Flat roof construction advice

Interested Bystander

Have a two-storey house which we doing some retrofit measures on this summer.
The house has an extended adjoining single storey garage area - approx. 7m x 4m floor space built in 1985 - with a pitched roof which is now in poor shape.
As we have great views from the rooms on upper floors in the house, I have always wanted to remove the pitched roof on the garage area to put down a flat roof and use it as a terrace.
So it is a good opportunity and makes sense to do it while the other measures are being done as they'll be fairly disruptive.

I could do with some guidance on where to start with putting down a flat roof designed for weight bearing activity.
I have a flair for destruction so removing the pitched roof will be a piece o cake and I work in steel fabrication so I plan on having a steel frame resting on the existing walls to support the weight of the roof and enable installation of a roof lantern to allow light into space below..
I don't have the credentials to construct a flat roof so will probably enlist the help of a proper roofer. And I have researched the pros and cons of RBMs, EPDM, asphalt, GRP, concrete slab, tiles and even green roof systems but can't help thinking that much of the advice out there actually conflicts.

So i'd like some input on which type of construction will give me the least trouble, best quality finish or best value for money. In fact I have no idea how much I should expect to pay but I have also heard that my home insurance premium will take a hit if I go ahead with this. Surely choosing a decent building method can negate a premium hike...

Calahonda52

The home insurance issue, IIRC, depends on the % area of flat: check it out.
Will you get PP for this: terrace, overlooking, changing profile of the building from the road?

https://www.nsai.ie/about/news/publication-of-sr-542014-code-of-practice

will give you roof construction details from an insulation/airtightness perspective.
Solar drive and decrement delay if the room beneath is habitable are two issues need considering

Interested Bystander

Re PP, I didn't even consider this and have no experience of same... I hope not needed as we are set back away from road, that side of house not visible until you are on the property, we do not overlook anyone and don't have a neighbour for a few hundred metres but they are uphill from us.

That NSAI doc is very detailed, will have to check that out after tea.
Plenty there to read up on Calahonda, thank you.

Calahonda52

Interested Bystander wrote: »

Re PP, I didn't even consider this and have no experience of same... I hope not needed as we are set back away from road, that side of house not visible until you are on the property, we do not overlook anyone and don't have a neighbour for a few hundred metres but they are uphill from us.

That NSAI doc is very detailed, will have to check that out after tea.
Plenty there to read up on Calahonda, thank you.

No problemo
http://www.environ.ie/search/archived/current/category/housing/type/publications?query=acceptable%20construction%20details
may help as well