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General: Loft Insulation Cost Comparison

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    • CommentAuthorjamesingram
    • CommentTimeFeb 25th 2014 edited
     
    R-values are created by dividing the thickness of the material (metres) by the k-value for a particular material. So for Warmcel100 we get an R-Value of 2.5 at 100mm. If you can get it at only £3.11/m² then it's just 3.11 divided by 2.5."

    UPDATED 25/2/14
    Warmcel100
    #recycled newspaper
    #100mm thick (lose fill)
    #£2.4m2 for 100mm thick inc vat (all)
    #Thermal Conductivity 0.040W/mK. at bit better than standard mineral wall ,( 250mm=270mm glass fibre approx.)
    #R-value 2.5

    £0.96 per 1m² of 1 R-value

    Knauf earthwool 100mm
    # U-value 0.044
    # R-Value 2.25
    # Roll Area 13.89m²
    # £16.75 (online seller)

    £0.54 per 1m² of 1 R-value

    Knauf eko roll 200mm
    # U-value 0.044
    # R-Value 4.54
    # Roll Area 5.5m²
    # £23 (BQ)

    £0.92 per 1m² of 1 R-value

    Supaloft roll 100mm (recycled polyester)
    # U-value 0.040
    # R-Value 2.5
    # £4.95m2/100mm

    £1.98 per 1m² of 1 R-value

    Celotex XR4200 200mm
    # U-value 0.022
    # R-Value 9.05
    # board Area 2.88m²
    # £86 (online seller) inc. vat

    £3.30 per 1m² of 1 R-value

    PIR 100mm board (best price)
    # U-value 0.022
    # R-Value 4.54
    # board Area 2.88m²
    # £33.60 inc. vat

    £2.57 per 1m² of 1 R-value

    cost / area / R-value is the formula to compute money per square meter per unit of R-value.
  2.  
    Thermafleece 100mm
    # U-value 0.039
    # R-Value 2.56
    # £6.76m2/100mm

    £2.64 per 1m² of 1 R-value
  3.  
    EPS70 100mm board (best price)
    # U-value 0.036 (standard 0.032-0.038 depending on density?)
    # R-Value 2.77
    # board Area 3 x 2.88m²
    # £52 inc. vat

    £2.17 per 1m² of 1 R-value
    • CommentAuthortony
    • CommentTimeFeb 27th 2014
     
    Earth wool wins then by a mile
    • CommentAuthorjamesingram
    • CommentTimeFeb 27th 2014 edited
     
    yes, but you've got to get it from the right supplier , many selling quilt combi roll round the £21-24 mark
    such as BQ and many building merchants

    This puts it pretty much on par with Warmcel100 DIY bags

    These various alternative insulations seem to have a bit more chance to compete since CERTs has stop
  6.  
    So one story is the old, old one.

    You can double, even quadruple, or halve the cost effectiveness of the identical product by buying intelligently and paying as little as possible for anything but the product itself.

    F
    • CommentAuthorEd Davies
    • CommentTimeMay 16th 2014
     
    Posted By: jamesingramEPS70 100mm board (best price)
    # U-value 0.036
    If that was true Passive House would be easy.

    More likely, that's the k-value. Ditto all the other posts, as far as I can see.

    Conductivity, k-value, κ (kappa), or λ (lambda) is a property of the material so you can say that the k-value of EPS70 is 0.036 W/(m·K) irrespective of the thickness.

    Conductance or U-value is a property of the particular buildup. For the simple case of a single material it is the λ divided by the thickness so the U-value of 100 mm of EPS70 is 0.036 W/m·K / 0.1 m = 0.36 W/m²·K.
    • CommentAuthorjamesingram
    • CommentTimeMay 16th 2014 edited
     
    yes K not U, but U for 100mm of material (insulation) expressed in term of R and £/m2/R

    as above 'R-values are created by dividing the thickness of the material (metres) by the k-value for a particular material.'
    (think that's right ??)
    • CommentAuthorEd Davies
    • CommentTimeMay 16th 2014 edited
     
    Posted By: jamesingramas above 'R-values are created by dividing the thickness of the material (metres) by the k-value for a particular material.'
    (think that's right ??)
    Yes, I think so too. So long as you're consistent with units (e.g., use metres rather than mm, as you say) you can work out what to multiply and divide by just by thinking about what effect they have on the result:

    More thickness => more resistance.
    More conductivity => less resistance.

    so get resistance by multiplying by thickness and dividing by conductivity.

    Alternatively, go straight to the cost-of-resistance merit figure:

    More cost of pack => more cost of resistance.
    More volume of pack => less cost of resistance.
    More conductivity of material => more cost of resistance.

    Cost_of_resistance = pack_cost * k-value / volume_of_pack.
    • CommentAuthorTriassic
    • CommentTimeNov 21st 2015
     
    I keep reading insulation prices are on the rise, are the costs in this thread still valid?
  11.  
    nope. needs updating
    • CommentAuthorShevek
    • CommentTimeJan 5th 2016 edited
     
    Icynene (K-value 0.039)

    # 270 mm thick @ £30/m2, fitted by installer (2013)
    # R-value 6.92
    # U-value 0.145

    £4.33 per 1m2 of 1 R-value
  13.  
    <blockquote><cite>Posted By: jamesingram</cite>
    </blockquote>
    Any up to date prices? Can't find the earthwool at that price...
    • CommentAuthorEd Davies
    • CommentTimeJan 5th 2016 edited
     
    http://www.wickes.co.uk/Knauf-Earthwool-Flexible-Slab-8-64m2-50mm/p/119081

    600 mm x 1200 mm x 12 (so 8.64m² per pack)
    Thickness: 50 mm
    Thermal Conductivity: 0.037 W/mK
    £29.69 each in 5-off quantities

    (£29.69 / 8.64 m²) / (0.037 W/(m·K) / 0.05 m) = £4.65 / m² at 1 R-value.

    Quite a few other sites with the “44” stuff (ie, λ = 0.044 W/(m·K) IIRC). Can't help feeling the Wickes price ought to be beatable, though.
    • CommentAuthorjamesingram
    • CommentTimeJan 6th 2016 edited
     
    checkout local magnet trade they often have offer on 100/200mm combi rolls
    or ebay for local small amounts
    • CommentAuthorTriassic
    • CommentTimeJan 6th 2016
     
    Ed, the Wickes web site you linked to quote a price of £3.82 per SQM ???
    • CommentAuthorEd Davies
    • CommentTimeJan 6th 2016
     
    Yes, but that gives a resistance of 1.35 m²·K/W. To get down to the benchmark R-value for cost comparison of 1 m²·K/W you need a bit more thickness so need to spend a little more on each square metre.

    Also, that's the one roll price, whereas I assumed the 5 off price. One roll isn't going to do a lot if you're trying get down towards 0.1 W/(m²·K).
    • CommentAuthorjamesingram
    • CommentTimeJan 6th 2016 edited
     
    magnet doing
    superglass 100mm
    # k= 0.044 R=2.27
    # £11.50 (£1.44m2)
    # 7.98m2

    £0.64 1m2 of 1 R value
  19.  
    Excellent, I'll see if I can get some this week. What thickness would you use in an attic space for superglass?
  20.  
    270 will meet the regs. Try 400-ish.
    • CommentAuthorcjard
    • CommentTimeJan 6th 2016 edited
     
    Seconds and co do super glass, currently have 130mm rolls in, I make it 46p/Rmm, 75% of magnets price
    • CommentAuthorcjard
    • CommentTimeJan 6th 2016
     
    They also have 200mm kingspan sheets for £30 a sheet, it's more than wool, but it's still a good price
    • CommentAuthorgravelld
    • CommentTimeJan 7th 2016
     
    Remember it will also slump under its own weight a bit. Or at least Earthwool does. If you're buying 100mm, get 5 layers.
    •  
      CommentAuthordjh
    • CommentTimeJan 7th 2016
     
    I think we're talking slabs, not rolls?
    • CommentAuthorgravelld
    • CommentTimeJan 7th 2016
     
    Sorry, missed that.
  26.  
    I'd say slabs are to expensive to stick in a loft, stick with quilt
  27.  
    Silly question but if I insulate the attic space with say 400mm wool, and I need to walk in the attic at some point to install the ducting for my MVHR system, what is the best method of doing so without falling through the ceiling?
    • CommentAuthorTriassic
    • CommentTimeJan 11th 2016
     
    You can get things called 'loft legs', Google is your friend here.

    You fix the loft legs in place, install the insulation and build your access walkway on top of the loft legs.
    • CommentAuthorgravelld
    • CommentTimeJan 11th 2016
     
    They don't normally allow enough clearance for 400mm though.
  30.  
    Yeah just googled, 175mm depth. Would PIR insulation be okay to walk on? Killing two birds with one stone

31 to 60 of 88

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