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Semi rant - House insulation
tegwin - 24/11/20 at 10:53 AM

Currently rewiring my house, unfortunately the plaster is in such poor condition it had to come off the walls as the wallpaper was the only thing holding it up.

Building control came to inspect the wiring and have pointed out that part L requires upgrades to insulation if more than x amount of the wall is exposed.

This is problematic because I would need to add between 50-100mm of insulation on the inside walls to reach the required U value.

This would mean the new kitchen that has been ordered won't fit. One of the internal doors will have to move sideways or it wont open. None of the existing radiators will fit because the wall-space available for them has shrunk. Not to mention the reduction in room size in an already tiny house.

Insulating internally on a single room basis will cause some pretty nasty temperature/condensation gradients where the floor voids meet the external wall which to me seems crazy from a damp/rot point of view.


I get that we need to save the planet but the enormous cost implication of trying to retrofit this to the inside of a tiny old house makes zero sense.


Urghh........ Rant over...

Anyone else have similar stories?

wylliezx9r - 24/11/20 at 11:00 AM

I didn't know that building control had to be involved with a re-wire ?

tegwin - 24/11/20 at 11:02 AM

quote:
Originally posted by wylliezx9r
I didn't know that building control had to be involved with a re-wire ?


Yup...They do want to be involved if you're doing it yourself....

[Edited on 24/11/20 by tegwin]

wylliezx9r - 24/11/20 at 11:03 AM

wouldn't that just be an electrical inspection and testing though ?

tegwin - 24/11/20 at 11:09 AM

Yes, but if they are on site for a first fix inspection and spot other stuff they are quite able to say whatever they like

Mr Whippy - 24/11/20 at 11:26 AM

Why did you get them involved... Oh man so much hassle for nothing. I built my house, wired it myself, apart from meter and got a polish electrician i know to check it an sign it off. That was it done.

Personally I'd fix the plaster, paint it and ignore their BS and if they raise it again tell them they are taking rubbish and show them a picture of the completed room.

You need to stay away from these desk jockeys with nothing better to do than quote rules.

[Edited on 24/11/20 by Mr Whippy]

nick205 - 24/11/20 at 11:27 AM

It does seem hard work having to effectively shrink the interior apce to accommodate the insulation. I have a different house (timber framed 3 bed semi), but I have added Celotex type insulation in upstairs walls where the plasterboard has been replaced and the room replastered. Makes a massive difference to the heat retention of the house for not much cash outlay.

I'm sure you probably have, but have I'll ask anyway, have you examined all the different insulation materials?

There may be a less bulky (thinner) way of achieving the required U value, but taking up less space.

gremlin1234 - 24/11/20 at 11:39 AM

you only have to do it if it is technically, functionally and economically feasible

so if it makes the room too small to fit a kitchen -its not feasible

see quoted section on this page...
https://www.labc.co.uk/news/when-do-i-need-building-regulations-approval-renovating-thermal-element

Sam_68 - 24/11/20 at 12:05 PM

quote:
Originally posted by gremlin1234
you only have to do it if it is technically, functionally and economically feasible

^^^ This.

Calm down and have a nice cup of tea, OP.

tegwin - 24/11/20 at 12:09 PM

Agree that getting them involved is hassle.... But without a certificate it's hard to sell the house on.

Hoop jumping is all well and good.....


ahah yes... a cup of tea is definitely required.

Sam_68 - 24/11/20 at 12:14 PM

quote:
Originally posted by tegwin
Agree that getting them involved is hassle.... But without a certificate it's hard to sell the house on.

Which is why trying to save money by doing it yourself is a false economy, in this case.

If you'd paid a qualified sparky to do the work for you, he'd have been able to certificate the electrics, the jobsworth from Building Control would never have become involved, and everyone would have been happy.

tegwin - 24/11/20 at 12:17 PM

Not sure that's entirely true. What does a re-wire cost on a semi? £3500ish?

Materials have cost me £600.... BCO fee was £400. Thats some saving. But you're right...you end up getting grief for the pleasure of saving a few grand!

Sam_68 - 24/11/20 at 12:55 PM

quote:
Originally posted by tegwin
Materials have cost me £600.... BCO fee was £400.


Now add the cost of insulating the kitchen wall, moving the door, replacing the radiators, losing the deposit on the kitchen order you've just redesigned, and finding somewhere else to live after your dodgy wiring has burned the house down.

joneh - 24/11/20 at 12:58 PM

quote:
Originally posted by tegwin
Agree that getting them involved is hassle.... But without a certificate it's hard to sell the house on.

Hoop jumping is all well and good.....


ahah yes... a cup of tea is definitely required.


That's what indemnity policies are for. I removed the window and door between my house and conservatory and told them either buy or don't buy. In the end it cost me £70 for an indemnity policy which was insisted on by the purchasers solicitor.

Another thought, what about that thin bubble foil insulation. Doesn't that have a high U value?

BenB - 24/11/20 at 01:06 PM

How long do people keep their certificates for? I did my own wiring so didn't get it signed off. The gas I put the pipes in and our GasSafe man soldered it and fitted the boiler to the manifold. But I didn't get a certificate for that either. When I bought the house I didn't get a certificate- which makes sense given that the insulation on the 50 year old wires had cracked and was completely missing in places!!

Just curious what happens in practice. I suspect I'm not going to sell the house for at least 20 years by which time even if I had been given a certificate I would have lost it!!!

Sam_68 - 24/11/20 at 01:31 PM

quote:
Originally posted by joneh
Another thought, what about that thin bubble foil insulation. Doesn't that have a high U value?

The best (thinnest for given performance) insulation that's available is this stuff:

Aerogel

... just don't look at the price!

cliftyhanger - 24/11/20 at 01:37 PM

quote:
Originally posted by BenB
How long do people keep their certificates for? I did my own wiring so didn't get it signed off. The gas I put the pipes in and our GasSafe man soldered it and fitted the boiler to the manifold. But I didn't get a certificate for that either. When I bought the house I didn't get a certificate- which makes sense given that the insulation on the 50 year old wires had cracked and was completely missing in places!!

Just curious what happens in practice. I suspect I'm not going to sell the house for at least 20 years by which time even if I had been given a certificate I would have lost it!!!


There is a lot of scare mongering, probably instigated by the "professional" bodies ie NICEIC/FENSA etc.
In reality nobody really worries very much, and at worst you get an indemnity as above.

Intrigued how BC can inspect the wiring properly. Do they lift flooring? Inspect how the cables are run in the walls? stuff like that to ensure it meets part P. Testing is only half, if that, of electrical work.

peter030371 - 24/11/20 at 01:38 PM

quote:
Originally posted by BenB
Just curious what happens in practice. I suspect I'm not going to sell the house for at least 20 years by which time even if I had been given a certificate I would have lost it!!!


Same as me. My extension done 4 years ago has a certificate but it doesn't cover the wiring I did around 2002 in the rest of the house. I also completly re-wired my sisters house in the early 90's. The electricity board had a hissyfit about fitting a meter but eventually did it. Guess which wiring went up in smoke last year (no real damage done, she spotted it and flicked the company fuse out)...her meter wiring not my'crap' wiring (the term given by the moaning meter fitter)

James - 24/11/20 at 02:49 PM

quote:
Originally posted by Sam_68
quote:
Originally posted by tegwin
Agree that getting them involved is hassle.... But without a certificate it's hard to sell the house on.

Which is why trying to save money by doing it yourself is a false economy, in this case.

If you'd paid a qualified sparky to do the work for you, he'd have been able to certificate the electrics, the jobsworth from Building Control would never have become involved, and everyone would have been happy.




quote:
Originally posted by tegwin
Not sure that's entirely true. What does a re-wire cost on a semi? £3500ish?

Materials have cost me £600.... BCO fee was £400. Thats some saving. But you're right...you end up getting grief for the pleasure of saving a few grand!



We re-wired my 4 bed detached about 6/7 years ago. It cost about £1200 in materials and some extra tools IIRC and then I paid £250 to a sparky to sign it off.

I think we were quoted in the region of £10k to get the pros in. They charge about £50 a socket alone and there's 80 of them!


Granted, there's plenty of bits I'd have done differently knowing what I know now but it's probably safeish. But then I drive car that I built knowing bugger all as well!


Cheers,
James

Mr Whippy - 24/11/20 at 04:47 PM

Have to say that wiring a 6 bedroom house was a lot less complicated than wiring a car. Plus I used heavier gauge wire for the showers than the regulations required at the time, something I'm very glad I did as they later changed it.

As for saving money... I spent a total of £85k building a house that was then valued shortly after at £340k so it does pay to do it yourself.

[Edited on 24/11/20 by Mr Whippy]

harmchar - 24/11/20 at 05:43 PM

Have you checked out Kingspan insulation? They used to offer much thinner insulation with better thermal properties than stuff that was 4 times thicker. It's pricey, but reckon it would save you moving all the stuff you mentioned in original post.

James - 24/11/20 at 07:13 PM

There's some multi-layer silver foil stuff (like a loads of layers of space blanket and thin foam fixed together) that my builder used that is supposedly amazing.

Might be worth a look at.

Cheers,
James

Sam_68 - 24/11/20 at 08:10 PM

quote:
Originally posted by harmchar
Have you checked out Kingspan insulation? They used to offer much thinner insulation with better thermal properties than stuff that was 4 times thicker.


quote:
Originally posted by James
There's some multi-layer silver foil stuff (


The multifoil stuff is largely snake oil: a lot of Building Control Authorities won't accept it, because it's been proven not to perform to the standards the manufacturers claim (mainly because you've got to compress it to fix it to the studs/battens, and where you so so, the performance nosedives: the manufacturers quote performance where it is fully 'puffed up' and uncompressed).

PIR insulation (Kingspan/Celotex) is the usual solution (it's expensive, but not fantastically so). As per my post above, the only readily available stuff that's better than PIR (but quite a bit more expensive) is Aerogel.

PIR has a thermal conductivity of 0.022 W(m.K)
Aerogel has a thermal conductivity of 0.015 W(m.K)

... so in other words, Aerogel is about 32% more efficient (hence about 1/3rd thinner than PIR, for equivalent performance).

For internal insulation, I wouldn't even entertain anything less efficient than PIR, so those are pretty much your only sensible choices.

steve m - 24/11/20 at 09:19 PM

I know it might seem a a bit lame, but have you thought about selling what you have got in the state it is, and moving on/up ?

I know its perhaps cheating the system, but it Dog eat dog out there in the real world,

Alternatively invest in some decent solar panels, and reap the benifit from power/heat and free, from them (no insulation reqiured) and when you sell up or move on, take the panels with you ?

James - 25/11/20 at 06:14 PM

quote:
Originally posted by tegwin
Currently rewiring my house, unfortunately the plaster is in such poor condition it had to come off the walls as the wallpaper was the only thing holding it up.

Building control came to inspect the wiring and have pointed out that part L requires upgrades to insulation if more than x amount of the wall is exposed.

This is problematic because I would need to add between 50-100mm of insulation on the inside walls to reach the required U value.

This would mean the new kitchen that has been ordered won't fit. One of the internal doors will have to move sideways or it wont open. None of the existing radiators will fit because the wall-space available for them has shrunk. Not to mention the reduction in room size in an already tiny house.

Insulating internally on a single room basis will cause some pretty nasty temperature/condensation gradients where the floor voids meet the external wall which to me seems crazy from a damp/rot point of view.


I get that we need to save the planet but the enormous cost implication of trying to retrofit this to the inside of a tiny old house makes zero sense.


Urghh........ Rant over...

Anyone else have similar stories?



Trying to think laterally on this one... but I don't really understand the problem you're describing. Is it a single skin/no cavity wall?

However, there was mention on Money Saving Expert on the Green New Deal dates being extended. Would it be worth investigating if you qualify and then at least seeing if your upgrades would be paid for?

Cheers,
James

tegwin - 25/11/20 at 06:18 PM

Cavity wall with insulation.

The new regs imply that if you refurbish a wall inside or outside Eg re plaster... you are supposed to increase the thermal efficiency of that wall by quite some margin not simply replaster.

In this instance as someone has pointed out it’s not economically or logistically possible to do much as the rooms are so small to start with.

Sam_68 - 25/11/20 at 07:15 PM

quote:
Originally posted by tegwin
Cavity wall with insulation.

If you have cavity walls with insulation, are you sure you need to upgrade them, anyway? What exactly is the current wall build-up?

Notwithstanding the test of 'technical, economical and functional feasibility', the Regs only require you to upgrade the thermal element (in the case of a cavity wall) to U=0.55.

I had assumed from your original description of needing 50-100mm. of internal insulation that we were talking about a solid brick wall.

If you already have an insulated cavity wall, it seems very unlikely that you'd need to do anything, anyway.

Have you pissed off the BCO? He ought to know perfectly well both the test of reasonableness and the implications of the required U-value, so if I didn't know better, I'd suggest he's on a deliberate wind-up.

nick205 - 26/11/20 at 01:19 PM

tegwin / OP

If you have to achieve this U value is there anything you could do on the exterior of the building?

I appreciate you'd need to be in keeping with adjacent properties, but it could be another way around the issue.

Alternatively are you allowed to request a different officer? Sometimes a different set of eyes and ears can help view things in a more realistic way.