but very disappointing.

[joe90]

9 minutes ago, ProDave said:

It sounds like they ticked all the boxes except for the "attention to detail" one.  As above, not very surprising, but very disappointing.

But, there is no “attention to detail” box for an EPC, I would be more interested in “cost to run over a 12 month period” (difficult for a new build) which would be much more accurate. My recent sale of my passive “esk” build took no account of the fact it was a self build which we all know means we care about how it’s built.

[Mr Punter]

1 hour ago, joth said:

Do they mention what the airtightness test result was? 

 

Yes it was 3.5 m3/h.m2.  These are often extrapolated from a couple of tests.

 

The door threshold looks really poor and was possibly never detailed correctly.

 

Velfac windows have the glass on the very outside of the system so the glass cannot be placed in the insulation zone on a cavity wall.  They require very careful and sometime awkward detailing to work well.

 

Plasterboard on dabs is nice and easy to do but useless unless the surface you are fixing to has no outside air.  So not blockwork or any holes through to the outside that are not 100% sealed (which they won't be).  The "We will put a continuous ribbon of plasterboard adhesive around the perimeter of the boards" never ever happens.

[nod]

1 hour ago, Mr Punter said:

 

Yes it was 3.5 m3/h.m2.  These are often extrapolated from a couple of tests.

 

The door threshold looks really poor and was possibly never detailed correctly.

 

Velfac windows have the glass on the very outside of the system so the glass cannot be placed in the insulation zone on a cavity wall.  They require very careful and sometime awkward detailing to work well.

 

Plasterboard on dabs is nice and easy to do but useless unless the surface you are fixing to has no outside air.  So not blockwork or any holes through to the outside that are not 100% sealed (which they won't be).  The "We will put a continuous ribbon of plasterboard adhesive around the perimeter of the boards" never ever happens.

On all my jobs a continuous line of adhesive does happen 

I can’t believe we are the only ones doing it right 

It’s poor management when it doesn’t and really easy to check at any stage afterwards A gentle tap around the perimeter 

 

Velfac arnt the best quality windows They are a contract window that most of the big players use and cheap

 

Ive said before on I visit different sites each week and haven’t seen an air test being carried out in the last five years It’s supposed to be 1-7 which is a joke in itself 

The major house builders get away with it Because the can 

Most of the new builds that I work on achieve a 2 on the air test Which must be done via a desktop 

[Roger440]

3 hours ago, nod said:

 

Most of the new builds that I work on achieve a 2 on the air test Which must be done via a desktop 

 

What does this mean?

 

[nod]

50 minutes ago, Roger440 said:

 

What does this mean?

 

The lower the number The better airtightness Less drafts Cheaper to heat 

[Roger440]

16 minutes ago, nod said:

The lower the number The better airtightness Less drafts Cheaper to heat 

 

I get that bit. Its the term "desktop" i dont understand. That suggests to me a theoretical test, not an actual real one?

[nod]

4 minutes ago, Roger440 said:

 

I get that bit. Its the term "desktop" i dont understand. That suggests to me a theoretical test, not an actual real one?

Never done Just a number 

I suspect yours has a very low score 

 

[joth]

6 hours ago, Mr Punter said:

Yes it was 3.5 m3/h.m2.  These are often extrapolated from a couple of tests.

Yeah I get a lot of developer builds aren't tested, I was asking specifically on the second set of thermal camera images which were done during an air test being conducted by the independent consultant. Did they actually measure 3.5 in that post-completion test? 

[saveasteading]

A proportion of units is air tested. Most likely selected to represent the varying models of house.

They are pre-advised so they are ready for testing, and the builder can do these ones reasonably well, for a good figure. These results are then applied to all of the same (untested) houses.

(Some people say) the developers have influence related to political donations,  hence the rules are not tightened. 

I'm pretty sure one air tester was suggesting to me that he could arrange ( write down) a better result if persuaded.

I can't of course say that happens.

[MikeGrahamT21]

Seen a fair few videos of mastic guys going on site, the site manager asking them to bodge something to pass the CML, only to afterwards rip out whatever it was and finish it properly with trims, but then they don't know whether its airtight or not.

 

The fact new homes are built like this, especially one badged up to be super eco, unfortunately is of no surprise. It is seriously disappointing however. Big house builders have no desire to build eco homes, they just want max profit to please their shareholders and board.

[saveasteading]

1 hour ago, MikeGrahamT21 said:

Big house builders have no desire to build

They don't see themselves as builders. Everything is someone else's fault or responsibility.

[Temp]

What we need is an organisation with teeth to set and enforce standards and quality in the building industry. 

 

Perhaps with powers to fine or disqualify builders and trades?

Edited December 11, 2023 by Temp

[saveasteading]

3 minutes ago, Temp said:

disqualify builders and trades?

I'm sure they would then drop into the cash, no insurance,  category.

The worst ones are there already with nowhere to fall to.

[joth]

17 hours ago, saveasteading said:

A proportion of units is air tested. Most likely selected to represent the varying models of house.

They are pre-advised so they are ready for testing, and the builder can do these ones reasonably well, for a good figure. These results are then applied to all of the same (untested) houses.

(Some people say) the developers have influence related to political donations,  hence the rules are not tightened. 

I'm pretty sure one air tester was suggesting to me that he could arrange ( write down) a better result if persuaded.

I can't of course say that happens.

 

All very familiar sounding.

Our principal contractor sent their air test guy, he was telling me all the "tricks" to improve the result. He just couldn't understand when I said no, I wanted the genuine result not a contrived one, even when I pointed out as the occupier, not a property developer looking to flip it.

 

This is why I was interested if the remedial works consultant, working on behalf of the owner, did a honest air test.for them

 

[Kelvin]

Having borne witness to a supposed quality team this isn’t in the least surprising. They genuinely think that because there’s a lot of insulation in the building then it must be good by default. When I explained that leaving gaps or even small bits unfilled significantly reduces the U value of the wall/ceiling it just went over their heads. Air tightness was like the dark arts. They are building houses with very little appreciation of building physics. Until the regulations tighten up and every house is properly tested then this isn’t going to improve. 

[JohnMo]

Think really until we have a suitably educated work force, we are stuffed. Really need some mechanism to make said training mandatory and more importantly meaningful.

 

Example - A builder recently bought our digger and was discussing the house, said he could never live in an airtight house, and would never build one, because they just go mouldy and are really unhealthy to live in, and wasn't sure why I bothered. Any discussion was straight over his head, as he was convinced otherwise.

 

Long way to go I am afraid 

[MR10]

Air tightness tester: you don't want a house that is too airtight, it'll get stuffy and if the MVHR unit breaks down you won't be able to breathe, that's why trickle vents are better and way cheaper than MVHR.

Me: (deep breath, count to 5, censor self) If the MVHR breaks down I'll just open a window.

True story !

 

[ProDave]

There really is a huge void between a lot of the mass market builders and best practice.

 

I am perhaps lucky that I never worked for any of the big builders but i did do a spell subcontracting for an "eco home" builder who actually took insulation, air tightness and attention to detail seriously.  And when it was shown to you, it really was not difficult to understand.  They had one basic principle, they built the structure of the building and NO subcontractor was to drill any hole through the outer wall of the building.  If the subbie wanted a hole, he showed them where they wanted it, and if they could not be persuaded him it was not required, then they drilled it and took care of sealing it after the pipe or cable was installed.

 

That company were the ones that detailed the design for my house, and then another local building firm, who I had also worked for, and I knew they had similar high standards built the shell for me.

 

The only experience I have of mass market builders was buying a late 1980's new build as my first house.  It was a very cold house, that i now recognise as being a great big plasterboard tent.

 

The principles of building well are so simple to grasp, that anyone that cares to actually listen could be taught all they need to know in a 1 day seminar.  Isn't it about time something like that is mandatory for all "builders"?

[Roger440]

22 hours ago, saveasteading said:

 

(Some people say) the developers have influence related to political donations,  hence the rules are not tightened. 

I'm pretty sure one air tester was suggesting to me that he could arrange ( write down) a better result if persuaded.

I can't of course say that happens.

 

Wasnt Robert Jenrick caught doing exactly that on behalf of developers?

 

It does happen. ( i may have recounted this before) A friend of mine does a bit of occasional development/house building. Built 2 houses. Needed air test. Chap turns up, had a look round and then said, what number do you want me to record. No intention to actually test anything. They forced him to test it.

 

As ive said in my rants about building control, the whole system is pointless. Once you have the piece of paper that says your word is accepted, you can do, whatever you want. Just sign off any old crap. There is no comeback, and no practical legal recourse for the consumer even if they knew or wanted to do so.  Applies equally to bco's, electricians and window fitters. Especially windows fitters.

[Roger440]

6 hours ago, Temp said:

What we need is an organisation with teeth to set and enforce standards and quality in the building industry. 

 

Perhaps with powers to fine or disqualify builders and trades?

 

Not going to happen. Cant happen. Will never happen. Id put good money on that.

 

Edited to add, there is no qualification requirement to be a builder. Anyone can be one. And is. So disqualification isnt an option even if there was a desire to do so.

Edited December 11, 2023 by Roger440

[Roger440]

23 hours ago, nod said:

Never done Just a number 

I suspect yours has a very low score 

 

 

Sorry, i think you may have misunderstood what i was asking.

 

Your post suggested that air tests were a desktop excercise, not an actual practical test. Is that what you are having done/experiencing?

 

I have no house to test.

[Marvin]

On 10/12/2023 at 15:36, Mr Punter said:

"We will put a continuous ribbon of plasterboard adhesive around the perimeter of the boards" never ever happens.

Unless your @nod