How far apart should gutter brackets be?

1The 900 mm figure and where it comes from

Brett Martin, a UK gutter manufacturer, states in its installation guide that gutter supports should be spaced at no more than 900 mm apart. That is manufacturer guidance for its own system rather than a British Standard, so always check the instructions for the product actually going up. Other makers publish their own limits.

The figure is a ceiling. Spacing at exactly 900 mm leaves nothing in hand, and gutters are rarely loaded evenly. Leaves, a blocked outlet and a week of heavy rain can put far more weight in a gutter than a dry measurement ever suggests.

Most good fitters therefore set out the brackets from the stop ends and corners and share the remainder evenly, which usually brings the spacing comfortably below the limit. A tape measure and a chalk line before the first screw go in are worth the minute they take, and they let you see where each outlet and union will fall before the brackets commit you to it.

2Where brackets need to be closer

There are places where an even spread is not enough. At every union between two lengths, a bracket close on each side stops the joint opening as the gutter flexes. Next to an outlet, where water is concentrated, the same applies. At an internal or external angle, a bracket on each leg keeps the corner square instead of letting it twist.

On a long elevation that carries a lot of roof, we also tighten the spacing, because a long slope sheds a large volume of water into one gutter. Wide-profile gutters hold more, and a fuller gutter is heavier, so the same rule applies.

If you can see a gutter dipping between two brackets, count the gap. A sag that opens up every winter usually has either a gap that is too wide, a bracket that has pulled out of soft fascia, or a pool caused by a poor fall, and the three often arrive together. Fixing only one of them gives a repair that lasts until the next gale, so we look at all three before suggesting an answer.

3Brackets, fall and the board they bolt to

Spacing cannot rescue a gutter laid to the wrong fall. Brett Martin suggests 1 mm of fall for every 600 mm, and FloPlast recommends 1:350 for its MiniFlo system, so manufacturers typically recommend a gentle slope to the outlet, roughly 1:600 to 1:350 depending on the system. Set it too flat and water stands; set it too steep and a heavy flow can overshoot the stop end, so the gradient has to be judged on the run.

Brackets must also have something sound to bite into. Screws driven into a fascia with rot behind them will hold for a month and then work loose. We probe the board with a bradawl during the survey and tell you if it needs attention first. A bigger section such as the ones in our guide to gutter profiles holds more water, so it asks even more of its fixings.

4Rafter-fixed and fascia-fixed brackets

Most brackets fix to the face of the fascia. Where a house has no fascia, or only a thin one, the bracket may need to go on the rafter feet instead, using a longer arm that reaches over the eaves. On older properties the rafter-fixed type often suits the structure better than a new board.

The same questions apply whichever fixing is used. Is the timber sound? Are the screws long enough and corrosion-resistant? Does the bracket sit square to the fall, so the gutter is held at the right angle instead of tipping forward? A poorly chosen fixing is the likeliest reason a new gutter starts sagging in its second season.

When we replace long runs in one piece, such as seamless aluminium gutters, the weight per metre when full is higher, and we treat that as a reason to bring the brackets in, not to stretch them out.

5Spacing with a water butt or a heavy cast iron run

A water butt fed from the downpipe does not load the gutter directly, but a diverter that holds water back can make a downpipe back up into the gutter in a storm. If you add one, see fitting a water butt to a downpipe for how to leave an overflow.

Cast iron is very heavy before any water goes in, which is why old runs have brackets close together and a stout fixing into the rafter. If you are replacing iron with a lighter section, the spacing you inherit is generous, and you can often relax it, though we would still stay under the manufacturer's maximum, because a gutter full of leaves and storm water weighs far more than an empty one.

For an idea of what replacing a whole run involves, see gutter replacement cost, and for the other parts of the roofline that share the same board, our gutters, soffits and fascias page.