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    • CommentAuthorWeeBeastie
    • CommentTimeJun 15th 2020 edited
     
    I had planned to have EWI installed on my small semi-detached bungalow, along with other energy-saving improvements. However, my adjoining neighbours really don't like the EWI idea because of the step it will create at the party wall, and the reduced eaves.

    They do have a point as the building is quite monolithic in appearance with no natural divide such as a downpipe at the boundary. They don't want EWI on their half of the building.

    Of course I could press on regardless, assuming the Council gives permission, but I'd like to consider alternatives. I do know that anything other than full EWI is a compromise but I also like to avoid conflict!

    The walls are 9 inch brick with painted harling on the outside and lath and plaster on the inside. I have problems with condensation and mould.

    I'm wondering whether the front and rear walls which adjoin the neighbour could be left alone externally and EWI added only to the side wall (east). Then IWI used on the front (N) and rear (S) walls. There would be very little IWI needed on the south wall as a new extension would deal with part of it, a large window another chunk, leaving only around 800mm adjoining the neighbour to deal with. The N would be more extensive.

    Would this be a sensible compromise? I understand from what I've read that IWI walls should be modestly insulated - u value no smaller than 0.5 - to minimise risk. Would mixing this with a lower u value EWI wall be a problem? Should I consider IWI on all three walls since there will be internal disruption anyway for electrics etc?

    Thanks for any advice.
    • CommentAuthorbhommels
    • CommentTimeJun 15th 2020 edited
     
    Opting for both IWI and EWI looks like a nice way of paying over the odds and getting the disadvantages of both ;-)

    It depends a bit on where you are, for most regions EWI is permitted development provided you make an effort to make it look the same as the existing finish, so planning permission is not required.
    Primary elevations are sacred from a regulations point of view, government guidance from 2013 explicitly states however that EWI is exempt to encourage people to insulate their homes. I will refrain from giving my opinion on your neighbours attitute (I am facing a similar "problem")
    • CommentAuthortony
    • CommentTimeJun 15th 2020
     
    No problem with the step
    • CommentAuthorWeeBeastie
    • CommentTimeJun 15th 2020
     
    Posted By: bhommelsOpting for both IWI and EWI looks like a nice way of paying over the odds and getting the disadvantages of both ;-)


    Yes, the cost is another factor. If the insulation job is too much of a compromise is it worth it? Maybe I improve the house in other ways and wait to see how it performs. Underfloor insulation in particular should make a noticeable difference and I will improve the bathroom and kitchen ventilation. I've lived in cold houses before and don't mind putting on a(nother) jumper, but here it's the condensation and mould in winter that I need to get rid of.
    •  
      CommentAuthorfostertom
    • CommentTimeJun 15th 2020 edited
     
    What makes such a step in the wall surface conspicuous, is if it creates a hard shadow at the vertical edge, and a difference in the shadow under the eaves horizontally. On a north wall, which gets little direct sunlight except low on summer evenings and early mornings, this is minimal.

    The vertical can be further minimised by making the transition into a fairly long smoothly curved S-bend, with no hard edge to create shadow contrast, just a gradation of tone. Adding a fake RWP will further confuse the issue by its shadow.
    • CommentAuthorbhommels
    • CommentTimeJun 15th 2020
     
    Posted By: WeeBeastie
    Posted By: bhommelsOpting for both IWI and EWI looks like a nice way of paying over the odds and getting the disadvantages of both ;-)


    Yes, the cost is another factor. If the insulation job is too much of a compromise is it worth it? Maybe I improve the house in other ways and wait to see how it performs. Underfloor insulation in particular should make a noticeable difference and I will improve the bathroom and kitchen ventilation. I've lived in cold houses before and don't mind putting on a(nother) jumper, but here it's the condensation and mould in winter that I need to get rid of.


    EWI is fantastic, not least due to the thermal mass of the walls becoming part of the warm volume, and the lack of fussy detailing compared to IWI. It will be very hard to get the same effect through other ways of improvement (unless.....)
    • CommentAuthorWeeBeastie
    • CommentTimeJun 15th 2020
     
    Fostertom - thanks for those suggestions. The discussion I had with my neighbours was friendly enough so perhaps I can pass on your design thoughts too. They are accepting of it on a detached house so there may be hope!

    bhommels - agreed that EWI would be the gold standard. If IWI is the practical way to go though, I'd be interested in Bauwer Light which may be less problematic to 'install' than sheet material as it would give a continuous finish. I know the rep was pushing it on this forum when it first came to the country.
    • CommentAuthorMike1
    • CommentTimeJun 15th 2020
     
    Maybe you could sell the benefits of EWI to your neighbours and have both front elevations insulated at the same time?
    • CommentAuthorWeeBeastie
    • CommentTimeJun 15th 2020
     
    Posted By: Mike1Maybe you could sell the benefits of EWI to your neighbours and have both front elevations insulated at the same time?


    Unfortunately, going by a couple of previous discussions on the subject I think they are closed to the idea. I'm not sure if there are reasons beyond aesthetic, but I have to respect their point of view. Some people may carry on regardless but I'm more timid than that, hence looking for the compromise!
    • CommentAuthorjamesingram
    • CommentTimeJun 15th 2020 edited
     
    how about using the gutter downpipes to make it look less obvious
    I post an example
  1.  
    100mm to 200m EWI on property boundry
      20200615_171047.jpg
  2.  
    .
      20200615_171025.jpg
    • CommentAuthorWeeBeastie
    • CommentTimeJun 15th 2020
     
    ji

    Thanks very much. I personally think that works well (though I'm not so keen on the appearance of reduced eaves depth). Good food for thought to approach the neighbours again.


    I'll wait and see if there are any other neighbour comments, what my architect suggests, and if it is approved by the Council (I assume it will as we are not in a conservation area).
  3.  
    I dont like the shallow eaves either . they look miserly :-)
    theres also the benefit of a bit of weather protection and shading from deeper eaves
    but to get the 200mm on we had to put up with it , fortunately when the places were built they had decent eaves
    • CommentAuthorphiledge
    • CommentTimeJun 15th 2020
     
    That step looks fine and I'd struggle to see how there could be significant objection given the advantages.

    For the OP, maybe a conversation with the neighbours about the growing(moral) need for insulation and the possible future pressure/statute to insulate.
    • CommentAuthorJonti
    • CommentTimeJun 16th 2020
     
    I assume you have done the calculations on the cost benefits of insulating externally and have shown this to your neighbour. If not then I would suggest doing so and trying to get them to do the same at the same time as this would reduce the overall M2 price and solve the look issue.
    • CommentAuthorbhommels
    • CommentTimeJun 16th 2020 edited
     
    Posted By: JontiI assume you have done the calculations on the cost benefits of insulating externally and have shown this to your neighbour. If not then I would suggest doing so and trying to get them to do the same at the same time as this would reduce the overall M2 price and solve the look issue.

    EWI is a hard sell just on cost / financial benefits, as it is still quite a lot of money even when doing 2 properties at once. There is no price tag attached to the increase in comfort that comes with EWI, and for most people it has to be experienced to be believed. As with most green measures really.

    @jamesingram: great pictures, thanks for posting! Gives me some ideas to approach my neighbour with.
    • CommentAuthorWeeBeastie
    • CommentTimeJun 16th 2020
     
    I have another neighbour who is very supportive and is pleased to see someone taking action to install energy saving measures. There are a couple of houses around here with EWI. However I'd think that many people are completely unaware of the existence of EWI, heat pumps etc. Most people I've spoken to don't know what heat pumps are. They know about loft insulation, UPVC double glazing and maybe cavity insulation....

    Makes me wonder how attitudes were to the introduction of gas when it started to replace solid fuel.
    •  
      CommentAuthordjh
    • CommentTimeJun 16th 2020
     
    Posted By: WeeBeastieMakes me wonder how attitudes were to the introduction of gas when it started to replace solid fuel.

    A stove or boiler powered from the mains, whether it be gas or electricity, is so much of an advantage over solid fuel - managing deliveries, stoking the stove/boiler/fire etc - that I don't think there was much resistance. Bit like electric lights replacing gas lights.
  4.  
    well the marketing campaign worked well
    I use the phrase "Cooking with gas" and my mother wasn't even alive then
    • CommentAuthorJonti
    • CommentTimeJun 16th 2020
     
    Posted By: bhommels
    Posted By: JontiI assume you have done the calculations on the cost benefits of insulating externally and have shown this to your neighbour. If not then I would suggest doing so and trying to get them to do the same at the same time as this would reduce the overall M2 price and solve the look issue.

    EWI is a hard sell just on cost / financial benefits, as it is still quite a lot of money even when doing 2 properties at once. There is no price tag attached to the increase in comfort that comes with EWI, and for most people it has to be experienced to be believed. As with most green measures really.


    I would have thought it is cheaper and better than IWI or at least this has been my experience. It also is far less disruptive which is an added bonus. Of course, it is cheaper than doing nothing at all except for two things. Firstly, there will be legislation coming down the road in the not too distant future requiring existing housing stock to meet higher levels of energy efficiency meaning many/most will be forced to improve the insulation of their property. Secondly, gas will become the next carbon fuel which will be removed from the market leaving electric heating as the logical last method of heating. It is expensive to heat with electricity.
    • CommentAuthorbhommels
    • CommentTimeJun 16th 2020
     
    @Jonti
    I agree with all your points as probably most on here would.
    It is just that for "normal" people, convincing them to spend several thousand £ on EWI to reduce the gas bill by a few tens £ per month is a big ask. From a purely financial perspective, even for my DIY EWI installation the payback time is well over ten years.

    I doubt there will be legislation that would require people to install EWI or IWI, or swap the gas boiler for an ASHP to stay legal anytime soon.
    • CommentAuthorEd Davies
    • CommentTimeJun 17th 2020
     
    Something that bothers me about the EWI/IWI hybrid is the cold bridges at the joins (outer corners). Not only would they leak heat a bit but, if the house already has a mould problem, they'd have it worse without the rest of the walls to help with dehumidification.

    OTOH, EWI on a retrofit is likely to have the same problem at the top corners with the lack of a good join to the loft insulation but that's not normally considered much of a problem. Of course, the perimeter/floor area ratio is worse on a bungalow from this point of view.
  5.  
    Posted by WeeBeastie: 'lathe and plaster”

    Incase it helps: lath and plaster linings seem to work differently from the solid walls that you may have read horror stories about IWI. Air circulates between the lath and the masonry and drys the masonry and allows for a drainage plane, a bit like an early version of a cavity wall, or Tony's modern 'plaster tents'. We found that removing a socket allowed a gale through, ditto under skirting.

    If you EWI, you need to block the cold air circulation behind the L&P or it will negate the EWI, this will mean breaking into the room linings (disruptive) but think through the moisture consequences before you block it.

    We took down the L&P and replaced with PIR boards between studs. We were careful to maintain the air circulation between lining and masonry, open to ventilated loft and underfloor, but sealed so it didn't get into the room. This is a common method round here when old buildings are converted.

    Over a decade we did each room bit-by-bit when redecorating, and sometimes had cause to reopen the earliest walls, no sign of damp or decay. The house was much warmer, and less draughty.

    The IWI was easy to join to the loft and underfloor insulation, but attention was needed to fix some cold bridges and insulation gaps at corners. The windows took over from the walls as the coldest condensation magnets in the rooms, so ventilation needed attention.

    IWI has something of a bad reputation which is a pity because IWI and EWI each have their place and their limitations, neither is right for everyone, but we could get more houses done more quickly if we considered both.


    Posted by WeeBeastie:"- u value no smaller than 0.5”

    Be very careful, this number comes from the influential 'Breaking the Mould' study which applied specifically to west-facing porous walls in Dublin that had been IWI'd in a particular way and absorbed 70% of driven rain. The author was very clear that any walls with different climates, different constructions, would have different outcomes and 0.5 might be safe or unsafe there, but unfortunately the 0.5 number has been picked up and applied as a magic number all over the place.
    • CommentAuthorMike1
    • CommentTimeJun 17th 2020 edited
     
    As WillInAberdeen mentions, restricting U-values to a low of 0.5 is misleading - see my post at http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16573&page=2#Item_1
    • CommentAuthorJonti
    • CommentTimeJun 18th 2020
     
    Posted By: bhommels@Jonti
    I agree with all your points as probably most on here would.
    It is just that for "normal" people, convincing them to spend several thousand £ on EWI to reduce the gas bill by a few tens £ per month is a big ask. From a purely financial perspective, even for my DIY EWI installation the payback time is well over ten years.

    I doubt there will be legislation that would require people to install EWI or IWI, or swap the gas boiler for an ASHP to stay legal anytime soon.


    Whilst I agree that most do not see the reason to do upgrading now there is no doubt that gas will become the next big target for the environment. No new gas boilers from 2025 in new builds so I would be surprised if gas survives much beyond 2030.

    For most there will be no cheap alternative fuel so the only way will be reducing the need to heat IMO.
    • CommentAuthorWeeBeastie
    • CommentTimeJun 18th 2020 edited
     
    <blockquote><cite>Posted By: WillInAberdeen</cite>
    Incase it helps: lath and plaster linings seem to work differently from the solid walls that you may have read horror stories about IWI. Air circulates between the lath and the masonry and drys the masonry and allows for a drainage plane, a bit like an early version of a cavity wall, or Tony's modern 'plaster tents'. We found that removing a socket allowed a gale through, ditto under skirting.

    If you EWI, you need to block the cold air circulation behind the L&P or it will negate the EWI, this will mean breaking into the room linings (disruptive) but think through the moisture consequences before you block it.
    .</blockquote>

    Thanks. So am I correct in summarising thus:

    If IWI, I need to keep the air gap behind the L&P, assuming there is good air flow through it.

    (I'd thought I would have to remove the L&P to remove any air gap since the now-colder brick and the timber studs for the lath would be more likely to attract moisture. Historic Scotland case studies are on solid stone; my walls are solid brick with painted harling, so not breathable to let moisture out the way?)

    If EWI, the gap behind the L&P needs to be blocked to stop air flow, or perhaps even better the L&P removed so air gap removed? How do I predict the moisture consequences?

    Obviously more to consider than I had at first thought....
  6.  
    Our existing studs were about 2"x1.5" iirc, we replaced some of them with treated 4x2s to give greater depth of insulation. As they bridged across the insulation, they were kept a bit warm from the inside.

    (Another benefit they were stiff enough not to need mid height support pegs into the wall. And the existing studs were on weird spacings that didn't match metric plasterboards. )

    But the studs are surrounded by insulation 2 sides and in contact with moving air, same as the rafters and floor joists are, so I wasn't too worried about them being damp.

    Over different rooms we tried different setups, such as fixing sheet insulation over the existing studs to reduce bridging and avoid fiddly cutting insulation to shape. There were pros and cons such as trying to fix the plasterboard through thick insulation. We didn't do it scientifically enough to say one method was 'best’.
  7.  
    Anyone else with experience of EWI with the presence of lath and plaster? Did you block the air flow into the mini-cavity the L&P creates, remove the L&P and plaster onto the brick to get rid of the mini-cavity, or indeed just leave it as is?

    If I have to remove the L&P would it be just as well to go for full IWI, thus avoiding a change in the external appearance disliked by the neighbours??
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