We have a 1930's detached house, which is fairly costly to heat at the moment. Its double glazed, not too draughty, It has loft insulation, but probably only 10cm thickness rather than whatever the current standards are.
I've been thinking about getting cavity wall insulation put in, but I've read about so many problems with peoples cavity wall insulation that you start to think it might cause more problems than it solves.
Is anyone on here involved in CWI? are most installations straightforward and work well? and its just a tiny proportion that make noise on the internet.
Basically - will I regret getting it fitted?
How big is your cavity and do you have any walls exposed to wind blown rain?
50mm cavity.
Not sure how I would know if I have walls exposed to wind blown rain - what would indicate that I do?
Upgrade your loft insulation to at least 300mm. That would be a priority for me. I just upgraded mine and it has made an enormous difference, and I wasn't starting from 100mm. Insulate your loft hatch and put draught strip around the seal
Then start looking for 'easy' wins like draughts around doors, behind skirting etc etc. If you add up all the gaps the air can move through, it can make a hole like an open window
When id done all that id start thinking about cavity wall
Lots of blown fibre was put into cavities that probably shouldn't have been chasing warm front grants 10 to 15 years ago.
Because its glass/mineral it was sold as water resistant, but as an aggregate material it happily holds onto water between the fibres.
Most of the horror stories come from improper installation by incompetent/unscrupulous installers.
If your cavity isn't full of snots and rubbish it could be worth it. I'd only use graphite polybeads and I.d want to make sure the exterior walls were in good condition and any exposed walls were appropriately assessed.
The install is pretty easy. Half a day at most.
As above, 100mm in the loft is inadequate. I understand that building regs were changed July 22 and the equivalent glass fibre depth to achieve required R values is now 450mm.
thanks for that info - sounds like CWI is an option.
The loft is a pretty horrible place to be, and quite hard to get to the extreme edges, but none the less I should probably get up there and do battle with the spiders , it shouldnt be too difficult a job to roll some insulation out. over the existing boards. The bigger job will be clearing the junk out that we keep up there.
I'm in a similar position, I wonder how much insulation value I could achieve by just spreading the loft junk out more evenly
😀
I have a semi built in 1928 - I had polybead install, it created dry rot and I had to pay to have the dry rot solved, then paid to get the poly beads out again to prevent further issues. about £7k wasted.
Do the loft.
Avoid CWI
I'm sceptical about the amount of insulation benefit we had when the beads were in. I reckon you could get a bigger benefit from insulating internal doors and properly heavy duty underlay in the bedrooms etc because the hallways are usually the coldest area and where all the rooms connect, especially if you have an old style front door (we still have the original door with the lead windows which looks great etc but it's not in the least bit thermally capable).
We had ours done last winter, no issues and the house is a lot warmer, the exterior walls actually feel room temp rather than being cold to the touch.
At the time they did a survey with various recommendations e.g if we replace the double glazing the replacements should have vents. If we re-do the kitchen the extractor should extract not recirculate. Stuff like that.
Installation took less than half a day for a detached house.
Check your local authority, they may cover it and the criteria was fairly loose, kids, any long term health issues, asthma, pensioners, etc. Even without that I guesstimated 5 years to payback, more like 2 winters since gas prices went crazy (although I think I've made the same savings again just by optimizing other factors so they actual payback at the new usage rate is probably about the same).
Not sure how I would know if I have walls exposed to wind blown rain – what would indicate that I do?
Have a google for it, there's a map available which puts you into various bands. You could Summarize it as
Anything vaguely west or exposed south coast - not a chance
West-ish - fine for a housing estate/sheltered area, less fine in exposed locations.
The rest - fine unless you're really exposed.
Not sure how I would know if I have walls exposed to wind blown rain – what would indicate that I do?
Have a google for it, there’s a map available which puts you into various bands. You could Summarize it as
Anything vaguely west or exposed south coast – not a chance
West-ish – fine for a housing estate/sheltered area, less fine in exposed locations.
The rest – fine unless you’re really exposed.
I was going to suggest you could go outside and look at your walls when it's windy and raining, but TINAS' suggestion is arguably more helpful 😀
Do the loft.
Avoid CWI
its these sort of tales I was worried about!
Anyway - have order a stackload of loft insulation so theres no backing out now! The spiders wont know whats hit them
Have a google for it, there’s a map available which puts you into various bands. You could Summarize it as
Looks like we are in a "moderate" area - south manchester
We had ours down last summer, 1980's detached house. Hadn't done it previously because I was worried about the damp scare stories. Turns out that our cavity was on the larger side of normal (or so the operator said). Wehad the polystyrene balls installed with an adhesive to bond them together. It has seemed to make quite a big difference to both unwanted solar gain in summer and also to keeping a more stable warm temperature in winter. The temperature drops slower when the heating is turned off. If its really cold we have the heating on in the morning probably takes an hour to get the temp up from 15 deg to 19 and then it wont kick in again during daylight hours on a sunny day as the solar gain is enough to maintain the temp. Very happy with it. We do have roughly 300mm of loft insulation and did new double glazed windows the previouse year. We are located in Devon so benefit from relatively warm climate but very wet. No signs of increased problems with Damp.
We had ours taken out because the interior walls were damp.
as above the walls need to be in good condition externally and in the cavity and in a low risk zone. Check on the available maps, and in an area protected by other buildings rather than on a hill. As this is not a spoon mentioned there should also be a list of recommendations to do at the same time to lower the risk. Monitor humidity in your home and do your best to generate less moisture and extract it at source. You will be left with thermal bridges that will get damp if you don’t either deal with them and/or ventilate your home properly. When you add loft insulation look at cross flow ventilation. You can get plastic panels that leave an air gap from the eaves but still allow you to insulate up to the edge of the roof. You want to be trying to cover the wall plate so the loft insulation meets the cavity insulation
I looked into it, but we're on the south coast in a 1930s semi with lots of wind blown rain in the winter months so decided against it. Next door have it without any problems, but they are on the down-wind side with an east facing wall so I think they are less likely to have problems, though they said they still get damp in the corners.
We had ours taken out because the interior walls were damp.
Ditto.
(1900s semi / blown fibre).
