Build regs for internal wall insulation?

[AJC211]

Gah, I’m in a pickle.

I’m having internal walls and ceilings/flat roof insulated as part of my journey towards getting an ASHP/more energy efficient house. Most of the walls are 1960s build cavity walls, assumed insulated on the EPC.

I’ve had an energy consultant and various builders quote for this insulation work and none have mentioned building regs…but now, 2 days into the work, I’m pretty sure I need building regs. So, GAH!

But I’m also pretty sure building regs will require me to put really thick insulated plasterboard on my small cottage room walls and make them even smaller…! Is there no leeway for old/small houses?? I also worried the Hybris + 38mm insulated Celotex plasterboard that’s already been put on the flat roof won’t be enough and will have to come down/out (R value Hybris 2.9, Celotex 1.2, which takes U value to 0.25 I think, which is higher than the figures I can find for building regs).

I assume this is a case of ‘stop all work and get building regs onto it ASAP’?? If I get building regs after the work, I’m worried it won’t comply, and it feels like an expensive assumption to make that it will…

 

[oldbutnotdead]

If you just stick insulation to (or frame out a stud wall on) an existing wall WITHOUT removing the plaster on the wall, insulating that wall is not notifiable. If you hack back to brick it is.
Yes there is wiggle room if a room would be disproportionally reduced in floor size by installation to current requirements (on a refurb)
Ceiling/roof insulation- 38mm sounds way too thin to be useful. 250mm of rockwool equals about 125mm of PIR...that's the current standard.

 

[winston1]

Why would you need to insulate internal walls? There is no heat loss if both sides are the same temperature.

 

[oldbutnotdead]

Why would you need to insulate internal walls? There is no heat loss if both sides are the same temperature.

Ahhh, valid point. I'm assuming op meant internally insulating external walls. Yeah zero point thermally insulating walls separating rooms in a common household (unless you're creating a sauna or an ice room )

 

[cdbe]

Unless you don't have a mains gas supply I presume you're doing this to save the planet and not save you money?

I was under the impression that ASHPs really need approaching "passivhaus" standards of thermal efficiency, not a bit of celotex stuck on the walls.

1960's cavity walls won't be insulated unless retro fitted, and if it isn't it should be done in the first instance, and if it is then checked to see if it is performing effectively (can be gappy and settle over time).

There are potentially serious condensation issues associated with insulating cold flat roofs from inside, hopefully whoever designed this has conducted a thorough risk assessment.

Internal wall insulation makes great sense, but generally only saves money if grant funded or DIYed.

In all of this, any forecast money saving will be based on current (hopefully short term) unnaturally high energy prices.

 

[winston1]

Internal wall insulation makes great sense, but generally only saves money if grant funded or DIYed.

How? As I previous said there can be no heat loss if both sides are the same temperature.

 

[cdbe]

How? As I previous said there can be no heat loss if both sides are the same temperature.

Bit pedantic. Clearly they mean internal insulation of external walls! Unless you think the OP is an idiot, however they are contemplating a heat pump.....