Are flat roofs inherently worse than pitched roofs ?

ZoZoZo

Hi,

I'm trying to understand the difference between a modern flat roof vs a pitched roof in terms of performance. I was surprised to find that most insurers won't even give a quote for a house with a flat roof which seems to imply that they are massively inferior. Despite this I see a number of new-builds are using flat roofs eg attached picture.

So, what's going on here ?

If flat roofs really are a disaster then why are new-builds using them ? Are they much cheaper to construct or something ?

Or if a modern flat roof is no worse than a traditional pitched roof then why won't the majority of insurers insure them ? Is this just a case of laziness on the part of insurers, flat roof is 'different' and in the minority so they just don't cater for it? I mean if flat roofs really are such a problem would builders not just raise one end of the roof a metre or so higher than the other to make it a 'non-flat' roof ?

Victor

'Flat roof' covers everything up to 15 degrees.

Quality of design and implementation for flat roofs can be very poor.

Oh, and builders don't care about insurance.

Meningate

Like everything else, it depends how it's done! That said, a pitched roof is far superior to a flat roof. Flat roofs are usually used as a cost saving or where a pitched roof just won't fit. The problem often encountered is that there are a lot of people who actually make a flat roof FLAT. daft as it sounds, that's a no no.
Just think about it. If you have a flat roof with one tiny hole in it, where is all the water going? Right, through the roof. Put a 3" slope on it and it still looks flat, but most of the water will bypass any future leak. Make that 6" even better. To put a slope on it only requires an extra wedge shaped piece of timber called tilt. This is placed on top of each joist before the roof is boarded. The cost of the extra slope is just a few € per joist. When boarding use plywood roof sheets, don't use chipboard.

antiskeptic

ZoZoZo wrote: »

Hi,

I'm trying to understand the difference between a modern flat roof vs a pitched roof in terms of performance. I was surprised to find that most insurers won't even give a quote for a house with a flat roof which seems to imply that they are massively inferior. Despite this I see a number of new-builds are using flat roofs eg attached picture.

So, what's going on here ?

If flat roofs really are a disaster then why are new-builds using them ? Are they much cheaper to construct or something ?

Or if a modern flat roof is no worse than a traditional pitched roof then why won't the majority of insurers insure them ? Is this just a case of laziness on the part of insurers, flat roof is 'different' and in the minority so they just don't cater for it? I mean if flat roofs really are such a problem would builders not just raise one end of the roof a metre or so higher than the other to make it a 'non-flat' roof ?

There is a massive conflict between the environment of a building site and the stipulations on "the instructions for use" sheet for everything used in the course of a build.

Waterproofer/plasticizer, for instance, will instruct that x amount be added to y amount of water and be thoroughly mixed before use -else the quality of the mortar will be compromised.

Since ensuring same is left to the tools on site (which frequently won't see access to measuring equipment) and the quality/concern of the worker involved) problems can be expected to occur. You see folk glug-glug plasticiser into the cement mixer. Or they get one glug and the container runs empty where glug, glug, glug would be closer to the mark.

Error, sloppiness, compromise is an inherent feature of site work. Pitched roofs are far more tolerant of error, sloppiness and compromise.

pointer28

I worked as a flat roofer and I'll never have one on my house.

Architects seem more interested in how they look than being watertight.