How far apart should gutter brackets be?

Gutter brackets are the clips or arms that hold the channel to the fascia board or the rafter ends. For plastic systems, Brett Martin's guidance on installing rainwater guttering says the supports should be no more than 900 mm apart. That figure comes from a manufacturer and not from a British Standard, so the leaflet with the system you actually have is the document that rules.

It is a ceiling. Fitting brackets exactly at the maximum leaves a full gutter, loaded with water and silt, hanging on its longest unsupported span. A careful fitter works well inside the figure, and closer still where the roof is large or the run is exposed. A sagging belly between two brackets is the clearest sign they were set too wide, or that one has pulled loose. Count the brackets along a run while you stand back from the house: a gap that looks twice as wide as its neighbours is worth a closer look.

Spacing is not even along the whole run. Every joint needs a bracket close to it, so that the seal is not pulled open under load or twisted by a gust. Corners, stop ends and the outlet over the downpipe take more weight and movement, so they get support on either side. Where two gutter lengths meet, a bracket either side of the union stops the joint twisting.

The same applies to any length that carries a long valley or the water from a dormer, because the flow there is heavier than elsewhere. If you can see a joint opening, a gap between the gutter back and the board, or water pouring from a union, a missing or loose bracket is a prime suspect. A failed seal and a failed support can look alike from the ground, so the roofer checks both before deciding which one to renew.

Cast iron is much heavier than plastic, and a full cast-iron run holds a lot of water on top of its own weight. It needs substantial brackets screwed or spiked into sound timber or masonry, and a gap closer than a plastic run would use. The right spacing comes from the maker or from the pattern of the original, which usually shows where the old fixings sat.

If the existing brackets on a cast-iron run are rusted, loose in the board or visibly bent, the run has moved off its line, and both the fall and the flow suffer. A heavy section hanging unevenly can also crack at a joint. Our answer on cast iron guttering repair goes through what can be saved. Aluminium sits between the two, and again the manufacturer's sheet sets the gap.

A bracket is only as good as what it is screwed into. A rotten fascia, a split rafter end or a board with old fixing holes gives the screw nothing to bite. Corroded or undersized screws can snap or pull out, and a bracket clipped into a gutter that has gone brittle cracks at the clip. These are the usual causes when a run that once sat true begins to dip.

Drive new screws into fresh timber rather than back into the same holes. If the fascia itself has softened, the board needs replacing before any bracket will hold, which our answer on rotten fascia boards explains. Re-using brackets from an old run on new gutters is a false saving, because the clips are the part that fatigue and sun have worn. A bracket that looks fine can already have lost its spring and let the gutter sit loose in it.

From the ground, look for a dip between brackets, a gutter pulling away from the board at one end, or a downpipe leaning out at the top. During rain, watch for water pouring over the front of the lip at a low point or dripping at a joint. These point at support problems rather than at a blockage, though the two often occur together, because a full gutter is a heavy gutter and the extra weight is what finds the weak bracket.

Do not hang on a gutter or lean a ladder against it to test it, because a plastic run can crack under that weight and drop you with it. A roofer working from proper access can count the brackets, measure the gaps and tell you whether to add a few or renew the lot. We take pictures of each loose or missing support, and once the survey is complete the price arrives as one total in writing. The guttering, soffits and fascias hub lists the full range of work, and our answer on a sagging gutter covers the repair.