Inside insulation on all outer walls

Francisq

Hi looking for advise if i currently have drylining in the house that was built in the early 80's e.g 20 mm fiber glass insulation that's behind the plasterboard slabs do i need to remove all this before i apply the new insulation ?

Thanks

Sleeper12

For the little benefits from the 20mm & the space it & the plasterboard is taking up, I would rip it out. I'd strip back to the blocks, put on a moisture barrier & then insulation boards with as much insulation as you have space for. I have 100mm in most of my rooms. Box room and bathroom are small rooms and could only justify 50mm

Edit vapor barrier

TimHorton

https://www.boards.ie/discussion/comment/120898179#Comment_120898179

what was the final wall made up of ? Was there a cavity ? Was is it worth it ?

Sleeper12

https://www.boards.ie/discussion/comment/120901121#Comment_120901121

1964 built house. Original house were cavity blocks only. No cavities between blocks or anything like that. Putting 100mm in brought the comfort levels right up. I often wonder if you ever save money on your bills but I can put hand on heart & say It was worth it for comfort levels alone. House heats up very quickly & holds the heat

Fibreglass dry lining often has mould problems since it will hold moisture which migrates through the wall. Its doing very little and will be a waste of space.

TimHorton

https://www.boards.ie/discussion/comment/120901153#Comment_120901153

I have added 100 mm PIR to the Internal Walls of the bedrooms my Bungalow , House only built 2005 with 50 mm PIR in the 100 mm cavity - I also removed Window boards and sealed all around that area with Expanding Foam /Airtight Membrane and Tape etc , Rooms are big so had the space for 100 MM Insulation /Vapour Barrier/30 MM Batten/12.5 MM Foil backed plasterboard - Also added 25 mm PIR to all 4 Window reveals and sealed, I was extremely diligent to ensure Sockets/Radiator Pipes were completely airtight. Last winter when a room was occupied it took very little heat to keep the rooms at 21 degrees , I had to add thermostatic smart valves as the newly insulated rooms were actually reaching 24/25 degrees ! , Going to get Cavity filled soon then may look at external insulation for living areas as disruption would be too much for internal , As you say the best gain is comfort levels , The 2 bedrooms at the north facing gable have gone from unwelcoming cold rooms to very inviting comfortable rooms that took very little heating to get to 20/21 degrees even on the coldest of days last winter.

https://www.boards.ie/discussion/comment/120901224#Comment_120901224

About to do the exact same on my new house, even down to adding the blown in to the cavities.

Francisq

Thanks Guys this is great advise and especially the work that needs to be done around the windows I'll be replacing them as part of doing the insulation when i decide which one to go for

I'm kind of thinking inside insulation rather than the outside as i believe the walls are a cavity blocks with no cavities between block however the front of the house is red brick so i maybe able to pump it..

GreeBo

https://www.boards.ie/discussion/comment/120898179#Comment_120898179

A vapour barrier should be on the warm side, not the cold side.

Putting this against the wall will cause condensation to form on it (as the wall will be cold)

Strip back existing including battons. Mechanically fix 50MM(or more) PIR to the walls. Tape your seams and to the floor and walls.

Mechanically fix plasterboard on top and fill/skim as required.

The existing stuff, where its actually fitted, will be loose and sagging and pointless in my experience.

Get professional, technical advice if you are going to add internal insulation AND get the walls filled, you may be moving the dew point within the building and causing interstitial condensation.