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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthortony
    • CommentTimeMay 11th 2009
     
    There are many, loss of space, inbuilt thermal bridges at every partition and floor, thermal bridging at the party wall if there is one, The possibility of outdoor air being able to get behind the linings and causing high heat losses, what to do about floor joist thermal bridging, the disruption, having to meet part L1B especially on stairs where the consequential narrowing would contravene other regs even fire regs. etc
    •  
      CommentAuthorbetterroof
    • CommentTimeJan 21st 2010
     
    I've just been asked by a client to look at doing bits of internal insulation. He wants do the skeiling and ceiling of his bathroom and the external walls and ceiling of his boxroom (we are going to refurb all his sash windows with slimtech dg units) aswell as upgrading his loft insulation.

    Will that work be applicable to building regs and is it worth doing in a piecemeal way?

    He is very keen to insulate as much as possible, and is happy to get creative, but he has a lovely old house, with original features in very good nick, so doesn't want to compromise that if he can help it....

    Any suggestions?
    • CommentAuthorarnyj
    • CommentTimeJan 21st 2010
     
    I have nearly completed lining bathroom with 8" wool on outside walls & 4" on party wall the effect of that was to make a cold bathroom, At last warm 56 F something I have been trying to achieve over past 15 yrs.

    we tested room with door shut and lost 7degs. so clad cieling with just under 4" kingspan and now it is a balmy 64degs F with 1 or 2 degs loss overnight.....

    I would say Yes although the devel is in the detailing I've still got to finish the window and am intending to buy some quality tapes from Ecological building systems as I can now see the snags of trying to do it on cheap, they will answer your Questions about building regs.

    Am now doing front bedroom....

    ta Arnold.
    • CommentAuthorJeff B
    • CommentTimeJan 21st 2010
     
    There was a long thread on the forum last year on this subject but I have searched and can't find it. There was a lengthy discussion about the involvement of the BCO if the area of wall to be modified exceeded 25% of the total area. It seemed a nonsense to me but according to the regulations it appears that if you make ANY attempt to improve the wall insulation in your property (on the grounds that any improvement is better than none and should be welcomed) requires you to comply with the current U-values for walls regardless of the age of the property! It also seems that this is open to different interpretations by different local BCO's. I talked to mine about my plans for additional internal insulation and he told me just to get on with it - he certainly wasn't interested in any formal application! Probably best to try an informal chat with yours first.
    •  
      CommentAuthorjonharris
    • CommentTimeJan 22nd 2010 edited
     
    I looked at insulating internal walls on my last 2 projects - lounge and hallway/landing. It was a no-go on both rooms because it would mean ripping down 100 year old ornate coving and plasterwork, repositioning large sections of staircase and attaching wooden strips to lovely sash windows to beef out the frame. Not to mention stripping several dozen square metres of plaster off walls, down to the brickwork, so I have enough depth to play with when building back up. Even this would only allow for a mere 1" of Celotex + plasterboard, and many would criticise that for not being enough. So binned the idea and spent the time/money elsewhere, like insulating under floorboards in the lounge, and secondary glazing and draught proofing our lovely stained glass sash windows in the hallway and landing. Something is better than nothing I guess. And I have not compromised the look of the house.

    Having said that I more than likely will insulate the internal walls in our bathroom because:

    A) It's got 3 external walls to the outside, so it's losing a lot of heat anyway.
    B) Not a big room, so not tonnes of plaster to rip off!
    C) There's not much in the way of period features in there that will get destroyed in the process.
    D) May be able to get 2" Celotex in there. We'll see. Is 2" that much better than 1"?

    May also attempt my office which has 2 external walls.
    Kitchen is a maybe, with all those cupboards I'm not sure how new plasterboard walls will cope with the load though.

    My personal conclusion is that internal wall insulation should be considered on a room-by-room basis, especially in period properties where important original features may be destroyed or compromised.
    •  
      CommentAuthorrogerwhit
    • CommentTimeJan 22nd 2010
     
    Bathroom - external walls - might there be hidden condensation - danger of mould & rot?
    •  
      CommentAuthorfostertom
    • CommentTimeJan 22nd 2010
     
    Victorian houses with 9" or 13.5" solid brick walls lined by lath and plaster, with attractive cornices, skirtings etc on the face of that, are a special case.

    Such buildings are terrible heat-losers as they stand, because of absence of inboard airtight wet-plaster - a non-lath and plastered building solid-wall building at least enjoys that advantage.The airspace behind lath and plaster is usually a place where outside air moves freely in out and around, when any breeze blows, through the hairline cracks that any masonry has. That means that the lath and plaster, far from providing a modicum of insulation, actually puts you in a tent, where outside air is only the thickness of the plaster away from the interior. Removal of such lath and plaster linings is a priority for any such building - which may well be Listed - so a conflict there!

    However, the lath and plaster zone will be anything up to 60mm, and if new insulation/lining can be fitted into that, then skirtings can be reinstated unchanged, and cornices can remain undisturbed, albeit at cost of a fudged-insulation band behind same. Of course, upper floors' wall insulation must be extended down thro the floor joist zone to link up with the top of the ceiling/cornice below. Many other technical/installation issues, but that's the principle.

    The challenge is to find insulation that's worthwhile, within that thickness, incl making the inside face of the exposed brickwork airtight (but vapour open). Multifoil, and aerogel spring to mind.
    •  
      CommentAuthorbetterroof
    • CommentTimeJan 22nd 2010
     
    Thanks for comments so far - I realise it's not going to be straightforward and I'm keen not to miss-sell him a load of work that may not have much impact.

    As far as I know, it's not lathe and plaster, just plaster straight on to stone. Space saving isn't a big factor. My initial plan was going to be remove skirting and rad, batten the walls and pack out to straighten and then use a 50mm or larger insulated plasterboard (or the pavadentro system from NBT). Then replace skirting and rad. I was going to use a multifoil for window detailing to save on space.

    Do I still need to go below the floor level? I don't think there is much cornicing to worry about (certainly none upstairs)
    •  
      CommentAuthorbetterroof
    • CommentTimeJan 22nd 2010
     
    My Client is also interested in some external insulation. he is an end terrace, and was thinking about insulating the end gable wall completely. He is then going to do some internal insulation on the rear upstairs room, maybe some underfloor insulation on the ground floor.

    Is it worth doing? I know it's better if you have a complete seal around the building, but he does not want to compromise the frontage (nice big bays etc).

    I realise it will definitely help in terms of draught sealing, but wasn't sure about cost effectiveness against insulation gain? :confused:
    • CommentAuthortony
    • CommentTimeJan 22nd 2010
     
    Yes -- to external insulation of the flank wall -- and yes to underfloor insulation

    Need to deal with thermal bridging where internal and external insulation change over.
    •  
      CommentAuthorbetterroof
    • CommentTimeJan 22nd 2010
     
    it's the detail I'm not 100% on... for example, how would you deal with the thermal bridge at the junction between loft space and external insulation? and if you didn't, how much effect would that have?
    • CommentAuthortony
    • CommentTimeJan 22nd 2010
     
    I would take the gable down, wrap the insulation over the top of the wall to join the ceiling insulation, prop and tie the purlins if necessary, carry the external insulation on to the roof line. but thats just me.
    •  
      CommentAuthorbetterroof
    • CommentTimeJan 22nd 2010
     
    me too, but I don't think he'll go for something like that. I need something less invasive I suppose. It will be a registered contractor doing it anyway, so I'll prob check that out with them. thanks for your help! :bigsmile:
    • CommentAuthorwookey
    • CommentTimeJan 22nd 2010
     
    How about foamglas bricks put into gable end to connect external and internal insulations? Bit fiddly but a lot better than taking the whole thing down. End wall is solid 9"? Could just extend inulstion up inside gable too, therby significnatly reducign bridging. Save foamglass just for corners where loads lowest and bridging worst?

    And doing a load of internal insulation is a lot better than nothing, even if there is bridging where internal walls connect. Again cutting in foamglas could fix this (tricky on structural walls?), as can bringing external insulation in 600mm or so (easier but not as pretty due to step).

    I've found internal insualtion to be very effective indeed, even in relatively thin form (35mm PIR), with good airtighness attention. Definately worth doing if external not popular/practical.
    •  
      CommentAuthorali.gill
    • CommentTimeJan 25th 2010 edited
     
    op states bathroom 'skieling' which indicates that the top floor is partly in the roof hence rendering tonys suggestion more practical as in reality its just the top third of the gable that would need to be deconstructed and rebuilt.

    The solution where internal meets external insulation at a corner joint is to return one at the perpendicular plane.
    ie. gable wall externally insulated = rear/front wall internally insulated + inner face of gable wall internally insulated up to 600mm.
    I think EST have a figure on minimum length of the return, but i'd suggest at least 600mm, for now cos its way past bedtime, in fact my alarm goes off in 41/2 hrs.... stuff it i'm off.
    • CommentAuthorEv
    • CommentTimeJan 25th 2010 edited
     
    Figures from Historic Scotland re walls which might be of interest:

    http://www.historic-scotland.gov.uk/u-value_measurements_traditional_buildings.pdf


    Personally I'm unconvinced about replacing glazing with Slimlite, as well as loss of original glass it might not be cost effective. Be interesting to see the results of the trial at Edinburgh World Heritage HQ on this.

    All papers produced so far:

    http://www.historic-scotland.gov.uk/index/heritage/climatechange/energyefficiency/climatechangeresearch.htm

    English Heritage on windows:

    http://www.climatechangeandyourhome.org.uk/live/research_generic.aspx
  1.  
    Can you inject insulation behind lath-and-plaster?
  2.  
    Posted By: passivhausfanCan you inject insulation behind lath-and-plaster?
    Yes! But not much.

    I've been meaning to post something on this thread about internal insulation as that is what I've done on the old house, and not much insulation at that.

    What we had, from bottom to top was a stone foundation that's about 30" thick which formed most of the basement wall; on top of that the groundfloor joists sit. Behind the joists, a triple brick solid wall and the gap behind the plaster and lath above was open into the basement. The gap behind the plaster and lath was about 1 to 1.5". On the first floor, the joists sit on top of the inner brick of the triple brick wall which then switches to double brick. The gap behind the plaster and lath was open to the ceiling joist space as was the gap behind the wall above. This then continues to the 1st floor ceiling and the gap behind the plaster and lath was open into the ceiling joist space.

    So basically there was a continuous gap from the basement up to the ceiling space above the upstairs. Even though the wall is solid, it's not draft proof and it was possible to feel the circulation of air when in the basement.

    I did a few different things at different times in different places. Since we renovated upstairs first, in a couple of rooms we left the plaster and lath in place and fastened 15mm pur foam board on top, held in place with 1x3" strapping to which new drywall was attached. In the rooms where the ceiling was lowered, foil-faced double-bubble insulation was extended across the old ceiling and taped to the foam board on the wall, forming (hopefully) and airtight junction. We ended up taking up the floor in one room and I stuffed batts of insulation between the joists, extending behind the plaster and lath above and blocking the gap. A new subfloor was put down and I foamed the junction between the wall foamboard and the new subfloor.

    In another room, the floor couldn't be taken up, but we ended up taking the ceiling down below. So the same thing - I filled the joist spaces at the wall junction with batts, blocking the space behind.

    In the groundfloor rooms, we didn't want to change the depth of the walls (as there was wainscoting in place) so it wasn't possible to add any foam board. So I drilled 3.5" diameter holes through the plaster and lath every 16" or so (which approximately corresponded to how the wall was attached to the brick on battens). These were done just above the wainscoting and about 1 foot below ceiling level (with the ceiling removed and before the batts went in). Then a nightmarish couple of days with a beast of a cellulose blowing machine (free rental if you buy 25 bales). Blowing cellulose through a 3.5" hole into a space that's between 1 and 1.5" deep is a challenge as the pipe blocks very quickly. Eventually we figured out a way to make it work. Hell of a mess! It was like a snowstorm in the rooms where this was done. In the end, only 4 bales worth ended up in the walls (which is about the correct volume). So I didn't get the machine rental free, but they only charged me for 1 day and I got a credit for the unused bales. Total cost: about Can$92 plus $30 to rent a van to get the beastly machine there and back.

    In the basement, again I stuffed batts between the joists to block up the space behind the plaster and lath above and to cover the naked triple brick wall.

    Since the insulation was put in, it is noticeably quieter in the rooms where it was fitted (even though it's only about 1 to 1.5" thick). The surface temperature of the wall is vastly improved - this was the area where the wall temperature was 14C when it had been -11C outside for 3 days - now the wall is very close to room temperature. Heating bill is down about 13% this season compared to last (on a cost per heating degree day basis) - last year only the upstairs had been done.

    For sure, it wouldn't meet UK part L regulations - but the U value of the wall has probably been halved and a lot of air leakage and thermal bypass issues solved, which probably makes more difference in the end. The cost of installation of the cellulose will have paid for itself by the end of this heating season for sure and the psychometric feeling is much better as we don't have cold surfaces radiating coolth anymore.

    Below is a picture just after part of the cellulose was installed. Heck of a mess!

    Paul in Montreal.
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