Internally insulating a room - materials & advice requir

[dooosuk]

I live in a 1911 terraced house. The rear bedroom has two external walls (double brick, no cavity as far as I'm aware) and gets very cold despite there being 270mm of rockwool insulation above in the roof.

Whilst the heating is on, the room is really hot but as soon as the heating goes off all the warmth is lost.

I'm thinking of removing the plaster from the two external walls (to minimise the loss of internal space) and then fitting insulating plasterboard such as Celotex PL4000, Kingspan K18, or a Gyproc Thermaline variant.

However, someone mentioned Marmox board. What are the advantages/disadvantages to Marmox over PIR board?

Are there any other boards I should be considering? (I'm just an enthusiastic DIYer so not particularly knowledgeable in this area).

Also, assuming I go for a PIR board any suggestions of thickness? Obviously it's only worth doing if it makes the room warmer but it's not the biggest room in the house and so I'd like to minimise the loss of internal space.

Thanks

 

[jeds]

Forget Marmox. Use a standard thermal plasterboard. Look up Lafarge Thermalcheck K or the equivalent British Gypsum or Kingspan. When you price it up bear in mind that the insulation element comes in various types and thicknesses. k is the best. A 50mm (overall thickness - including the board) would be OK. 60mm would be better.

All boards can be fixed mechanically - my preferred method. Boards can also be fixed with adhesive (dot and dab) but you must get the correct grade of board for that. e.g. Kingspan K17 is for dot and dab - K18 is for mech fixing.

 

[dooosuk]

Thanks John. I'll concentrate my research on thermal plasterboards then.

Any reasoning for preferring mechanical fix over dot & dab?

 

[jeds]

No really strong reason. I'd slightly revise that and say mech fix if the wall is reasonably flat, dot and dab if it's a bit rough. Either will do a good job.

 

[ban-all-sheds]

Fixing things to the walls?

CH pipes?

Cables/sockets/switches?

You need to make it and keep it vapour-tight.

And you need Building Regulations approval.

 

[dooosuk]

Thanks Ban...

The boards come with a vapour barrier don't they, I wasn't expecting to have to do anything further.

Yep, understand I need to check the CH pipes and sockets allow for installation. This shouldn't be a big problem with the walls I'm looking at.

For Building Regs, I assume it's because of the 'thermal change' (Regulation 22 and 23). From looking it seems I need to adhere to Part L, Schedule 1 which seems pretty straightforward.

Any advice on the best way to apply for Build Regs approval. I assume I won't need full plans so can I just do the work and apply for Regularisation or should I submit a Building Notice?

 

[ban-all-sheds]

The boards come with a vapour barrier don't they, I wasn't expecting to have to do anything further.

I imagine (hope) that the maker will have installation instructions on what to do with joints and window reveals.

For Building Regs, I assume it's because of the 'thermal change' (Regulation 22 and 23). From looking it seems I need to adhere to Part L, Schedule 1 which seems pretty straightforward.

Approved Document L will have guidance on how to comply.

I assume I won't need full plans so can I just do the work and apply for Regularisation

Don't do that - it will cost (typically) at least twice as much.

or should I submit a Building Notice?

A "full plans" submission would be less risky, and no more expensive. You don't need actual drawings (or if you do you can copy any detailing from the Lafarge/Kingspan/Celotex/BG/Knauff website), just a description and a statement, backed up by info from the maker, of the U-value you'll achieve.

Better to find out before you start if the council are happy with what you plan to do than than wait until you've done it and risk them saying "nope - do it again".

 

[dooosuk]

Thanks ban...all very useful information for me.