EWI on a early 1900's semi detached?

[kentar]

My property is semi detached, early 1900's, solid brick, with bay windows. The exterior is pebbledashed above the dpc. There is a bit that is bare brick (for show I guess) below the ground floor windows at the front of the house which extends all the way across the front of the house.

 

 

I'm considering EWI through the ECO scheme. I've a company that can install it. I'm just trying to do some homework beforehand and wondered what the general consensus was? I know it can be extremely beneficial, but how does it fare long term? Is it the right decision?

 

What questions should I be asking?

Am I doing the right thing by fitting it to an old property?

Will I ruin the look of the property?

Do I need to bring the windows out?

Can I maintain the look the the timber above the first floor bay window?

 

Another thing that worries me is that the house will be out of keeping with the rest of the houses on the road. None of them have EWI. I believe they're all pebbledashed (I will check this). They're all slightly different in architectural style as well, so the only property that matches the look of mine is the one that i'm attached to. Perhaps that's a good thing?

[Mr Punter]

EWI can work OK on buildings with nice large expanses of wall.  With the curved bays, projecting window, porch and being semi detached, yours (at least from the front) does not look a good candidate.

[marmic]

be very careful you don't cause a damp problem............. 

[Mike]

It could be done, but it would need care & extra cash to preserve the existing visual appearance - don't do anything that will harm that as it would undoubtedly cut the property value.

 

So, use brick slips to retain the look of the bricks, and mimic the timbers on the gable. The small upstairs window will the the most difficult. I'd move it forward together with the dental courses above (to maintain the visual appearance and due to the angle at which it meets the wall) and would want the insulation below it sculpting into curves to look similar to the existing. The other windows would be OK as they are. I'd  temporarily remove the porch, which would then need some adaption to reinstate it - or bring the whole thing forwards by the thickness of the insulation.

 

If all that's too much, then just leave the front and insulate the other walls, where the energy savings will be greater as they presumably have more actual wall to insulate. I rather suspect that would be my solution.

 

BTW, worth having a chat to your neighbour to see if they're interested in doing theirs at the same time, to keep it as a matching pair.

 

Edited Friday at 12:52 by Mike

[Nickfromwales]

Spend the money blowing the cavities full of bonded beads. 
 

Very slim returns vs the time / money / disruption, and trying to make it look like it hasn’t been done. 
 

Of EWI isn’t done meticulously then you’ll be worse off than you are now. Lots of council done dwellings now complaining about huge damp issue; black walls / wallpaper peeling away etc. 

 

This is just not a candidate for a readily priced / achieved EWI installation, which you need to be able to justify costs vs ROI.

[marmic]

solid............   cavity fill also becoming a problem as I predicted years ago! 

[Nickfromwales]

2 minutes ago, marmic said:

solid............   cavity fill also becoming a problem as I predicted years ago! 

For wool yes, not heard of issues with EPS beads? 

[marmic]

i've read some mortgage companies are starting to get twitchy about anything thats been filled - no idea if thats true or to what extent however. Personally wouldn't touch anything thats had cavities filled with anything!

[-rick-]

8 minutes ago, marmic said:

i've read some mortgage companies are starting to get twitchy about anything thats been filled - no idea if thats true or to what extent however. Personally wouldn't touch anything thats had cavities filled with anything!

 

Isn't that the majority of houses that have a cavity?

 

I thought the bulk of houses built with cavities without insulation had now been filled. Obviously there have been a variety of techniques used and problems identified with some but it's been step three of improving insulation in houses since the 80's. 1 and 2 being loft insulation and double glazing.

[ADLIan]

I used to be involved with injected cavity wall insulation as a system designer. The failure rate, measured by claims on the guarantee scheme was unbelievably low, less than 1%(?) of all installations. There were poor installs/poor surveys many years ago when lots of grants were available but still a very low failure percentage. 

[Nickfromwales]

4 hours ago, ADLIan said:

I used to be involved with injected cavity wall insulation as a system designer. The failure rate, measured by claims on the guarantee scheme was unbelievably low, less than 1%(?) of all installations. There were poor installs/poor surveys many years ago when lots of grants were available but still a very low failure percentage. 

Great perspective, thanks. 

[Redbeard]

Beware air movement in the cavity. I had mine insulated with 'bonded' (ha!) EPS beads to a questionable standard as we had found really significant air movement in the cavity when doing minor works prior to EWI. I am not convinced we 'got it' 100%, but the EWI would have been incredibly expensive external wallpaper if we'd not addressed the cavity issue. As @Mr Punter said yours does not look a promising front elev for EWI with the oriel, bays and porch. I worry about the standards on 'down-to-a-price' work, and I would want drawings of how they would address the bays etc. I have seen some aesthetically dreadful 'solutions' and none which avoided serious thermal deficiencies except where the contractor had removed the bay windows, resin-anchored threaded rod in and fitted new bays on top of the EWI. Very nerve-wracking till they are on and right, I would guess.

[ADLIan]

No glue = cost saving!!

[Mr Punter]

29 minutes ago, ADLIan said:

No glue = cost saving!!

 

The glue is quite expensive but too much can apparently be worse than too little.

[SimonD]

1 hour ago, Redbeard said:

air movement in the cavity when doing minor works prior to EWI

 

Couldn't agree more. I had to do a lot of careful prep work prior to installing our ewi. I had to rebuild most of the underfloor vents as there were big gaps allowing air movement into the cavity. And also lots of carefully sealing along the wall plates at the top of the walls as well as round all other penetrations.

 

Unfortunately like all retrofit approaches, care and detail needed and it's never a straightforward as you might think.

 

The other disadvantage as I have recently found is then fixing anything to the ewi - it's a right pia. And then don't let ignorant contractors loose on any later where they have to touch, drill through or fix to the ewi without full supervision! I just had one here recently who said they just use standard wall plugs. I said no you don’t!

 

Ever seen the results of a mindless sds drill going through ewi from the inside and what happens to the mesh and thin coat render??? 

 

Don't get me wrong, EWI is great, but it does have its drawbacks on some things.

[Mike]

12 hours ago, Redbeard said:

Beware air movement in the cavity.

Top advice when there's a cavity - but the brickwork under the window (and the original post) indicate that there isn't one to worry about in this case.

[kentar]

I stated in the first sentence that it's solid brick. I have no idea why some of you are talking about a cavity.

[SimonD]

9 hours ago, kentar said:

I stated in the first sentence that it's solid brick. I have no idea why some of you are talking about a cavity.

 

You haven't been on buildhub to know that there is always OP  scope creep. Has to be. Whether it's relevant or not it has to happen just in case and because it might just be relevant to someone else reading the thread at some point in the future.

 

It does drive some people a bit crazy  but wouldn't be buildhub without it 😁

[Nickfromwales]

12 hours ago, kentar said:

I stated in the first sentence that it's solid brick. I have no idea why some of you are talking about a cavity.

Fast thumbs and lazy eyes.

 

Oops 👀. 

[Nickfromwales]

So. EWI it is!!!!

 

Now to discuss the pros cons and caveats of this, so that @kentar can be kept as a member here….. 

[marmic]

https://www.bbc.co.uk/news/articles/c3w965gz8zgo 

[marmic]

I'm no expert in EWI and not planning to research as wouldn't use!  But IMO:

• very careful consideration needs to be given to structures on an individual basis.
• There will I am sure be plenty of companies out there full of BS so probably advisable to ensure very careful due diligence
• There will I am sure be good ones too - and if eveything taken into account and building suitable it's probably ok?
• If buildings are built to 'breath' - which many with solid walls are - sealing things up on the outside may not be a great idea.
• Assume walls should be dry before applying to avoid trapping moisture in - which can then only go one way
• And if vapour internally needs to be prevented from getting into the structure and staying there causing rot and mould etc stopping it is easer said than done on an existing building
• Additional ventilation may be required? - passive or mechanical?
• Localised thermal bridging I'm guessing could also be an issue? (eg window reveals)?

Only my opinions/thoughts.....................

 

briefly back to the cavity conversation - I find most people seem to forget and/or don't know the original reason for them, and is also a mystery why many think bricks and stone etc are waterproof!  They aren't - which is why wall ties have drips and cavity trays are necessary at abutments etc.  Porosity will vary significantly. (obviously render/coatings a different conversation). Somebody I was talking to years ago was told by a so called 'expert cavity insulation installer' they would seal up the holes made in bricks to ensure water didn't get in!  There are other issues IMO with pumping insulation into cavities but I'll leave it there as don't have all day!

Full fill cavity insulation on new builds is I believe subject to location / exposure (regs) and needs to be very carefully specified and installed to avoid moisture tracking across. But I don't believe anything is stated with regard to the porosity of the outer leaf(?)  - problem is who would define?!  The difference between a relatively impervious brick or sealed render/coating etc and a handmade stock brick or limestone is huge.    I shall now get back into my pram and say no more. 😀 

 

   

[marmic]

ps -  if all boxes ticked so far and it's dry ensure installation correct to ensure rain/moisture can't get in behind - particularly at eaves/verge/reveals.  also consider detailing at dpc, especially at corners. I don't know but I'd personally dig deeper to establish if thermal bridging at ground floor - wall connection level becomes an issue???? 

 

google 'ewi problems' - AI overview interesting

 

I really will now be quiet!!

[marmic]

15 minutes ago, modernvillaco said:

Excellent points raised here. From our work at ModernVillaco , we’ve seen that moisture control and vapor diffusion are often overlooked in EWI projects. Especially in humid climates, it’s essential to combine insulation with a ventilated cavity or a vapor-permeable system. That balance between airtightness and breathability makes all the difference in long-term durability.

merci -  I may be wrong but i think EWI is commonplace in central europe too probably with not as many issues? new build and refurb?  But the climate is drier, hotter, and colder than here in UK..........

[Roger440]

O wouldn't entertain the idea, especially not on that house, and especially under the government eco4 scheme.

 

As per BBC link posted earlier, 98% of ewi installations have an issue. 98%!!!!?!

 

And no one has even mentioned that with a solid wall, is there even a DPC? Quite likely not, in which case, ewi will prevent the moisture on the base of the wall evaporating outwards. So there's only on place it can go.

 

Just, no, no, no.