Loft Insulation - to also help stop dust.

[BigPig]

Hi

I want to add some extra insulation in the loft. I currently have a good 15 inches between the floor joists, but I want to add some underneath the actual tiles themselves. The house is a 1920's and so I can see the underneith of the tiles and the battons along with the horsehair mixture that was used to keep the tiles in place. This has started to crumble in places and causes lots of dust in the attic. I want to put some insulation between the roof rafters and also then use the very thin space insulation (looks like tin foil they give runners) to hold the thicker insulation in place and attach to the rafters. Is this something I should do - I just wondered about ventilation? Is there anything else I should be aware of if I was going to do this?

Cheers - sorry its an epic!

 

[mointainwalker]

Your 15" of current insulation is already way beyond what is reasonable as the law of diminishing returns ( both money spent and energy saved) cuts in much before this.

Insulating the rafters is never sensible when the joists are insulated, in your case it would be absolutely ridiculous.

If you want to keep the place cleaner, just fix a suitable plastic sheet over the rafters and leave it open top and bottom.