External wall insulation worth doing on half the house?

[totallyrandom]

Bottom half of our house is red brick (9-18 inches depending on where you measure). Upper part of house is covered in original 100 year plus pebbledash which is now blown in many places. So we need to rerender the back and two side elevations (top parts only). Has any one on here used external wall insulation when doing this and did it make a big difference? I can sort of see how it would make a big difference if the whole house was done (and roof super insulated so no heat gets out) but am not sure whether it is worth spending the money in my case. Am worried that the heat loss/cold from downstairs brick will travel upstairs through joists etc and that it will be a waste of money. But it is easier than insulating from the inside for me as don't loose picture rails and original skirting board etc and by doing this external walls in most bedrooms would be done. If anyone has had this done and energy bills were down a lot/lots more cosy at night etc please let me know. We already have double glazing or secondary glazing in most rooms and building control was happy with roof insulation.

Haven't done it but interested in doing our side return wall so watching...

Howver we HAVE got new double glazing on al the back sahs windows on our house, front ones are too detailed to replace and are still single glazed. There is a noticeable difference in the heat loss once the heating goes off.

Only other logical approach is that when working out heat loss/ radiator sizes required etc you need the details of each wall, outside, construction etc. I would think that any improvement makes a difference. Problem with all these things is that they are expensive upfront with a potentially long payback. Although they undoubtably add to comfort levels in an old house.

We have one first floor room with a damp plaster problem and are having new insulated interior board / plaster. Only on one wall as that is the only one that needs replacing but I am working on the principle that even one wall immproved will make a difference!

I also found some insulating underlay called Thermafoil which I plan on laying in ground floor rooms to reduce the cold coming up from floor level.

totallyrandom, did you choose to put ewi on the upper half of your house in the end? and if you did, has it been worthwhile?

I am looking at a similar scenario for our house and DH not sure if worthwhile and reckons we should just spend a lot more money on heating!

does anyone else have experience of just putting ewi on the top half of a house?

It is rare in the UK but will make a big difference in the upstairs rooms, so they will hold their heat at night when the heating is probably off. Useful if you have solid walls with no cavity.

If you are hacking off the old pebbledash this is a good time to do it. I have seen it done in Switzerland but not here. The makers of rigid insulating boards (certainly Knauf) make a special board for this purpose designed to be rendered, and will have an information and specification sheet online. Make sure it is all done in accordance with makers specification. They may possibly have an accreditation scheme for local installers.

We had it done for free on whole house-it made a huge difference to our heating bills (went down) and temp was much more stable.

Realise this started as a very old thread, but... as it's now revived....

Interested in this. We have solid walls and a big exposed outside wall all along the side of our house - it is the wall where the hall, staircases, landings are though, two bathrooms and one tiny bedroom we use as a study - so no 'living' rooms or bedrooms. Do folk think it would be worth doing (would be 3 storeys, but easy access for workmen), in terms of warming the house and also in terms of reducing gas bills ?
I clearly know nothing about this but wonder if "sealing up" the outside of the house brings any other problems, perhaps such as condensation in to play ??

Some people say that and worry about it-we weren't in the house long enough to find out!

it will tend to reduce condensation, because the cold external walls will now be maintained nearer room temperature, also their thermal mass will keep the room temperature more even.

For a while you can expect the windows to steam up more, as the walls, being warmer, will dry out and lose their moisture to the air. This should be tacked with ventilation, as usual. Future condensation (e.g. from baths and cooking) will be more visible on the windows rather than being un-noticed soaking into the walls. It is common when walls are insulated, and some people make the mistake of thinking that the insulation has caused damp, when in fact the reverse is true and the house is drying out.

we live in a conservation area and I didn't realise until recently that we could go down this route. was all organised to apply for the next round of green deal home improvement scheme but the govt has just cancelled the whole scheme!!

Brilliant - thanks PigletJohn that's really useful

if you want to make a very rough guess of how much it will reduce heat loss, try this calculator, once filling in uninsulated solid walls, and once with insulation.
calculators.baxiknowhow.co.uk/boiler-sizing/

It tries to calculate whole-house heat and HW load on the boiler, assuming IIRC 20C indoors and 0C outside

Most days it will not be that cold, and you will not be heating the house 24 hours so it will not be very accurate.

Your EPC certificate (if you have one) may also say.

I found with CWI that as well as a substantial saving on energy, the house became more comfortably warm. e.g. if you came home unexpectedly at lunchtime, or got up at night, with the heating having been off for 5 hours, it would not feel chilly.

Thanks again. Will have to now work out how to track down a company that does it

start here www.knaufinsulation.co.uk/ or Kingspan

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