Insulation question(s)


#1

We had an extension built earlier this year. The insulation is amazing and spending time in that part of the house is a toasty joyfest.
The rest of the house is cold. And it’s not even winter yet. **Which insulation option should we choose? **Here is some extra info:

  • The outside of the house has brick cladding in parts and pebble dash on others. Although it’s detached, it fits in with the style of other houses in the estate so we’re hesitant about external insulation.
  • During the extension project we saw inside the walls. There is a cavity which has a fairly thin piece of polystyrene in the middle (house built in early 1990s). This doesn’t fill the space so I wonder if pumping into it is an option.
  • Internal insulation seems like a runner. The only hesitation is that we would lose space.

Bonus question about internal insulation: the bathroom and en suite have relatively narrow walls/windows to the outside. I mean, they are rectangular rooms where the long side is an internal wall. Is it worth dry-lining the narrow walls? My hesitation there is the upheaval it will cause because the walls in question have toilets up against them.


#2

The partially filled cavity can be pumped, i got it done. My house is a late 50’s 3 bed semi, a kitchen extension had partially filled cavities but the rest of the house had none but the whole thing was pumped.

Look at your attic and draft proofing first, windows second, walls last. Attic gives most dramatic effect. Pumping the walls is easy, no mess internally, takes about 2 hours and mine cost €1k. Dry lining would be my last choice of all of this, you loose space, your walls aren’t as good at supporting shelves, you may come against spaces where doors open and shut near a wall you want to dry line and finally you might be creating / exacerbating a damp problem.

Also if you have any open fireplaces that you don’t use get a chimney balloon or consider a stove.


#3

Thanks a lot, that’s very helpful.


#4

Anyone care to recommend a supplier/fitter in Dublin?

Got a few quotes last year but didn’t go with any of them in the end as didn’t get feeling a comfort. Think there a lot of cowboys in this business so any good experiences gratefully received.


#5

Regarding the drafts:
We got a window repair man to come around and examine our windows. He replaced the brackets (which had buckled over time) on all but 3 windows. The improvement was immediately apparent with a couple of the windows. Once he was done I went around outside myself and used silicone around the window frames to fill any gaps between the frame and the window gap. I used expanding foam under one sill that had a bit of a gap.

I filled in one air vent altogether in a room that had a partition wall knocked and therefore had two vents.

The kitchen has a hip extension again with no access to the roof space to inspect the insulation situation. The playroom has it’s own roof with no access hatch and I assume very little insulation. I’ve had to go around with silicone under the skirting boards in our playroom. Both of these areas are the coldest parts of the house. There’s a discernible temperature drop in the floor tiles as you walk into the hip extension. Investigating the roof insulation in these parts of the house is on my to do list.

Sorry for the hijack Ixelles but I’d like a definitive answer from the Pin on this one. A timber frame house. I understood pumped wall insulation is a no no as you need to leave an air gap for the membrane to breathe. But technology and times change. Did I imagine reading somewhere that there is such a thing as breathable beads. And is it more expensive than regular beads?


#6

No worries at all - interesting question


#7

I’d be very cautious on pumped wall insulation.

Was searching for links there to a site I read some good discussion on this before. Can’t find right now.
Some of the possible issues (not all equally serious or likely):

  • cavity walls are designed first and foremost to keep moisture (especially driven rain) out of the internal wall layer and living space. Filling the cavity compromises this.
  • filling of the cavity is often uneven, gappy. Can leave thermal bridges and condensation problems.
  • depending on the insulation, settling/degradation can happen over time
  • moisture in the cavity can corrode the metal ties that normally hold the two layers of the wall together.
  • is there really a pay-back over reasonable time period?
  • reduced breathability of building fabric can create problems with damp and/or insulation
  • insulation value of existing building fabric (e.g. brick/timber) deteriorates with increased moisture and heat. Insulation can undermine this.
    You’d really want to get good advice on this, and not from an insulation provider (if all you’ve got is a hammer… etc.,)

#8

There was supposed to be announcements in the budget re retrofitting funding being increased. Did I miss it or did the independents decide that that needed to diverted somewhere else at the last minute??


#9

Also this is a discussion on cavity wall. I’m not sure it’s definitive one way or another askjeff.co.uk/cavity-wall-fill/


#10

Thanks you! That’s actually the page I was remembering when I was looking for relevant link.


#11

This is the SEAI page on cavity insulation. I suppose they are honest brokers in this? No mention of downsides but I have read elsewhere that getting an even spread can be an issue because you’re pumping blindly into a space.


#12

Beware the approved companies under the SEAI grants scheme, any I’ve had quotes from (for attic insulation/upgrading heating controls) just seemed to lob the ‘saving’ onto their bill, one could be mistaken for thinking it’s all just a great big scam with the consumer being screwed once again. :unamused:


#13

Would be slow to go with cavity fill. Questionable re: level of insulation provided (it’s not as efficient as solid insulation per mm/depth , problems with installation, route for water transport across the cavity (the cavity being there to prevent water transmission - bridge it and you … er … bridge it)

Internal is messy but it does provide a relatively easy install (easy enough to get uninterrupted coverage of the wall. Hanging stuff isn’t that much of an issue - plasterboard itself will hold a lot with the right fixing (e.g. a curtain rail) or you can drive through to the wall behind for really heavy stuff

Would second focus on draughts. Often overlooked as an issue but paying back in spades. I’ve avoid chimney balloons (which are fiddly to fit and can get sucked up the chimney (but not necessarily out of the chimney, necessitating a visit from the sweep). I use a soft childs ball a couple of inches bigger in diameter than the (typically 8" diameter flue) which sits snugly into the bottom of the flue, won’t get sucked up and is easy to take in and out.

If the floor is suspended wooden then draughtproofing beneficial there. Wind comes up past the floor and the floor/wall interface and into the room under the skirting. Sealing between skirting and floor (assuming you’ve not got carpet) will close this major gap. It doesn’t matter if it’s not water tight - the house needs ventilation after all. Your just aiming to minimise things.

Exitex (an Irish company) make a decent weatherseal for doors (aluminium profile with rubber seal) which, if fitten correctly cuts down the bulk of draughts entering via a wooden front door.

Attic (as someone has already mentioned) is the first port of call. Solid insulation is tricky to fit between joists but it will give the best result vs. rockwool. It’s got to be cut accurately to size and have gaps foam filled to stop heat leakage. The alternative, rockwool and the like, need to be a foot or more thick (uncompressed). Cheap and easy to do but it means you’ll be laying it on top of your ceiling joists and so can’t use the attic for storage. You can add rafters on top of the existing over a portion of the attic and deck that for storage, whilst still allowing sufficient thickness of rockwool.


#14

I’d second the good colonel.

I did a bit of reading on external cavity wall insulation. There are various claims. It is not very scientific because unless you go dissecting a large sample of houses you will never really be able to tell if the cause trouble.

I was pretty convinced by the stories of damp issues though following the process. Precautionary principle should also apply, once it is done there is no going back!

I spent a tenner on foam insulation for around the doors and older windows and it made an immediate, appreciable difference.


#15

but the ball eventually deflates and could get stuck up too??


#16

Maybe it’s just a middle aged British thing, but does anybody remember those kids’ balls that were small football sized, but made of sponge foam? I’m sure they’d do the job just fine and be heavy enough to stay in place.

Otherwise, if you’re worried about suction, maybe consider a plastic carrier bag stuffed full of foam packing chips and tied tightly shut. You can squish it in to position and if your fireplace has a grate, or fireguard (even ornamental), you could tie it to that to keep it in place. If you use fishing line, the tether will be effectively invisible from the room.


#17

not sure about middle aged … but they are still a thing; targeted at the youngest kids - a good deal smaller than a regular soccerball


#18

He does seem qualified. I would point out though:

a) I’ve never heard of anyone using blown rock wool in Ireland

b) He has no quantitative data

c) “filling with bonded beads takes several hours” --this is simply not true, 3 hours tops for an average house and even if it does then surely it’s not such an obstacle.

d) The number of houses that have had this done in Ireland must be huge, judging by the external evidence on a walk through any old enough housing estate (i.e. the filled drill holes which are often hard to see.)

The area I live in is a collection of small estates, all dating from late fifties to early sixties and I reckon close to 60% of maybe 400-500 houses have had this done in the last decade.


#19

We hmm’d and haww’d over cavity wall insulation during the summer, we had a look at what AskJeff had to say about cavity wall insulation being a possible damp bridge etc, as cavity walls were really intended to stop rain penetrating the house. Anyway, the upshot is that we ended up getting the walls pumped about a month ago with the bead insulation. It was quick and easy from our point of view with zero disruption, it was done in a morning. You could feel the effect almost straight away, it seems very effective and though it is of course early days yet, there aren’t any damp issues.

What we also did before deciding to get the cavity wall insulation is have a think about where our prevailing weather comes from - i.e. the rain! Like most areas in Ireland all the wet weather tends comes from the south-west/west and, because we are on the coast, it tends to be blown in on a strong wind sort of horizontally across the house rather than falling straight down vertically (there’s always a breeze here!). We live in a semi-detached house and as it happens we are actually pretty well protected from the worst onslaughts from the south-west, so on that basis we thought it was worth getting the cavity wall insulation done. I will report back on any damp issues if they arise.

Just on the subject of dry lining and insulation of a wall that hasn’t got cavities - the prevailing wisdom on that front seems to be that the most effective form of insulation for these walls is to get an insulation layer put on the outside of the wall rather than the inside - it is apparently much more effective, but also much more expensive. It might be a good solution for Ixelle’s bathroom wall dilemma though.


#20

If the external surface of your walls is in good condition, and you have no issues with damp, then it is highly, highly unlikely that you will see any issues from getting your walls pumped. If your external walls are not weather proof then there is a chance they will absorb moisture, and further a chance it will be transferred through the leaves.

I know many people who have had this done, not one has reported damp issues.