Cavity Wall Insulation

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pnagle

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I am thinking of getting my cavity walls insulated as my house is pretty cold and I read that ~35% of a house's heat can escape through the walls. However, how do I know if the walls were not built originally with some form of insulation? Is there a simple method or do I need to start drilling holes!? And, even so, is it still advisable to get the insulation 'topped-up' with a more modern insulator? Also, anyone got a rough estimate as to how much insulating the walls will cost?
(I bought my house recently but it was built in 1990. It is ~1600sq feet. The attic is well insulated but the house only has single-glazed windows...my next task after the walls!)

Thanks
 
A definative way is to have a look whilst your windows are being replaced, when your old windows are taken out you will have unrestricted view of your wall cavity, could be better to tackle after your window replacement as your new windows could compromise well fitted insulation
 
If your meter box is placed in the outside wall you could open it and have a look at the back of it. Sometimes there are holes in the plastic material through which you should be able to spot the cavity and it's contents.Otherwise you have to drill a hole somewhere (not in the meterbox unless you are an electrician!!), one should be enough. But very likely the gable is not insulated, this was not demanded by the building regulations so builders saved on it.Is that still the case btw?
 
Did you consider insulating the outside of the house?
 
Thanks for the replies. Regarding insulating the outside (or the inside) of the house, I'm under the impression that these are much costlier and messier jobs than just filling the cavities with insulation.
 
Yeah you're right. I've just seen a few houses with outside insulation and the effect is amazing. Were you going to use Cellulose? Does that settle?
 
I took Heinbloed's suggestion and checked out the meter box. Indeed there were holes there that showed me the cavities and showed me that there was no insulation in them. Great suggestion...thanks.
 
Has anyone heard of a hybrid system where insulation batts and pumped insulation are used?
 
Hi Lucret.
The best option is to have the walls "pumped" with insulation. This will involve some drilling. My parents had it done and it turned out to be a great investment. Each of the external walls were drilled from the inside at about 7 feet above floor level. They drilled the holes every few feet or so. You can use the likes of Pollyfilla to fill in the holes and sand them down.
Another option would be to stick insulated slabs (dry-lining) on all the external walls but having the wallls pumped would be a much better job.
Let me know if you want the name of the company who did it for them.
 
I just had a guy down from an insulation company to check out my cavity walls. Apparantly, the gap is 100m of which 50mm is already filled. Thus, if I'm to get the walls insulated I would be adding another 50mm of insulation. Is this worthwhile, or is there sufficient insulation already? The cost is ~€1500 and the house size is ~1500sq feet...spot the link!
 
The insulation will pay for itself in a few years. Record your fuel consumption now and in the future if you go ahead. You'll then have invaluable advice for the next poster in your situation. Polypearl are IAB approved. Icynene is also good but not closed cell. The insulation would also have the benefit of making the walls more airtight and sound proof.

Someone in the vendor you go for will give you the new U value of the wall after pumping. A good plumber would do heat loss calculations based on the current and future U values.
 
Thanks Lucret. I have also just received a quote of €1050 from a company using mineral wool cavity filling. This is a lot cheaper but they will need to drill more holes that the bonded bead approach (e.g. Polypearl). Also, the beads appear to be a better insulator from my readings. Thus, I am tending to go with the bonded bead option. Would anyone agree/disagree with my thinking?
 
I would suggest (as suggested by slave1) that you look at doing your windows first. If you fill the cavity with insulation first (an adhesive is also added to the insulation as it is being pumped in causing it to 'set' in the cavity) it may get damaged or some may come out when you replace the windows at a later date. This would result in a lower thermal insulation around the windows. Maybe ask the insulation companies what has been their experience in these situations
 
Yes, I took that concern on board and did ask the bonded bead company. They said they would guarantee that none of the stuff would come out if I got the windows. He agreed to put that in writing for me. Ideally, I should get the windows first as you suggest but the insulation is a quicker and cheaper job.
 
Damonac,

Is polypearl based in Galway only? Did a websearch and could only come up with reference to them in that county. I'm Dublin and considering insulation (see other current post - for warmth double glazing or insulation?).

Do you have a website for polypearl? Do they do work in Dublin?

tks
 
Do all houses have cavity walls (my house is from 1970)?:eek: Or is it possible that we have bricks with holes in them that are supposed to form that function?
 
Pnagle , you did well for asking the company to get the confirmation in writing. And they seem to take their job serious, so for € 1500 you would get a good deal.As Lucret has said the investment would pay for itself by the fuel saved on heating. A glass- or mineral wool filling is a tricky thing. Cavity walls are build to keep the outside moisture -the horizontal/diagonal rain- away from the interior part of the wall. Fibrous material can act like a wick, like a sponge, soak up the water and then sagg. Not only would gaps in the insulation pattern occour but once the moisture is trapped it's only slow to evaporate back when the weather(the outside wall) is dry again. Polystyrene beads do not sack, they take up very little water and , if fixed /bonded with a mineral based glue (not an organic glue!), they won't rot either.Even when dipped under water polystyrene keeps it air content and therefore is insulating. Life vests are filled with polystyrene, I have never seen a life vest or raft filled with glassfibre (smiley) .
 
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