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Insulation

Recommended Loft Insulation & Boarding (ceiling 1.5" x 3" joists / Battens" with 450mm centres)

Anonymous user 09/03/2024 - 3.26 PM

Hi, I have just recently purchased a 3 bed house which is currently undergoing refurbishment. I've cleared out the loft and the insulation in their was patchy at best and a combination of a small layer (approx 30mm roll with a top of of loose fill (up to about 70mm). I am fully aware of the recommended amount of insulation being 270mm Rather then add to what was there, i decided to clear all the old insulation and start afresh. I am now at a point of selecting insulation (after research I was looking to use Knauf Eko Roll or Space Insulation (partly as its endorsed by the Energy Savings Trust) with a 100mm base layer with a 200mm top up layer. Everything I have found appears to be precut to fit those with 400mm or 600mm centres, but having measured ours, it appears they are 450mm centres and our "joist" or Roofing Battens that the ceilings are attached too are 1.5 x 3 (35mm x 78mm) Can anyone one point me in the the best direction of insulation roll to use? I've also been looking at the "LoftZone Storefloor" system to board out the loft. Any one used this before? Thanks in advance PS. Further to the first comment, my concern with cutting rolls is the amount of wastage I would have at the ends of each roll if the rolls are 1140mm and I’m cutting at 42mm intervals to fit my gaps!

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3 Answers

Anonymous user

You can cut the rolls with an old hand saw while they are still in wrapping to your desired width. Regards Damien

Answered31 December 2021

ADR Property Maintenance

Rating: 5 out of 5

Boston

you are over thinking this far to much, 100mm rolled out between your ceiling joists 200mm running in the opposite direction to prevent cold spots job done, as long as your only using the loft for light storage it really shouldn't be a problem, as most loft joists are fairly small really only designed to fit the ceiling onto, they will not withstand heavy loads without first beefing up the size of the joists. good luck Alex

Answered4 January 2022

Handimen (Home & Garden)

Rating: 4.8 out of 5

Tunbridge Wells

Generally the point of insulation is to prevent heat loss from rooms below the “loft floor” Given you have cleared all existing insulation, the simplest way would be to rolling out 100mm bottom layer insulation between the length of the loft floor joist should, this should be straight forward enough. Rolls usually come in 1.2 metre widths (3 x 40mm sections) Naturally you may need to work around any cross timbers & electrics, but there should be little or no wastage. 100mm rolls cover 8.3 m2 each 170mm rolls cover 6.5 m2 each 200mm rolls cover 6.5 m2 each These are average dimensions and depend on outlet sourced. (Wickes tend to be competitive)! Whether you decide to use 170mm or 200mm as a top layer, it’s best to cross lay over the lower joist / insulation. If you are intending to creat a storage area. I tend to cross - lay kiln dried timber, set 35 > 40 cm apart to accommodate the 40cm top layer and allow the floor to hold anyone walking over? Adding no less than 18mm loft boards, again Wickes (or B&Q). Depending on the depth / height of any secondary (top) joist, I mostly use 2x4s (95mm x 47mm x 2.4 long) or 2x5s (120mm x 47mm x 2.4) timbers. 100mm below boards in my opinion is adequate to any storage area. With either the 170mm > 200mm to non boarded area’s. Lots of info, but hopefully helpful Good luck 👷🏼‍♂️

Answered11 January 2022