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Green Building Bible, Fourth Edition
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    • CommentAuthorscrimper
    • CommentTimeNov 7th 2013
     
    Have searched and searched, but not a whole lot of info on the various options for full fill insulation - can I trouble the great hive mind for a few tip offs?

    Basic outline ... the new build element of our big renovation is about to start (tomorrow!!) ... with two 100mm skins of blockwork (inner one cement, outer one thermal) ... with 100mm cavity that my 'builder' wants to full fill. We will have a render finish, and are not on a terribly exposed site - so I'm perfectly happy with the core strategy. But tomorrow I HAVE TO buy this insulation, and I haven't done my homework properly ... so a little stressed now it's gone midnight!

    I've priced up on Xtratherm 100mm phenolic (seems to be about £17 per sq. m) ... but are there any other comparison products I should look at do you think? Another product by Jablite seems to be about £11 per sq. m but is not foil backed or phenolic.

    Am not aiming for super ambitious U-values, but am very conscious of all those wise words about the wisest money being spent on insulation etc. ... so any help or pointers would, as ever, be very very gratefully received! Especially any tips on which of the major suppliers/trade suppliers are offering the sharpest deals right now ... I have 150 sq. metres of the stuff to buy ...
    • CommentAuthortony
    • CommentTimeNov 7th 2013
     
    Sheet insulation is very difficult to work with and likely to perform poorly unless installed by Mike George.

    I would open the cavity up by oversailing the blocks 25mm each way and use 2x 75mm top U value fibreglass batts if you cant face the wider cavity then 100mm "32" grade batts, no misses, no gaps, no mortar snotts, nylon ties not metal ones etc
    • CommentAuthorDarylP
    • CommentTimeNov 7th 2013
     
    Scrimper,

    Are you sure that is Xtratherm 'phenolic'....? I have only seen PIR (lambda 0.022)
    You are building in UK?, if so you will need to leave at least 25mm clear cavity on the o/s of any rigid insulation to appease your BCO/AI, so with a 100mm cavity you are looking at 75mm rigid board thickness.

    I imagine your builder is happier with full fill because he/she is used to it, cannot be bothered to spend the time cutting/fitting rigid boards, and the mineral wool batts give and allow a greater tolerance.

    With 100mm cavity, full fill is better from a U-value pov than partial fill.
    Look at the lambda of various batts, 032 is the best but v expensive. 035 is probably a happy medium.

    Good luck:smile:
  1.  
    Just to add to the above comments.

    You mention cement blocks internal and thermal external - are you sure you have that spec the right way around? Lightweight blocks require equally lightweight renders - not something that I see bieng done on many jobs... I also don't like lightweight blocks at all (as Tony will I'm sure agree....) mutual backslapping over:whorship:
    • CommentAuthortony
    • CommentTimeNov 7th 2013
     
    lightweight blocks crack and shift about too much, this compromises aesthetics airtightness and ones pocket when it has to be repaired or rebuilt.
    • CommentAuthorscrimper
    • CommentTimeNov 7th 2013
     
    Ok all - had a bit of reprieve on the timing, but still wavering between the Jablite and the Xtratherm. You're quite right ... the Xtratherm aint phenolic ... and a brain seizure had me stating the lightweight blocks on the outside ... doh!

    So ... the six hundred and seventeen pound question is ... do I spend 56% more on my 100sq. m of insulation to get a W/mK of 0.021 vs the cheaper Jablite option which weighs in at 0.032?

    And - this may sound crazy, I don't know - but given that one half of my house is going to be relatively poorly insulated (two skins of brick with cavity fill and render) ... does fitting very good full fill in one half mean that I'll just be forcing the heat through the existing walls?

    Really, really lightweight questions I know ... I apologize ... just feeling my way here, and your help much appreciated!
  2.  
    As mentioned above in UK you cant full fill with solid boards , so neither would be the correct answer , 100mm cavity , max board thickness 75mm.
    As other mentioned go cav bats, 32 if you can afford it , and go for tony's suggestion of 150mm cavity (75/75 bats)
    you'll never ( or will anybody else) notice the lost 25mm internal/externally.

    Re forcing heat loss to less well insulated walls, they'll only loss heat at the rate they were. but this will become a higher proportion of overall heat loss.
  3.  
    I'm not sure what people think of it on here, but as I didnt "trust " the brickys with insulating the walls properly I had polybead platinum balls blown in afterwards. Now thats full fill where your slabs can not be?
    •  
      CommentAuthorjoe90
    • CommentTimeNov 7th 2013
     
    Posted By: jamesingramAs mentioned above in UK you cant full fill with solid boards , so neither would be the correct answer , 100mm cavity , max board thickness 75mm.
    As other mentioned go cav bats, 32 if you can afford it , and go for tony's suggestion of 150mm cavity (75/75 bats).


    So just to confirm, you cant full fill with boards but you can with bats or polybead balls?

    Whats the merits of bats verses polybead balls? cost/U value?
    • CommentAuthorjamesingram
    • CommentTimeNov 7th 2013 edited
     
    joe , yes as far as I'm aware. (edit :site exposure need to be considered)
    Andy , hadn't thought of that, heard of it done quite a bit , good idea , just have to make sure the bricky leave the cavity nice and clean.
    What was your cost to blow the plat. poly beads in approx. m2 ?
  4.  
    <blockquote><cite>Posted By: jamesingram</cite>joe , yes as far as I'm aware.
    Andy , hadn't thought of that, heard of it done quite a bit , good idea , just have to make sure the bricky leave the cavity nice and clean.
    What was your cost to blow the plat. poly beads in approx. m2 ?</blockquote>

    From memory £6.50 /m2 based on 100mm cavity, in Cheshire (last year)
    Bricky quotes were made cheaper, due to not "messing around" with insulation!
    Mines brick outer skin so had it blown in pre plasterboard from the inside! I was a little sceptical as to how full the fill would be and how stuck together the balls would be, but I had a few areas I could "check" afterwards and I was very impressed!
  5.  
    Yes , done knock throughs on previously beaded walls and was impressed with the way they filled well and held in position. £6.50m2 sounds good , better than scrimpers £11m2 for eps cav board. Cav 32 bats are around £11m2 ish for small orders . looks the way to go at that price
    What the U value for plat. beads ?
  6.  
    <blockquote><cite>Posted By: jamesingram</cite>What the U value for plat. beads ?</blockquote>

    Did a quick search as I cant remember the exact details without digging out all the paperwork and found this figure -

    Polypearl Platinum has a Lambda Value of 0.033 w/m2
  7.  
    kaycel super plus is U<30 but this is in board form
    • CommentAuthorDarylP
    • CommentTimeNov 7th 2013
     
    A builder I know uses Polypearl blown in for new build apartments, as he cannot trust the brickies to install the insulation properly.... it means the job is finished quicker, the brickies are happier as they can concentrate on what they are good at, so a 'win/win'!

    Cheers:smile:
    • CommentAuthorEd Davies
    • CommentTimeNov 7th 2013
     
    Posted By: andy-cheshirePolypearl Platinum has a Lambda Value of 0.033 w/m2
    That's a direct quote from their site: http://www.polypearl.co.uk/polypearl-platinum-for-builders.php Hardly confidence inspiring: it should, of course, be “W/m·K”.
    • CommentAuthorscrimper
    • CommentTimeNov 8th 2013
     
    Well ... I am assured (by an ex building officer who is helping project manage my build) that full fill in my situation is NOT contrary to any part of the building code ... so if anyone can post a link to the part that refutes that, I would be very interested to look at it. As joe90 points out, if this was the case it would make a bit of a mockery of the whole cavity fill process!

    Talking of which - this is why I love this forum ... I would never have thought of simply using cavity fill for my new build sections as well, but I can see that it might make a lot of economic sense providing it is planned for ahead of time. Shall do lots more investigation today ...
    • CommentAuthorjamesingram
    • CommentTimeNov 8th 2013 edited
     
    Scrimper ,it is area dependent , ie. wet west coast usually no full fill at all . Solid boards and quilt/blown-in has different properties so different regs. also depends on manufacturers guidance
    http://www.planningportal.gov.uk/buildingregulations/approveddocuments/partl/bcassociateddocuments9/acd
    "The suitability of full fill cavity construction is dependant on the exposure of the site and the nature of the outer leaf. Further information is given in BR262 ‘Thermal Insulation: Avoiding Risks’, NHBC Standards, and Zurich Building Guarantees Technical Manual."
    • CommentAuthorjamesingram
    • CommentTimeNov 8th 2013 edited
     
    there are newer board products like these below , that are called full fill , you'll notice they have a profile on the front that creates a gap to reduce moisture problems on the outside of the board.
    http://cavitytherm.com/cavitytherm/
    http://www.greenspec.co.uk/products/built-in-full-fill-insulation/springvale-platinum-fullfil/
    http://www.jablite.co.uk/site/technicaldata/33/33.pdf
  8.  
    Posted By: andy-cheshireI'm not sure what people think of it on here, but as I didnt "trust " the brickys with insulating the walls properly I had polybead platinum balls blown in afterwards.
    Have you ever looked inside an unfilled wall cavity? You will see mortar bulging out from both interior faces, huge heaps of mortar snots on top of all the wall ties & mortar filling the base of the cavity. These create huge thermal bridges & in extreme case can lead to moisture penetration.

    I once had a summer job removing mortar snots from the base of cavities of new houses. The amount of mortar depended upon the bricklaying team, but in some cases it was 6-8 inches deep & completely filling the cavity tray. The builder concerned stopped using cavity trays at DPC level as a result, letting the mortar drop down to the foundations.

    If you fully fill the cavity with mineral wool batts as work proceeds then there's a limit to the amount of mortar that can bulge into the cavity, there'll be no mortar on top of the wall ties & its not physically possible for mortar to drop to the base of the cavity. However, doing it properly requires consistent sequencing & all work needs to be covered to stop the mineral getting wet & slumping in the cavity.

    David
    • CommentAuthorjamesingram
    • CommentTimeNov 8th 2013 edited
     
    David , the old method to stop this was a plank of wood as wide as the cavity with 2 strings , left in the cavity and pulled up as you go along to catch and clean the snots . Though I'd imagine this might be a rare thing :neutral:
  9.  
    I've only seen it in NHBC guides.

    David
    • CommentAuthorjamesingram
    • CommentTimeNov 8th 2013 edited
     
    My bricky did it, but then he's in his early 60s , usually full fill now with bats , stay well clear of boards. Though I think getting it blown in after is a possibility ( as long as you use the plank ) and worth further investigation.
    • CommentAuthorscrimper
    • CommentTimeNov 8th 2013
     
    Thanks James & David ... yup, we are nowhere near coast, and finish will be full render so we're ok on both fronts. All cavities excavated so far have been nice & dry & clean of debris ... must have had a few 95mm wide planks on the go in the late 30's!
    • CommentAuthorscrimper
    • CommentTimeNov 8th 2013
     
    One question remains ... where are all the 'premium' cavity wall installation companies? Why when I search the internet for a CWI company do they all, and I mean ALL, look really flaky and make me feel super nervous? I don't actively look to overpay for anything in this life, but this is the kind of job that I would happily pay a 50% premium for in order to get the comfort of knowing I'm dealing with a really well qualified crew who have an in depth understanding of what they're up to and a top notch professional attitude etc ...
    • CommentAuthorDarylP
    • CommentTimeNov 8th 2013
     
    scrimper,

    Are you building in England or Wales? If so " top notch professional attitude etc" might be hard to find....?
    If you look at the BBA certs for the rigid PIR boards in cavity walls, they will have min. clear cavity specified.

    However if you do get full-fill with rigid boards accepted by your BCO/AI please let us know....

    Good luck:smile:
  10.  
    Scrimper

    In my current temporary bungalow I had the cavities filled with rockwool fibres a few years ago. It’s one bedroom and got a stick built 4”x2” frame. I drilled all the holes carefully finding where all the noggins were. It took the team all day to fill the walls and ceiling. In my previous three bed semi my neighbours had there’s cavity filled and the team were there two hours maximum and they had to drill the holes! The neighbours thought cavity wall insulation was a waste of time! Watch them like a hawk.
    • CommentAuthorscrimper
    • CommentTimeNov 8th 2013
     
    Well ... based in England, but my building team is from Poland working long hours to a great standard ... they look on in amazement when the English scaffolders swan off at 2pm for the day!

    I've now looked in detail at the Approved Document relating to full fill ... and it's quite clear that even if I lived on the edge of John O'Groats I'd be fine to have full fill through 100mm cavities as long as I had full height render ...

    Am pretty much settled though on injecting beads throughout at the end. Just have to find a Polish contractor ...
    • CommentAuthorDarylP
    • CommentTimeNov 8th 2013
     
    scrimper,

    Yes you can have full fill, with cavity batts, but not with rigid 'plastic' boards.

    Some Polish gangs did some fantastic EWI jobs in our village last year. Cannot fault their work ethic!

    Cheers:smile:
    •  
      CommentAuthorjoe90
    • CommentTimeNov 11th 2013
     
    Is there anything to stop you filling cavities yourself with poly beads bought in bulk (apart from the problem of wind blowing them everywhere during the fill)?
   
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