loft insulation

[joemanzini]

Hi, wondering if anyone could answer my questions.

I have a 1930's house. I need to increase the insulation, at the moment it is only (loose fill) the height of the joists 7 cm.
I am aware that I can raise the height of the joists..and increase the insulation..making sure to raise the wiring as well.

Now here is the real problem, I have loft flies, and , I want to use the loft for storage. If I where to sheet insulate the rafters, leaving the 50mm breathing space, could I seal off the rest of the loft, to prevent the flies entering, thus also stopping ventilation to the actual loft space.If I added this extra insulation, would it be worth increasing the insulation between the rafters..or would that be overkill.
Apologies for the length of this question.

 

[MFC_1980]

if you are going to insulate the rafters and create a warm roof then you dont need insulation between the joists. If you keep the insulation between the joists then make sure you have decent ventilation and be sure not to block the eaves vents when adding the insulation..if it's just for storage - the easiest way would be to upgrade your existing insulation and concentrate on ventilating the space.

best,

N

 

[joemanzini]

thanks N

I am starting to understand, correct me if I am wrong please.
Creating a warm roof, is esentially creating another room to the house.

A. If I where to insulate the rafters, seal the loft space, then the ventilation would be confined to the space required by that process, and I would have to remove the rafter insulation to allow heat to rise?

B.Could I as you sugested, increase the normal insulation in the rafters, and then put some kind of mesh to prevent the flies access around the eaves, and would this inhibit the ventilation, and cause any problems.

Thanks J

 

[MFC_1980]

yes the eaves and fascia vents can be meshed to prevent birds and insects entering through them. you can buy them designed for this purpose that should be fine.

The ventilation is to get rid of the warm air and vapour that rises through the insulation at ceiling level (anything above the insulation is generally cold so the warm air contacting causes condensation)
check this out:

http://www.secondsandco.co.uk/Pages/pitch-btwn-rafter.html
http://www.insulateonline.com/index1.htm?pitched3.htm~main

hope that helps

 

[joemanzini]

Thanks N, please have a look at this if you can, its almost my loft as it is, but without the rafter, though there are some shorter purlins

This is interesting, it appears to be a cold roof, but faced with plasterboard to create a cleaner more useable space...it all looks great in the end, and the floor strengthening is creative, trimmer joists hung by metal ties from the original joists.

Is this all possible, it appears to be, creating a cold loft space, but essentially sealed with just plaster board. I am still a little confused here about ventilation and condensation by the use of plaster board on the rafters.

I would be interested in your comments. Thanks J

http://www.above-it-all.co.uk/lofts/pictures/03.html