Flat roof vs Pitched roof cost

dilby

Hi all - I've got an extension nearing it's end that's being built by a local builder. The original plans had a pitched roof, but after realising the architect had not accounted for the right pitch roof actually fitting below the upstairs window, we had no option than to go for a flat roof. At the time the builder said it was around the same price after I had asked if it would save me money, but I've just had the final bill where he says the flat roof is a lot more work and materials and has charged an extra £1000 for a 3x4m extension. He was going to get a roofer in to do the pitched roof but did the flat roof himself. From what I can read a flat roof is meant to be cheaper, but are there circumstances that this sounds fair that anyone can think of, or do people smell something fishy? And yup I should have got things more tightly agreed, this has been a huge learning curve for me.
Thanks everyone!

grumbler

Did you consider making the first floor windows a little smaller? That's what my friend did to get 15 degrees pitch he wanted.

And yes, similarly, it was the architect's incompetence.

Jeepers_Creepers

What covering does this roof have, Dilby? And what level of flatness? Will it spoil the overall look to go 'flat'? And what covering was going on the pitched roof?

I'm not an expert in this, but I always understood that flat roofs were significantly cheaper to build than pitched. When you add in that this guy is going to do the work himself rather than sub-contract it out, I can't help thinking he's on to a nice extra earner.

BUT, I don't know.

DevilDamo

Pitched roofs are generally more expensive then flat roofs as there is more material for staters. Flat roofs may end up being more expensive if they’re an after thought, i.e. builder allowing and quoting for a pitched roof but last minute changes resulted in a flat roof.

What angle was the original pitched roof? Assuming it was a lean-to, could a gable ended roof had worked?

dilby

Thanks for replies all. To answer some questions the architects plans were way off - the final pitch we could end up getting was only 6 or 7 degrees max. He just hadn't accounted for the upstairs windows which are very tall.  We did explore option of changing the windows but decided that was the more expensive option. The flat roof is EPDM and admittedly it's probably more complex than normal; the extension is in an L (2 existing walls) and the building inspector asked him to add ventilation around the rooflight because of that so there was good airflow. I don't know whether that's something i should pay for or if the builder should be expected to know that. Although there is a flat roof light the pitched roof was meant to have 2 velux windows.

Alter_ego

Sue the architect for the difference in costs?