External House Insulation?

Brrr! Our house (1939 3-bed end-of-terrace concrete lump) is sooo chilly.

We've insulated bits of the house as we've done them up - kitchen and attic conversion are toasty warm.

Alas the majority of the house is frizzly freezing with uninsulated solid conrete walls.

Insulating the internal sides of the walls would take up too much space (e.g. no room for bath in bathroom if we lost even an inch, stairs would be too narrow, etc.)

So I was wondering about insulating the external walls of the house. I know I'd still have to heat the thermal mass of the walls but surely it would improve matters and make the house a bit easier to heat.

(At the mo we have the heating come on at 6am and at 6:40 when I get up you wouldn't know it was on, its so cold - have to supplement it with a fan heater)

Has anyone tried external insulation? Any pitfalls to watch out for? What sort of costs are involved? Any recommendations for suppliers?

We recently did up our house and went with outside insulation for the existing part of the house. Contractor basically bricked up large blocks of styrofoam against the existing house and then plastered over so house appears the same. We can't believe the difference. As the house previously wasn't well (if any) insulated now it is toasty. Previously we would have had the heat on all day in this kind of weather and it wouldn't have been great.
You really need to tackle draughts as well; getting the house as air tight as possible is a major help as well. Don't know how much it would cost as a stand alone job as we did it as an overall job.

Hi Coolaboola,

I have just spent the last month frying my head on insulation methods - here is the executive summary.

External insulation seems the best option but is the most expensive at around €100-120/m2. Can be a bit messy around windows, doors, soffits etc. There will be a step at any property boundary (for semis and terraced only). It may require planning permission if it changes the front facade dramatically. Also, read something about needing to excavate out footpaths to get insualation down to the foundations. Sound like a good job overall be pricey to do it well.

Internal, also messy but less expensive and if you do not have a family in the house all day, quicker to heat up the house without heating all the walls. Potentially a DIY job if you are proficient.

Personally, I would go for internal except where space makes it absolutely impossible. Can you get a smaller bath?

As far as I know you have to get a specialst installer to fit external insulation to the house. The installer (usually people in the plastering profession) will apply the system that they are trained in and approved for. The system involves fitting an insulating board (e.g. polystyrene or phenolic) to your external walls. This board is then covered with a mesh and corner beads (at the edges) and the surface is then rendered usually with a primer, basecoat and final coat. A warranty, certification etc for the job is provided by the company who offer the system and this is usually 10+ years.
Companies that supply this service are people such as Wetherby, Webber, Parex, Greenspan etc. Most will tell you that it's very popular in big jobs such as office blocks, however it appears to be making it's way now to regular homes. Cost including fitting appears to range from 90euro or so per sqm to 150euro per sqm (plus vat). However every job is unique and the installers would need to size up your job re complications such as around windows, soffits/eaves overhang, drains, cills etc.

My advice is to go with a system that has IRL or GB certification and agree with the installer exactly what they will do. For example will the prepare the area, remove downpipes and make good everything afterwards such as rerouting any drain feeds etc.

Regards
Franm

All very useful information. Thank you very much for taking the time to reply. Sounds like its a big job, both physically and financially. But the prospect of toastiness... (as she hugs a hot water bottle as she types)

I would suggest a wall coating. {Looks like paint!} It will prevent further penetrating damp, and, because it is micro porus, it will let the walls breath, and the rain that has built up over the last 70 years will evaporate out of the walls, and in time, the walls will dry out completely. Dry walls are warm walls! It costs about €56 per sq metre

Damp Man said:

I would suggest a wall coating. {Looks like paint!} It will prevent further penetrating damp, and, because it is micro porus, it will let the walls breath, and the rain that has built up over the last 70 years will evaporate out of the walls, and in time, the walls will dry out completely. Dry walls are warm walls! It costs about €56 per sq metre

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Is there a brand name for this?

Thanks for that info Damp Man. Any more details on the type of coating? Name? Who supplies it (in Dublin)? Do I apply it myself? The front of the house is pebble dash - can such a coating be used there?

Have you thought about pumping the walls with insulation?

baldyman27, pumping insulation only suitable for walls with some form of cavity in the construction. My walls have no cavity... they're solid concrete all the way through. So pumped insulation is not a option for me.

Damp Man said:

I would suggest a wall coating. {Looks like paint!} It will prevent further penetrating damp, and, because it is micro porus, it will let the walls breath, and the rain that has built up over the last 70 years will evaporate out of the walls, and in time, the walls will dry out completely. Dry walls are warm walls! It costs about €56 per sq metre

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This sounds like snake oil. Do you have a link to the product?

Similar problem with my extension, very poorly insulated, the exterior walls were not plastered or sealed as there is a very small gap between the extention and the neighbours. is there any pumpable sealant/insultaor that can be pumped onto exterior walls?

brian mc said:

Similar problem with my extension, very poorly insulated, the exterior walls were not plastered or sealed as there is a very small gap between the extention and the neighbours. is there any pumpable sealant/insultaor that can be pumped onto exterior walls?

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[broken link removed]

This gives you the options.There are lots of companies around the country who can pump insulation to cavity walls.