Loft Insulation Upgrade

[MikeGrahamT21]

Hi,

 

I'm wanting to upgrade our loft insulation, and just wanting some confirmation that my idea is OK.

 

Currently we have 100mm fibreglass insulation between the joists (I've just been up and measured, they measure around 107mm deep), and we currently have loft boards, which I'd like to retain for storage purposes. House is 1968, with traditional roof with purlins, so no crossing timbers in the main storage area. Current U value somewhere around the 0.4U mark. Total space is around 6m x 5m (35m2) (bungalow)

 

I've thought about quite a few different methods, loft legs (too expensive), just laying insulation over and losing storage space (not ideal), and then my final thought... my final idea is to cross these existing joists with more 4x2 joists (we would need 24x (47x100x3m) to cover the whole area at the relevant spacing for the loft boards), and then lay another 100mm fibreglass inside these, giving 200mm overall (i appreciate that's still not up to the regulatory 270mm, but the extra 70mm ontop of the 200mm doesn't bring down U values as much as the initial extra 100mm on top of the original 100mm, and the cost is far greater) which would land us somewhere around the 0.21U mark, so effectively halving the U value for the cost of the wood (£136), and a bit of insulation (i've already got 3 rolls of 100mm, so likely wouldn't need much more).

 

Now this is all well and good, and whilst i do all the work, which i'll do myself, i'm going to ensure all of the electric (lighting) cables which are up there are in good nick, and the circuits are as simplified as possible (and theres a couple of junction boxes which need taking out) (Low energy lighting by the way, so overheating cables shouldn't be an issue). I did however think of one draw back, and that is the 200KG of timber required as extra to what is already up there...now in my mind, this will be absolutely no problems at all, but I'd like a little reassurance before i bring our entire ceiling down lol! Theres not a massive amount of stuff in the loft storage wise, certainly nothing heavy, and no water tanks or anything like that.

 

Any feedback greatly appreciated.

 

Regards

Mike

[SteamyTea]

I made large 'sausage rolls' of insulation from weed control barrier stuffed with mineral wool.

Stapled these to the roof rafters leaving a ventilation gap.  Works well.

 

Has the advantage that you get a bit of gentle warning before you crack your head on a timber.

Edited September 21, 2017 by SteamyTea

[MikeGrahamT21]

Yeah good idea for that bit, what about the main bulk of the work?

[Ferdinand]

In many areas of the country there are setups that will insulate your loft for free, regardless of circumstances - even now.

 

Call the Energy Saving Trust to check:

Quote

 

A quick way to check if you qualify is to call the Energy Saving Trust and answer a few basic questions on 0300 123 1234 (England, Wales and Northern Ireland) or 0808 808 2282 (Scotland)

 

 

 

 

In some places it *is* means tested; in others not. The same applies to Cavity Wall insulation iirc. More information is here:

http://www.moneysavingexpert.com/utilities/free-cavity-loft-insulation

 

Quite often they will want a partial contribution if you have over 100mm. One way to deal with that is to decide that your shed / downstairs underfloor / whatever needs insulating, and recycle the existing insulation for such a purpose. But check in general terms first :-) ,or you may get a warm shed and a cold house if they say no! Some might suggest this is a little marginal, but it is funded by us.

 

There may be building regs records of what was done to your house in the past but that probably will not be a problem.

 

On loft legs - what is too expensive? The cheapest I have seen is about 85p each delivered if you order 120+ from here:

https://www.lbsbmonline.co.uk/loft-flooring-leg-175mm

 

I hope that is helpful in finding possible alternatives.

 

 

Edited September 21, 2017 by Ferdinand

[MikeGrahamT21]

They are the cheapest i've seen actually for the legs. Not fussed about paying for insulation, its cheap anyway, and i've got most of it already.

 

How about my idea with the 4x2 crossing the 4x2 which is already there to allow an additional 100mm for around £136? I think thats going to be cheapest, since i'd probably need over 300 loft legs to do it with those, though at that price it may be do-able, i'll work it out.

[MikeGrahamT21]

What i really need to know is, will putting 200KG of timber up there affect anything?

[Onoff]

39 minutes ago, MikeGrahamT21 said:

What i really need to know is, will putting 200KG of timber up there affect anything?

 

200KG is only like two big blokes standing up there. And they would be near point loads rather than evenly distributed.

[MikeGrahamT21]

you know i thought exactly the same thing about 5mins after i'd written that! lol

 

I sure think thats going to be the most cost effective solution, giving the best overall value (i.e. improvement on u value vs cost).

[Ferdinand]

I think your idea is more cost effective, and your price is good for new timber.

 

However, cheaper is available on eBay depending on delivery or collect, and as low as £1 per metre for reclaimed.

 

Or try a request on Freecycle ... people have to pay to dispose of old timber or take it in themselves sometimes.

 

And are 18mm OSB or chipboard sheets cheaper than loft flooring ... your space is almost exactly 2 x 5 8x4 sheets, which would be about £15-18 each or a bit less for OSB3 Wickes or chipboard B&Q? COnsiderably less at Wickes if you nurdle the discounts and trade account etc. B&Q cut it up for free in many stores, and at Wickes you take a saw and horse and cut it in the car park if no van.

Edited September 21, 2017 by Ferdinand

[Onoff]

Make sure your loft hatch is big enough to get the big T&G boards up there! 

 

Take this opportunity to sort your electrics and make sure it's all in good nick. Replace traditional screwed JBs with maintenance free ones if they're going to become inaccessible and watch for covering cables any more than they already are with insulation. 

[Simplysimon]

we've an open loft, floored and p/boarded by previous owner, i can barely get from one end to the other due to 'stuff', if i was to legally convert it i would need to upgrade joists, forgot, i'd need to empty it first, and then if used as a bedroom there would be less weight in it than there is now prior to upgrading joists.

[MikeGrahamT21]

I plan to re-use the chipboard (loft boards) which are already up there, another plus for using 4x2 so I can line the centres up as i need them. I'll keep looking for cheaper timber, won't be doing it til next year now anyway, as I've too much on at the moment, just trying to make a plan of action.

 

Yeah will definitely be taking a close look at the wiring, i know theres a lot which can come out, as we've replaced it with new stuff. There will be more insulation going on the wiring, but as I said before, theres barely anything flowing through them, as its only LED lighting, so I'm not concerned about that.