Low pitch roofing sheets

[Squaredy]

I notice that in Australia there are special roofing sheets designed to cope with ultra low pitch roofs (as low as 1 degree in fact).  Does anyone know of such a product available in the UK? 

 

I am wondering about the options for my garden room (that I am building), which is going to have a slope of just 2 degrees.

 

I am aware that traditional wisdom is that this is too low for corrugated steel - but if the Australians can do it, why can't we?

 

TRIMDEK® | Lysaght

WWW.LYSAGHT.COM

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Rib-and-pan roofing and walling

Ironically the company that make this Australian product is an offshoot of a firm that used to be based near me - at the Orb steelworks in Newport.

[monkeybusiness]

I’m about to install a large flat roof on my house and am going to follow this thread with interest.
TATA have a product called colourcoat urban (I think) but it doesn’t work on the limited pitch you are aiming for apparently. 

[Woodworks]

2 degrees would probably be fine if you can do the run with one sheet. Its joins where leaks become a problem with water running up under it IME

[Squaredy]

12 minutes ago, Woodworks said:

2 degrees would probably be fine if you can do the run with one sheet. Its joins where leaks become a problem with water running up under it IME

All in one run is no problem, and I was thinking I would use a sealing strip; to seal where the sheets overlap, and indeed to probably overlap two or even three corrugations.

[Squaredy]

15 minutes ago, monkeybusiness said:

I’m about to install a large flat roof on my house and am going to follow this thread with interest.
TATA have a product called colourcoat urban (I think) but it doesn’t work on the limited pitch you are aiming for apparently. 

I have just looked up Colourcoat Urban (now called Catnic urban) and as you say it is only intended for a slope of 5 degrees or more.

[Woodworks]

42 minutes ago, Squaredy said:

All in one run is no problem, and I was thinking I would use a sealing strip; to seal where the sheets overlap, and indeed to probably overlap two or even three corrugations.

At the gutter end you may find the drips run back under the sheet a bit and dont drip from the end. You could  run a line of sealant on the under edge to stop this happening. I should add I have only done very low angle sheets on log sheds so not the same quality as required for a garden room

[Squaredy]

28 minutes ago, Woodworks said:

At the gutter end you may find the drips run back under the sheet a bit and dont drip from the end. You could  run a line of sealant on the under edge to stop this happening. I should add I have only done very low angle sheets on log sheds so not the same quality as required for a garden room

Yes I agree I have experience of this drip back.  I get it quite a bit on a roof here at my work site which is around 5 degrees, so yes I was planning on putting some sealant or similar under the edge so the drips behave themselves.

[openspaceman]

1 hour ago, Squaredy said:

All in one run is no problem, and I was thinking I would use a sealing strip; to seal where the sheets overlap, and indeed to probably overlap two or even three corrugations.

Yes two overlaps should be enough, I have an extension with a low pitch, about 2 degrees on my bubble meter, it has clear  PVC corrugated sheets and if one gets partially blocked then in heavy rain it can dribble over. I have attempted a sealant on the inner ridge overlap but sweeping debris off (mostly moss from the adjacent roof) is the most effective.

 

I think the PVC has 5 or more years life and if I am still around will replace with corrugated polycarbonate, like on my log store, and two overlaps.

[coppice cutter]

2 hours ago, Squaredy said:

All in one run is no problem, and I was thinking I would use a sealing strip; to seal where the sheets overlap, and indeed to probably overlap two or even three corrugations.

Also need to seal at the 'top' of the roof.

 

As shallow as that water could easily blow back up the roof and leak at the high end.

[Squaredy]

1 minute ago, coppice cutter said:

Also need to seal at the 'top' of the roof.

 

As shallow as that water could easily blow back up the roof and leak at the high end.

Ah, good point thank you for that.