I spent most of august filling the gaps between between the wall plate and the rafters with the pieces of Kingspan and Celotex that I had pulled out of skips, truly recycled roof insulation.
Insulation between wall plate,rafters and roof deck.
I didn’t have enough to finish the entire roof so I had to buy some French compressed polystyrene insulation which was pretty expensive stuff, and doesn’t have the aluminium foil covering on either side like the British stuff.
There’s not a lot of information on the web about thermal insulation around Velux windows and I’m reluctant to spend too much money insulating a roof only to lose a large amount of heat through the 6 Velux roof windows.
Roof Insulation Price Comparison Table
| Insulation Type | Manufacturers Description | Roll / Sheet Size | Price Per Square Metre |
| Celotex PIR Insulation Board | Easy to use thermal break product for use in floor, wall and roof applications
Lightweight and easy to install Achieves the same level of thermal insulation as almost twice as much glasswool insulation Suitable for all construction projects where minimal thickness is essential Classified as an A rated product in the BRE Green Guide which makes it amongst the most environment friendly building products |
25 x 2400 x 1200mm | £6.07 |
| Wickes General Purpose Insulation Slab | Versatile thermal and acoustic insulation
Ideal for loft conversions and partition walls Flexible edge on all 4 sides – for ease of installation |
1200 x 600 x 100mm | £7.33 |
| Thermawrap Loft Insulation | Easy installation Loft Insulation. Lightweight and flexible. Reflects radiant heat for increased warmth and energy savings. Keeps houses warm in winter and cool in summer.
Thermal Resistance up to 1.033m²/kW A Top-Up Insulation Product for Attics & Roofs Can be Retro Fitted to Improve Existing Environments Equivalent to 55mm Polystyrene Class 1 Surface Spread Flame Tested to BS 476 Part 7 |
400mm x 5m | £4.45 |
| Airtec Double Insulation | Easy use Airtec Double Insulation. 25m. For multiple applications including dry lining, cavity wall insulation, pitched roofs and stud walls. Also suitable under floorboards and in attics and garages. More user friendly than conventional insulation.
Thermal Resistance up to 1.455m²/kW Suitable for Walls, Roofs & Under Suspended Floors Typically Used for New Builds, Refurbishment & to Insulate Behind Dry Lining Lightweight Time-Saving Equivalent to 55mm Polystyrene NHBC Accepted |
1.5m x 25m | 2.90 |
| Thermafleece | Thermafleece has been the UK’s first choice of sheep’s wool insulation since it was launched in 2001. Thermafleece is a high density, wool rich insulation that is the first choice when maximum thermal and acoustic performance and breathability are required or in space limited situations.
Manufactured to meet the highest quality and performance standards and using British sheep’s wool, Thermafleece is the only wool based insulation to hold BBA certification. Thermafleece has a thermal conductivity of 0.038 W/mK and is available in a variety of dimensions suitable for all your application needs. Thermafleece is supplied in slab form with standard lengths of 1200mm with three thicknesses, 50mm, 75mm and 100mm and two widths, 400mm and 600mm. |
50 x 600 x 1200 | £5.47 |
| Froth pak & Handi-foam spray foam | Spray applied polyurethane can be sprayed into place, which greatly simplifies and speeds up the installation. Spray foam therefore offers significant benefits over other forms of insulation. Firstly it can be applied quickly whereas sheet foam has to be accurately cut and fitted. Other important advantages of spray applied foam include: Sprayed foam adheres well to under-felt and even roof tiles, which will stabilise the roof structure and prevent tile slippage. Spray foam has a closed cell structure which make it impervious to moisture, thus, the foam has excellent damp-proofing qualities as it seals the roof from the inside. Spray insulation can easily be applied as a DIY project, therefore cutting the cost of hiring expensive specialist contractors. | 20m2 at 50mm coverage | £24.75 |
| Recycled Celulose fibre | Excel Warmcell 100 loose-fill cellulose fibre natural insulation is produced from 100% recycled paper and has a high insulation value (k = 0.040 w/mk). It is non-toxic, non-irritant and extremely easy to use. This cellulose insulation has been treated with inorganic salts to provide pest and fire resistance. It is specifically for use between joists in lofts and under suspended floors. | m2 at 100mm coverage | £5.06 |
Note to self: Next time you build a roof ensure rafter spacing is exactly 600mm it will make fitting roof insulation much easier!
Tags: Insulation, rafters
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I would not consider multi foil, such as Airtec Double Insulation or Thermawrap, you should check out this site before purchasing this kind of insulation
http://www.healthyheating.com/Page%2055/Page_55_o_bldg_sys.htm
I am converting a barn myself and I am wondering which method of insulation to go for. When I initially tiled my barn roof I fitted cheap velux style windows, and whilst these are double glazed it seems to me that any heat that is retained by the insulation in the roof will be lost through these windows.
One could easily spend £40/square metre on insulation only to lose this heat through the roof windows. The best roof windows that I have found, the Fakro FTT Thermo Timber triple glazed roof window quotes,”Mid pane U value 0.5W/m2k, window U value 0.94W/m2k”, in the specification. 300mm of Rockwool is said to provide 0.40w/m2k, any ideas? The zero heat building seems a long way away!
There are a couple of companies selling cellotex/kingspan seconds on ebay. I have bought from the one based in Goole and the sheets are just as good as new sheets of insulation. They have obviously been left outside for a while and the foil is sometimes a bit dirty, but these sheets are always concealed. The price for 25mm celotex was less than half the price Wickes were selling for. I managed to get 14 8×4 sheets inside my estate car – cut the sheets into 8 x 2 and then cut a small piece of the end.
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