No1 Roofing manufactures and supplies a wide range of half round gutters.
With sizes from 150mm diameter to 450mm diameter – in standard lengths as well as custom cut lengths up to 8 metres.
The smooth pressed, non-segmented profile eliminates square corners and prevents the build-up of water and dirt.
The curved base of the profile creates a faster flow of water, as the water is channeled to the centre of the gutter, maximising drainage performance.
Features & Benefits
- High water-carrying capacity
- Smooth pressed, non-segmented profile eliminates square corners and prevents the build-up of water and dirt
- Curved base of the profile creates a faster flow of water as the water is channeled to the centre of the gutter, maximising drainage performance.
Colour Options & Finishes
Standard No.1 Roofing & Building Supplies Half-Round Gutters are manufactured from 0.55mm bmt ZINCALUME® and COLORBOND® material.
Heavier gauges of ZINCALUME® as well as stainless steel are also available, in plain profiles without the front bead.
Half round gutters sizes are from 150mm diameter up to 450mm diameter.
No1 Roofing Half Round Gutters are supplied cut to length up to 8 metres.
- COLORBOND® Steel – full range including ULTRA, MATT, METALLIC & STAINLESS STEEL
- ZINCALUME® Steel
- Galvanised Steel
- Stainless Steel – 304 GRADE & 316 GRADE
- Other – please enquire
All building products need to be checked for compatibility with adjacent materials, whether they are part of the current project, pre-existing or planned building elements.
Contact No.1 Roofing & Building Supplies for more detailed information.
A gutter fall of not less than 1:500 is recommended.
The Brackets are manufactured from 3mm Aluminium - 5005H34 GRADE - (and powder coated to suit) with a fold over tab at the front and a fold out / hook tab at the rear to hold the gutter in place.
Gutter Diameter (mm)
Max. Bracket Spacing (mm)
Values of rainfall intensity in the table and map are for 20 year ARI, 5 minute durations and have been derived from AS3500 part 3 ‘Stormwater drainage’.
Note that rainfall records in Australia are limited and any data carries a degree of uncertainty. The 20 year ARI values should only be used for external eaves gutters.
For internal / box gutters use 100 year ARI values.
20-Year Rainfall Intensities for NSW (mm/hr) - Design rainfall intensities adapted from NCC, Volume 2, Table 126.96.36.199.
ARI once n 20 years mm/yr
ARI once in 100 years mm/hr
New South Wales
For any given roof area the larger the gutter, the fewer downpipes required. The Table below acts as a guide.
Catchment area calculations must take the roof slope into account. For slopes up to 23 degrees, only a simple plan area of the roof is required.
The selection of the number of downpipes is carried out in accordance with AS3500.3 (Stormwater Drainage).
For Half-Round Gutters larger than 225mm in diameter, hydraulic design must be carried out by a suitably qualified person to determine the number and size of downpipes required.
Half Round Gutter Brackets
Heavy duty type A4 brackets are manufactured in aluminium with a powder coated finish for all size gutters.
Downpipes must have sufficient capacity to allow for gutter drainage.
They can be manufactured in all materials in lengths up to 4 metres (90mm and 225mm diameter) and all downpipes are tapered.
For larger diameter downpipe, please contact us and we will advise.
Effective Cross-Sectional Area & Downpipe Size
Gutter Size (mm)
Effective Cross Sectional Area* (mm)
Round Downpipe Diameter (mm)
* Area for Half-Round profile. TBD – Downpipe size to be nominated by hydraulic engineer.
A full range of standard and custom rainwater heads and downpipes is available and can be fabricated from a wide range of materials to suit the No.1 Roofing & Building Supplies Half-Round Gutter.
Buy Half Round Gutters
We stock a huge inventory of gutters, downpipes and accessories for every roofing project no matter how big or small.
Not sure what gutter you need, you can call us for an estimate on the desired product.