[Beki]

@geoffers I definitely need to get in the attic to see what my insulation is like. What do you mean when you say lay it at right angles to the joist?

[geoffers]

Originally Posted by Beki_EONNext

@geoffers I definitely need to get in the attic to see what my insulation is like. What do you mean when you say lay it at right angles to the joist?

Original insulation is between the joists, so lay the second layer on top of the joists, in the other direction (90⁰ to the original insulation direction)

[Beki]

@geoffers Oh that makes sense. What difference does that make?

[geoffers]

Originally Posted by Beki_EONNext

@geoffers Oh that makes sense. What difference does that make?

Less likely to get heat seeping up through gaps, and less likely to compress the existing insulation as the weight of the new is supported across the joists. 👍

[Beki]

@geoffers - Thank you for explaining that. Guess I'll have a busy weekend when the kids are with their grandparents 😂

[Mailman]

Originally Posted by geoffers

Absolutely - current building regs are for 270mm of insulation, so if you've currently got say 100mm in between joists, just add another 170mm at right angles to the joists.

This can cause access problems however, so you may need to use some raised boarding for access - see my above posting re: loft-legs (though may be difficult in your case with reduced headroom)

I should have added that there is pre-existing loft boarding up there. I'll have a good look up there the next day or two. Possibly there is more insulation up there (depth-wise) as the joists are not clearly visible in most of the roof space.

Re loft legs, I had already thought of redoing the existing boarding up there but I'm already wandering around like a chimpanzee as it is ridiculously easy to clatter my head on the rafters but I'll double check that the depth of insulation is adequate. 👍

[meldrewreborn]

@Mailman

i seem to recall that the first inch of insulation produces the greatest reduction in heat loss, the second inch less so, the third even less and so on. Of course the cost of the insulation per inch doesn’t change, so gradually each added unit of insulation produces diminishing gains.

the other thing to bear in mind is water pipes and electricity cabling ( esp ceiling lights if halogen). When I did my son’s loft I rewired it so the ring main for the lights was high up and easily accessible . With cables to switches and lamps running vertically down through the insulation. A lot more work but much easier to adjust later. I wonder if @retrotecchie approves?

[geoffers]

Originally Posted by meldrewreborn

@Mailman
the other thing to bear in mind is water pipes and electricity cabling ( esp ceiling lights if halogen). When I did my son’s loft I rewired it so the ring main for the lights was high up and easily accessible . With cables to switches and lamps running vertically down through the insulation. A lot more work but much easier to adjust later. I wonder if @retrotecchie approves?

There can be fire-safety issues if wiring is left under insulation - lightly loaded lighting cable is probably ok, but anything carrying significant current should be kept in free air

https://forum.ovoenergy.com/my-smart...ooring%20above.

Re: water pipes - I'd keep them under the insulation for additional protection from freezing

[meldrewreborn]

@geoffers

but the water pipes would need physical protection if you can’t see them!

[Mailman]

@meldrewreborn @geoffers

No hot water tank in the loft and no water pipes routed through the loft space so that is not a concern. AFAIK any wiring that exists up there feeds ceiling LED bulbs (def no halogens) and they are seldom switched on for any amount of time other than a means of lighting going from room A to room B. I did have an EICR survey done on the house when I moved in - the original live/neutral wiring was replaced with 'Twin and Earth' plus the house was missing a vital earth as well so that was put in at the same time. Nothing untoward was brought up re a potential cabling/insulation issue although that does not mean this issue is absent!

When I have a cronk around I'll try to see what is going on with any cabling that I find.

My real problem is that with access to maybe 1/4 of the loft space (via loft boarding) means I have to use crawl boards to get to the remaining 3/4, with very little room to maneovre and even than I have limited clearance which only gets worse the closer I get to the eaves (due to low pitch of the roof). That and the misting up with goggles grrr. I don't suffer from claustrophobia but the experience is really not nice. With heavy rain forecast in The North over the coming days I'll need to check that watertight integrity is intact anyway and have a ferret around.