External with Internal insulation

Ya I know what your suggesting but it was a waste of my valuable time doing that for two reasons the walls weren't great in the rooms so we're being plastered anyway. And I want to make a warm attic in future. So not messing around throwing warm boards on a wall up there through a small attic access. Plenty of other work to get on with.

The value was better spent in this case lining inside the living envelope for this use case.

Membranes next which will open opportunities for the attic and also solar install.

:)

You forgot to include a FEW Very important factors which must also be consider by Homeowners when deciding on where to fit insulation on an external walls.

1. €€€€€€ Cost of external wall insulation verses the cost of internal wall insulation. This is very easy to calculate. This is very important to all homeowners
2. EWI must be completed in 1 operation and paid for immediately
3. Uninsulated Cavities must be filled if EWI is to be applied. This is another approx €3,500 Cost of EWI
4. Internal Wall Insulation can be carried out in stages, over time, to suit the homeowners budget
5. Is the external plaster / finish in a perfect condition
6. Can the EWI be continued below DPC
7. Can the EWI be continued up to insulated the entire wall / heads above all window and door opes, above the soffit and must be connected to the Attic Insulation (I understand that must EWI salespeople (Trotters Independent Trading) don’t bother doing this)
8. With EWI - Cost of moving all windows and external door frames out to the EWI, and necessary internal repair works to all reveals and soffits of all opes (I understand that must EWI salespeople (Trotters Independent Trading) don’t bother doing this)
9. Is the internal plaster finish in perfect condition
10. Does the house need to be renovated and re plastered internally
11. Does the house need to be re plastered externally
12. Will the EWI diminish the narrow soffit, and alter the original character of the house
13. In Semi Detached houses the solid concrete block Party wall will constitute a Cold Bridge, and will therefore need to be insulated. This is another cost on EWI.
14. I would not recommend EWI to old very damp, very thick stone walls of very old houses. (bearing in mind that walls cannot breathe - and contain rising dampness- which must be allowed to evaporate to the external atmosphere).
15. Etc etc
16. People here are giving their preferences in relation to EWI -v- IWI to OP’s.
17. Every home is different and must be critically analysed by an experienced Construction Professional, before deciding on a course of action - to be explained in detail to to Homeowners, who will make the final educated decision.

Thinking logically. Your walls are already insulated. You are considering the external wrap. Why? Likely because your heat loss is still bad. Therefore, your heat loss is more than likely not by conduction through your walls and therefore adding external insulation will do little, if anything at all, to your heat loss issue.

Your heat loss is likely caused by convection losses (i.e. air leakage or draughts). EWI does not address this generally and you need to find the primary leakage issues and address these. The solution is unlikely to involve adding more insulation layers.

Get an independent heat loss survey done which covers not just your heat loss issues but also addresses appropriate ventilation. Make sure you're home during it so you see for yourself what's happening and get appropriate & realistic advice on how to address the various issues found. Independent in the sense that the surveyor is not affiliated to any other business selling insulation, ventilation systems, heat pumps etc.

7+8 - I've not seen this done yet. So most contractors must be in this Delboy group. Have you experienced it being done properly?

Thanks for the replies.

So in reality at present there is somewhere between 1 and 10% chance of getting the job done below plinth and above soffit in a retrofit scenario, unless you do the work yourself?

Assuming you've a) already filled the cavity (in my case loose white bead), b) the cavity is very narrow (in my case 50mm), c) were fully gutting the inside of the house anyway, d) could live with losing a few inches from the rooms. Would you be better to insulate on the inside instead of this "standard/poor" external approach?

One out of lots ! - Possibly/Probably a well-informed homeowner.

Were the windows installed before or after insulation was fitted. If before, how were they supported. Was it just using the straps tied back to wall surrounds. I see at least one company offering an insulated support that can be bolted to the wall for the window to sit on.

After, I boxed the Opes out 100mm into the 200 mm insulation layer.

Nice deep window internal sills now though :)

18mm minimum Plywood marine grade. Never use OSB for this purpose. It has no business being used for this.OSB is great but not for structural use.

The ply was sealed with sika, but then has a bitumen wrapped tape applied all over it. Had to keep the tape a bit warmer on a rad as weather was cold . Abysmal to work with when cold.

When my mother got her house done last year as part of the seai scheme you had to take what was on offer. In the words of the guy that carried out the initial inspection "if you don't agree to any of the proposed works, then they will cancel all aspects of the upgrade". So I get the feeling that if you were to insist on them digging up footpaths and removing soffits, there would be a stop put on the works or the insistence that you shut up and put up. I had intended to either tackle them or ask them if I could organize the prep works (dig paths and remove soffits). But as my mum wasn't keeping well at that time, I just let it go to get them in and out as soon as possible to avoid too much stress for her. So alas I will never know if they would have played ball. But my gut felling would be that I would have been told to go away, as these guys flew through the work, never taking more than a 10 minute break. 5 days total to do a small 3 bed bungalow.

I had discussions with them all and got verbal agreement that if I dug up paths and removed soffitts they would insulate. Impossible to get this in writing though.

So I have chosen someone and placed a sizeable deposit with the quote saying work is to be done to SEAI standards. I’m expecting a real fight when it comes down to it.

Yes I had installed windows first by window company . So they were on. But I was also the ewi installer too. So then wrapped after. I only got a plasterer to finish. As I've zero faith in my skills in that dark art.

I would have gone the same route as you too but I’m caught with needing to do one gable from my neighbour’s property and couldn’t get insurance to cover me and eliminate risk of claim on them.