Anyone got/had external insulation installed?

[MisterBoy]

One suggestion that came up regarding energy efficiency when we bought our solid-brick Victorian house was external insulation - avoiding the need to redecorate and deal with some period features, etc.

Particularly on our long north wall I've thought about it on and off but I've never met anyone who has it to ask about it... what is the material used, what is the process, how big and expensive a job is it, etc.

For anyone here who has had it done, looked into it, or actually installed it, I'd love to hear your pros and cons.

 

[Mr Chibs]

Not had it, as mine is internal.

Old chap across the road had a quote for a Victorian 3 bed detached, external insulation... it was nearly £20k needless to say he didn’t do it.

I’ve seen it done, quite straightforward application, which you could probably do yourself, apart from maybe the rendering.

 

[phatboy]

We have it all over our house, it made the house liveable. It is now possible to heat the house, and it stays nice and warm for a long time. It does take a while to get warm initially, and stays warm for a couple of days after the heat has been turned off.

It was done 5 1/2 years ago, and cost approx. £100/sqm (without allowing for windows and doors) , excluding any access equipment.

Ours is covered in Graphite EPS, but some now favour mineral wool. It then has 2 base layers of flexible render with mesh added, then a topcoat of self coloured render. You can get brick slips as a finish too, or cladding over it.

The process was:
Ensure existing finish was stable, if not remove
Fix 3x3 timber to anywhere on the house that things would be attached, like satellite dishes, gates, hanging baskets, lights
Fit base rail
Cover house in 90mm EPS boards, and fit using 5x insulation fixings per board. Below base rail fit 40mm boards and fix.
Add insulation around window and door reveals as thick as reasonably possible
Render everything
Clean up
Silicone joints to all windows, doors and soffits

Tim

 

[m0t]

We've got it on our 1930s semi. Cost about £12k in 2015.

Process for ours was similar to phatboys but they didn't do any work to the existing surface (our render was coming off in chunks). The explanation was that the insulation encapsulated the bad render and the fixings went through into the brick.

It was done as part of a council scheme and inspected by them during the process so I assume that was correct.

Heating bills fell almost immediately by about 15%.

They struggled with some of the finishing where a ground floor extension joined the rest of the house. I had to fix it myself as they went bust and so did the insurer of the guarantee.

I would recommend reading up about how the junctions and joins are supposed to look to make sure it is being done correctly as it is installed.

 

[MisterBoy]

Thanks. Intersting point @phatboy about how it affects heating performance. I'd never have thought about that but I suppose the insulation being outside, your existing brick wall acts as thermal mass and smooths out heating changes? Not sure if that's good, bad, or neither

Price-wise it's obviously a big outlay but I suppose you have to cost up what building out one or two stud walls in each room and redecorating would run to. Especially if this then triggers a full redecorate in every affected room!