As for the problems, just try buying insurance with a flat roof and you'll have an idea of the additional cost. A small leak can cause massive problems with even the smallest amounts of rain, that's why flat roofs are a problem.
I think some caution is needed. Flats roofs can last for 20 to 30 years if the design and material is top quality.
So maybe you should ask a knowledgeable surveyor to report on it. If he gives it the thumbs down you should use a re roof estimate to reduce your offer. Have a look at the link for good advice.
If you like the property, then yes.
You won't get planning to change the pitch of the roof.
We DIY-ed a 50sqm flat roof replacement with rubber membrane for about 600 quid.
That is a new extension and the roof would have to have been signed off by building control. We have moved on from the days of a bit of felt and bitumen. They would never be passed if there was going to be a problem.
If you put in an offer your Surveyor will check that it is OK.
UK
There are newer roofing products on the market which last much longer than the traditional tar/felt systems. Would cost a few thousand - depends on the surface area, basically. I had my extension done 3 years ago, it cost around ￡2,500. I consider it a worthwhile investment.
To replace a flat roof with a pitched one is not economically feasible. Most flat roofs aren't flat, they should have a slight pitch. Go on the roof with a level and check for yourself.
One for your surveyor to answer...
Im a first time buyer, and have found a property that is within budget and everything else is fine but a few people have put me off buying this property because of its flat roof.
http://zoopla.homesandproperty.co.uk/for-sale/details/33033646#CzxIX633HGUrW8kh.97
is it really a deal breaker, what problems may it cause and can it be replaced with a pitched roof-if possible how much would this cost (estimate)
thank you very much for your time, much appreciated!
