Hi Guys
A mate of mine wants help [1] insulating his loft in his old house and I'm after any ideas and guidance on options, a quick archive check has only some old suggestions, so I'm after newer info or a better solution than mine below.
The house is 100 years old, the attic room was servants quarters(!) and bit that needs doing is vast at 5.6m square, with a walk under purlin at
1.9m, the flat bit of the ceiling is probably over 3m high forming an area 1.2m wide but with no access above. The roof is 8" x 6" rosemary tiles with failing tiering mortar so damn windy. The eaves areas are to be conventionally insulated with space roll between the joists and the 'walls' probably with EPS slab, the rafters are only 4" deep and with tiering mortar encroaching on that gap above and Lath and Plaster nibs below, so no easy access to insulate above L+P and below the tiles (but see below) so an internal solution is needed.The lath and plaster ceiling is in fairly poor condition and really needs pulling down and replacing with PIR between rafters and insulated plasterboard below, BUT he doesn't have enough money for that, so 'plan A' (TM) is to stud the ceiling and use EPS and normal plasterboard, or plan B is to use insulated plasterboard screwed straight onto the existing ceiling (hopefully ?).
Any of this a goer?
I haven't checked the rafter pitch yet but I think 16" is likely, but it looks a bit variable... The plan is only to board the roof area between the purlins but try and shove some rigid insulation up to there from the eaves area, and to purlin level it is just that bit wider and taller by a gnats (I think) and this keeps the cost and complexity down.
I envisage 8'x4' sheets running along the existing flat ceiling and then cut sheets following the angle, with just a batten just to fiddle the old curve transition if fixing boards direct is possible.
Given the lack of funds, what is likely to be the best 'bang for buck'? I hope directly fixed PIR insulated plasterboard, rather than EPS and plasterboard, as this might get better insulation values for the same outlay?
If I have to batten the roof for EPS, is just along the roof sufficient, so four timber lengths with end framing? If I can fix insulated plasterboard straight to the existing ceiling I assume a screw every rafter at say 4 across a board would do?
As you might tell I'm a bit out of my comfort zone and realise I need guidance, I know if I use EPS I should put a vapour layer between it and the PB and if I use 'good' insulated board it will have foiled PIR but how to arrange a seal between ceiling and sloping boards for instance, would SBR or somesuch on the PB side be enough if the seam was sealed? I plan to try and fiddle a decorative curved transition between flat and angled boards to try and mimic the underlying ceiling so a good seal is easy enough on the room side.
What have I missed then?
I will probably use Travis Perkins for my materials unless anyone knows a better supplier in Wirral/Merseyside are?.
Don't want much do I ?
Thanks
Neil
[1] Me doing it all as I have 'the tools' [2], he doesn't even own an electric drill never mind an SDS/AG! (he does have a can of WD40 though. ;-) ) [2] Including a Fein Multimaster :-)