# External insulation - worth it?



## JohnJay (27 Nov 2019)

Hi, 
Currently getting quotes for external insulation. It seems expensive at min €6500 just do do the front and back wall of a terraced house. Is it worth it?

I need to get my house external plastered anyway, which will probably cost 3k.


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## noproblem (27 Nov 2019)

Allow for the SEAI grant from that price and make sure whoever you get to do the job is "good". Yes, it's well worth doing but that is very expensive for what you're getting done.


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## JohnJay (27 Nov 2019)

Thats 6500 after the grant, over 8500 before the grant. In fairness, that also includes full attic insulation, but that doesnt cost a fortune. 
2 quotes so far from 2 companies, both around the same. Waiting for quote #3.

Plus another 400+ to the ESB to move their wires.....


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## noproblem (27 Nov 2019)

Can you not pump insulation into the cavity?
In any case I think the builder sees that by doing the external insulation he's also covering the plastering job that you need. Although it is very expensive I can see he's almost as cheeky as yourself by pricing it as he did.


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## galway_blow_in (28 Nov 2019)

noproblem said:


> Can you not pump insulation into the cavity?
> In any case I think the builder sees that by doing the external insulation he's also covering the plastering job that you need. Although it is very expensive I can see he's almost as cheeky as yourself by pricing it as he did.



Pumping the cavity doesn't come close to external insulation in terms of improving heat retaining performance


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## jpd (28 Nov 2019)

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## noproblem (28 Nov 2019)

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galway_blow_in said:


> Pumping the cavity doesn't come close to external insulation in terms of improving heat retaining performance



I well understand that but in his case it's only 2 walls and would be perfectly adequate in a terraced house.


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## Alkers86 (28 Nov 2019)

That's around the same ballpark figures we've been getting. IT's a no brainer if you were thinking about spending 3k plastering in any case.


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## Coldwarrior (28 Nov 2019)

noproblem said:


> Can you not pump insulation into the cavity?


It's probably a solid or cavity block wall so not suitable for pumping


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## JohnJay (28 Nov 2019)

Coldwarrior said:


> It's probably a solid or cavity block wall so not suitable for pumping


Correct. Its a cavity block wall, so pumping is not an option. 
The area of insulation is not huge, my windows are pretty big, so not  much wall left around them. The main reason I like the idea of external insulation is that it will provide a decent seal around windows and doors and it will also insulate the cold bridge where floors meet external walls. 
I'm going to loose out on some of the benefit seeing as my neighbours wont be insulating there walls, so this will create another cold bridge. So thats part of the reason I am asking if its worth it for a Terraced house.


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## galway_blow_in (28 Nov 2019)

its a tiny sum , i was quoted 25 k NET of the grant two years ago , id go for it too only we dont plan to remain here long term but that decision had not been arrived at two years ago


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## JohnJay (28 Nov 2019)

yeah, but my gas bills are not huge anyway. I'd be a long time saving 6500. 
I just wonder how effective it is on a terraced house. 
Plus, the grants for external are not that great at present. I wonder if I'd be better waiting a few years when a) the materials might be better and give better results, and b) the grants might be better to persuade us to make our houses more efficient.


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## paper-folder (28 Nov 2019)

We had our semi-d externally insulated as part of a larger project that included replacement windows, some cavity and internal insulation and upgrading the attic insulation.   We reckon that we reduced our gas bill by 50%.  However the big benefit that we see is that we typically run the central heating for a 1 hour boost cycle and that could do us for the night.  Before this, the house was cold again 15 minutes after the heat went off.   So the improvement in comfort is worth it even if the payback in purely financial terms is long.  We have ours 9 years now and haven't had any problem, but the contractor does need to be careful with the detailing, like how they treat the interface with the neighbours and what is done with your windowsills.  It seems like the techniques and materials have improved in that time.  We were also delighted to get rid of our pebble-dash and get a smooth finish on the walls instead.


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## Coldwarrior (29 Nov 2019)

JohnJay said:


> yeah, but my gas bills are not huge anyway. I'd be a long time saving 6500.
> I just wonder how effective it is on a terraced house.
> Plus, the grants for external are not that great at present. I wonder if I'd be better waiting a few years when a) the materials might be better and give better results, and b) the grants might be better to persuade us to make our houses more efficient.



I've the same conundrum, was quoted 20k net of grant last year to do my (detached) house. My gas bills cost roughly 1000 per year so even if it saved me 33% as the installers usually claim, it'd take me 60 years to make that back. OK gas prices and carbon taxes will likely go up in the future but the ROI would still be extremely long. Hopefully they'll be better grants/incentives in the next few years to make this more viable.

If I needed to get the house re-plastered anyway though I think I'd probably go ahead and do it.


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## galway_blow_in (29 Nov 2019)

Coldwarrior said:


> I've the same conundrum, was quoted 20k net of grant last year to do my (detached) house. My gas bills cost roughly 1000 per year so even if it saved me 33% as the installers usually claim, it'd take me 60 years to make that back. OK gas prices and carbon taxes will likely go up in the future but the ROI would still be extremely long. Hopefully they'll be better grants/incentives in the next few years to make this more viable.
> 
> If I needed to get the house re-plastered anyway though I think I'd probably go ahead and do it.



More advantages to it than savings on heat bills, fitting external insulation will slow down the ageing process on a house, thus preserving value


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## Coldwarrior (29 Nov 2019)

galway_blow_in said:


> More advantages to it than savings on heat bills, fitting external insulation will slow down the ageing process on a house, thus preserving value


Do you mean aesthetically? It definitely improves the look of an older house (when done well) and I'd love to get it done, but the advantages don't justify the cost for me right now.


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## galway_blow_in (29 Nov 2019)

Coldwarrior said:


> Do you mean aesthetically? It definitely improves the look of an older house (when done well) and I'd love to get it done, but the advantages don't justify the cost for me right now.



I mean keeping dampness at bay


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## JohnJay (29 Nov 2019)

The grants for external are quite poor compared to grants for other types of insulation. Its limited to 2750 for a terraced house, while the limit for internal/drylining is 1600. Its a much lower % of the cost compared to internal. The benefits of external are (said to be) much greater than internal, you would imagine the grants would reflect this and be an incentive for house owners to go this route.


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## odyssey06 (29 Nov 2019)

fwiw I think you will get more bang for your buck from new windows if that is not already on your list.

Also, just mentioning that some home owners have had issues with broadband installations etc after getting external insulation - the likes of Virgin Media etc are reluctant to 'puncture' the insulation. Not sure if the installers can leave an access duct or something to make such installations easier.


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## JohnJay (29 Nov 2019)

I agree with you on the windows. Mine are already replaced and I know from a previous property that new windows and doors was the best investment made to reduce heat loss. 
Its also interesting that the SEAI dont give some sort of grant for new windows and doors. It makes you wonder how well thought out their grant scheme is.


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## Alkers86 (2 Dec 2019)

The effect


Coldwarrior said:


> I've the same conundrum, was quoted 20k net of grant last year to do my (detached) house. My gas bills cost roughly 1000 per year so even if it saved me 33% as the installers usually claim, it'd take me 60 years to make that back. OK gas prices and carbon taxes will likely go up in the future but the ROI would still be extremely long. Hopefully they'll be better grants/incentives in the next few years to make this more viable.
> 
> If I needed to get the house re-plastered anyway though I think I'd probably go ahead and do it.


The cost of energy, particularly the burning of fossil fuels for home heating is likely to increase dramatically over the next 60 years.

Depending on the existing windows, I would actually wager you'd earn a payback quicker with the EWI.


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## JohnJay (2 Dec 2019)

Alkers86 said:


> The cost of energy, particularly the burning of fossil fuels for home heating is likely to increase dramatically over the next 60 years.


Very true. But chances are that technology and the quality/effectiveness of insulation will also improve. So the 100mm of insulation we use in 2020 might be obsolete by 2030. 
Its not long ago that we thought 80mm of yellow fiberglass in our attic was the best thing since sliced pan!


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## shweeney (3 Dec 2019)

If your heating bills aren't that high, why are you even considering it?

Eliminating draughts might give you better bang for your buck.


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## roker (30 May 2020)

When you say internal insulation, does that mean cavity or inside the house?
There has been stories of cavity insulation causing dampness by blocking the air space in the cavity, is this a concern, has anyone experienced it?


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## Black_Knight (31 May 2020)

roker said:


> When you say internal insulation, does that mean cavity or inside the house?
> There has been stories of cavity insulation causing dampness by blocking the air space in the cavity, is this a concern, has anyone experienced it?


I would consider internal insulation to be dry lining the internal walls of a house.


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## Prosper (2 Jun 2020)

roker said:


> There has been stories of cavity insulation causing dampness by blocking the air space in the cavity, is this a concern, has anyone experienced it?





noproblem said:


> Can you not pump insulation into the cavity?


SEAI say the absolute minimum cavity for pumped in bead insulation is 40mm and in the UK it's 50mm. My house was built in 1987 and the cavity is only 30mm when you subtract the width of the aeroboard polystyrene that's in the cavity. So in some cavity walls the pumped insulation is not appropriate.
Also, is it allowed to put up external insulation on a terraced house without the agreement of neighbours on either side? I don't know the answer to this but I would have thought you'd need the neighbours agreement.


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