Build pitched roof over flat roof?

[StephenStephen]

I've never been a fan of flat roofs - seems like having water sitting on a tiny pitch is a recipe for disaster...

..anyway - we've a flat roof single storey extension with a couple of problems or three:

-water is finding its way into the inside of the chimney - might or might not be a problem with the roof, could be higher up the chimney etc
-it's cold! poorly insulated
-presumably, being a flat roof, I'll need to periodically replace the surface

So I'm thinking - why don't I build a pitched roof on top of the flat roof?
It'll last longer, and I won't then need to worry about replacing it, and it'll be warmer.
Any thoughts? Is this bonkers?
It's a bit of a fiddle, because I've the chimney breast to work round, the (black) downpipe from the gutter, and the (grey) vent from the drain.
Any thoughts gratefully received...

 

[Elastomeric]

Fairly straightforward . Soil can be moved over, and as long as the windows have decent lintels that can take the load.

 

[Tigercubrider]

I think you may need permission but I'm no expert
I have thought the same bout mine, although my pitch would need to be shallower due to low windows

I would remove the asphalt to get to the framing though

 

[noseall]

That balanced flue may clash with any soffit you may intend having along with the new pitched roof, otherwise crack on.
Maintenance to the items above that roof would be simpler in its current state so I would strongly suggest rectifying any problematic areas and consider renewing or at least cleaning the gutters etc.

 

[garyo]

Any thoughts? Is this bonkers?

I did something similar to my garage, and used the existing wall plate and joists with modification.

To progress your thinking, draw yourself a cross section so that you can experiment with the roof pitch and the effect that it'll have on the eaves overhang and fascia depth, and how that interferes with the window. You'll need to determine the position of your wallplate.

 

[garyo]

Something like this might get you thinking:

 

[StephenStephen]

Something like this might get you thinking:

Thank you very much - very helpful

 

[nuzuki]

Sorry dont mean to hijack the thread or anything but garyo could you tell me what program you used to knock up that drawing?

Thanks

 

[garyo]

an to hijack the thread or anything but garyo could you tell me what program you used to knock up that drawing?

I did that in Visio around 8 years go. I wouldn't recommend that now unless for very simple constructions: It's too much work if you're producing multiple elevations and plans for PP/regs submission because each drawing is completely independent of another, meaning that any slight alteration needs to be repeated 4 or 5 times (for however many elevations/plans etc you have)

Now, I would (and do) use Sketch-Up. With the Layout plugin the workflow is tremendously efficient.

Note - this is from an amateurs point of view. I expect the designers on here would use AutoCad or similarly ££££ packages.

While we're at it, there are various issues with the construction detail in the diagram... during implementation I realised there were better/easier ways of doing various parts, but the drawings were approved by LABC so served the purpose.

 

[nuzuki]

Thanks Garyo, I do have sketchup installed but havent got round to having a play with it.