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  1.  
    Hi folks,

    I'm new to the forum and the more I read up on internal wall insulation the more confused i am getting so I would really appreciate any practical and pragmatic advice on my scenario!

    I went ahead (rather hastily in hindsight!) and took all the old plaster off the interior of an external wall (9inches solid brick). I know that the wall is mostly dry as most of the plaster was bonding plaster and my builder said that you usually wouldnt put that on an external wall because it sucks up a lot of moisture. Having said that the bottom meter had been replaced at some point and it came off a lot easier there making me think there is a slight rising damp issue with the wall there. I could re-do the injection damp course here though.

    The ceiling in this room has already been plastered and I have had the place rewired already so I know I'm probably doing this arse-about-face, but I thought this was going to be a fairly simple DIY job just dot and dabbing PIR board onto the wall but I realise now there is a lot more to think about.

    I need to be able to hang kitchen units on the wall though so the dot and dab method is out the window. Im also now concerned about the wall deteriorating if its left cold and the condensation gets to it. The other problem is I only have about 7cm to work with because there is a doorway along that wall that will get eaten into if i start making thickening the wall out with layers of pb, insulation and battons etc....

    In hindsight I probably would have left it how it was and waited until I could afford external wall insulation, but I didnt even consider external insulation until I read up on this forum. What should I do?
  2.  
    here is a photo of the wall in question
      IMG_3497.jpg
  3.  
    here is a photo of the doorway im constrained by..
      IMG_3499.jpg
  4.  
    1. You're not really constrained by the doorway as you could make a chamfered return into it or move it over?

    2. I don't have much experience only having done two projects myself but I'm a fan of foam on glue and insulated plasterboard, faster, easier and worked out cheaper than batoning, time to do it etc.

    3. if you know the height of your units just put up some baton, a small cold bridge isn't as bad as people make out on here
    •  
      CommentAuthordjh
    • CommentTimeOct 18th 2016
     
    What's the outside of the wall look like? Is it exposed brick, or rendered with something and if so what?

    Generally, if you can do EWI then it's better performing and less complicated than IWI. So maybe you should consider that. It all depends on your circumstances and plans.
    • CommentAuthorpg3property
    • CommentTimeOct 18th 2016 edited
     
    Posted By: Victorianeco1. You're not really constrained by the doorway as you could make a chamfered return into it or move it over?

    2. I don't have much experience only having done two projects myself but I'm a fan of foam on glue and insulated plasterboard, faster, easier and worked out cheaper than batoning, time to do it etc.

    3. if you know the height of your units just put up some baton, a small cold bridge isn't as bad as people make out on here


    Thanks I must admit I was thinking along these lines but some of the scary sounding 'interstitial condenstation' and the like were worrying me. Can I confirm that by "insulated pb" you mean like K17? Would you put some aluminium foil around the edges of the baton too?



    Posted By: djhWhat's the outside of the wall look like? Is it exposed brick, or rendered with something and if so what?

    Generally, if you can do EWI then it's better performing and less complicated than IWI. So maybe you should consider that. It all depends on your circumstances and plans.


    Yes I definitely understand this after looking around on the forum. I'll attach a photo of the exterior. It might be something I can save up for, I was considering repointing and applying a good quality watersealer as a job for next summer. Only problem is i've just put all the new waste and soil stacks in so I dont know how they go working around them, especially when the main soil stack is tucked in to the corner like this!
      IMG_3507.JPG
    • CommentAuthortony
    • CommentTimeOct 18th 2016
     
    I would do 75 or 80mm thermal boards and add a batten to the difficult doors, as thick as possible insulation in the reveals and skim the lot, do the other wall with the window in it too.
    •  
      CommentAuthorBauwer
    • CommentTimeOct 18th 2016 edited
     
    Traditional solid walls could be difficult and least cost effective part of a building to insulate. However, adding vapour permeable insulation to solid walls can lead to a significant reduction in heat loss without causing long-term condensation, moisture and dump issues while achieving a cost effective solution.

    As traditional buildings need to ‘breathe’ the use of vapour barriers and other impermeable materials (EPS or phenolic boards) commonly found in modern buildings should be avoided when making improvements to energy efficiency, as these materials can trap and hold moisture and create problems for the building.

    The interface between existing walls and added impermeable board insulation can be susceptible to cycles of evaporation, condensation and salt crystallisation. As such locations are hidden from view; major deterioration may have taken place before anybody becomes aware that there is a problem.

    Permeable materials such as lime or thermal render, plaster act as a buffer for environmental moisture, absorbing it from the air when humidity is high, and releasing it when the air is dry. In the opposite, modern construction relies on mechanical extraction to remove water vapour formed by the activities of occupants.

    If the walls are already damp before installing impermeable insulation these effects will potentially be exacerbated. Under these circumstances it is particularly important to allow walls to ‘breathe’ in order to dry as effectively as possible.

    For traditional buildings with highly permeable external walls, the need to prevent impermeable layers precludes the use of modern EPS or XPS boards , as well as the use of protective finishes which bar moisture vapour movement.

    Hope this helps,

    Best regards, Alexander
    http://bauwer.co.uk
  5.  
    Posted By: BauwerFor traditional buildings with highly permeable external walls, the need to prevent impermeable layers precludes the use of modern EPS or XPS boards

    XPS is impermeable. EPS is not, it is permeable and IMO perfectly good for EWI on solid brick walls. I have used EPS on traditional stone/rubble walls with very good results and no ill effects.

    For EWI applied to the building in the photo above, it should be fairly simple to extend the soil pipes where they exit the wall to give the required stand off and the EWI can be covered with a flashing at the gutter line if you do not want to extend the eves. A flashing atop the EWI can also be used at the tile line on the ground floor extension.
    • CommentAuthorgyrogear
    • CommentTimeOct 19th 2016
     
    Posted By: Peter_in_HungaryEPS is not, it is permeable and IMO perfectly good for EWI on solid brick walls


    +1

    My EPS keeps me nice & warm, for free !

    gg
    • CommentAuthorowlman
    • CommentTimeOct 19th 2016
     
    Isn't this thread about IWI?
    • CommentAuthorgyrogear
    • CommentTimeOct 19th 2016
     
    well, Yes - we seem to be trying to help the OP with IWI by telling him to consider... EWI, I guess...

    :sad:

    gg
  6.  
    Posted By: owlmanIsn't this thread about IWI?

    Well - yes, but when second best is problematic - then consider the best !! ...... EWI
    • CommentAuthorgravelld
    • CommentTimeOct 19th 2016
     
    Just don't do this.
      CtmtGd-WEAAIEq8.jpg
  7.  
    Well IMHO, that facing window outside completely messes up the EWI option. I would go with pre-bonded IWI panels (ie to PB) with foil back and glue it with low rise expanding foam and I think I would move the door out a bit; not as bad a job as it sounds and simplifies no end the IWI undoubtedly giving a much nicer look afterwards.

    Love the pic gravelld - looks like snakes and ladders.
  8.  
    What I would do with the facing window is to put 2 cm of EWI on the return to the window (standard over here and not usually possible to put more) and I would feather the adjacent wall EWI down to meet the 2 cm fixed onto the return. The thicker the EWI the further away the feathering would have to start. OK cold bridges will be evident but this must be better than IWI or nothing as 10 cm should be easily achievable.

    Good photos. The soil stack looks like old cast iron, a bit expensive to stand off for the EWI and I can understand why they did not bother. The soil stack that is the subject of this thread looks to be plastic, a fairly easy job to move outboard to accommodate the EWI.
    • CommentAuthorRedDoor
    • CommentTimeOct 20th 2016
     
    OP says "need to be able to hang kitchen units on this wall". What's the best system to fix wall cabinets through IWI?
    • CommentAuthorgravelld
    • CommentTimeOct 20th 2016 edited
     
    Is it possible to include the soil stack on the inside of the thermal envelope in those cases?

    How much space is there going to be in that yard with a decent amount of insulation???
    •  
      CommentAuthordjh
    • CommentTimeOct 20th 2016
     
    Posted By: gravelldIs it possible to include the soil stack on the inside of the thermal envelope in those cases?

    Usually the stack is ventilated, so you still have a penetration through the roof and a cold pipe inside the thermal envelope. Plus you need to make sure it is still somewhat accessible for maintenance. So ideally you want a different drainage design in the first place and compromises are understandable.

    The windows are more worrying to me.
  9.  
    Posted By: djhThe windows are more worrying to me.
    Me too. Sticking that drainage pipe out at all further and it is going to be ugly as sin with the nearest pipe obscuring part of the glass. I still think IWI.
    • CommentAuthorwookey
    • CommentTimeOct 21st 2016 edited
     
    What's the best system to fix wall cabinets through IWI?


    I put the insulation (100mm) on first, then a batten (50mm) set (and glued) into the insulation. This way you don't get a thermal bridge but you do get something solid to fix to. For lighter things this is fine. For heavy radiators or kitchen cupboards you need to put a couple of frame fixings through to the wall. Use stainless for least thermal bridging. You could put in a standoff if you didn't think the insulaiton was solid enough. Depends what you end up using. Something like Hempcrete is very solid and so is XPS. PUR less so but with a chunky batten it should be OK.

    As to the general problem it's tricky. Those windows really are in the way. and the stack too. Putting in narrower windows with EWI is the best way to do it, but expensive if you aren't doing the windows anyway. Tapering in the corner would work. No-one will notice that it's a funny shape. You probably want some IWI too at least on the corner where the EWI is minimal, but do the sums - maybe it doesn't actually make much odds as the first bit of insulation is the most effective.

    Now that you've made a mess on the inside it might be a good idea to put some (breathable) IWI in, but only to U=0.5 or so to minimise damage risk. Then you can put thin EWI on the outside at some point and get a decent U-value. I know all about fitting IWI PUR (which is thin, cheap and effective), but for single-skin brick that's not really the best plan, as Bauwer said, so choose something natural (woodfibre, Dialholite evolution, hempcrete).

    The other thing that would be best is to insulate below floor level which involves digging a trench outside and or taking out the concrete inside, but that may not be in your plan? I'd also put in some foamglass blocks or high-strength XPS to fix the bridge at the door threshold.

    Do you have a standard you are aiming for? I picked AECB silver for this house.
  10.  
    Wookey - as usual you have cut through the chaff and sorted it. Wish I had thought of that! Couldn't agree more with everything you say (in hindsight).
  11.  
    If your cupboard placement is not finalised, you could substitute a sheet of 18 - 25mm ply for the batten.
    •  
      CommentAuthordjh
    • CommentTimeOct 21st 2016
     
    Posted By: Nick ParsonsIf your cupboard placement is not finalised, you could substitute a sheet of 18 - 25mm ply for the batten.

    I put a couple of large wall cupboards in an external utility room, screwed to moisture resistant platerboard with plugged holes. Looked good and my wife filled them with bottles and jars and things. We were content. :cool:

    A week or three later we were sitting in the living room one evening when there was an almighty crash. It's difficult to know exactly where outside sounds are coming from but we eventually discovered that these cupboards had pulled the screws out and fallen to the floor. Luckily they hadn't done much damage, apart from a few broken bottles, and the cupboards proved strong enough to survive the drop to the floor themselves. :shocked: :shamed:

    So now there's a sheet of 18 mm plywood cut exactly to the size of the cupboards fastened to the wall with LOTS of screws, and the cupboards are screwed to that. :bigsmile:
    • CommentAuthorwookey
    • CommentTimeOct 21st 2016
     
    There are _lots_ of boards stronger than plasterboard (all of them in fact :-). So just using cementitious boards, or MgO, or OSB or ply can all be made to work.

    For my garage I used 2 layers of 50mm PUR and set 50mm vertical battens at 0.6m spacing (i.e half-board width), with 2 or 3 frame fixings in 3m height, then MgO boards. Shelf brackets go into the battens. Airtightness layer behind the battens.

    http://wookware.org/pics/house/extension/html/505-IMG_4533.JPG.html

    This is very strong and pretty warm.
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