Internal house insulation

[brightspark]

the prats ring my brother up and say they have done a survey his house attic needs insulating he then goes off on one and says when the xxxx have you been in my attic to know and they put the phone down fast

 

[Blobber]

The biggest problem is the house is over 250 years old, brick built, no footings. no damp course, goodness knows what's under the the concrete floors
Obviously over the years its been "improved" with injected damp course, external render and modern internal plasterwork, I think but dont know that any damp is caused by condensation on some of the cold external walls so was hoping insulation would stop that?? we do run 2 dehumidifiers which have helped massively
In an ideal world we would knock the house down strip the render off, replaster internally with something breathable and live happily ever after but that wont happen in my life time unfortunately

 

[Cobbler]

I either put the phone down or tell them it's a rented property (it isn't) then they put the phone, in either case the number gets added to the call guardian block list.

We had a spate of calls about conservatories, couldn’t get rid of them. I told them “yes come & do a survey, but you know we live in a 3rd floor flat …. That shut them up for a while. The current pitch is “I am your local energy advisor” the same as Robbo gets. I know immediately it’s a cold call, as no-one else rings on the landline anymore, anyone that knows us uses the mobile.

 

[Erie Fred]

What does some infrared pix of the outside of the house show ?

 

[gaz1]

water damage is one thing you can save some stuff smoke damage means everything is thrown out

insulated plasterboard means 1/2hr fire protection and then the insulation will burn

a fire test between different materials

rockwool when falls can put out the fire whilst insulation board sets alight and produces dangerous smoke and fumes

between the tests above the rockwell is the only metal building that did survive

 

[Blobber]

Lots of helpful suggestions as usual and me house is going to to burn down

 

[Popcorn]

The it's that damp it wouldn't burn.......

 

[Smallfry]

We had a spate of calls about conservatories, couldn’t get rid of them. I told them “yes come & do a survey, but you know we live in a 3rd floor flat …. That shut them up for a while. The current pitch is “I am your local energy advisor” the same as Robbo gets. I know immediately it’s a cold call, as no-one else rings on the landline anymore, anyone that knows us uses the mobile.

What about the flights to Mexico booked using your credit card ?

Which account ? Your account. I have several accounts, which one ? Your account ?

 

[addjunkie]

The biggest problem is the house is over 250 years old, brick built, no footings. no damp course, goodness knows what's under the the concrete floors
Obviously over the years its been "improved" with injected damp course, external render and modern internal plasterwork, I think but dont know that any damp is caused by condensation on some of the cold external walls so was hoping insulation would stop that?? we do run 2 dehumidifiers which have helped massively
In an ideal world we would knock the house down strip the render off, replaster internally with something breathable and live happily ever after but that wont happen in my life time unfortunately

Id look at external insulation with render over the top if you happy with the inside. To insulate an old property inside properly you really need to do the floors too. So unless you have plenty of height it gets difficult, and digging out old floors to insulate below is a nightmare. If you want to do half a job, back to bare brick, build a box inside and insulate it, or dot a dab insulated board. Avoiding cold bridging around window reveals is very difficult and requires lots of care.

Probably cheaper/easier to build a nice new kit bungalow down the garden and bulldoze the house.

 

[gaz1]

Id look at external insulation with render over the top if you happy with the inside. To insulate an old property inside properly you really need to do the floors too. So unless you have plenty of height it gets difficult, and digging out old floors to insulate below is a nightmare. If you want to do half a job, back to bare brick, build a box inside and insulate it, or dot a dab insulated board. Avoiding cold bridging around window reveals is very difficult and requires lots of care.

Probably cheaper/easier to build a nice new kit bungalow down the garden and bulldoze the house.

thats spoken about here

Post in thread 'External wall insulation is it any good?'

Oct 9, 2025

im a builder by trade

cavity insulation causes damp issues as theres no cavity to get rid of any drips or leaks it also has issues with pointing so any cracks will cause issues in the end

external insulation well is more of a con to a degree whilst it does show the house is well insulated the cavity draft (air bricks ) is well below the threshold heat will still blead out through that point the cavity area is also cold

internal insulation pick wisely first off im not a lover of composite insulation its a fire hazard and if it gets a light its black its also 1/2hr fire boarded

does...

• gaz1

 

[Gareth J]

The biggest problem is the house is over 250 years old, brick built, no footings. no damp course, goodness knows what's under the the concrete floors
Obviously over the years its been "improved" with injected damp course, external render and modern internal plasterwork, I think but dont know that any damp is caused by condensation on some of the cold external walls so was hoping insulation would stop that?? we do run 2 dehumidifiers which have helped massively
In an ideal world we would knock the house down strip the render off, replaster internally with something breathable and live happily ever after but that wont happen in my life time unfortunately

Your house isn't suitable for internal WI

if you internally insulate, you will reduce the wall temperature. This will push the dew point closer to the inside of your house and encourage damp there and degradation of the wall. It'll lower the external surface temperature of the wall and increase the chances of it staying saturated resulting in an increased chance of freezing weather causing spalling to the brickwork.

External wall insulation on the other hand, has the potential to reduce all the risks above.

 

[gaz1]

if you have a cavity and air bricks external insulation is useless as the cavity is still getting warm and cold due to the air bricks

solid construction like some council buildings that works fine with that sort of build as theres no cavity ( eg : flats )

old properties use core heating to keep warm ( wall radient heat ) whilst wimpey houses ( external brick with wood framing and insulation with a cavity )

 

[addjunkie]

What height are your ceilings..if there is plenty of height, and the current concrete floors are sound, you could lay a membrane then kingspan over the top and a new floating floor. Do this after you've built a wood box with 3x2 20mm inside your existing walls and filled with foil backed kings-pan and taped all the joints creating a new vapour barrier. Re board and plaster. Obviously rewire and replumb while you do all this. A couple of weekends should see you done!

 

[Gareth J]

if you have a cavity and air bricks external insulation is useless as the cavity is still getting warm and cold due to the air bricks

solid construction like some council buildings that works fine with that sort of build as theres no cavity ( eg : flats )

old properties use core heating to keep warm ( wall radient heat ) whilst wimpey houses ( external brick with wood framing and insulation with a cavity )

Cavity on a 250+yr old house?

But yeah, on a cavity, options are different.

 

[Blobber]

What height are your ceilings..if there is plenty of height, and the current concrete floors are sound, you could lay a membrane then kingspan over the top and a new floating floor. Do this after you've built a wood box with 3x2 20mm inside your existing walls and filled with foil backed kings-pan and taped all the joints creating a new vapour barrier. Re board and plaster. Obviously rewire and replumb while you do all this. A couple of weekends should see you done!

6 foot 9 inches ceiling height so were pretty low already, dont think there is going to be an easy solution

 

[reb78]

6 foot 9 inches ceiling height so were pretty low already, dont think there is going to be an easy solution

My solution was to do nothing! The roof areas are insulated well and appropriately but my walls need to breathe as they are all stone - about 18 inches thick. I am sure we can get very close to passive houses with new builds but trying to achieve that with old housing stock just risks causing problems so it may be that higher heating bills are a thing we need to accept to allow our houses to function as well as they can.

 

[addjunkie]

6 foot 9 inches ceiling height so were pretty low already, dont think there is going to be an easy solution

Bit of digger action and then

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[Bobtail4x4]

if you have a cavity and air bricks external insulation is useless as the cavity is still getting warm and cold due to the air bricks

solid construction like some council buildings that works fine with that sort of build as theres no cavity ( eg : flats )

old properties use core heating to keep warm ( wall radient heat ) whilst wimpey houses ( external brick with wood framing and insulation with a cavity )

in theory a wall cavity should be unvented, assuming the bricky understands cavity liners and closes the cavity at the eaves that is.

 

[gaz1]

in theory a wall cavity should be unvented, assuming the bricky understands cavity liners and closes the cavity at the eaves that is.

dream on is all i can say, ive done enough roofs new and old and that top of the cavity isnt sealed

what does happen is the air goes between the cavity up into the loft and down the other side

if you have air vents on the roof then it goes up from the cavity air bricks up into the roof and then out through the roof vents

as goes for the insulation it is fitted onto the inside wall and onto your ceiling so it bridges the cold spot but not always

 

[Bobtail4x4]

I said in theory,

getting the trades on side is a different matter,