Extension roof opinion

[Dad'n'lad]

Hi all. Will be starting a single storey rear extension next March. This is to replace an old badly built one, housing our downstairs ( and only ) bathroom. I am going P.D, building notice, due to lack of funds, and doing everything myself, from new drains to getting a spark to hopefully sign off the electrics. It will be as wide as house (4.58M) and extend 4.0M. Eaves at 3M.
I would like maximum internal roof height, and would like opinions on mono pitch versus pitched. Will be hot roof as don't want ceiling. Cost and ease of build, or problems with BCO to be considered. Thanks for your time reading. Good luck with your own projects/jobs.

 

[^woody^]

You would normally design the roof to fit in with the existing house style, and taking into account planning requirements and constraints such as the upstairs windows and pitch, and not just base it on opinions of what is best.

 

[Dad'n'lad]

Cheers Woody. 1897, gable ended at rear with one upstairs window. Slate roof. Planning say in same style, so ill match the bricks and use slate. The 4M height comes 3 courses under the window, and the pitch is set as i need the 3M eaves height. ( but will be as good if not a degree or two better than what im ripping down) 14 degrees i think i can achieve. I wasnt sure if there was more pressure on the wall plates at either side on a pitched, or the long wall parallel to existing. I have to put my own basic drawings in to planning, and ask the BCO as i go along. Ive had to take a 5 year loan out to do this which takes me close to retirement, which is also when my mortgage will finish. I dont have a grand or more for architects or structural drawings, it would take me a year to save that.

 

[^woody^]

A flat roof would be cheapest and easiest. Then a mono pitched - which also avoids gutters at the boundary and associated drainage. "Pressure on the wall" is not a factor, as construction is the same regardless.

 

[Dad'n'lad]

Thanks Woody. Have a good un.

 

[SpecialK]

Any roof windows? 14 degrees is fairly low pitch.
I managed to squeeze top tiles in a course under the upstairs windows (Not ideal for flashing). Went out 3.3m and have a 20 degree pitch...

 

[Notch7]

Cheers Woody. 1897, gable ended at rear with one upstairs window. Slate roof. Planning say in same style, so ill match the bricks and use slate. The 4M height comes 3 courses under the window, and the pitch is set as i need the 3M eaves height. ( but will be as good if not a degree or two better than what im ripping down) 14 degrees i think i can achieve. I wasnt sure if there was more pressure on the wall plates at either side on a pitched, or the long wall parallel to existing. I have to put my own basic drawings in to planning, and ask the BCO as i go along. Ive had to take a 5 year loan out to do this which takes me close to retirement, which is also when my mortgage will finish. I dont have a grand or more for architects or structural drawings, it would take me a year to save that.

as you have a restricted budget, please make sure you do your research as far as possible in regards to foundations and drainage.

foundation depth and type is determined by stability of ground and whether you have any trees nearby which would have an impact. For example, oak, leylandii, willow etc within 15 metres.

 

[Dad'n'lad]

No roof windows, SpecialK. I would love to sneak it up a couple of courses but i'd assume the nearest course to the 4m max height, is where the flashing will need to be. Here is the existing. Conservatory and previous extension all going. New extension full house width.

 

[Dad'n'lad]

@Notch7. Thanks for that. The garden to the left has Leylandii on its left border, maybe 7 metres to where my footings will go. soil has a lot of clay too so im thinking i might have to go 2 metres deep. Im planning on beam and block as the garden slopes down. The house floor level is about halfway up the bottom conservatory door glass, there are two steps up into my kitchen.

 

[^woody^]

Will that be permitted development?

Wrap-around comes to mind.

 

[Dad'n'lad]

@ Woody. Its only from left hand edge to downpipe. 4m out in this direction, 4.58m wide, 4m high and 3m to eaves. I have 180 foot garden from rear of conservatory so fine on the 50%. Have i missed something? Thanks

 

[SpecialK]

You need 75mm of upstand minimum of the lead flashing so you can go tight under the window if required? (ideally remove window, fit flashing and tray then refit). The tile top would be a course and a half maybe below the window?
What about making the window smaller? - Roof windows add a massive amount of light into the rooms you are covering up. I fitted 3 sk06 velux to mine. No regrets apart from the weight of them when fitting! (Triple glazed!)
Hopefully you can get the roof over 15 degrees...

 

[Dad'n'lad]

@SpecialK, because that would be over my 4m maximum height for P.D. I saw a graphic on the internet that showed 14.8 degrees, and on another it says 18 degrees for the same calcs. I will have to work it out to within a centimetre, based on my rafter heights , battens, tiles etc soon anyway. Thanks

 

[^woody^]

I'd seriously re-check your belief that this is PD

 

[Dad'n'lad]

@woody. Having been following this forum for a year or more, ive seen your valued comments many times. If you can point out which part i'd be falling foul of, i'd be grateful. Personally i reckon youve just not grasped whats being removed, and what i'm creating, using this existing photo. Because im less than 2m from boundary, and its detached, the rules are easy to understand.