Cavity Wall Insulation Query
Discussion
Last week I had Cavity Wall Insulation installed. The house is a four bed link detached built in 1985. The installers managed to use 24 bags of Rockwool insulation.
Afterwards, I mentioned to my neighbour(who's an electrician)that I'd had it installed and he said "why, it's already got it"? He says that he's noticed several times when drilling into the walls that there's a layer of polystyrene (or similar) in the cavity.
So, if he is correct, how did they get 24 bags of Rockwool in to an already filled cavity and have I wasted my money?
Afterwards, I mentioned to my neighbour(who's an electrician)that I'd had it installed and he said "why, it's already got it"? He says that he's noticed several times when drilling into the walls that there's a layer of polystyrene (or similar) in the cavity.
So, if he is correct, how did they get 24 bags of Rockwool in to an already filled cavity and have I wasted my money?
Chris_H said:
Slagathore said:
Is it possible that the previous owners of his house had in put in?
How old are the houses?
Build in 1985 and I've owned it since 1987, so I think unlikely.How old are the houses?
If it's the sheet stuff, then it would have been put in when the house was built.
Just had a quick Google, as I thought cavities were usually filled with the little polystyrene balls (when being added at a later date), but I've just read that they can blow the Rockwool in?
If they've blown the Rockwool in, they'd have blown it in the gap that is still left in the cavity. As you can just make out in that picture.
So there is, in theory, space for them to have blown the Rockwool in to. Just not really necessary and now the cavity is full, will that not just transfer damp from outer skin to the inner skin?
If they've blown the Rockwool in, they'd have blown it in the gap that is still left in the cavity. As you can just make out in that picture.
So there is, in theory, space for them to have blown the Rockwool in to. Just not really necessary and now the cavity is full, will that not just transfer damp from outer skin to the inner skin?
Edited by Slagathore on Sunday 10th October 12:34
Hmmm, that doesn't sound good! This company did a survey first whereby someone came around and did a test drill to see what was what. I didn't ask if there was already insulation in there as I assumed that as they were going ahead, I needed the insulation.
I have all the paperwork so if there's any problems down the road with damp, then surely they can be held responsible?
I have all the paperwork so if there's any problems down the road with damp, then surely they can be held responsible?
It's likely the builders installed the minimum required to meet the regs at the time. I don't know what was required at that time but they may have put say a 25mm board in and left a 25mm cavity. The fibre will reduce the airflow through the cavity and therefore reduce the heat loss.
Slabs installed in the 80s will probably have been installed with gaps anyway So your rockwool will have filled them as well.
All sorts of materials have been used over the years. My recent extension looked as if a variety of dead cats were stuffed in. The trick is has it been installed properly? and the answer is unless you watched the wall being built with insulation is that it is anyone's guess.
Generally we are crap in this country at installing insulation as builders just don't get the point.
All sorts of materials have been used over the years. My recent extension looked as if a variety of dead cats were stuffed in. The trick is has it been installed properly? and the answer is unless you watched the wall being built with insulation is that it is anyone's guess.
Generally we are crap in this country at installing insulation as builders just don't get the point.
The next thing is wait for a windy day and go round looking for draughts armed with a mastic gun. Round pipes skirting boards doors etc.
When you lift a carpet check the floorboard gaps, apply mastic and cover with paper until dry or if keen lift the boards insulate between the joists and replace with chipboard.
When you lift a carpet check the floorboard gaps, apply mastic and cover with paper until dry or if keen lift the boards insulate between the joists and replace with chipboard.
MJG280 said:
The next thing is wait for a windy day and go round looking for draughts armed with a mastic gun. Round pipes skirting boards doors etc.
When you lift a carpet check the floorboard gaps, apply mastic and cover with paper until dry or if keen lift the boards insulate between the joists and replace with chipboard.
Keen?When you lift a carpet check the floorboard gaps, apply mastic and cover with paper until dry or if keen lift the boards insulate between the joists and replace with chipboard.
Fvckin sadistic more like
I'd rather pay more for the gas/leccy!
I,m sure you will see a huge difference.
My house is circa 85 and the insulation was crap, thin yellow rockwool type stuff (not sure on correct name).
So i put up just an extra 100mm in the loft on top of what was about 70mm (probably used to be 100mm) , that alone made a noticible difference.
I then have insulated most cavitys upstairs and have in my bedroom ensuite had to construct a stud wall in front of the old block wall in prep for the tiling, this wall has 70mm literally stuffed in, the floor has thermal tile backer boards and the room has ufh. so most of the walls in there are double insulated, the floor is done and so is the loft above.
Since i turned the c/h back on about a couple of weeks ago i am amazed at how well it works, i really am.
The boiler seems to come on for about an hour in the evening and thats it, the house stays warm all night. I have 2 rads on upstairs totalling about 3500btu in a 4 bed and my bedroom/ensuite which is 3/4 tile with just ufh which has not even been turned on stays at around 20deg.
Infact the whole 4 bed house has only got about 22000 btu of rads, i have no carpets/finished floors down yet and its always around 20 deg which is perfect.
Of course the test will be when it gets properly cold but i recon another layer in the loft and it will be excellent.
My house is circa 85 and the insulation was crap, thin yellow rockwool type stuff (not sure on correct name).
So i put up just an extra 100mm in the loft on top of what was about 70mm (probably used to be 100mm) , that alone made a noticible difference.
I then have insulated most cavitys upstairs and have in my bedroom ensuite had to construct a stud wall in front of the old block wall in prep for the tiling, this wall has 70mm literally stuffed in, the floor has thermal tile backer boards and the room has ufh. so most of the walls in there are double insulated, the floor is done and so is the loft above.
Since i turned the c/h back on about a couple of weeks ago i am amazed at how well it works, i really am.
The boiler seems to come on for about an hour in the evening and thats it, the house stays warm all night. I have 2 rads on upstairs totalling about 3500btu in a 4 bed and my bedroom/ensuite which is 3/4 tile with just ufh which has not even been turned on stays at around 20deg.
Infact the whole 4 bed house has only got about 22000 btu of rads, i have no carpets/finished floors down yet and its always around 20 deg which is perfect.
Of course the test will be when it gets properly cold but i recon another layer in the loft and it will be excellent.
Our old house(2 bed end of terrace) was built in '98, our new house (5 bed detached) built last year has LOWER bills! Roughly 3 times the size, of course not all down to insulation but no doubt it makes a difference. Whether the house will still be standing in 50 years is another matter, lack of ventilation worries me, if you read some of the posts from builders on here they seem to be having big problems with condenastion in roof spaces.
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