Question answered
Half round, square or ogee gutters?
The short answer
Half round gutters suit most houses and shed debris easily, square gutters hold more water for the same width and sit neatly against a flat fascia, and ogee gutters echo the moulded cast iron on Victorian and Edwardian roofs. For a heavy downpour, capacity matters more than shape, so we pick the profile around the roof area and the look of the house.
The shape of a gutter changes how much water it carries, how easily it clears and how it looks against the fascia. Half round, square and ogee each suit some houses better than others.
Half round: the plain, forgiving shape
Half round is the shape you probably picture: a smooth curve like a pipe cut lengthways. It is the oldest profile in common use, and on a plain bungalow or a 1930s semi it looks right because nothing about it competes with the house.
The curve helps when things go wrong. Leaves and grit tend to wash toward the outlet rather than settling in the corners, so a half round gutter is generally the easiest to keep clear. It also takes brackets without fuss, and the fittings are made by every maker, so replacement parts are easy to find.
Where it gives ground is capacity. A half round gutter of a given width holds less than a square or deep one, so on a large roof slope or a long run into a single outlet you may need a wider section or an extra downpipe to keep up in a storm.
Square and box profiles: more room in the same width
Square, or box, gutters have flat bottoms and straight sides, which gives them more internal volume for the same visible width. On a roof that sheds a lot of water, such as a long hipped slope or a large rear extension, that extra space can be the difference between a gutter that copes and one that spills over the front.
They also sit tidily against a flat fascia on a modern house, and the straight line reads as deliberate. The trade-off is that the flat bottom can hold silt and leaf mould, so these gutters need clearing more often if there are trees nearby.
Deep-flow versions are available in plastic and aluminium and are sometimes specified where a standard half round has repeatedly overflowed. If water is coming over the front rather than leaking at a joint, capacity is the first thing to check, and a change of section is often the fix.
Ogee: the moulded look from Victorian terraces
An ogee gutter has an S-shaped face, moulded to look like the cast iron that was fixed to Victorian and Edwardian houses. On a villa or terrace near the seafront it is usually the most sympathetic modern replacement for a failed cast iron run, because the face line matches the original.
It holds a respectable volume, and the curved front hides the contents. In plastic or aluminium it is lighter than iron, and fixings are simpler. The profile does lean on the shape of the face though; some ogee styles have narrower throats than their depth suggests, so check the figures given for the specific product.
In a conservation area, or on a listed building, the profile and material can matter to the planning officer. Ask the Adur & Worthing planning team before you commit, and keep the existing profile where you can. Our page on shared gutters covers one situation where you may need to match a neighbour's run.
Matching capacity to the roof, not the catalogue
The right size comes from the roof area that drains into the gutter and the number of outlets. A short run to a single downpipe on a small lean-to hardly tests any section. A long slope of tiles feeding a gutter with one outlet at the far end is a different matter, and so is a roof that dumps a valley's worth of water into a single corner.
We look at the whole drainage picture on the survey: the area above, the length of the run, the outlet positions and the size of the downpipe. If a gutter overflows only at the front of a long elevation, a second outlet or a deeper profile may do more than a straight like-for-like swap, and it is usually cheaper than coming back to put right a gutter that was too small.
Fall and fixings still have to be right whichever section you choose. A bigger gutter is heavier when it is full, so the spacing discussed in how far apart brackets should be is worth reading before you decide.
Water butts, downpipes and the look of the whole roofline
Whatever profile goes up, the downpipe has to suit it. A square gutter with a round pipe works, but a square pipe may look tidier, and some fittings only come in matched sets. If you plan to take water to a butt, check the pipe size against the diverter, which we cover in fitting a water butt to a downpipe.
The roofline as a whole matters too. Fascia, soffit and gutter are seen together, and the gutter reads as part of that line. For a wider view of how the parts relate, see the roofline explained, or the main gutters, soffits and fascias page for everything we fit.
Colour is the last decision. White is common, black suits many older houses, and aluminium comes in a range of coated finishes. Pick the one that sits well with the window frames and the brickwork, and ask to see a sample length against the wall.
Gutter shapes: two decisions that catch people out
Can I swap half round for square without changing the fascia?
Usually yes, if the fascia is flat and sound. The brackets are different and the front edge sits slightly differently, so we check the board and the height of the first drop. Water must still shed into the gutter, not behind it, which is worth confirming while the old run is down.
Is a bigger gutter always better for heavy rain?
Not by itself. A bigger gutter with a flat run or a single blocked outlet still overflows. Capacity helps only when the fall is right, the brackets hold the weight and the downpipe can take the flow away, so we look at all of those before recommending a larger section.
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