On 22 Sep, 01:50, neil wrote:
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 :-)

There needs to be no air leaks through your insulation, it's important
to fit and seal it really well. If you want cheap insulation board
there is here.
http://www.aandainsulationservices.com/
There are other places too, search "seconds+ insulation +board"
It's about half the price of undamaged stuff delivered.
It has small mechanical damages (easily fixed) and voids in the
foam. You can fix the voids with canned foam injected through the
foil covering.
Canned foam is the best way of fixing your boards too. Cut them
undersize put in place and inject the foam along the edges.