Roof design- what is this bit?

[Homeyhouse]

I am having a side return extension and back extension. The two pitched roofs meet and are different pitches that connect.

Can anyone enlighten me about the end box shape. Why does the roof go flat rather than continue the pitch roof to meet at the guttering? I think this would have been much more attractive architecturally and streamlined.

I'm not sure it can be undone now but thought there might be a reason I'm not getting.

@pigletjohnmay know...

@PigletJohn

I don't know. It looks very strange to me. As if the roof designer did not have accurate plans of how the walls would be built, and somebody bodged the corner afterwards. I suppose there is a pillar and padstone with an RSJ over the opening, and the roof timbers on top, perhaps they were higher than the roof should have been.

Was it designed by an architect?

Have you got copies of the plans? You can probably get them from the local council, as there would have been Building Control and probably Planning Permission applications.

These are the construction plans

Sorry, too small to read and I can't make it out. There might be some text explaining the roof detailing

The circled bits of this drawing are the most important parts of the drawing to ascertain if it's the designer or builder at fault, looks like the angle of the slope has been miscalculated and someone's botched a fix. Can you show us close-ups of the roof plan and the rear elevation?

This is a close up

The side return roof pitch is a lower gradient whereas the back section is shorter and steeper. I think the box is so that the roof height can be the same height as the guttering on the right?

No one has mentioned it being a mess up. I can't tell if it's on the original plan.

@Pigletjohn is added some close up's of the plans

Well the drawings clearly show the sloping ridge line meeting the corner of the extension/ neighbouring building line, so it's not the designers fault. The builder has taken it upon themselves to change the design. There may be a reason, maybe a drainage or structural issue, such as if the wall was built further out than it should have been and they started out the roof at the correct angle according to the drawings, but found out halfway through it wouldn't meet properly so changed tactic. However it's more likely a botch, covering up a poor decision by someone on site. Should have been discussed with you as its a deviation from the approved plans.

Looks like a bad design from the beginning. A lean to with roof windows in ,then a lead flashing on next doors wall would have looked better.

@Diyextension do you mean an extension the same as the neighbours?

I didn't want a low ceiling (except for the roof light) but wanted some height internally. I like the feel of a pitched roof inside and didn't really want a box type feel.

The neighbours looks like a flat roof ?

something like this but with lead flashing against the neighbours wall.

Looks like the guttering on the party wall line was too high so when they put the other pitched roof on they then discovered that the party wall gutter wouldn't match up with where the rear roof line ends. What a botched job. Expensive to correct to plans too. It's the architect or builder project managing?

@Diyextension that's what ours is- except this odd added bit. A pitched roof to side and front with lead flashing against their wall. Ours is just lower as there wall in very high.

The builder is project managing it. It's odd because in every way they have been excellent. Going above and beyond to do extras that j wouldn't think of. It's just this end pitch

How bizarre. I can't read it but is that what the plans dictate or has the builder just done like that? If the builder decided, it suggests an error in measurement or gradient.

It does look a bit of a bodge. I would be speaking urgently, especially if not as per the plans. I know my neighbour had an extension and a problem roof and the builder had to get the contractor to strip it all off and re do...not what you want to hear I appreciate

While it may appear odd, it also looks to be done properly. Ask the builder what the discrepancy is between the drawings and the reality. Roof heights and pitches are fixed by the plans, location and height of the new extension walls, minimum pitch requirements and the existing upstairs windows.
Just ask them to explain why it’s like that. You could also get the architect back to have a look.