Insulating parts of loft

12 Mar 2011
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United Kingdom
So in the loft now is a used bedroom, the roof is not insulated at all, the plasterboard to the roof behind it is slate, no felt or anything. In the room is also a partition wall leading to empty 'roof' space that is used for storage. This wall is going to come out and floor boards laid and rest of the roof plasterboarded and so on to extend the room slightly.

The roof.. I will measure the depth of and then use suitable insulation boards cut to fit in the gaps leaving around 40mm gap behind for ventilation ? This alright seen as there is no felt. I will then plasterboard to this.

I also plan to do this where the existing ceiling is as that's coming down to be replastered. .

The edge. So where the roof is at its lowest in the room is about two foot of the wall, i plan to batten this wall, insulate and plasterboard meeting to the roof. There is quite a draft where the top of the roof is and tiles start. What's the best way of dealing with this, leaving it or doing as someone's suggested and filling with foam to fill along the gap?

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By the top of the roof I assume you mean apex, that being the case I would suspect this was part of the roof ventilation original design. As your intention is to retain a 40mm gap between the insulation and the tiles I would recommend that you keep this gap to allow the continuity of the flow, but somehow isolate it from the insulated void. A sketch of it's current layout would be handy...pinenot :)
So i have made a (bad) rough drawing to give the idea of what the loft is like and what it roughly will be like.

In the first drawing is how the room is, no insulation, on the second drawing is where i plan to have the walls and insulate them, i have no access to above the ceiling where the apex is as it would mean the ceiling coming down which is something i would prefer not to do.

I am hoping that even with the insulation in as it is and placed correctly with the right board should help with the room, i believe there is one of the worst parts for the room being cold at times, the draft in the eave space is massive bring it along with the wall that is currently sectioning it off being made out of thin chipboard stuff doesnt help.

I have included a picture that i have used in another thread so you can get an idea of what its currently like and where i will be insulating too.

Thanks for the help :)


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Just thought I'd try explain myself a little better with this pic

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If you could adapt this layout and stand the vent tray up in the stub vertical wall section and then contrive a means of providing channeled voids between the underside of the roof and the combed ceiling within every second rafter void say, both possative venting and full insulation could be provided. Alternatively if you use a rigid insulation between rafters leaving a 40mm gap between the vertical & combed ceiling and the internal side of the roof, creating a positive open channel for air circulation to the void above the ceiling. The use of foil backed plasterboard would provide a vapor barrier but I don't think it would really be needed...pinenot

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