On 11/05/2021 17:27, Fredxx wrote:
On 11/05/2021 16:32, Chris Bacon wrote:
I came by an old concrete double garage, which had an apex roof, and
I
want to convert it to a flat roof.

Your new trusses would be slightly longer, they would have to be
modified to match the positions of your concrete posts. Otherwise looks
a plan though the span feels very long. There is probably no need for
the additional angle if the original span is unchanged.

I presume you're worried about your neighbours and the need for planning
permission. Why not erect as is, with the fallback of making flat if the
need comes?

Thanks for the reply. Yes, "flattening" the existing trusses would give
ne ~5,000 mm rather than the ~4800 required, so I'd probably trim the
inner ends more than the outer, deeper ends, and weld on 40mm x 40mm x
3mm "lehs" about 500 long on average (taking into account the roof's
fall, and the ~250mm of leg that would be attached to the posts).

The existing trusses have a piece of 25mm x 3mm flat bar as a tie, which
wouldn't be quite so convenient for attaching a ceiling. I could perhaps
adjust the fixing position of the flat bar to save money on buying 30mm
angle, and suspend battens...

Yes, I think the neighbours will kick up a stink. The total height,
leaving things as they are, would be about 2700. As things are now, the
ends of the trusses would also encroach on the vertical space available
(~2,000mm) inside, at the edges, so I like the idea of "flat" for that
reason too.

Being "tight", I don't want to have to re-do the job. There's the
"loophole" that planning says that the height is measaured from the
highest adjacent piece of ground, and I've dug out the slope the
building's on by about 200mm, which would help, but the council's
planning people are extremely unhelpful about what would comply with the
rules, and suggest that I piut the thing up, and they wi;ll send someone
to see about it when a complaint is made! Argh! Grr!