Boarding an insulated loft

How can you satisfactorily board part of a loft given the large
thickness of insulation now recommended? I know this question has
been asked before, and I have searched the group's archive, but none
of the suggestions has really been very practical. Most ideas have
been to raise the boarding above the insulation by effectively
increasing the height of the joists, but apart from the sheer effort
involved the extra weight must compromise the use of the loft for
storage.
Would it be possible (at a price) to use one of the foil-based
insulating products, in place of some or all of the existing
insulation, to achieve the necessary U-value but with a considerably
reduced total thickness?
Richard.
formatting link
reply by email change 'news' to my forename.
Reply to
Richard Russell
What I did in our loft was to screw 2 lots of 2 x 2 to the existing wood and then add another 4 inches of insulation.
In order to keep the additional weight down, so as to continue to use the loft for storage, I laid light weight floor boards spaced with gaps that you could not get your foot stuck in them. Just don't consider using chip board, it is just too heavy and will compromise the strength of the loft floor.
Works fine here.
Dave
Reply to
Dave
The extra weight of the wood is trivial I would have thought. I suppose you could always replace rockwool with 100mm celotex which is supposed to be twice as effective. You might get your money back in 100 years or so.
Reply to
Stuart Noble
Dear Richard This is not a good idea but if you insist then the best way would be to increase depth of the ceiling joists AND increase the stiffness and strenght at the same time. This can be achieved by careful gluing and screwing of, say, 10 mm plywood to the side of the existing joists using a decent structural UF or similar glue and screws or nails at, say, 150mm centres up as high as you want the new floor - shall we guess 300mm up? Then put your new 4 x 2" along side the top of the ply and similarly glue and screw/ nail. You will find you have now constructed an (almost) "I" beam and if it has been done correctly will be nice and stiff . It is quite possible that a calculation may reveal that you only need do this every other set of CJs - but it may not - you would have to get a timber engineer to do this for you. One problem to overcome would be at the eaves where the top part of the chord would not be complete resulting in an incomplete balancing of the moment between tension and compression zones. I suspect but dont know that this so close to the bearing would not be a problem but you might have to suplement this by putting ply on the other side and forming a box beam for say 1000mm from the wall. I would then put on the lightest boading you can get away with and load up the sides before the middle and only use it for light and bulky things Dont forget the effects of duration of load on timber. Chris
Reply to
mail
I'm sure that I once read somewhere that the best way is to move the insulation layer to the slates/tiles with a vapour barrier - some of the modern insulating materials should be good here - then board with insulating boarding. You don't want any insulation at all in the new floor, as this removes a source of heat for your new room and can lead to problems with wiring etc. The floor can then use interlocked boarding to spread the load.
I'm not saying that this is right or wrong, but it seems a sensible way to do it.
Reply to
mick
We did both. There was existing insulation between the joists (expanded mica) so we added to it then boarded. Then we put slabs of something between the 'ceiling' members and clad over that.
Yes, the space is cold but that's fine because it's used for storage only, not living (we haven't planning permission or whatever else is needed for that). The house has benefited.
Mary
Reply to
Mary Fisher
In message , Mary Fisher writes
Darn, I just choked on my coffee. I feel that this confirms that I need new spectacles. I read mica as mice.
Reply to
Bill
I need a new keyboard because I genuinely spluttered tea on my keyboard the other day.
It did some very weird things and I thought I must have a virus, the 'faults' changed daily. There was a drop of liquid which moved over the printed circuit under the keys, making new connections and macros from time to time.
I was pleased when in deperation I tried another keyboard and it worked, I'd tried all sorts of other tricks which didn't.
You've been warned!
I also need new spectacles, it comes to us all :-(
Mary
Reply to
Mary Fisher
There is no intention of it becoming a 'room' - it's a big house with plenty of space anyway. All I am talking about is the use of the loft for storage, and only a central 'walkway' would be boarded (I would guess at most one-quarter of the total area). On that basis, even if we took the easy way out and dispensed with half the insulation thickness over that area it wouldn't have a huge impact on the overall thermal performance (especially considering that the 'liberated' insulation material would be used to increase the thickness in some of the non-boarded regions).
Richard.
formatting link
reply by email change 'news' to my forename.
Reply to
Richard Russell
I did exactly that for a customer last week. A walkway 1:2m wide & 7m long + an area 1.2m x 1.2m behind the loft access. Nearly 10 sq mtrs of space, but less than 25% of the floor area.
I told the customer that boarding the loft would reduce the effect of the insulation & he didn't care, storage space was more important than 'saving the planet' to him. Customers choice if I give him honest information.
I simply slit the insulation over the joists & tucked it down so the chipboard panel laid flat. Compressing the insulation material obviously has an effect on its ability to insulate, but 18mm chipboard has some insulation value anyway.
Like many people he belives that most of the environmental 'we are doomed' stuff is over hyped rubbish & wants to get on with his life.
Reply to
The Medway Handyman
Board the lot. In a 'cold ' roof the vents lead to massive airflow over rockwool, and this really dents the insulation values.
Cross joist if necessary to get the depth.
Reply to
The Natural Philosopher
e> >
We moved recently to a seventies bungalow with the same problem, and with the added complication of a low headroom trussed roof, which I suspect you do not have. It came with approx 4" of fairly new glass fibre insulation between the trusses/joists, the original having been only an inch or so.
My compromise solution to improving the insulation without loosing too much headroom:
Glue and screw 2x2" timbers to the joists/truss tops, in the centre section only. Buy a load of seconds of 50mm foil backed Kingspan boards via ebay. These were cut to fit between the new 2x2"s in the centre area, and laid across the joists in the outer areas. Board the centre area only with 8x4 chipboard flooring above the kingspan. I also lifted the existing insulation first, and laid strips of polythene as a vapour barrier - this was done as a "sensible precaution" and was was probably the worst part of the job.
This has made a noticeable difference - during the recent cold snap the part of the house that has been completed was much warmer than the end that still has mostly just the 4" glassfibre.
Despite this I have only lost 2.75" of headroom - which I can live with, and the kinspan cover has noticeably reduced the glass particles that float in the breeze, and make me cough. It also reduces wind losses of heat from loft ventilation compared to a glass fibre surface (see Kingspan's info).
As for the weight loading of the chipboard - on arrival there was a 50 gallon watertank sitting over three trusses. I calculate this water load as around 75 kg per truss, and there does not seem to have been a sag problem over the last 35 odd years. The distributed weight of the boards should be much less per truss. Incidentally the tank is now gone - heatbank.
I've made sure that high current wiring (rings, immersion, shower) are above the insulation, but not worried too much about lighting, as there is more margin for de-rating in a 6A/1mm circuit.
I realise that this solution is not fully to current building regs, but it is equivalent to about 8" of glassfibre, and gives me a sensible amount of storage and loft access. It may give you some ideas, but of course your own solution is for you to find (legal bit!).
Charles F
Reply to
CJF
If you were to tuck the existing stuff between the joists, then lay a board like you suggest over the joists, you could screw your flooring down through it and would have no need for additional joists since it is stiff enough to take the weight.
50mm "seconds" would be ideal for this sort of application. You could probably get them at £12 per 8x4 sheet.
Reply to
John Rumm
Why will properly secured chipboard (that's the key in making a box construction) compromise the strength of the loft floor?
MBQ
Reply to
Man at B&Q
Last time I was in that situation, I gave the keyboard a shower and left it in a warm place for a week. I am still typing on it now. There is very little chance the water would cause any damage, unless the keyboard had not dried out properly.
Dave
Reply to
Dave
On Nov 22, 12:14 am, "The Medway Handyman" > has an effect on its ability to insulate, but 18mm chipboard has some
Together with the layer of stuff being stored. In our case amongst other things are clothes, bedding & countless layers of paper (pages of books) which will insulate quite nicely.
Amen to that.
MBQ
Reply to
Man at B&Q

Site Timeline Threads

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.