Flat to pitched roof

[jimAuk]

Hi

I have a two story extension with a flat roof which the neighbours tell me is approximately 30 years old.

Currently there are no leaks from it but it is showing evidence of curling at the edges, bubbling on the roof area and some cracking on the small up-stand around the edge.

The other main point is insulation. The rest of the house loft area has in excess of 300 mm of insulation and you can tell the difference when you open the door to the room under the flat roof, it is like walking into a fridge.

So I would ideally like a pitched roof (clay tiles) like the other main roof. But due to the off set of the main roof and being at right angles to it as well + a current dormer window in the main roof, merging in the two roof would be very hard.

SO I think it would be best to treat the section as a stand-alone roof ideally hip ended, and running into a valley at the joining of the old roof.

I am quite a competent DIY'er and I mean more than IKEA flat packing, therefore I would like to consider this as a project (possibly next year) Is this feasible or will you laughing like the OH did when I mentioned it to her!!!!

I have seen many company that will produce the trusses their design and even come on-site and measure up for you. Or am I best just knocking up and cutting timber to size?

Given the old roof is till water proof, and I am not planning to tie into the existing pitched roof, this project (as I see it) would be less weather dependant and last to a time scale given the solidness of the main flat roof (for the time being)

Any tips please

The area of the flat roof is approx 4300 x 5900 mm any rough costs?

Would I need planning permission? / building regulation?

 

[noseall]

you may need a planning application, but i don't know for sure.

trusses are relatively easy to fit, though the bracing and strapping i find fiddly.

a traditional cut roof requires a bit more thought.

you need plenty of tools.

...and dry weather, not only for weathertightness but also because there will be power tools everywhere.

it will cost around £2-2500 for materials and scaffold.

 

[jimAuk]

Thanks very much for that, that sort of backs up what others have said and some quotes (minus the labour).

Allready checked that planning not required, but building regs are.

I have plenty of power tools from previous projects, and always a good reason to buy a new one

I think ready made trusses are the way to go, I am waiting for a reply from a local truss manufactuer. I asusume they can also do hips?

But a bit a thought will still be needed in merging into the old roof/valley.

I am giving myself 2 years with the current flat roof (with some patching / temp repair).

I think a smaller project to pitch a small square bay window might be a good test of my skills!!!

 

[jimAuk]

I have done a couple of quick drawing of my propsed plan

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• jimAuk
• 8 Feb 2009
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• jimAuk
• 8 Feb 2009
• 1

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• jimAuk
• 8 Feb 2009
• 1

The apex height of the new roof would be ~ 1.70 m and the angle of the roof about 38 deg. Does that sound OK.

As you can see from the drawings I would not be able to run into the height of the main house roof ridge, due to the center line of the new extension being too far off the end of the ridge of the main house which runs north to south on the main plan drawing.

The other two drawings show isometric elevations. On one side a vale would be needed, on the other due to the old and new roof being at different angles I assume lead flasshing on the vetical face

 

[jimAuk]

Was just looking back, and spotted my old post so thought I would update.

Below is picture taken about 1 month ago. The whole job is now completed and signed off by BCO.

VERY pleased with it.