Insulation question(s)


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


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.


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:


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.


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.


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


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.


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


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.


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.


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.


So straddling both draughts and insulation we have wall vents.

Upon investigating why our house lost all heat almost as soon as I turned off the gas I found that all the wall vents were simply a piece of plastic on the inside and out with nothing in between.

In a best case scenario you might have some fancy passive vents but you always a pipe from the outside to in on a very slight angle.

In our case just a series of holes in the walls. The lack of a pipe meant that cold air had immediate access across every wall so you would get draughts even coming through plug holes.

Have still to resolve. Would appreciate any recommendations. Seems when it’s not done right the first time diy options are scare.


Thanks for reminding me. Have the exact same issue with the couple of vents that I did investigate but have yet to tackle it. Pipe in place in both of them but not lined up with the vents so alot of air blowing through the grills will go between the walls.

Was thinking of tackling it myself. What do you mean by your last sentence?


In modern houses Vents were installed to prevent carbon monoxide poisoning, especially if there is a gas fire. A carbon monoxide detector might be a better solution.


Urghh, meant scarce. I can find a couple of options online but not much.


Tagging on to the insulation debate

I’m thinking of external insulation on our 1930’s (very cold) house. Spoke with an insulating company who have been mentioned positively several times on this forum & like the sound of their sales pitch which admittedly means very little

My question is the house is semi-detached, red brick on ground floor & pebble dash at bedroom level. If this is externally insulated will the appearance change significantly? The insulating company say they will be able to replicate the existing appearance, albeit the walls will obviously be a little thicker than the neighbour due to the insulation. I’m meeting their rep later in the week & will ask for details of other sites, but just wondering if anyone has carried out this job & what impact it has on the house appearance?


@TQ32, First explain your concern to the rep and ask them if they have done any similar houses. Then ask them for the address and go look for yourself. If they can’t point to examples then find another company who can.

Ideally both houses would get the job done at the same time, so just on the off chance it would be worth discussing it with your neighbour. It might be something they are interested in and the company might be able to reduce the price a bit for both jobs.

With regards the dashing, it is important that the material used (and the process) is suitable. Some systems (rigid boards) can’t be applied directly to dashing (although some systems are ok if the boards are sealed with adhesive around the edges to prevent convection behind the insulation). A Rockwool system like this might be an alternative solution.

With regards the brickwork, that’s straightforward enough. Brick slips can be bought to match the existing brickwork and then stuck on to mimic the original. Brick slips can also be made from salvaged brick if necessary. Again, look at examples that the company have done and while you’re at it have a chat with the owners and ask them if they are satisfied with the company.


To go back to a previous question on vents…
Something like this? … illes.html

I bought something similar for an extension and they seem fine to me! Easy to fit, with the tubes fitting over each other. Put the outer tube in place and then expanding foam around it to seal around it, then fix the inner one. For a more DIY solution, 4 inch sewer pipe cut to size and foam around.


I started this thread a full year ago - and have done almost nothing about it in the meantime…

Got quotes for cavity, internal and external. Reckon we’ll go with the cavity on one side of the house and internal on the other - only one side is suitable for pumping. However, we are wondering whether we should also get internal insulation in the living room as this is on the side which will be pumped. We’ll be getting some built-in shelving in that room and redecorating so don’t want to find out afterwards that we should have added insulation.

  • Any thoughts on whether it’s necessary to use dry-lining on walls that will also be pumped with beads?
  • Are there any downsides to doing this?


Have large double glazed windows still letting in the cold and letting the heat out.
So I did some quick research and got a large roll and bubble wrapped the inside panes. Noticeable effect on heat loss, or maybe it’s a placebo effect