Loft Installation question re laying over boards

[1jim]

Hi
Does anyone know if the professional loft insulators will lay loft insulation over a partly boarded loft?

My loft is approx 1/3 boarded, I had planned to buy the insulation and lay properly where possible and then lay some over the boarding (I dont know if that will work insulation wise but my thinking was that it has to be better than northing??) but when costing it out it seemed cheaper to get someone else to lay it for me but if they are going to come and survey and tell me to take all boards up etc then its not worth wasting their or my time
any advice welcome on if this is ok to do and if they will do it
thanks
jim

[fluffymuffy]

It's not a good idea to board a loft.

If you put boards over the insulation it squashes it down to a level where it's not very effective as an insulant. The insulation works on the principle of storing so many inches of air.

A boarded loft gives the impression that it's a load bearing floor - which it isn't. Your ceiling joists were sized to take the weight of the plasterboad and perhaps a bloke with a torch above once in a while to inspect the roof space.

Lofts, especially those insulated from the rest of the house, are very poor spaces to store things.

Sorry - this isn't a very helpful post - I just like to moan about loft boarding .

[latecomer]

Of course if the insulation under the boards is just to the top of the beams then it will work as intended while still allowing you to have a floored area.

[1jim]

the trouble is the loft is already 1/3 boarded, only used to store suitcases etc and is used to access the boiler. Dont really want to have to go to the trouble of taking it all up and relaying it over the insulation. Just really need to know if having insulation on top of the boards has any benefit at all really and if it has will the people who do the grant schemes lay it over boards
thanks
Jim

[lilac_lady]

I had a partially floored loft and the insulation installers covered it all except an access path to the water tank. The didn't lift the boards up. Hope this helps.

[1jim]

thats great thanks, it will work out a fair bit cheaper to get them to do it for me than buying it myself which is odd really but I guess theres no way accounting for government/business sense
jim

[Angela]

I am a loft (and cavity) insulation surveyor and my company will not lay over boarding.
All boarding must be taken up,and just a 1/2 metre (wide) walkway must be made so if anyone has to work on your cold water tanks or boiler they can see where to tread.
The insulation will not be effective if placed over boards.
Again you must not board over insulation as this will compact it and causes condensation and more problems.

HTH

[fluffymuffy]

Originally Posted by Angela

The insulation will not be effective if placed over boards.

Whyever not?

[wallbash]

Mate has just moved into a new build, masses of wonderful insulation

But have spent time bagging lots of it up !!!
House is very small , but for the cost of a few pounds he can have all the storage space he wants. Still has 'some' insulation , between rafters.

Yes his heating bills will be higher, but far lower than the storage he was paying for.

Life is always a compromise.

[wildmandy]

Originally Posted by Angela

The insulation will not be effective if placed over boards.
Again you must not board over insulation as this will compact it and causes condensation and more problems.

HTH

That's nonsense! Insulation WILL work over boards.
Insulating under boards is also very effective, seeing that normally 100mm thick rolls are used between the joists which are normally around 12-13cm high. Thus it won't be compacted.

Mandy

[djohn2002uk]

Originally Posted by wildmandy

That's nonsense! Insulation WILL work over boards.
Insulating under boards is also very effective, seeing that normally 100mm thick rolls are used between the joists which are normally around 12-13cm high. Thus it won't be compacted.
Mandy

Except that the recomended thickness was 270mm 10yrs ago. Must still be at least that now if not more.

[wildmandy]

Originally Posted by djohn2002uk

Except that the recomended thickness was 270mm 10yrs ago. Must still be at least that now if not more.

True, but any insulation will work and the first 100mm is the most effective. 170mm thickness should be placed over the joists (or over the boarding).

Mandy

[djohn2002uk]

Originally Posted by wildmandy

True, but any insulation will work and the first 100mm is the most effective. 170mm thickness should? be placed over the joists (or over the boarding).
Mandy

Should doesn't come into it, I've not seen any regs or recomendations stating such, especially over boards. If the loft is required to be boarded for storage, then the best way is to extend the size of the ceiling joists where the boards are needed by screwing 4"x2" timbers on top of the joists making 8" in total, and "screw" the boards down adding stability to your new joists. If you lay 270mm insulation, the boards will compress it very slightly but not enough to make any noticable difference.

[ceridwen]

I suggest you read the bit about this in "Teach Yourself - Saving Energy in the Home". Its £9.99 in the Teach Yourself series of books.

There is a section in there on loft insulation. I have duly made a note myself about it - basically they say that there is "loft board insulation" available for those with boarded lofts and that one lays a layer of this loft board insulation on the boarded area. For maximum savings then use a 2nd layer of loft board insulation.

Thus - a sandwich in effect:

layer 1 - loft boarding
Layer 2 - loft board insulation
Layer 3 - loft board insulation

Planning to do this myself at some point.

That book is well worth buying generally for all the energysaving tips in it - I've made a note of quite a few things I wasnt aware of.

[27col]

If you have insulation over the loft boards then there is no point in having the loft boards, so why not remove them. Otherwise, if you put anything in the loft onto the insulation, it will will be squashed and its effect negated.
Basically you have to decide between insulation(and thus, less energy costs) or a measure of storage. Which do you want most.
The other alternative is, as has already been suggested, to raise the level of the joist tops to allow another layer of insulation to be added.
I was in my loft today to make start adding insulation. My compromise will be to leave a smallish area near to the hatch, boarded for storage and to double the insulation everywhere else. The other part of the project will be to ruthlessly clear out the accumulated 'stuff'.

[amcluesent]

What of you were to unroll some of the mirrored film over the insulation then lay the chipboard? Also, what is the 'U' value of 20mm chipboard, that will insulate too.