When Is Deepflow Better Than Standard Half Round?
A deeper gutter becomes useful once roof area or water volume starts increasing.
Long elevations can send a surprising amount of water towards one outlet during heavy rain. Outlet position and downpipe size matter here too, so choosing Deepflow doesn’t mean drainage capacity becomes unlimited.
Appearance is another reason people choose it. Deepflow keeps a traditional curved profile, so it works well on period buildings where a modern square gutter might seem out of place.
For smaller roofs, standard cast iron half round guttering may still be perfectly suitable. Bigger isn’t always better.
If you send us the roof dimensions and planned outlet positions, we can help you work through the options.
What Parts Make Up a Deepflow Gutter System?
A basic run normally starts with 6ft gutter lengths, brackets, union connectors, stop ends and an outlet.
Corners need matching angles. Your outlet connects into the downpipe system below, normally using bends or offsets to bring the pipe towards the wall.
You may need:
- Deepflow gutter lengths
- Fascia, rafter or rise-and-fall brackets
- Gutter unions
- Stop ends
- Running or drop-end outlets
- Internal or external angles
- Cast iron downpipes
- Downpipe bends and offsets
- Pipe brackets
- Shoes or drainage connections
- Cast iron hoppers on more involved layouts
Try to keep the gutter and fittings within the same system.
Cast iron profiles from different manufacturers can have small dimensional differences, especially around sockets and joint details.
How Is Cast Iron Deepflow Guttering Installed?
Cast iron is heavy, so bracket setting needs doing properly before any gutter lengths go up.
For this system, brackets should be positioned at maximum 915mm centres. Extra support is normally placed close to outlets and angles, with brackets no further than around 300mm from these fittings.
Socket joints need a small movement gap too. Around 3–4mm should be left rather than pushing adjoining pieces tightly together.
The joints are sealed using the matching jointing system or suitable sealant, with M6 x 25mm bolts, washers and nuts securing the connection.
One tip from experience: spend more time setting the first brackets than you think you need. Once several heavy cast iron lengths are fitted, correcting a poor fall becomes a much bigger job.
Primed or Pre-Painted Black Deepflow Guttering?
Primed cast iron costs less and gives you freedom over the final colour.
The primer is not intended to act as the permanent exterior finish though. Once installed, the system needs suitable finishing coats applied on site. Pay close attention to joints, cut edges and any marks created during fitting.
Pre-painted black arrives with its finished coating already applied. It costs more, but saves work on site and gives a consistent finish across the gutters and fittings.
For restoration work where an existing colour needs matching, primed can make more sense. For a straightforward black system, pre-painted is often easier.
Can Deepflow Guttering Use Different Downpipe Sizes?
Yes. Our Deepflow range includes outlet options for 2.5" and 3" downpipes.
The best combination depends on how much roof area is feeding each outlet. A larger gutter paired with too few or undersized outlets can still struggle during heavy rain.
This is why gutter size and downpipe size should be planned together rather than chosen separately.
If you have a large roof, send us the dimensions before ordering and we can help check the system.
How Long Does Cast Iron Deepflow Guttering Last?
Cast iron can remain in service for many decades when the coating is maintained and joints are kept in good condition.
It isn’t maintenance-free. Painted surfaces should be checked for chips or exposed iron, and any early corrosion is best dealt with before it spreads.
The good bit is repairability. A damaged length, bracket or joint can often be replaced on its own rather than changing the whole rainwater system.
Keep the gutter clear of leaves, check outlets every so often and inspect the coating during normal roof maintenance. A little attention goes a long way with cast iron.
Replacing Existing Deep Half Round Guttering?
Measure before ordering.
We recommend checking:
- Overall gutter width
- Gutter depth
- Length of each section
- Outlet diameter
- Downpipe diameter
- Socket direction
- Existing bracket type
- Internal and external corners
