advice on removing fibre glass blanket insulation

[scholesboy]

i have been told to replace my old fibre glass blanket insulation in my loft , does anyone have any advice on how to do this safely ,???? thanks also i want to lay some boards down in the loft for storage , is it possible to do this or will effect the insulation ????

[Thermo]

leave it there and put the new stuff over the top of it. Its still doing a job and it saves getting rid of it

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[masona]

scholesboy wrote:

i want to lay some boards down in the loft for storage , is it possible to do this or will effect the insulation ????

Put down 3"x1" timber flat in the opposite direction of the ceiling joists then T&G chipboards on the centre of the 3"x1". This will allow for a cross air-flow under the boards and no need to notch out the joists for electric cable or pipe.

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[Julii]

I am in a similar position; we only have shallow ceiling/floor joists in the loft, and existing fibreglass-type fluffy-type insulation (you can tell I'm not really a diy type!) that is only about 10 cm deep (if that). To get to equivalent of 270mm deep insulation, don't I have to take up the old insulation, and replace it ? So how is it best removed safely?

[JohnD]

No, you don't have to take the old stuff up. It doesn't wear out and it doesn't rot (unless perhaps it's made of shredded paper of sheeps wool, when it might also have insects and mice in it).

It's just a layer of material.

The new insulation is another layer of the same material.

So if you already have 100mm and put another 100mm on top, you will then have 200mm. There will also be a slight advantage that any joints or careless fittings in the new one will probably not be in the same place as the old one, so will compensate for them.

Do you expect to want to walk about in the loft in future, or store your old Kylie albums up there?

[Julii]

JohnD wrote:

Do you expect to want to walk about in the loft in future, or store your old Kylie albums up there?

Sorry, I wasn't making myself clear. We really do need the loft for storage -- a huge amount of stuff. Plus we need easy-enough access for things like the cable modem, the TV aerial, we wnt to get a wind turbine in near future, the electrics in the ceiling, etc.! So we were thinking to put in the sort of insulation that is much thinner but equiv. insulating (the aluminium foil + bubblewrap). I'll ask questions about that in another thread, though.

[McD]

Its horrible stuff. Get a load of bin bags, face mask, rubber gloves and disposable boiler suit (the type with the hood), and some duct tape.

The best bit of advice I was given as to tape the wrists of the boiler suit and the gloves so that none of the glass wool can come into contact. Basically it will find intself in any crevice left exposed and itches like hell.

Best of luck.

[JohnD]

The reason I asked about walking about on it, is that your loft timbers are probably about 100mm deep. If you put thicker insulation than that down, it will swamp the timbers and you won't be able to walk on them or see them. You would need to deepen the timbers, by putting deeper sections either beside or on top of the old; or at right-angles to them and on top (which will help spread your weight). Then you can put your insulation between the various timbers, and some kind of flooringf on top of that, to walk on or store your stuff. If you expect to use it as a habitable room, or put anything heavy up there, you will have to beef up the timbers a lot.

[masona]

I still yet have someone to proves to me another top up of 100mm will make a real saving in heating bills, I was told the money spent on topping up will take over 10 yrs to recoup!!!!! I still think the best way is with the 3"x1" method then use the foil foam insulation just under the T&G flooring, the type you use behind radaitor to reflect the heat back then you haven't got the headache of raising the flooring as with 200mm+ insulation

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[JohnD]

Hugely thick insulation has diminishing returns. When I used to know that sort of thing (I can hardly remember it now) but the principle is that the first "x" thickness cuts the heat loss by "y"%", then the next "x" cuts the remaining heat by "y"% of what's left

so (my figures are made up here) 50mm of glass fibre might cut the heat loss by 50%

An additional 50mm would cut the remaining 50% by 50% = 25% of the gross.

An additional 50mm would cut the remaining 25% heat loss by 50% - 12.5% of the gross

An additional 50mm would cut the remaining 12.5% by 50% - 6.25% of the gross

An additional 50mm would cut the remaining 6.25% by 50% = 3.1% of the gross

So (if my figures were right, which I'm sure they aren't)

If you had 150mm of insulation, it would save you (50+25+12.5)= 87.5% of your original heat loss

If you put another 50mm in, it would save you (50+25+12.5+6.25)% of your original heat loss = 93.75%

The advantage in topping up 150mm to 250mm is surprisingly small.

I agree with Masona, if you had put the money in the building society for 10 years, it would probably have grown just as much, without you having to get dirty and itchy putting it there.

[masona]

Good stuff! Just worked out for another 100mm top up on my loft I would've to spend another £320. So let say £30 year saving per year, that's over 10 yrs if the calculation is right!

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Always judge a man by the way he treats someone who is of no use to him