Loft Insulation

frogga

Hello All,
Our house was built in 1953, we moved in in 2000.

We boarded out half of the loft space and put down an old cord carpet to walk on, we left the edges as bare joists/beams as it was too low to walk under or store anything under.
We stored all the Tadpoles old toys and memory boxes up there. One Tadpole has swum away from the pond and taken all her stuff, the other has just had a massive clearout and removed all of his stuff.  I only have a very few things up there but I'm decanting it to the garage as the loft is smelly anyway.

I want to have nothing up there except loft insulation and a few spiders. 

Mr Frog says if we put the roll of that thick yellow insulation stuff we will have to lift all the boards we put in as we can't just roll it our and put it on the top.

Question One - Why can't we? When I questioned Mr Frog he got huffy because I was questioing him so didn't give me a proper resaon (so I suspect there is no proper reason). So in your expert opinions, if I want to now put proper loft insulation up there, can it just be laid on top of the boards and the carpet, or have I got to life that all up? 

Second Question ~ Is the original old insulation that is around the edges good enough, or is it better to remove all that and replace it with fresh new stuff?

Last Question - Would you leave the boards and carpet down and not bother with loft insulation except for the edges as it wont make that much of a difference doing the middle bit anyway?

Your thoughts and opinions always gratefully received

Frogga xx

Ebe_Scrooge

Q1.  There's no reason you can't lay new stuff on top of the boards - obviously you'll then lose all the storage capacity, as you can't put anything on top of it.  That's the reason a lot of people lift the boards, top up the insulation, then replace the boards on legs.  That way you get the recommended thickness of insulation and can still store junk up there.

Q2.  You need to top up round the edges as well, otherwise you'll be wasting heat by not having the recommended thickness.  No need to take the old stuff up, just put the new stuff on top of the old.

Q3.  Same as Q2 really - there's no law that says you have to top up the insulation, but you really ought to.  It's just about the cheapest thing you can do to reduce heat wastage and therefore save yourself money.  The boards themselves will stop a miniscule amount of heat from escaping, you really do want to get the insulation over the whole loft area up to current standards.  Like I say, no need to remove what's there already, just add more on top to bring it up to scratch (scratch being the operative word if you're using bog-standard fibreglass !).

BUFF

You could just put it on top but if I am understanding you correctly then a large % of the loft won't be insulated very well.
However, the proper way to do it (assuming that the joists are typical dimensions) would be to put insulation between the beams & then another layer going across the beams. If using glass wool you are looking for a typical thickness overall of 270mm+.
if you want you could board over that using something like https://www.diy.com/departments/diall-loft-storage-stilt-pack-of-12/3663602538240_BQ.prd

frogga

Ah ha, so I was right! It can just go over the boards!!  And I will go right to the edges. Great to know I can just top up the old stuff and don't have to replace. There is insulation under the boards that we laid down years ago, just not to todays standards, so if I lay ontop of the boards it will be fine.
Thank you so much for such quick replies. Thank you for the B and Q link with the legs but I dont want to put anything back at all as I'm in the 'clearing out' mood, not the 'storing more !!!!!!' mood. 

frogga

Last quick question ~ how thick should I get it? B and Q sell it in 3 thicknesses, 200mm, 170mm and 100mm. Am I looking at rolling the 200mm ontop of what is there, or doing it twice so I have 400mm in total plus hte old suff underneath?

Thank you x

FreeBear

I would lift the boards before fitting any insulation - It cuts down on the amount of dead space being heated, and also reduces the risk of draughts blowing around under the insulation. Yes, it is a pain to unscrew the boards, but having the boards on top, you know where it is safe to put your feet next time you go up there.

How much insulation to put down ?

Well, that depends on whether the boards are on loft legs (stilts) or just fixed to the ceiling joists. If the former, you will be limited by the amount of free space. If the latter, Wickes do two lengths. One at 175mm, the other 300mm. Use the shorter one in conjunction with 175mm insulation. The longer ones, go for 200mm insulation and have the option to top up with 100mm at a later date.

Currently boarding my loft out with the 300mm legs, and will end up with ~375mm of insulation once completed. That will future-proof me when minimum recommended levels get increased again.

ryan7

I was confused at tadpoles..
Anyways, Mr Frog is correct. If you just lay on top then the dead space / air gap  between the the ceiling and boards will mean warm air will still escape in the attic. 

Rosa_Damascena

ryan7 said:

I was confused at tadpoles..
Anyways, Mr Frog is correct. If you just lay on top then the dead space / air gap  between the the ceiling and boards will mean warm air will still escape in the attic. 

Why couldn't Mr Frog explain that in the first place?