What is better, square or round guttering?

Square or round is not a style argument, it is a capacity and maintenance decision, and the roof settles it.

If you need guttering systems or guttering systems in Godalming, we cover the whole area, with our own local roofers, a real person on the phone and a 25-year written workmanship guarantee.

Call Scott on 07428 300474 for a free survey and a fixed price in writing.

What is better, square or round guttering?

Neither shape is better on its own. Square guttering usually carries more water for the same width and suits modern or square-fascia houses, while round guttering clears debris more easily and suits older and period properties. The right answer is whichever profile matches the roof area, the rainfall load and the building.

Capacity is decided by the roof, not the shape you like

Rainwater sizing is a calculation, not a taste. The roof area draining into the gutter, the pitch, the number of outlets and the fall all set how much water has to move. We size to BS EN 12056, which is the rainwater standard, and that number decides the profile before anything else does. A square 112mm gutter holds noticeably more than a half round 112mm gutter because the section is deeper and the walls are vertical, so on a big pitched roof with one downpipe, square often wins on arithmetic alone. On a modest roof with two outlets, half round is plenty and no amount of extra capacity will do anything except cost more. If you need guttering systems or guttering systems in Guildford, we cover the whole area, and the first thing we do is measure the roof rather than guess the gutter.

The failure we get called out to most is not a burst gutter. It is an undersized one, overflowing in heavy rain at the same corner every time, soaking the fascia and eventually the wall behind it.

Debris behaves differently in each profile

Round guttering has no internal corners. Leaves, moss and grit tend to keep moving towards the outlet, and when you do clear it, a hand or a scoop reaches every part of the section. Square guttering has two internal angles at the base, and that is where silt and moss sit and set hard. Under trees, and much of Surrey and the Wey Valley is under trees, that difference is real. It does not make square guttering wrong, it makes it something you clear more often.

There is a related point about moss. If a roof is shedding moss into the gutter every autumn, the gutter is the symptom. We soft wash and hand scrape rather than pressure wash, because pressure washing strips tile surface and pushes the same debris straight into the gutter you just cleared. Whether you need guttering systems or guttering systems in Woking, we cover the whole area, and we would rather deal with the cause than book you in twice.

• Half round clears itself better and is easier to clean by hand.
• Square holds more water for the same nominal width.
• Square collects silt in the base corners, especially on shallow falls.
• Deep flow and ogee profiles sit between the two on both counts.

The building usually makes the decision for you

On a Victorian or Edwardian house, half round on rafter brackets or a cast style profile looks right because that is what the elevation was designed around. Swapping it for square rarely improves anything and often looks wrong from the pavement. On a 1970s or newer house, or anything with a deep flat fascia, square or ogee sits flush and reads as intended. Ogee is worth knowing about: it has a decorative front face, a squarer section behind it and reasonable capacity, which is why it turns up so often on modern estates.

Then there is the material. Plastic is the default and it is fine, but it expands, contracts and eventually goes brittle at the joints. Seamless aluminium is formed to length on site, so a long run has no joints along it at all, and joints are where gutters leak. Both round and square profiles are available in aluminium, so the shape question and the material question are separate. Our full page on guttering systems sets out the profiles and materials we fit and where each one earns its keep.

Fixing and fall matter more than profile

We replace a lot of gutters that were the correct size and the correct shape and still failed, because the brackets were too far apart, the fall was flat or backwards, or the outlet was in the wrong place. Brackets at wide centres let a full gutter sag between them, and once it sags it ponds, and once it ponds it silts up and overflows. That is not a profile problem.

The same applies to what the gutter is fixed to. If the fascia is soft, no bracket in it will hold, so the fascia gets sorted first. If the roof edge has no proper drip or the tiles overshoot, water jumps the gutter in heavy rain regardless of how much the gutter could have carried. Searching for a roofer near you who will actually look at all of that before quoting a shape is a fair thing to want, and it is how we work across the villages and towns we cover.

Scott has been on Surrey roofs for more than 36 years, and the honest position is this: if your existing gutter is the right size and only the joints or brackets have gone, we will say so and repair it rather than talk you into a full replacement in a different profile. If it was never big enough, changing shape is part of the fix, and the fixed price we put in writing will say exactly which parts are going and what they are being replaced with. Every job carries our 25-year written workmanship guarantee, handed over before we leave.