To discuss your project give us a call on 01392 861763

Sustainable Building Forum

The place to share best practice advice about all things sustainable building. Use the search icon to find the topic you’re interested in or register as a member to comment on topics and ask your own questions.

Notifications
Clear all

Internal wall insulation for room with mixed wall types, and what to do for walls underfloor

 
johnwa
(@johnwa)
Member

Hi,

I have an old solid brick house c 1900 that has been extended over the years. I'm renovating the 1st floor bedrooms with internal SWI, which in all cases have 2 external solid walls, 1 internal solid wall and 1 internal stud wall.

Could I use the same wood fibre boards insulation all the way around the room? or should i be looking at wet-process for the solid walls and dry process for the stud walls? or even dry-process for the internal solid wall?

I am thinking of going for 60-100mm on the external walls and 60mm on the internal walls.

Also what do you advise for the wall areas below the floorboard? should the insulation be taken all the way down to the ceiling below, or does other approaches need to be taken to keep any moisture away from the joists?

 

many thanks

John

Quote
Topic starter Posted : 20/03/2022 12:08 pm
Chris Brookman
(@chris)
Member Admin

Hi John

For your external walls I'd suggest either 60 or 100mm Beltermo Room wood fibre boards (dry process, square edge board) and then for your internal masonry partition, you only really need 20mm boards to prevent thermal bridging. For your internal stud partition you will need a T&G board and so I'd suggest the Beltermo Ultra boards, which start at 40mm thickness.

The floor zone should always be insulated so ideally you should cut your floorboards back and take the insulation around the floor joists and down to the ceiling. It would also be best to cut the ceiling back when you insulate below the floor and then join up the two layers.

The spec for the external walls would be as follows:-

Existing wall, plaster removed

5-10mm Baumit VitonFein clay plaster

60mm BeltermoRoom wood fibre insulation board, mechanically fixed

5mm Baumit RK70N lime plaster, incorporating Baumit StarTex mesh

2mm Baumit Klima Glatte fine lime skimming plaster

interior

Hope that helps.

ReplyQuote
Posted : 21/03/2022 9:48 am
johnwa
(@johnwa)
Member

@chris so you'd recommend dry process board for internal SWI rather than wet process ones?

ReplyQuote
Topic starter Posted : 21/03/2022 12:55 pm
Chris Brookman
(@chris)
Member Admin

Hi John

Not so much one over the other, more I think this would be the most economical and effective solution for you.

Hope that helps.

ReplyQuote
Posted : 01/04/2022 4:51 pm
Share:

CPD Training

We offer CPD training for architects practices across Devon and Cornwall.

Software Modelling

We offer dynamic heat and moisture modelling as well as condensation risk analyses.

Building Plan Review

If you have some plans and would like our opinion on which materials would be the best for you, contact us.

Overview

Back to Earth is a natural building material supplier. We're not your typical builders'​ merchant though and instead work closely with our clients during the planning, designing and building phases of projects.

Back to Earth is a proud signatory of the Anti-Greenwash Charter:

© 2018 Back to Earth