Internal Wall Insulation - Any experiences?

[Cheib]

Hi, we live in an old house (circa 1850 to 1900 with solid walls. Been in it for a year, we’re going to do some work next year to the kitchen and dining room, opening them up etc. Part of the drive to do this is to give us some more energy efficient space in the house, architect has said we should take this opportunity to insulate the walls whilst we are doing the work. We may look to do so in other parts of the house (my son’s bedroom has three external walls so is very cold) as well as looking to add double glazing (we’ve got large single glazed sash windows).

I found this thread excellent thread on different construction methods https://www.pistonheads.com/gassing/topic.asp?h=0&...

But I would be very interested in people’s experiences of internal wall insulation. Has it made a big difference to the house/rooms where you’ve had it done ?

[Evoluzione]

EmailAddress said:

I haven't read the thread linked but we battened(sp?), Insulated, and double plasterboarded with the good stuff an external wall with a good amount of plaster and it's been pretty good.

I think the air gap made the most difference but it's certainly a luxury not everyone can afford. We lost nearly 8" total I would guess.

ETA. The wall went from cold to the touch to negligible.

Were these solid walls?

[Cheib]

EmailAddress said:

I haven't read the thread linked but we battened(sp?), Insulated, and double plasterboarded with the good stuff an external wall with a good amount of plaster and it's been pretty good.

I think the air gap made the most difference but it's certainly a luxury not everyone can afford. We lost nearly 8" total I would guess.

ETA. The wall went from cold to the touch to negligible.

Wow 8” seems like a huge amount of space to lose. There would be scope for something like that in the big family space but there’s no way we could do that in my son’s bedroom as that would mean losing over a foot of floor space in the width of the room

[Cheib]

EmailAddress said:

I haven't read the thread linked but we battened(sp?), Insulated, and double plasterboarded with the good stuff an external wall with a good amount of plaster and it's been pretty good.

I think the air gap made the most difference but it's certainly a luxury not everyone can afford. We lost nearly 8" total I would guess.

ETA. The wall went from cold to the touch to negligible.

Wow 8” seems like a huge amount of space to lose. There would be scope for something like that in the big family space but there’s no way we could do that in my son’s bedroom as that would mean losing over a foot of floor space in the width of the room

[Evoluzione]

Cheib said:

EmailAddress said:

I haven't read the thread linked but we battened(sp?), Insulated, and double plasterboarded with the good stuff an external wall with a good amount of plaster and it's been pretty good.

I think the air gap made the most difference but it's certainly a luxury not everyone can afford. We lost nearly 8" total I would guess.

ETA. The wall went from cold to the touch to negligible.

Wow 8” seems like a huge amount of space to lose. There would be scope for something like that in the big family space but there’s no way we could do that in my son’s bedroom as that would mean losing over a foot of floor space in the width of the room

8" isn't a foot. It's 2" more than 6" which is half a foot.
You can't insulate without losing space, it's up to you (using U values) as to how much thickness you can afford to lose with your insulation.

[Cheib]

Evoluzione said:

Cheib said:

EmailAddress said:

I haven't read the thread linked but we battened(sp?), Insulated, and double plasterboarded with the good stuff an external wall with a good amount of plaster and it's been pretty good.

I think the air gap made the most difference but it's certainly a luxury not everyone can afford. We lost nearly 8" total I would guess.

ETA. The wall went from cold to the touch to negligible.

Wow 8” seems like a huge amount of space to lose. There would be scope for something like that in the big family space but there’s no way we could do that in my son’s bedroom as that would mean losing over a foot of floor space in the width of the room

8" isn't a foot. It's 2" more than 6" which is half a foot.
You can't insulate without losing space, it's up to you (using U values) as to how much thickness you can afford to lose with your insulation.

I’m aware that 8” isn’t a foot. As I said in my original post my son’s bedroom has external walls on three sides so in that case we’d lose 8” on one wall and then the two other walls that face each other we would love 16” combined.

I’ve only been reading about this for a few hours but from what I have seen so far I have not seen anything where that much space has been used but then as you say it may well be what is necessary.

[Magooagain]

Metal stud walls in front of existing internal walls then PIR insulation inbetween studs. Then plasterboard or insulated plasterboard or more PIR onto the studs then plasterboard.
100mm altogether or a bit more if using a thicker PIR on top.

[Equus]

Magooagain said:

Metal stud walls in front of existing internal walls then PIR insulation inbetween studs...

Why would you use metal, given that it results in the worst thermal bridging known to man?

[PhilboSE]

1950s house here with a 50mm cavity wall. Previous owners literally stripped it back to bare brick, installed 75mm PIR internally between stud work on all exterior walls, then new plasterboard and of course all new skirting and architrave. Then ran out of money and marriage at about 95% completion of the whole project so I’ve been finishing it all off.

I don’t have any before/after comparisons on energy usage but with thermal gain through 9 sets of French doors facing south-west we’ve only just had to put the heating on this week (south east).

If you have the opportunity to do it and can afford to lose 100mm all round then it probably results in the most efficient result as you are reducing the mass that you end up heating. Will obviously only work well with high spec solutions on windows etc.

[PhilboSE]

Cheib said:

I’m aware that 8” isn’t a foot. As I said in my original post my son’s bedroom has external walls on three sides so in that case we’d lose 8” on one wall and then the two other walls that face each other we would love 16” combined.

I’ve only been reading about this for a few hours but from what I have seen so far I have not seen anything where that much space has been used but then as you say it may well be what is necessary.

If you want to insulate then your options are: external; cavity or internal. All have implications. If insulating internally then it’s a balance between u value and thickness.

You can get plasterboard with just 1” of foil backed PIR already attached, that would make a difference and only lose 2” all round. However it’s probably worth taking some professional advice on the actual construction details to avoid potential condensation issues in the building fabric.

[Evoluzione]

Cheib said:

Evoluzione said:

Cheib said:

EmailAddress said:

I haven't read the thread linked but we battened(sp?), Insulated, and double plasterboarded with the good stuff an external wall with a good amount of plaster and it's been pretty good.

I think the air gap made the most difference but it's certainly a luxury not everyone can afford. We lost nearly 8" total I would guess.

ETA. The wall went from cold to the touch to negligible.

Wow 8” seems like a huge amount of space to lose. There would be scope for something like that in the big family space but there’s no way we could do that in my son’s bedroom as that would mean losing over a foot of floor space in the width of the room

8" isn't a foot. It's 2" more than 6" which is half a foot.
You can't insulate without losing space, it's up to you (using U values) as to how much thickness you can afford to lose with your insulation.

I’m aware that 8” isn’t a foot. As I said in my original post my son’s bedroom has external walls on three sides so in that case we’d lose 8” on one wall and then the two other walls that face each other we would love 16” combined.

I’ve only been reading about this for a few hours but from what I have seen so far I have not seen anything where that much space has been used but then as you say it may well be what is necessary.

He wrote '8" overall'. This is 4" per wall, or as we should be saying, 100mm per wall, so not as bad as you think, but yes a fair chunk of wall gone in a small room.
On the other hand, 100mm of the correct insulation will make a very positive impact.
I'm about to go down this path myself and can tell you what you do is linked with exactly how your house is built, from exactly what and how it's performing at the moment.
We don't know any of those details and even then we can't see it either. What works for one house in one part of the country may not work for another.
Retro-fitted insulation can be split into two types - breathable and non breathable.

Old solid walled houses can react very badly to the wrong kind of upgrades, so it's up to you or your on-site advisor to choose the correct materials out of a whole myriad of options. The less risky it is, the more expensive it gets.
To do it in a breathable (low risk/no risk) insulation can cost anywhere from £300 to £600 per sqm, fitted. Then you have breathable paint finishes on top of that, skirting boards and the windows will have to be renewed first too.

You could take a risk and do one room and see how it goes. But remember as you go around the house you'll find some exterior walls more exposed to bad weather than others which could cause problems with the wrong insulation.

[Equus]

Evoluzione said:

To do it in a breathable (low risk/no risk) insulation can cost anywhere from £300 to £600 per sqm, fitted.

Breathablle insulation isn't low/no risk, when fitted internally. Just the opposite, in fact.

[Evoluzione]

Equus said:

Evoluzione said:

To do it in a breathable (low risk/no risk) insulation can cost anywhere from £300 to £600 per sqm, fitted.

Breathablle insulation isn't low/no risk, when fitted internally. Just the opposite, in fact.

Go on, explain how a recognised system properly fitted could cause issues and name it.

[Lotobear]

Popcorn ready

[OutInTheShed]

Equus said:

Evoluzione said:

To do it in a breathable (low risk/no risk) insulation can cost anywhere from £300 to £600 per sqm, fitted.

Breathablle insulation isn't low/no risk, when fitted internally. Just the opposite, in fact.

Internal insulation can be high risk in some buildings.
Basically all the ends of your joists are now outdoors in a damp, unheated wall exposed to the weather.

[Cheib]

Evoluzione said:

He wrote '8" overall'. This is 4" per wall, or as we should be saying, 100mm per wall, so not as bad as you think, but yes a fair chunk of wall gone in a small room.
On the other hand, 100mm of the correct insulation will make a very positive impact.
I'm about to go down this path myself and can tell you what you do is linked with exactly how your house is built, from exactly what and how it's performing at the moment.
We don't know any of those details and even then we can't see it either. What works for one house in one part of the country may not work for another.
Retro-fitted insulation can be split into two types - breathable and non breathable.

Old solid walled houses can react very badly to the wrong kind of upgrades, so it's up to you or your on-site advisor to choose the correct materials out of a whole myriad of options. The less risky it is, the more expensive it gets.
To do it in a breathable (low risk/no risk) insulation can cost anywhere from £300 to £600 per sqm, fitted. Then you have breathable paint finishes on top of that, skirting boards and the windows will have to be renewed first too.

You could take a risk and do one room and see how it goes. But remember as you go around the house you'll find some exterior walls more exposed to bad weather than others which could cause problems with the wrong insulation.

Sorry I missed that it was 4” per wall.

House is built from brim brick but different elevations have different finishes. Front is painted, part of the house the first floor is tiled and another part it’s unpainted brick. External insulation isn’t an option as it would be massively complicated and its a big house, we are not going to try and insulate the whole house.

My son’s bedroom is a prime candidate for insulation as is the kitchen dining room space which we are going to do work to next year. This is going to be done at the same time as upgrading the existing heating system (gas fired rads) in most of the house and hopefully going with a heat pump in the new living space (if we can get the insulation right to make that viable) and potentially my son’s bedroom as it is right above it. Rest of the house we’re going to be lifting floorboards as when the previous owners refurbished the house the replaced the pipes on the central heating system but stayed with a single pipe system….so we need to install a twin pipe system.

Some pictures to give you an idea of the different external elevations

Anyone who can suggest a company that advises on this kind of thing I’d be very interested




Yes I know the pointing needs doing

[Evoluzione]

OutInTheShed said:

Equus said:

Evoluzione said:

To do it in a breathable (low risk/no risk) insulation can cost anywhere from £300 to £600 per sqm, fitted.

Breathablle insulation isn't low/no risk, when fitted internally. Just the opposite, in fact.

Internal insulation can be high risk in some buildings.
Basically all the ends of your joists are now outdoors in a damp, unheated wall exposed to the weather.

Let Equus respond.
If something is breathable you do not get 'damp, unheated wall exposed to the weather', that is a symptom of unbreathable.

[Equus]

Evoluzione said:

Go on, explain how a recognised system properly fitted could cause issues...

CBA today.

I'm getting sick of idiots who think that they're experts in vapour control because they once laid a floor in a house.

Think for yourself, for once.

This is a condensation risk diagram for a cavity wall with an insulated cavity:



1) Tell me what happens to the temperature profile (the red line) if you move the insulation to the inside face of the wall.
2) Tell me what happens to the dew point profile (the blue line) if you increase the breathabilty of the element that's nearest the warm face of the wall.
3) Tell me what happens to the green shaded condensation risk area.

[Equus]

Evoluzione said:

If something is breathable you do not get 'damp, unheated wall exposed to the weather', that is a symptom of unbreathable.

Don't (as a number of the more clueless participants on this forum are wont to do) confuse rain penetration of moisture (liquid) from the outside with water vapor (a gas) from the inside.

Liquid water doesn't 'breathe' anywhere.

[Evoluzione]

Equus said:

Evoluzione said:

Go on, explain how a recognised system properly fitted could cause issues...

CBA today.

I'm getting sick of idiots who think that they're experts in vapour control because they once laid a floor in a house.

Think for yourself, for once.

This is a condensation risk diagram for a cavity wall with an insulated cavity:



1) Tell me what happens to the temperature profile (the red line) if you move the insulation to the inside face of the wall.
2) Tell me what happens to the dew point profile (the blue line) if you increase the breathabilty of the element that's nearest the warm face of the wall.
3) Tell me what happens to the green shaded condensation risk area.

But that isn't what we're talking about here so I can't see the relevance? We are discussing putting a breathable insulation system onto an already breathable, but solid wall. Or maybe a (still functioning), but lightly modified solid wall.
Essentially what that does is just make the wall thicker, but it still works (breathes) as it should as there is no vapour control put in place.
On that last note however there are now what are called 'intelligent vapour control membranes'. These (seemingly) know which way to let air and vapour go through dependent on the changing conditions.

I am doing my own research though, i'm just about to embark on a 150 page rather scholarly piece on the subject written by some professors and people with letter after their names.
You can have your cake and eat it.
Well, maybe with a bit of icing missing perhaps.