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Guttering buying guide

Updated: 23 October 2026

You are at a fascia, or beside a shed, with a tape measure and a basket that mixes 112 mm half round, square line, a 76 mm mini system, and a stick-on strip a couple of centimetres deep. A guttering buying guide has to start with the roof you already have, because those shapes do not share fittings. By the end you should know whether you are matching a house profile, sizing a small new roof, or looking at the wrong object. The [gutter comparison](/hub/diy-supplies/gutter) is only three amazon.co.uk listings, and it is not the sizing tool. A purchase through our links can earn a commission at no extra cost to you.

You are at a fascia, or beside a shed, with a tape measure and a basket that mixes 112 mm half round, square line, a 76 mm mini system, and a stick-on strip a couple of centimetres deep.

Our top picks

FloPlast FloPlast half-shed pack, 2 m

Best overall

FloPlast FloPlast half-shed pack, 2 m
7.5/10about £46.30
View offer
Bocguy Bocguy adhesive J, 5 m

Best value

Bocguy Bocguy adhesive J, 5 m
7.4/10about £24.98
View offer
Funnytek Funnytek adhesive J, 5 m

Alternative

Funnytek Funnytek adhesive J, 5 m
6.6/10about £17.99
View offer
On this page
  1. 1.Start with the gutter you already have
  2. 2.House size, in published figures
  3. 3.A small roof is a different system
  4. 4.Square, ogee, and metal
  5. 5.Outfall, then the three listings

Start with the gutter you already have

If a length is already on the house, the next piece has to be the same profile. Half round, square, ogee, and a deeper section each have their own unions and outlets, and a clip from one will not lock into another. The Plastic Centre's note is practical: take a piece of the old gutter to the counter when you are patching, rather than guessing from a photo.

House size, in published figures

A normal UK house eaves in the FloPlast range is 112 mm half round with a 68 mm downpipe. That is the 2026 brochure's domestic pair. It is not the 115 mm gutter in Approved Document H. A 112 mm union will not click onto a 115 mm length. On the Angels Plastics table, at 75 mm of rain an hour, 112 mm half round at 1:600 is about 62 m² with an end outlet. Do not paste that guide's 75 mm row onto 76 mm MiniFlo, which has its own 20 m² line.
FloPlast FloPlast half-shed pack, 2 m

Testsieger

FloPlast FloPlast half-shed pack, 2 m
7.5/10about £46.30
View offer

A small roof is a different system

Sheds and summerhouses often use 76 mm mini gutter and a 50 mm pipe. FloPlast calls that MiniFlo and limits it to 20 m² for each outlet, with the outlet in the middle and the fall at 1:350. You do not gutter a house with the mini system because a pack was cheaper, and you do not force house fittings onto a mini fascia. Past that area you want a second outlet or 112 mm, not a longer 76 mm run. Screws and the water butt are on the shed guttering page.

Square, ogee, and metal

Half round is the common domestic shape because it is widely stocked. Square line is the sharper shadow under a fascia. The Plastic Centre notes that square corners hold debris more readily, so a run under trees needs clearing more often. Ogee will not accept a half-round stop end. Match whatever is already fixed. Cast iron belongs where the original section is expected. Bradford's guidance is like for like. A cheap adhesive J is not a discount half round: it has no downpipe and no bracket.

Outfall, then the three listings

Size is wasted if the water has nowhere legal to go. Approved Document H sets an order for rainwater: a soakaway or other infiltration first, then a watercourse, then a sewer. A water butt is reuse, and a full butt still needs an overflow that is not a foul stack. The table's clipped row is a 76 mm shed pack. The other two rows are self-adhesive J strips for a door or a van. The adhesive or clip page separates those jobs. If the fascia is high, rotten, or cast iron, stop and use a roofer.

Common questions

What size gutter does a normal house use?
In the FloPlast domestic range a normal house eaves is 112 mm half round with a 68 mm downpipe. Approved Document H's table, as reprinted by Forest of Dean, uses 115 mm half round with a 63 mm outlet up to 53 m², and 75 mm with a 50 mm outlet up to 18 m². Those are different nominal sizes. Match the fitting on your fascia, or the maker's pair, rather than the nearest number in a table.
Is 112 mm the same fitting as 115 mm?
No. FloPlast's half round is 112 mm. The Building Regulations table uses 115 mm. The unions, outlets, and stop ends are not a shared part, even though the widths look similar in a photograph. If you are patching, take a cut piece to the counter. If you are starting new, stay inside one maker's system for the whole run, including the downpipe.
When is 76 mm enough?
FloPlast's brochure limits MiniFlo, its 76 mm gutter with a 50 mm pipe, to 20 m² for each outlet when the outlet is in the middle and the fall is 1:350. That covers one side of a small shed for many people. It is not the Angels Plastics figure of about 24 m² for a different 75 mm half round, and it is not a house eaves. A larger roof needs another outlet or a 112 mm system.
Half round or square?
Match whichever profile is already fixed to the house. On a new run, half round is the widely stocked domestic shape, and square line is the sharper alternative. Square corners hold leaves more readily, so a square gutter under trees will want clearing more often. Neither shape accepts the other's fittings, and neither is a 76 mm mini part.
What downpipe goes with each?
FloPlast pairs 112 mm half round with a 68 mm pipe and MiniFlo 76 mm with a 50 mm pipe. The Approved Document H pairs in the Forest of Dean note are 50 mm with 75 mm gutter and 63 mm with 115 mm gutter. Use the pair that belongs to the gutter you chose. An outlet from one system will not seal onto the pipe from another.
Where does the water have to go?
Approved Document H prefers a soakaway or other infiltration, then a watercourse, then a sewer. Keep rain out of the foul sewer where a separate surface-water drain exists. A water butt is allowed as reuse, and it still needs an overflow that does not tip into a foul stack. A new downpipe into the nearest foul gully is the arrangement to avoid.

Related pages

How to fit a gutter

Gutter

Adhesive gutter or uPVC gutter: a door, van or roof

Best gutter: the shed pack against two drip strips

Shed guttering: one side of a small shed into a butt

Sources

Public UK sources and the amazon.co.uk listings compared on this page. Listings captured 21 October 2026. Updated 22 October 2026.

  1. Approved Document H (retrieved 22 October 2026)
  2. BS EN 607:2023 eaves gutters (retrieved 22 October 2026)
  3. FloPlast MiniFlo (retrieved 22 October 2026)
  4. FloPlast rainwater brochure (retrieved 22 October 2026)
  5. HSE: ladders (retrieved 22 October 2026)
  6. Wavin Osma rainwater manual, July 2024 (retrieved 22 October 2026)
  7. Bradford rainwater goods (retrieved 22 October 2026)
  8. Angels Plastics guttering guide (retrieved 22 October 2026)