Which gutter size you need
The most common mistake is choosing a gutter by eye, or by whatever is left in the van. A gutter that is too small overflows in heavy rain and sends water down the façade and into the foundations. One that is too large simply costs more than it needs to.
The table
What matters is the roof area draining into that one gutter, in square metres — the eaves length times the rafter length, not the footprint of the house.
- ▸up to 83 m² — 280 mm gutter, ø80 pipe
- ▸up to 150 m² — 333 mm gutter, ø100 pipe
- ▸up to 243 m² — 400 mm gutter, ø120 pipe
- ▸up to 443 m² — 400 mm gutter, ø150 pipe
When to use two outlets
For gutter runs over 10 m it is best to fit two outlets. The gutter then falls from the middle towards both ends, each half drains its own water, and you size for half the area.
The sizes we keep
For half-round gutters: 280, 333 and 400 mm developed width. Hooks, end caps, outlets and corners exist for all three in matching colours, so the whole system fits together.
For square gutters we make 110 mm and 140 mm bases.