Loft Space

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

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Think Iposted to wrong place ....

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

Reply to
Jon Rowlan

I see that if you block up all the gaps in the roof, and insulate the roof like mad then the roof could become damp, however loft conversions insulate the Apex and the roof becomes part of the house and all the gales are locked out and everything is fine.

Anyway back to your roof. If I understand your description correctly you have the old ceiling floor with new 9x3 beams running across it. I fail to see why you care about the old ceiling at all. I would have thought you could just assume that it didn't exist and was just the same as any other floor in the house. So surely if you first block up any gaps to the outside world, and then place insulation and/or t&g floor above the new beams then any rising air from the house would warm both the new/old beams and prevent them from getting damp / rotting.

Please note that I am not an expert, and might be talking complete rubbish.

Reply to
James

Between the Ceiling of the house below and the floor of the loft above, I have the eaves and these are vented to the outside world. I am reliably informed that this is essential for a healthy roof - it must be ventilated. I need to keep the warmth down in the house and warmth above in the loft whilst still letting the roof "breathe",

jON

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