Flat v pitched roof

twohooter_2

I am in the process of planning a 4m x 4m contemporary extension at the rear of my house to create an open plan kitchen, family dining room. I had originally thought I would go for a very contemporary look with a large section of stack slide doors with a flat roof and modern roof lantern. I had heard Sarnafil was the best product to go for on a flat roof . However, I have heard that even with the modern advances in flat roofing, they still have issues with maintenance, insurers don't like them and they can have a negative effect on resale values. I'm not sure if this is true. The square box style glass and render room I had in mind suits a flat roof from an aesthetics point of view but I am wondering if I should rethink and go for tiles with Velux windows . Any advice welcome...

ChumLee

By 4m sq do you mean 4x4?

If so can you get a pitched roof in that space without effecting the first floor windows?

twohooter_2

Sorry - yes, I meant 4m x 4m so 16m sq. Do you envisage a problem with a pitch for that size? I hadn't thought there would be an issue but I know little about such things. If the room will not accommodate a pitch then a flat roof it will be I guess. I'm in a modern 3 bed semi if that helps.

Furts

The rule of thumb is to avoid flat roofs at every opportunity. They are a source of ongoing problems and even those that do perform have a life expectancy that is a fraction of a tiled roof. Insulation, ventilation, workmanship, materials quality and an abundance of cowboy installers are some of the issues.

If you consider any typical new housing site over the last 30 years be it Bovis, Barratt, Persimmon etc. few, or perhaps none, will have flat roofed extensions. This applies to kitchens, utility rooms, garages and walk in bay windows. Each time a pitched roof will be used. There are sound technical, and common sense, reasons for following this.

twohooter_2

Thank you Furts - I may have to have a chat with the architect and have a rethink.

bob_a_builder

If so can you get a pitched roof in that space without effecting the first floor windows?

But a pitched roof doesn't need to have have a massive angle on it
just greater than 15% ?
http://great-home.co.uk/a-guide-to-roof-construction/

onomatopoeia99

Only situations to consider a flat roof IMO are conversion of an existing structure with a flat roof to habitable (e.g. an attached garage), where circumstances like planning or location relative to the house prevent installation of a pitched roof (and it looks like the garage I want to convert falls into one of those categories, so I have been researching flat roofs).

Other than that, avoid.

ed110220

It also depends a lot on the style of the existing house what will fit better. With many houses a flat roofed extension is less visually disruptive. For example almost opposite me there is a house with an extension on the front which to me looks bad as the ridge of the new roof almost touches the bottom of an upstairs window. It also doesn't line up with the window above, so the whole thing has a bodged on look. If they had stuck with the flat roof of the original open porch it would have been more satisfactory.

Modern flat roofing coverings such as EPDM or fibreglass should last decades.

DRP

twohooter wrote: »

Thank you Furts - I may have to have a chat with the architect and have a rethink.

has your architect recommended using a flat roof?

Funnily enough mine was very keen on flat roof - he thinks you'll get 20+ years out of the modern flat roof systems.

Based on the experience of friends and family , so we specified a dual-pitched (gable) roof - we couldn't fit a lean-to roof under our 1st storey windows.

Our architect was a little put-out, but remember he's working for you.

andrewf75

Furts wrote: »

The rule of thumb is to avoid flat roofs at every opportunity.

I think thats outdated. Lots of modern extensions are flat roof with lanterns.

System

wrote a big reply and then it wouldn't send... oh well, basic points...

If they are carefully detailed, specified and installed they can be good and problem free, however they will only be as good as the person fitting them (and finding penetrations on something like single ply is a nightmare!)
We always name specialist contractors to carry out works like this unless we are sure the main contractor is 100% confident/capable in installing the product properly.
However it is possible to retain a modern aesthetic with a different roof, maybe you could post the plans and we could suggest suitable alternatives?