£1 per roll Loft Insulation

p1kef1sh

I'm starting to smell a rat. Salisbury told me at 10.30 yesterday that a. they had been inundated with requests and b. the rolls had all gone. Yet I keep reading about how local branches are still supplying. I suspect that Salisbury can't be bothered. Has anybody managed to get some from there?

feda16

got mines home last thursday and fitted on sat, took 3 1/2 hours to do, recommend this to anyone, Tesco was my cheapest deal offered at £200 until i found this gem for £15

stepm

Having got some of the Npower/Build Center loft insulation, what a disappointment. I have insulated lofts before but never have I seen such poor material to work with as this Npower Rockwool. For one thing, it is very fragile. It's OK if you are unwrapping the roll and letting it unroll across your loft, but if you have to manoeuvre it in any way, it very easily disintegrates. It also has a lot of lumps of fused glass in it and it is terribly irritable to any exposed skin. It is supposed to be for DIY but I would not recommend it.

stepm

The best way to cut it is with a serrated bread knife; works very well. BUT beware that this stuff disintegrates very easily when you handle it!

John_Pierpoint

stepm wrote: »

Having got some of the Npower/Build Center loft insulation, what a disappointment. I have insulated lofts before but never have I seen such poor material to work with as this Npower Rockwool. For one thing, it is very fragile. It's OK if you are unwrapping the roll and letting it unroll across your loft, but if you have to manoeuvre it in any way, it very easily disintegrates. It also has a lot of lumps of fused glass in it and it is terribly irritable to any exposed skin. It is supposed to be for DIY but I would not recommend it.

Isn't this RockWool stuff molten slag, a bye product of the metal refining industry, that has been put through a giant candy floss machine?

The glass stuff, such as the light green one made from our surplus of wine bottles, tends to be softer and more springy.

Deluks

andrew-b wrote: »

It has a carbon footprint but the energy saving properties of the installed insulation outweigh it.

See http://rockwool.co.uk/sustainability/the+road+to+zero+carbon and nearby webpages. Actually the 170mm Knauf insulation i have sat in my loft waiting to fit that i got from Homebase earlier in the year is called "carbon zero insulation" - how it compares to Rockwool i'm not sure exactly!


Could be more hassle than it's worth and cable could easily be damaged..making the cable more dangerous than being under the insulation in the first place. Cables do get brittle with age..messing with them may cause internal breaks..more hassle!



As in my previous post don't use terracotta plant pots ..use proper fire hoods such as these:
http://www.tlc-direct.co.uk/Main_Index/Lighting_Menu_Index/Fire_Cover_Downlight/index.html

"In a fire situation the cover expands internally to fill all the available space with a highly insulating fire resistant char. Thus, the fire is unable to penetrate the hole and the cover is able to give additional insulation protection to the ceiling void to reduce the chance of heat build up and ignition of flammable materials such as accumulated dust and insulation."


Don't understand what you mean here...170mm insulation above ceiling joist = 6 3/4 inches... how is a 2"x2" timber going to help? Or do you mean 6"x2" which is commonly available in DIY stores. 7"x 2" is actually also available from timber merchants. Good point about not nailing though.

Yeh, the long term energy saving of insulating your home will pay for itself several times over in carbon terms, I was just thinking about the Rockwool factory receiving a load of orders from Npower and them chugging away through the winter producing thousands of rolls, ironic no?

I remember seeing the Knauf rolls in Homebase for £5 a roll in the summer, is that sheepswool or the recycled plastic bottle stuff? Both of which are more eco than rockwool although sound and fire insulation performance will be pants in comparison.

The fire hoods are designed to prevent the spread of fire from one dwelling/habitable room to another. Putting them in the loft is a waste of money, if a fire has reached the bedroom ceilings then saving your christmas decs and old Shirley Bassey LP's will be the last thing on your mind. Flower pots are a cheap and easy way of making sure the insulation won't contact the lights, but the top of them should be left exposed.

I meant adding 2x2 timber to the top of the existing joists (at right angles) once the insulation is laid. Joists are generally 4x2 or 5x2 for trusses, and the rockwool will squish down slightly when boarding the loft. This means you can still put some boards down in the loft without missing out the benefit of a certain degree of insulation. The 2x2 will also add a little strength to the existing structure, not a lot but an improvement on just boarding on top of the ceiling joists.

Good point about aged cable, personally I would remove any fixings but obviously DIY competence and a degree of care needs to be taken.

andrew-b

Deluks wrote: »

I remember seeing the Knauf rolls in Homebase for £5 a roll in the summer, is that sheepswool or the recycled plastic bottle stuff? Both of which are more eco than rockwool although sound and fire insulation performance will be pants in comparison.

Recycled glass bottles...link here - from the sales pitch the only carbon neutral loft insulation in the UK. Meets the same fire performance, thermal performance and acoustic performance. I took advantage of the Homebase £5 summer deal on the 170mm..100mm wasn't in the deal and i missed the last Npower/buildcenter £1 deal not long after! Will be interesting to see the difference between that and the rockwool when fitting.

Deluks wrote: »

Flower pots are a cheap and easy way of making sure the insulation won't contact the lights, but the top of them should be left exposed.

Better than nothing i suppose ..not so much about protecting the contents of the loft as preventing the spread of fire through the loft void to other rooms.

Deluks wrote: »

I meant adding 2x2 timber to the top of the existing joists (at right angles) once the insulation is laid. Joists are generally 4x2 or 5x2 for trusses, and the rockwool will squish down slightly when boarding the loft. This means you can still put some boards down in the loft without missing out the benefit of a certain degree of insulation. The 2x2 will also add a little strength to the existing structure, not a lot but an improvement on just boarding on top of the ceiling joists.

So if i've got you right your suggesting lay the 170mm between the 4"x2" ceiling joists then board on top..with the 2" extra timber on top over most of the area you've then got 150mm of insulation rather than the recommended 270mm. So better than 100mm of insulation, worse than 170mm and alot worse than 270mm.

My thinking for a walkway & boarded area in my loft was screwing down 6"x2"s (or better 7"x2"s) perpendicular to the 4"x2" joists with boards on top - 100mm insulation between the 4"x2"s, 170mm between the extra timbers (squashed to 150mm if using 6x2s). Probably would need a few noggins fitted between the extra timbers for stability and securing them might be a bit tricky.

Still your 2x2 plan could be a good compromise for me ..have your 2x2 plan for a walkway to my tanks in the loft..with my 6x2 plan for a raised platform for storage near the walkway ..then i'm maximising insulation and accessibility. Don't want to spend too much on timber though!

Deluks

While 270mm is the recommended, it doesn't work that 270 has twice the insulation value of 135mm, the more you increase the depth the less of a payback you'll get, so of the 270mm you could say that the first 150mm is doing 'more work' than the remainder. So don't get too obsessed with reaching the full 270mm depth if you plan to board out, even the timber itself will have some limited insulation value. 6x2 on top of the current joists will be expensive, tricky to install, eat headroom and add unnecessary weight to the ceiling below. Use 2x2 or 4x2 maximum, and you will still have a reasonable amount of insulation. Did you also know that the foil backed insulation boards such as celotex, kingspan and xtratherm have twice the insulation value of rockwool. 50mm of this stuff will match 100mm of rockwool, so you could lay some of this between 2x2 over the existing joists, and have an equivalent of 200mm standard insulation in the space of 150mm. (100mm rockwool + 50mm rigid insulation board) Only downside is that it's expensive, costing around £15 - £20 for a 2400x1200 sheet of 50mm.

Darth_Vader_3

moneyhoney1 wrote: »

I am the earlier post #19.
I have 42 square meters of loft space with no current insulation. I put my measurements into the calculator online and they worked out that I need the following:-
DIY100 DIY ROCKROLL 4.8MX1200X100MM
16.00 @ £0.87
Line Total: £13.92

DIY170 DIY ROCKWOOL ROLL 2.8MTR X 1200MM X170MM
26.00 @ £0.87
Line Total: £22.62

Carriage and Packing: £0

Total value, including carriage and packing, excluding VAT : £36.54
VAT : £5.48
Total value including carriage and packing and VAT : £42.02

I'm not too good at the math, does this look right?

It looks like you've doubled your quantity. Did you refresh, go back or something? I'd phone them up, should be easy to amend the quantity.

andrew-b

Deluks wrote: »

While 270mm is the recommended, it doesn't work that 270 has twice the insulation value of 135mm, the more you increase the depth the less of a payback you'll get, so of the 270mm you could say that the first 150mm is doing 'more work' than the remainder. So don't get too obsessed with reaching the full 270mm depth if you plan to board out, even the timber itself will have some limited insulation value. 6x2 on top of the current joists will be expensive, tricky to install, eat headroom and add unnecessary weight to the ceiling below. Use 2x2 or 4x2 maximum, and you will still have a reasonable amount of insulation. Did you also know that the foil backed insulation boards such as celotex, kingspan and xtratherm have twice the insulation value of rockwool. 50mm of this stuff will match 100mm of rockwool, so you could lay some of this between 2x2 over the existing joists, and have an equivalent of 200mm standard insulation in the space of 150mm. (100mm rockwool + 50mm rigid insulation board) Only downside is that it's expensive, costing around £15 - £20 for a 2400x1200 sheet of 50mm.

Thanks..whatever i do will be a compromise but will be better than what's there already! Expect i'll end up with an excess of insulation because of it!
Will probably come down to price of timber in the end. Need to get up there and clear out the loft before i can do anything though! Doesn't help that i've got two big rolls of carpet up there!