Sagging cavity wall insulation and our coldest room in the house - looking for surgestions..

[bobbyb]

Hi everyone!

Im in the process of re-insulating my son's room, which is a loft conversion room, done back in the 80s.

 

It's always been the coldest room in the house (by far), so I'm currently removing the old plasterboard and discovering what a terrible, rushed job they must have done with the insulation back then - there are gaps everywhere, some pretty sizable.

But anyway, that's the context, not the issue. The issue is the exterior wall.

Ive drilled a few holes (from the inside) and inserted an endoscope camera, and Ive discovered the cavity wall insulation has sagged. I'd estimate its only halfway up his wall in this section.

So the question is, what should I do about it?

 

Should I top it up, or should i simply install some 100mm PIR to the interior wall - or maybe another option? Any advice would be amazing.

[Nickfromwales]

5 hours ago, bobbyb said:

Ive discovered the cavity wall insulation has sagged. I'd estimate its only halfway up his wall in this section.

Hi.

 

What type of insulation is in there? Topping up the cavity is defo the best option, so you can keep the 'cold' as far outboard as is possible.

 

What insulation is in the attic room (or that you hope is in there)?

[bobbyb]

1 hour ago, Nickfromwales said:

Hi.

 

What type of insulation is in there? Topping up the cavity is defo the best option, so you can keep the 'cold' as far outboard as is possible.

 

What insulation is in the attic room (or that you hope is in there)?

HI! its a fluffy stuff, probably fiberglass or similar 

the rest of his room (internal walls/celing) are filled with gappy PIR

 

[Nickfromwales]

5 minutes ago, bobbyb said:

HI! its a fluffy stuff, probably fiberglass or similar 

the rest of his room (internal walls/celing) are filled with gappy PIR

 

Ok, thanks. One option is to remove the alarm box and have somebody blow bonded EPS beads into the cavity to finish it off. Gives better draught prevention, and will push down into any gaps in the existing insulation.

 

Once done, alarm box goes back on to cover the hole required to inject.

[saveasteading]

How much work would it be to strip that wall, or the top half , insulate and re-board?

[Nickfromwales]

6 hours ago, saveasteading said:

How much work would it be to strip that wall, or the top half , insulate and re-board?

It's a masonry cavity wall I assume, so not practicable?

[bobbyb]

16 hours ago, Nickfromwales said:

It's a masonry cavity wall I assume, so not practicable?

yeah, that's beyond my skills!

but! Although you can't see from the photo, this is a bungalow with a very shallow-pitched roof. It might be possible to remove some tiles and gain access to the cavity space. But unsure if thats a thing that can be done

[Nickfromwales]

24 minutes ago, bobbyb said:

yeah, that's beyond my skills!

but! Although you can't see from the photo, this is a bungalow with a very shallow-pitched roof. It might be possible to remove some tiles and gain access to the cavity space. But unsure if thats a thing that can be done

You just risk damaging the felt, if it's original bitumen stuff vs new membrane, so I'd avoid that tbh and just get a price supply and fit for the blown bonded beads, and carry on foaming gaps and fitting new plasterboard etc internally.