New build with Flat Roof

[dave88888888]

Hi

I'm a regular punter not a builder, so very limited knowledge of building standards.
I have seen for sale a new build Georgian style town house with traditional looking features (including a flat roof!!!) But built to modem day standard s.
As a boy my father told me NEVER buy a house with a flat roof as it's asking for trouble.
The sales man told me these modern flat roofs are as good as or better than traditional Tile roofs. (Yeah???).
I've since looked on the Internet and it seems modern flat roofs with all the advances are guarenteed for 30 years; that's not long and I take no comfort from this 30 year guarentee.

I was hoping they'd say 100 years. My NHBC guarantee is only 10 years.
Should I be worried? Im paying top dollar for this house and although it looks nice I'd rather it last 100years like a normal tiled pitched roof.
Thanks

 

[freddiemercurystwin]

It all depends on the standard on workmanship, the same as any roof. If done well it will last if not it won't.

BTW its very doubtful that any roof claim (unless structural) would meet any NHBC claim criteria. Your NHBC is really there for subsidence or something really major, its as much to keep the mortgage happy.

 

[Nige F]

The only flattie you could guarantee for 100 years is a Lead or Hard metal one - I`ll bet hardmetalking will be along soon

 

[dave88888888]

Thanks Freddy for your reply.
Is there a goldrstandard flat roof manufacturer. Is there a Mercedes benz type roof that I can bench mark my new build flat roof by.
I'm not a fan of new build houses, I've bought one from a major builder in the past and it was very poor quality. The new new-build house I'm currently looking at is by a high quality local builder made on a much smaller scale and the quality of the build seems much higher.
I can't check the flat roof for obvious reasons but how can I verify the quality and durability of the roof? The house is 3 stories and the roof forms part of the 3rd floor elevation. It is tiled over on the front where the gabled windows are but I cant see if the flat surface is tiled and if there is an incline for drainage.
What would you do to verify the longevity of the new roof?

 

[freddiemercurystwin]

We assume the house is finished? Is the developer in the process of building others or are they all for sale at present?

There is little you can do other than a visual inspection with binoculars. This is all a surveyor would do other than getting on a ladder or other means and inspecting up close. I would be religiously checking out the build of the rest of the house or what you can see of it, if its all pretty good then one could maybe assume the standard of the roof matched the rest of the property. At the end of the day you have to take a chance with a new build. Same as an older property. All flat roof types are much of a muchness (apart from metal) and will give similar guarantee times but as mentioned workmanship is the key. Of course there will be a 12 months defects period whereby the builder is bound to address any issues that may crop up, assuming he is happy to come back. Are you buying from a developer or a builder? Has he built other properties? Have you asked for references or to visit his previous customers? They may or may not be open to such a suggestion.

 

[dave88888888]

Hi Freddy. Yes all houses are built on the development.
All specs are high standard. The doors are solid wood, there is no exposed pipe work in the bathrooms, the build is brick and block. They seem to be a reputable local builder, been going 30 years.
But I don't believe they've built flat roof houses before.
I'm just paranoid. Based on comments so far it seems no matter how good a new builder is using modern materials the roof wont be lead or copper etc so even if its a good quality flat roof the average life is 30 years? Is that correct?
So in 20-30 years when the builder has disappeared I can expect leaks and then a bill for a new roof. £20k?
Is that a fair assessment?
Given I'm not a builder my visual inspection by binoculars won't reveal much. What practical reassurances/ proof can I get from the builder to know the roof isgoing to last more than 30 years.
If it was a tiled pitched roof I wouldn't even be thinking about such problems. Am I right to be worried?

 

[tony1851]

IIRC Marley guarantee their concrete roof tiles for 50 years, clay tiles probably the same, though some can last a lot longer.

But for flat roofs, the quality of workmanship is crucial. When I started out, the typical flat roof was just bituminous felt - life around 10 years, if reasonably well-done. The modern single-sheet materials are supposed to last a lot longer, but if the workmanship is poor, who knows?

In most instances, pitched roofs are more forgiving of questionable workmanship. It's a gamble.

 

[hardmetalking]

Did someone mention my name??!

Yes a metal roof can last in excess of 100 years but as the previous comments have mentioned its all down to quality of workmanship.

Personally if I ever bought a house with a flat roof I would immediately change it to have a small pitch. 5 degrees is enough to encourage the water to drain away. When flat roofs fail they do so in a big way!

 

[freddiemercurystwin]

What is the flat roof material?

 

[dave88888888]

I will call the technical guy at the developers to get the specific details of the roof.
Its a beautiful looking house, at least it is when it's new and the roof is still working.
The sale guy told me "modern flat roofs are high-tech and have as long a life as pitched roofs" he's bound to say that but could there be any truth in it?

He said "the roof is multi layered to keep cool in summer and warm on winter using the latest technology materials" are there such materials that allow a significantly longer life?

When companies build a Georgian townhouse is it normal to have a slight angled slope to the roof? To me that would make sense and if it were 5 degrees it wouldn't be visually noticeable but would probably provide major drainage improvements than being completely flat.

 

[tony1851]

completely flat.

It won't be completely flat but will have a slight fall, though probably not 5 deg.

 

[dave88888888]

Still waiting for report fromthe builder...
When a developer is building a new house and has the choice to build the flat roof at a 1° angle or a 5° angle or even a 10° angle, if the gradient of the roof is not even visible from the road then why wouldn't they always choose the steepest incline possible?

If the construction cost is the same but the effectiveness of the roof drainage improves significantly then doesn't it always make sense to build the roof at the steepest possible angle?

 

[hardmetalking]

My point exactly!!

 

[Xenon]

There's only one flat roof guarantee on paper at the moment, and thats from a company called Pluvitec, and the gaurantee is not worth the paper its written on.

The absolute rolls royce of flat roof materials is Bauder, i fitted my first one near 30 years ago, and its still going strong.

If its been put on by the builders subbie, its probably EPDM.

 

[dave88888888]

I've had the specs of the roof.
It has a 1:40 drop.ie a 16mm drop in height for evert meter.
To me that seems almost completely flat, when I ssked why they didnt build at a steeper angle they said that 1:40 is the standard building requirement. I wanted to say thst surely building at a steeper angle would make the roof more effective, but that not sure thst pushing the point would achieve anything.
The materisl used is called Trocal and is some kind of membrsbe used in sub-aqua/ scuba diving environment. It caims to be resiliant and has a 30 year guarentee. Which means in 30 years I'll be forking out fir a new roof, great!
Would you avoid this type of house or am I being paranoid?