Cavity Insulation

[transatlantic]

My house loses heat quickly and so am looking into what I can do about it during the summer ready for next winter. I know that my loft insualtion isn't great and is under the recommened 270mm, so I'm going to get that sorted for sure. It's cheap, easy to do, and can be removed if it causes issues. However, I have a feeling that the issue is more to do with the walls, as they're always stone cold to the touch. The non outward facing walls (i.e those between my neighbour, and between rooms) aren't nearly as cold.

From what I gather there are a number of different cavity wall insulation methods, as well as exterior methods. I'm wondering if anyone has had anything done and what the outcome was? Did it help? .. did it have any side effects?

I can't quite decide what to do. Do I risk having it done and it potentially going wrong, causing damp etc, or is it not worth the risk and I should just suck it up and pay the extra heating costs?

There is a lot of negativity towards cavity wall insulation on the interent, but they're often old stories. I'm hoping things must have improved since then with the technology.

 

[novocaine]

the previous owners of our place had it done.
I'm trying to find a way of having it undone.
the outer leave is porous and the cavity was bridged, all that moisture went in to the inner leaf. when I opened up an inspection hole in the gable end the stuff that came out was soaking wet (you could sqeuze water out of it) but dried as you got higher, as would be expected. gave the apperance of rising damp, it isn't though.
I'm going have all the ties replaced as they've rotted.
the holes where they injected the smoo are acting as little funnels.
the back of the bricks is starting to blow out.

in short, I wouldn't recommend injected wall insulation to my worst enemy. it's great on a new build where the cavity remains intact and the mortar isn't lime based, not on old properties though (ours is 1940s).

 

[DTR]

the previous owners of our place had it done.
I'm trying to find a way of having it undone.

Interesting to know, thanks for the warning (sorry for your misfortune, though). On occasion I've considered getting it done, but only the front wall of our house is cavity; the side and rear are single-skin.

 

[Phil Pascoe]

The R.I.C.S. recommend that cavity wall insulation isn't installed in areas of extreme weather conditions ... which of course is exactly where most people would think about it :? ... and counts out half the UK.

 

[novocaine]

The R.I.C.S. recommend that cavity wall insulation isn't installed in areas of extreme weather conditions ... which of course is exactly where most people would think about it :? ... and counts out half the UK.

the gable end of our house is exposed, it gets the driving rain most of the time, but this was ignored by the installer, because it was being paid for by grant, so as long as they got their money they didn't care, funny enough, they went out of business 3 years later, so any guarantee is null an void. but the same name appears on another company with "& son" tagged on the end.

another government grant scheme based on "green policy" with no actual four-thought to the consequences.

 

[transatlantic]

The R.I.C.S. recommend that cavity wall insulation isn't installed in areas of extreme weather conditions ... which of course is exactly where most people would think about it :? ... and counts out half the UK.

the gable end of our house is exposed, it gets the driving rain most of the time, but this was ignored by the installer, because it was being paid for by grant, so as long as they got their money they didn't care, funny enough, they went out of business 3 years later, so any guarantee is null an void. but the same name appears on another company with "& son" tagged on the end.

another government grant scheme based on "green policy" with no actual four-thought to the consequences.

This is exactly what I'm worried about, but at the same time - I can't help but think there must be companies out there that will do the proper assessment and give unbiased advice. I'd obviously go with a company that has been around for a while.

 

[treeturner123]

Transatlantic

What is the construction and external finish of the external walls? Without knowing, it is difficult to give advice.

Phil

 

[transatlantic]

Transatlantic

What is the construction and external finish of the external walls? Without knowing, it is difficult to give advice.

Phil

It's brick <-> Cavity <-> brick. No external finish. Not really looking for advice in regards to construction, ....more peoples experience.

 

[treeturner123]

It's just that if it was rendered externally, the best solution would be external overclad insulation which has a similar final finish to render.

As others have said, cavity insulation in exposed situations can be problematic. My view (not experience) as a surveyor is that a blown material or beads would be a better bet but I have no hard evidence to confirm!

Phil

 

[sunnybob]

I used rockwool in two seperate houses, done by a reputable company which I cant remember the name of now (the last one was 20 years ago).
Absolutely fan dabby dozy. ZERO problems, and the difference on the heating bills was boggling.

The first house was way back in 1980. it was a 60's build brick outer and it was on top of a hill with views for miles. They drilled 2" core holes in the bricks to pump it in, and then cemented the cores back in so well it had to be pointed out to people who asked about it. With the loft insulated and boarded as a work room, I kept that semi warm with a single gas fire downstairs and a single flame hall heater upstairs.

The second house was done in mid 90's, and it was a 5 bed detached. I fitted CH in the house and the whole thing was warm with the boiler just ticking over.

But you MUST insulate the loft. around 60% of your heat goes upwards.

 

[transatlantic]

I used rockwool in two seperate houses, done by a reputable company which I cant remember the name of now (the last one was 20 years ago).
Absolutely fan dabby dozy. ZERO problems, and the difference on the heating bills was boggling.

The first house was way back in 1980. it was a 60's build brick outer and it was on top of a hill with views for miles. They drilled 2" core holes in the bricks to pump it in, and then cemented the cores back in so well it had to be pointed out to people who asked about it. With the loft insulated and boarded as a work room, I kept that semi warm with a single gas fire downstairs and a single flame hall heater upstairs.

The second house was done in mid 90's, and it was a 5 bed detached. I fitted CH in the house and the whole thing was warm with the boiler just ticking over.

But you MUST insulate the loft. around 60% of your heat goes upwards.

60%? well - That figure seems to change from website to website. It's often around the 20% - 40%, never heard it as high as 60% though

 

[sunnybob]

I was very into alternative energy way back in the 70's. Had to special order books from the library (do you remember libraries?)
looked at ground pumps, propellor turbines. oil drums cut in half, etc etc. as well as all types of insulation.
Way back then before any insulation was fitted, the normal calculations were 60 % upwards, 40 % outwards.
Now that almost every loft has some form of insulation the figures will vary. But no way as low as 20% upwards. Pretty sure we all know that heat rises, yeah? So how can 80% go sideways?

 

[DrPhill]

FWIW: we own a 1920's brick built bungalow with cavity wall insulation installed by a previous owner under a government grant. It is one of the warmest houses I have lived in. We have seen no obvious bad effects of the cavity insulation, but that could easily be a lack of knowledge on our part. Certainly no damp (well there was damp, but it was a leak in flat roof leading).

I am not sure that this adds a lot to the discussion, but it does show that problems do not always occur...... and that the positive benefits are noticeable.

 

[jimmy_s]

We had cavity wall insulation in the previous house and had no issues (installed before we bought the house) Walls were rendered though.

If it was me I would be looking at blown beads as opposed to foam injection or considering re-lining the walls or external wall insulation.

The heat will flow up/ down and sideways via conduction. Cavity wall insulation will drop the U value of the wall from about 1.5w/sqmk to about 0.45w/sqk so the heat loss through the walls could drop considerably.

If its a suspended timber floor and you can get under it then its also worth considering insulating the floor.

 

[MikeH]

We had the stuff blown into the walls some years back. It was a sort of fluffy white stuff, bit like pillow stuffing when you looked at it. We had one problem, they blew a bit too much in and so it went up and out into the eaves in the loft. It then blocked the airflow in the loft but of course we could not see that. First we knew of it was when I went up into the loft in the depths of winter and found condensation dripping from the rafters! Got them back to clear the excess and it has been fine since.

I do know that if they don't give full coverage in the walls then you will end up with a cold spot on the internal wall at that spot, as a result any moisture will condense in that spot on the internal walls. Typically this will be in hard to spot corners etc and so the first you know is mould on some walls.

 

[Matt@]

we had this done a few yrs ago on a grant basis. I would have sent them away if they had used any kind of soft filling as have heard horror stories about this stuff. In the event they pumped in polystyrene beads. Its made no difference whatsoever to heat loss. Also the beads get everywhere - under the floor, down behind the drylined walls and under the kitchen units etc. I would definately not have any cavity insulation done in a future property. Loft insulation a bit different though - I can see the value in that.

 

[Lons]

I have a house built around 1980 (bradstone / cavity / block and it is important what type of contruction in fact!). The insulation was installed during construction and is polystyrene beads and the only problem during the 30 years we have owned the house is that if any alterations are carried out you lose loads of insulation and the bloody stuff goes everywhere.

No issues with damp and our house is quite exposed. If you have serious bridging across wall ties etc. then you probably already have damp issues but insulation can make it worse.
Every external leaf of a cavity wall is porous to some degree unless rendered, that's one of the main reasons for the cavity to allow any ingress of moisture to run down the inside of the outer leaf and away through weep holes. Any problem walls can be protected by regular spraying with waterseal.

As said though you need to get your loft sored first!

Bob

 

[thetyreman]

ordinary rockwool is good but try and find the heavy density one, it's even better for heat and sound.

 

[RogerS]

I'm opting for100mm internal insulation between the studs. 60 sheets of Kingspan seconds are on their way.

 

[Phil Pascoe]

http://www.secondsandco.co.uk? :lol: