Regulars will have noticed my regular naive posts about EWI, installing windows etc etc.

After taking a step back I have decided not to pursue the EWI segment. Instead, I'm reviewing a render only solution, while still installing high quality windows, full filling the cavity an treating the eaves properly.

The first reason is cost. Not just treatment of the actual wall (although it appears about double the cost to insulate and render), but the the downstream works:

- Extending gables
- Digging foundations
- Moving drains
- Treating lean-to roofs at the same time

The second reason is complexity. First world problems and all that, but I have run out of mental energy both to try to understand, design and plan this, while also running a business and bringing up a young family. Obviously, I could hire someone to do that, but please see the first reason.

Quite honestly, I feel revitalised since deciding to dith EWI.

My intention is to pursue EWI later, maybe in a decade or so. In some ways I think the end result might be better - it allows more budget to purchase better windows, and we could do the EWI at the same time as the roof later, allowing us unlimited space at the eaves.

So now I need to consider how going render-only will affect things. I am considering the full gamut:

- Ignoring the render and hoping no-one gets hit by falling patches
- Just patching what we have
- Removing and re-rendering with S+C
- Removing and re-rendering with a silicone system
- Removing and re-rendering with an insulating render, e.g. Bauwer, Diathonite

I know BC might raise an eyebrow if we remove and re-render as we are treating more than 50% of the wall. Hopefully the fact that we are also full filling the cavity AND using a high performance window product will convince them of good faith alongside our intention to fit EWI later.

I am considering the window detail separately... see http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15728

Any thoughts on the re-rendering options?

This is exactly the type of response I hoped for when I posted - to further challenge my preconceptions. My thoughts:

I'm not sure how much patching up is required. I would estimate 10% of the render is blown, small cracks cover 80% of the render across all elevations and 15% of the corner beads have rusted through and require replacing. There are a few places where there are holes in the render at the corner of windows for water to get behind. Also the base track is shot in a number of places.

This render layer will likely form the AT layer in the future, so having cracks in it is a no-no. I don't think it's any good anyway because of water ingress that may/may not occur.

An EWI person also suggested looking at the substrate behind the cracks, because if that's cracked we should really do something about it (straps or whatever an SE says).

I asked a local lime plasterer to look, he came to the conclusion we might as well take it all off... but maybe he would say that ;-)

Posted By: Peter_in_HungaryWould you normally have the air tightness layer outside the cavity?

Yes, on retrofit and when you don't want to create massive internal disruption.

PU foam will offer some AT benefits but it won't be continuous because there are some sections of full fill EPS for which I cannot guarantee AT, so therefore it's the render layer.

Posted By: Peter_in_HungaryThe general advice is if the render is not blown then leave it on and EWI over it. Obviously it depends upon the condition and stability of the render that is not blown and sometimes it can be difficult to differentiate between 'good advice' and 'job creation'

Agree. As above, I'm not EWI'ing.

Posted By: Peter_in_Hungary

Posted By: gravelld

Posted By: Peter_in_HungaryWould you normally have the air tightness layer outside the cavity?

Yes, on retrofit and when you don't want to create massive internal disruption.

But this means that the cavity has to be air tight - which could be a big ask.

Well... the render layer outside the cavity has to be air tight, yes, and then connections to the roof etc.

Posted By: Peter_in_Hungary

Posted By: gravelldI'm not EWI'ing.

- Yet

Correct, so I guess another option is just let the render fall out over the decade or so it takes to save up for EWI and look worse and worse with time.... note there is also some holes in the render at windows, which water could get behind. I don't think combining a full fill cavity with a wet external leaf is a good idea...

Paint it with some strong paint, so the render is held together by the paint, and the cracks are filled by it.

Gyrogear, which particular act of a dog would require us to sheet up a whole building?! I await your reply with bated breath!!

10 years is a long time to wait before you fit EWI. 10 years of a colder home, higher energy bills and a decade less for the ROI. I'd suggest that if you're 'kicking the can' down the road for a decade, then the EWI just isn't going to happen and you should perhaps accept that. and move forward?

Instead, I'd look at alternatives. Perhaps put EWI on a single wall (i.e. a north wall) and render the rest. If that's not possible then see if there are some insulated renders available. The combination of an airtight and slightly insulated render that sheds moisture is going to be more thermally beneficial than a patchwork of blown, leaky render.

Sorry, I missed out a icon

But there are loads of flexible paints, and crack fillers.

Posted By: djhSorry, I missed out a http:///newforum/extensions/Vanillacons/smilies/standard/tongue.gif" alt="" title="" > icon http:///newforum/extensions/Vanillacons/smilies/standard/sad.gif" alt="" title="" >

I did wonder!

Posted By: gravelldPhD as well, you must be some sort of super human.

- no, more like someone who has taken on too much and is ending up getting nothing finished!

I squeezed some sand and cement into some of the cracks in mine, how long it will last is anyone's guess. In my case the base coat is absolutely solid to the wall, and its the harled outer coat is detached from the base coat. I considered at one point removing the out cot and leave the flat base coat, but I don't know if yours is coming right off down to the brick/stone.

Posted By: gravelldIt might not happen @Pile-o-Stone which would be a great shame. Thanks for your thoughts.

I know how you're feeling, and like Kenny_M, I feel your pain. I have a long list of things I'd like to carry out on our old, cold house but lack of funds are also proving to be restrictive. Our original plan was to internally insulate our house a room at a time, as we renovated/redecorated. We have one room fully insulated and should be looking at moving onto the next one (our living room). However, the cost of insulating, moving radiators & power sockets, re-plastering, re-flooring and the massive disruption and emotional drain is making us rethink the whole thing.

We have made a big improvement to the heat retention of the livingroom by replacing an old multi-fuel stove and replacing it with a room sealed gas stove. When it was off, the old stove must have been acting like a big heat sink and sucking warm air out of the living room. We certainly have felt a huge improvement since we replaced it. We are now looking at moving the doorway into the living room. Currently there is a double door that opens into the heart of the room, causing a draft right where we are sitting when the dog or cat push the door open (and they can't just open it a little - they seem to have to open it as wide as it goes!). Instead we are moving the door to the end of the room, far away from where we are sitting. Hopefully this will be another relatively minor (in expense at least) change that will have a big impact on the thermal dynamics in the living room.

What I'm trying to say is that you should try and get some cheap/quick wins that might reduce your energy bills by 30% for little financial outlay, and not stress too much about the big jobs that might reduce your energy bills by 80% but will never repay in your lifetime.

I've joined a renewable energy company for my gas & Electricity. I take cold comfort in the idea that at least the energy I'm wasting is green .

the payback of insulation improvement is obviously an important factor. I've EWI'd my large bungalow and recent extension, it was hard work both mentally and physically. But my aim was both reduced heating bills and a much improved living environment. This winter was a revelation, the house was still reasonably warm in the mornings after very cold nights with no heating having been run for at least 10 hours. And no more mold growing on the inside walls in cold corners. Interior temperature is much stabilised, fluctuating mostly in a 3 or 4 degree range rather than big 10 degree swings in some rooms when the heating was off. And the thermal envelope is not yet complete, I still have to do the below DPC line plinth insulation to foundations. And while we have loft level insulation, it's thin and patchy, the upper floor has been converted for occupation but is not yet insulated, once done I think it's going to bring further improvements to the living conditions and I expect interior temp to stabilise further. MVHR also planned.

if you can EWI, now or later, I highly recommend it. It's more than just reduced heating bills, in my case it's made our home a much nicer place to live.

Ok, another question...

Is it possible to EWI on EWI with the sticky block method? Example build up, inside to out:

1) Wet plaster
2) Inner leaf
3) CWI full fill
4) Outer leaf
5) EWI (including adhesive) ~35mm
6) Silicone render
7) EWI ~250mm
8) Silicone render

Reason I ask: if it turns out to be not-much-more to EWI a thin layer instead of render-only if we were to strip and re-render. Steps seven and eight to follow later.

Posted By: gravelldIs this the type of thing you were thinking of @djh?

Not particularly, no. As I said, there are loads of possibilities depending on the condition of the substrate and the desired end result. The two I have personal experience of are Beeck Quartz Filler and a rubber-based waterproofing paint. For different circumstances of course and maybe neither match your situation.

As regards elastomerics it might be worth reading http://www.paintinfo.com/cn/cnp-020.shtml or similar.