Insulation and wiring in a flat roof space

13 Feb 2008
Reaction score
United Kingdom
Following on from a previous post, I am now taking down the lath and plaster from the ceiling in an attic room. Above it is a space about 7inches high, and above that the flat roof. Three questions:

1 - when I insulate this space, I presume I should leave the normal 50mm gap between the top of the insulation and the roof. Since there is no natural ventilation through the flat roof (only via the sloping roof to the sides of the flat roof), do I need to leave a larger gap or do anything else?

2 - I was planning to use something like Kingspan K7 for the insulation. Is it easy to cut this so that it wedges itself in place between the roof timbers, or will I need battens to hold it up there before I put the plasterboard in place? Also, any other suggestions for insulation materials?

3 - Finally, I'd like to put in halogen downlights in this area of flat ceiling. Are there any tricks for how to put all of this together without getting my knickers in a twist! In my mind ( ;) )it involves first running the cables to the right place, putting in the transformer etc, then putting up the insulation leaving gaps for the cables and for where the lights will be inserted through the plasterboard, and finally putting the plasterboard up and cutting holes in it for the lights (remembering where I originally wanted them!) Anything missed? Any shortcuts?

Sponsored Links
Wouldn't recommend recessed light fittings in a flat roof.

You should fit loft caps over recessed light fittings to maintain the integrity of the ceiling in the event of a fire, these generally are like an upside down flower pot so without access from above would be impossible to locate properly. They also prevent heat build up to the insulation

Also you should leave the transformers in a position where you could access them, again not easy in a flat roof, as they regularly fail and need replacing (well they do in my flat anyway :LOL: )


All good points, thanks for that. Given the increasing difficulty with recessed lights, I think I'll abandon that part of the quest - you've probably saved me a lot of bother!

Anyone with any advice re the other points (type of insulation, how to keep it there, and ventilation requirements)?

Ta again!

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links