Anyone know about Inverted Warm Deck flat roof insulation?

[randers]

Hi. I have a partial flat roof over the kitchen, and it's FREEZING in there in winter. I doubt that the insulation in the flat roof is up to much so am thinking about improving it.
The flat roof was redone about 4 years ago so ideally I wouldn't want to have it stripped off, but have read about Inverted Warm Deck insulation. I contacted the only local (Leics) roofing company which mentioned Warm Roof insulation but what they said suggested they actually knew even less about it than I did. So I thought I'd be better getting some advice I trusted more!

Am I right in thinking that it can just be added over an existing roof without the roof covering having to be re-done? And can it be walked on (it is the access to a couple of windows, which need to be cleaned now & again). Thanks.

I'd also be interested in knowing if it's an expensive thing and if it's simple - could a decidedly-moderate DIYer do it himself?

 

[^woody^]

How do you propose to weight the insulation down and secure it, and what will all this depth look like from the sides?

 

[randers]

These are some of the questions I'm hoping to find answers to myself Woody. From what I've read a layer of ballast goes over the insulation (need to be heavy ballast - I'm in a windy spot!) and that would have weight implications for the load-bearing capacity of the existing roof. But I can find nobody locally who advertises that they do this method and therefore might know how it would work in my situation.

 

[^woody^]

It is normally heavy concrete paving slabs rather than just a layer of ballast such as gravel

And the roof edge needs to be built up to retain this and form a wind break to prevent lifting. Parapet walls are more common to achieve this.

In practical terms, think about how much this will all cost compared to how much you think you might save.

It might be better (and cheaper) to rip the ceiling down and insulate the roof that way

 

[tony1851]

With an inverted roof, you need a little more insulation than normal because rainwater percolating through the joints chills the (existing) waterproof finish, drawing more heat away.

 

[randers]

Thanks both - it's probably not the solution for me then. I appreciate the info you've given.