I have a c. 1900's house that has been extended to approx. twice its size.
Over the new part of the house is a modern loft room.
Over the old part is an old loft.
I have removed the original Apex wall leaving the supports for the Purlings intact (when I say "I" of course I mean I got a reputable builder to do it!), then we installed 9x3 timbers above the old ceiling to support a new floor.
There will be a 6 inch step between the old and new lofts.
After gale force winter I _have_ to get the loft floor down and insulated before this time next year.
I do not know how to do this properly ... my plan is :
a) remove old insulation
b) fit polythene vapour barrier between old ceiling joists (leaving joists free), tape joins and overlap about 12 inches. Staple to joists.
c) fit new insulation between old ceiling joists.
d) Build wooden step between old and new loft
Now this will seal in the new floor area (sort of) but I cannot work out what to do next. I know that I need to let the gale force winds air the roof, I want to install the smallest possible Knee wall and use WarmWall insulation between the roof timbers so that they are exposed, but how do I insulate the new floor from the gales that is passing underneath and above the ceiling joists?
Do I use flat boards of insulation under the t&g boards that I plan to lay on the floor joists or do I use that flat foam stuff that you can cut to size and wedge between the joists?
And what do I do about the step down from old house loft to new ... 6 inches of uninsulated timber ..
don't get me wrong - I am not about to go and seal every hole in the house with Mastic ... I am not that concerned about heat loss but just think I ought to be a bit more concerned than at present where all the heat of the house goes straight through the roof eaves.
I have been to the bookshop and bought everything they have on the subject ... I think I am now qualified to build a loft to die for on the top of the Pentagon in Washington ... but the skills don't really relate to a small rectangular loft in the wild of the Kent outback ...
Any idea or speculations and observations would be very much appreciated.
thanks all,
jON