Low pitch roofing sheets

[Deafhead]

Southern sheeting profile sheets might do it. I've just done a couple of outbuildings, super stuff. 

[Retired Climber]

In my experience, very shallow angles are ok when the roof is new and everything is straight, but they can be a pain when the roof ages and dips / sags between supports. 

Edited October 12, 2022 by Retired Climber

[difflock]

If there is ANY possibility or likelyhood of feet trampling over the roof for access for whatever reason, consider thicker/stronger sheeting, I did a roof 20 odd years ago and used the "recommended" 1.0mm thick(I think?) sheeting, a proper delicate bollocks! you look at it sideways and it "crinks". I later did another roof with, again I think/vaguely remember 1.5mm thick sheets, and it is a different roof to walk over.

[dumper]

Most sheet companies will size the sheets to your roof so 1 piece top to bottom you can get insulation bonded to the underside you can have the ridge folded to any size you need so go oversize and the then use foam fillers stuck with mastic to stop water blowing under a run of mastic along the drip line will stop run back and maybe go oversize on the gutter,, a line of felt along the bottom of the sheet will also help, if you use sheet make sure you drill through the ridge carefully not to crush the profile 

might be worth covering roof with ply or sterling board to give more support to the sheets

Edited October 12, 2022 by dumper

[coppice cutter]

5 hours ago, Retired Climber said:

In my experience, very shallow angles are ok when the roof is new and everything is straight, but they can be a pain when the roof ages and dips / sags between supports. 

Another good point.

 

With things that shallow there's no scope whatsoever for sagging or bowing.

[Squaredy]

2 hours ago, coppice cutter said:

Another good point.

 

With things that shallow there's no scope whatsoever for sagging or bowing.

No I totally agree - I remember learning many years ago that even flat roofs should never be flat.  The main roof on my house is 90 year old clay tiles with no felt underneath.  It leaks a bit in dozens of places when it rains hard, but of course having a 30 degree slope nothing ever puddles.  And as it has gaps everywhere it is very well ventilated so when moisture gets into the joists, it dries off again quickly.  If it were flat it would be a disaster.

 

I may not go for the super flat roofing sheets, but I am investigating all the possibilities, and appreciate very much everyone's input.

[openspaceman]

6 hours ago, Deafhead said:

Southern sheeting profile sheets might do it. I've just done a couple of outbuildings, super stuff. 

The OP is a bit far from E Grinstead; I used their euro therm seconds for my shed, they add a bit of stiffness as well as insulation, which also fends off condensation.

[NJA]

9 hours ago, Deafhead said:

Southern sheeting profile sheets might do it. I've just done a couple of outbuildings, super stuff. 

I've used them a few times, good stuff.  May be worth picking their brains even if you're too far away to buy from them.

[dan blocker]

You’ll have condensation with a tin roof. 2 degree is about 100mm fall in 3.00 metres, why not use chipboard as a decking and cover in a EPDM Rubber Membrane. It’s easy to install and with a long life.

[Squaredy]

1 hour ago, dan blocker said:

You’ll have condensation with a tin roof. 2 degree is about 100mm fall in 3.00 metres, why not use chipboard as a decking and cover in a EPDM Rubber Membrane. It’s easy to install and with a long life.

There are ways to avoid condensation.  I have changed my design again and will have a pitched roof after all.

 

 Interesting discussion about flat roofing though.