Cavity wall insulation

[Davos87]

Be interested to hear of anyone's experiences good or bad.
I live in a 4 bedroom 1930 property out in the sticks., quite exposed and and the house gets battered at times by strong winds coming off the Hambleton Hills that I live opposite. My hallway is particularly cold despite a radiator and friend saying getting it insulated really is a no brainer. The rooms coldest run adjacent to the large expanse of external wall at the side of my property alongside my drive and thats the prime candidate for the cavity insulation. The brickwork is in sound condition to my untrained eye. However, I'm naturally cautious and have read some troubling stories of damp, increased condensation problems and reluctance from some companies to rectify faults should they arise after installation etc?
Friend of mine had the blown bead insulation installed a few years a go and says its made a significant difference to the ' feel' of his property although his house is relatively modern compared to mine.
He got a free survey and subsequent free installation with a supposed 30 year guarantee but he has mislaid all the details of the company he used. How can I find out if I might qualify for this and source reputable installers? How is it done for free? Do the companies claim back costs from government green energy efficiency schemes for example? I have had a cursory look online and there seems to be companies falling over themselves to come out and give you a survey and advise whether its appropriate for your property but still have reservations. What have I got to lose unless the good folk on here know otherwise?
Thanks in anticipation of any advice.

 

[Beebo]

Do you definitely have a cavity wall. My house is 1936 and has a solid wall. The external walls get very cold.

 

[numbnuts]

We had it when I was living with my parents in the winter the whole house was so warmer and in the summer a lot cooler, I'm living in a flat now which also has wall insulation and the heating is hardly on during the day even when it is bitterly cold outside and again a lot cooler in the summer months too.

 

[Ajax Bay]

My house was built in '36 (relatively exposed to southwesterlies). We had CWI done a few years ago. The installation was trouble free and I don't think I paid, but had to pay for scaffolding - about the same as the saving in the first year: it did reduce the heating bills. I think you need to employ your Yahoo-fu to find out more.

 

[midlife]

Just moved to a 1933 house, had to do a bit of work in the front room and the CWI was patchy at best so went for insulated plasterboard on the external walls,

 

[Archie_tect]

The Green Initiative ended in disgrace some years ago...

How wide is the cavity? Less than 75mm [3 inches min ideally, but probably 2" if 1930's cavity] won't provide significant benefits as the wall ties act as a cold bridge. There will be a saving which should save the cost of installation in 3-5 years depending on the cavity width.

The cavity needs to be inspected by CCTV to check the condition of the wall ties and the bottom of the cavity for mortar 'snots;' bridging the cavity which is allow water to cross if fully filled in such an exposed location. Have a look at Sheffield Insulation Group [used them for 25 years] https://www.sigretrofit.co.uk

Polystyrene beads stick together but can leave voids which again allow water to build up and cross the cavity leading to damp if the installation isn't thorough.

The better alternative is to insulate with min 3" of closed cell insulation board such as Xtratherm and render/ ship-lap board [horizontal rot-proof composite boards or larch/western red cedar if you prefer wood] the external walls which adds another weatherproof layer and increases the internal thermal mass of the house on the 'warm side'.

Insulating the inside is OK if the rooms are large and square.

Don't forget to insulate the floors if you have underfloor vented void under timber floors, and put 450mm 'Earthwool' [rockwool] quit;t in the ceiling voids [leaving a 50mm gap to the underside of the sarking felt below the rood battens for cross ventilation]- not forgetting to insulate and weatherstrip the roof hatch..

 

[BoldonLad]

Not directly comparable to your situation, but, for what it is worth:

- Detached House, built in 1985
- Urban Environment, so, not particularly "exposed"

We had cavity wall insulation installed, and, loft insulation increased to then current standard (in about 2003) when a grant was offered via Government or Local Authority, I forget which.

We have not had any adverse effects (ie no condensation, damp etc), but, neither have we had any noticeable positive effects. Heating bill not reduced by any noticeable degree, and, wife still permanently "cold".

 

[Slick]

The cavity is there for a reason, don't fill it.

 

[screenman]

The cavity is there for a reason, don't fill it.

You try building a house without filling them now, building standards would have a field day.

 

[Slick]

You try building a house without filling them now, building standards would have a field day.

Not up here, new build still have a cavity and the insulation is on both external and internal leafs. Mostly timber frame up here now though for house bashing.

 

[screenman]

Not up here, new build still have a cavity and the insulation is on both external and internal leafs. Mostly timber frame up here now though for house bashing.

Times have changed then , I built this one 10 years ago and had to stuff them.

 

[Globalti]

Far far better to clad the house with Kingspan and a timber cladding so that the walls become a heat sink, or dry-line the entire house with Kingspan and foam-backed plaster board.

Or demolish and rebuild.

 

[Archie_tect]

If I were to built my own house now I would definitely use a timber frame/ insulated SIP panel system using 144 reg x 38 timber studs faced with building breather membrane on 9mm OSB board with 120mm Kingspan/ Xtratherm insulation between the studs to provide a 25mm service zone faced with plasterboard. The service zone avoids having to upsize the electric cables which overheat when buried in insulation. A slightly better way is to use a insulated multiple foil blanket layer with 38x25 battens to create the service zone which provides the serviced zone inside the insulated vapour check layer to the stud wall - reducing the U-value to about 0.08 but with the additional cost of the extra layers.

On the outer face you can batten and clad with anything you like as a rainscreen or build a cavity brick/block outer leaf with a 100mm cavity partially filled with 50mm closed cell insulation [again Kingspan or Xtratherm backing onto the OSB board to eliminate the cold bridge of the timber studs. This would give a U-value of about 0.11 W/sqm.DegC which with 450 quilt insulation in the loft [0.1 U-value] and 150mm Xtratherm in the floor [0.12 U-value] means you get as close to thermal perfection as you can get without spending an unreasonably stupid amount of money!

One day... when our children reproduce and we move south to live near them so we can be involved grandparents!

 

[Grant Fondo]

The Tories race to the bottom has resulted in house improvement grants, photovolaic and next ground source heat pump grants vanishing next year. I get that the recession intervened, but where is all this heading?

 

[Slick]

Times have changed then , I built this one 10 years ago and had to stuff them.

I renovated a block of flats about the same time and as part of the renovation the cotton wool (as I call it) cavity fill was hoovered out but it was sodding and when I told the council I didn't want my cavity refilled with anything they insisted on using the glued polystyrene balls and I could leave it out of the renovation but they wouldn't be financing the project. So I have been forced to use it, but thankfully it's not in every project.