# Cavity Wall Insulation



## pnagle (5 Jan 2006)

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


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## slave1 (5 Jan 2006)

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


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## Sue Ellen (5 Jan 2006)

There is some discussion on this subject in the AAM key post on Insulation.


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## z102 (5 Jan 2006)

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?


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## Touch Wood (5 Jan 2006)

Did you consider insulating the outside of the house?


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## pnagle (6 Jan 2006)

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.


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## Touch Wood (6 Jan 2006)

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?


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## pnagle (9 Jan 2006)

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.


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## Lucret (9 Jan 2006)

Has anyone heard of a hybrid system where insulation batts and pumped insulation are used?


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## damomac (9 Jan 2006)

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.


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## pnagle (11 Jan 2006)

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!


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## Lucret (12 Jan 2006)

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.


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## pnagle (12 Jan 2006)

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?


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## BankRobbers (12 Jan 2006)

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


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## pnagle (12 Jan 2006)

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.


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## Sue Ellen (12 Jan 2006)

This other discussion taking place here could be helpful.


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## babydays (13 Jan 2006)

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


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## BankRobbers (13 Jan 2006)

www.polypearl.com


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## babydays (13 Jan 2006)

Do all houses have cavity walls (my house is from 1970)? Or is it possible that we have bricks with holes in them that are supposed to form that function?


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## z102 (13 Jan 2006)

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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## pnagle (18 Jan 2006)

I just got another quote...foam fill...€2000. The sales guy was totally against bonded bead because a) the adhesive in bonded bead corrodes the electrical cabling of wires within the cavity b) the bonded bead will still fall out to some extent if I open a wall later for windows c) if the insulation boards that I already have in the house are not absolutley flush against the wall then the beads (that are dropped from a height) will be 'trapped' behind the boards and not fill the cavities properly. He tells me "99%" of houses have this problem and that is why the foam is a better solution. Is any of this true?? I don't trust the guy to begin with (but the company he represents are all above aboard and certified etc). His original quote was €2250 and I got him to drop it to €2000 in ~20 seconds....then I knew he was really screwing me!


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## z102 (18 Jan 2006)

You found out what was obviously. The electric cables are usually laid in so called "chases" within the intirior wall of a double walled structure. So there wouldn't be any contact between the EPS beads and the PVC insulation of the cables. On the continent they don't have the requirement to lay the PVC coated copper cables in extra ducts to shelter them from the impact against styrene. Not in the Netherlands, Austria or Germany where I have seen PVC in contact with EPS installed. Though I'm not an electrician , so take my views with care, I'm just an observer. 
The ESB wants the meter box installed within the wall - what's idiotic but Irish standard - and connected with a duct. After installing the meter box and after the electricians fix the fuse box they draw the mains cable through that duct and connect it to the meter. The ducting will protect the cable against direct contact with the EPS, so you're fine with the Irish legislations.
Kick out that foam installer, but use a soft boot, he mightn't know any better.
When employing the bead blower than fix in the written contract that you might want to check his work with an infrared camera and- if he had failed on some spots- he must do his job up to standard without extra costs.Any reasonable company has that stated in their guarantees/contract anyhow.


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## TheGreenMan (19 Jan 2006)

pnagle said:
			
		

> I just got another quote...foam fill...€2000. The sales guy was totally against bonded bead because a) the adhesive in bonded bead corrodes the electrical cabling of wires within the cavity



I had heard this the other way around, ie that the expanding foam insulation degrades PVC but the bonded bead did not so I would double check this.

Reading [broken link removed] from SEI it says:

Polystyrene insulation should not be placed in contact with
PVC-coated electrical wiring, otherwise the PVC may degrade.
Also, steps should be taken to ensure that any electrical wiring
covered by the insulation does not overheat.​
Do you know what was used in the foam fill?


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## minion (20 Jan 2006)

i got this done on a 3 bed bungalow in Dublin for €650 last year.  would imagine a 2 stoey house should be less than double that.
It was the beads.
The guy drilled his holes and showed me inside the wall on a little tv screen he had attacthed to a tiny camera.  They checked for obstructions and if they found any they drilled another hole underneath so the beads would fall to the bottom.

The attic was already insulated.
Noticed the difference that very night.  The house usually cooled down an hour after turning the heat off before but stayed warm for ages after we got the insulation done.  I figure the heating is half the time it used to be now.

Thats rubbish about the stuff falling out of the walls. there is glue injected with them and after an hour you can see how solid it gets in the vents.
You actually have to but a hole through it for your vents when it sets.

These are the guys who did it for me

http://www.abbeyinsulation.co.uk/


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## TheGreenMan (20 Jan 2006)

babydays said:
			
		

> Do all houses have cavity walls (my house is from 1970)? Or is it possible that we have bricks with holes in them that are supposed to form that function?



You should be able to check what you're walls are like if you have access to a vent or something that can be taken off the wall.   Our house is from the '50s and uses cavity blocks (bricks with holes) and not cavity walls (two courses of bricks with a gap between).   I think with cavity blocks only expanding foam is possible as the others like beads can't find their way around all the holes in the bricks.


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## pnagle (20 Jan 2006)

Thanks for the feedback. Just another question re. bonded beads: the quote I got was for ~€1500 for standard bonded bead, and ~€1800 for a bonded bead that is graphite-coated (?) and gives 20% better insulation according to the salesman. Has anyone any feedback on this graphite-coated stuff and is it worth the extra money?


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## AileenF (19 Jul 2006)

Interested to know if anyoned out there knows the difference in the white standard bonded bead and the graphite-coated ones?


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## z102 (20 Jul 2006)

The graphit ones are better insulating. They're not just coated but the graphit is combined with the PS even within the bead, use a razor blade and cut a bead open and have a look.


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## serotoninsid (20 Jul 2006)

*Re: Feasibility of cavity insulation in this instance?*

Just want to check what people think as regards the feasibility of wall insulation in the following scenario:

Old 1920s house with very thick stone walls; All rooms (with the exception of one room) were 'lathed' & plastered in the 1980's in order to solve a dampness problem ie. water ingress  through the wall - and also to improve the finish as walls were crooked.  There is very little space between the plasterboard finish and the solid wall ie. just the thickness of the lathe.

Q1.Would it be difficult/impossible to pump foam/bonded bead into this cavity?
Q2. If we carry out this work, would it result in the original problem ie. dampness, reoccuring due to the foam/bonded bead providing a 'bridge' for moisture from the damp solid wall to the plasterboard finish?


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## Carpenter (20 Jul 2006)

babydays said:
			
		

> Do all houses have cavity walls (my house is from 1970)? Or is it possible that we have bricks with holes in them that are supposed to form that function?


 
Your house may be of cavity wall construction, probably a 2" cavity, but as suggested you could check your meter box location to be certain.  As a check you can also measure your wall thickness (at an open window), which in the above scenario would amount to 1/2" plaster internally +4" block+ 2" cavity+ 4" block + 3/4" external render= 11 1/4" overall or 285mm.


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## david ross (23 Jun 2009)

pnagle said:


> I am thinking of getting my cavity wall insulations 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


hi
To install cavity wall insulation, your property must have two masonry brick or block walls, with minimum 50mm of space between them. Homes built between 1930 and 1995 are the most commonly requiring cavity wall insulation. If your home was built before this period, the property probably has solid walls. If it was built later, insulation is most likely included within the walls.
                    Many Irish dwellings have cavity walls that could be filled. You can find out if you too have cavity walls by measuring your walls at a door or window for thickness. If the walls are solid, the measurement will be around 23 cm thick, while if a cavity exists, the wall will be around 30 cm thick. You can also contact the SEI


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## david ross (18 Jul 2009)

babydays said:


> Do all houses have cavity wall insulation(my house is from 1970)? Or is it possible that we have bricks with holes in them that are supposed to form that function?


hi,
Homes built between 1930 and 1995 are the most commonly requiring cavity wall insulation. If your home was built before this period, the property probably has solid walls. If it was built later, insulation is most likely included within the walls.                    Many Irish dwellings have cavity walls that could be filled. You can find out if you too have cavity walls by measuring your walls at a door or window for thickness. If the walls are solid, the measurement will be around 23 cm thick, while if a cavity exists, the wall will be around 30 cm thick. You can also contact the SEI to survey your property in this regard.


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## Lak (18 Jul 2009)

Foam cavity insulation has had a poor reputation for years and was as far as I am aware supposedly classed as being not fit for purpose, the reason being I can not recall.
However the foam is NOT IRISH ACCREDITED and is not recognised by SEI for the purpose of attaning grants, if you pay for this type of insulation expecting to be reimbursed to the tune of €400 on the HES scheme then SEI will not pay out pure and simple, I know this for sure as an insulator I know had to be removed from the SEI register as the foam product he used is not on the SEI list.
The polypearl plus has a thermal conductivity of 0.030 ...polypearl platinum 0.037 (better)


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