Steel eaves gutters – rusting

Causes

There is insufficient fall to drain water 

There are leaves or other debris in the gutter, or weeds growing, retaining moisture and preventing water from draining away 

Metal debris (swarf and roof offcuts) were left in the bottom of the gutter when the roof was installed 

There are incompatible metals together, resulting in corrosion – for example, copper guttering with galvanised steel inserts

There is water flowing from copper (vent pipe or downpipe) onto galvanised or zinc/aluminium or aluminium/zinc alloy steel

Listed under: metal, steel, Roof, gutters, durability, corrosion, rust

Cause

There is insufficient fall to drain water 

Repair

  • metal eaves gutters should have a minimum fall of 1:500 (2 mm per metre). Where the required fall cannot be provided, PVC gutters that do not rust are a better option

  • where the rusting is relatively light and has not gone right through the steel, remove rust by lightly sanding. Apply a zinc-rich/corrosion-inhibiting primer, then at least two coats of paint designed for use on steel

  • where the rust has gone right through the steel at multiple points, the gutters should be replaced

  • when working at height, always let someone know. Ensure the access ladder is in good condition and is securely set up on a solid level base. The correct angle for the ladder is 1 metre out from the wall for every 4 metres of height. 

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Cause

There are leaves or other debris in the gutter, or weeds growing, retaining moisture and preventing water from draining away 

Repair

  • clear away leaves and other debris on a regular basis as frequently as required. Leaf guards may be fitted to keep gutters clear

  • where leaves come from tree branches overhanging the roof or gutter, consider removing the branches

  • ensure the gutters have a minimum fall of 1:500 (2 mm per metre) to prevent water ponding

  • where the rusting is relatively light and has not gone right through the steel, remove rust by lightly sanding. Apply a zinc-rich/corrosion-inhibiting primer, then at least two coats of paint designed for use on steel

  • where the rust has gone right through the steel at multiple points, the gutters should be replaced

  • when working at height, always let someone know. Ensure the access ladder is in good condition and is securely set up on a solid level base. The correct angle for the ladder is 1 metre out from the wall for every 4 metres of height. 

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Cause

Metal debris (swarf and roof offcuts) were left in the bottom of the gutter when the roof was installed 

Repair

  • clean out the gutters then follow the guidance for the repair above

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Cause

There are incompatible metals together, resulting in corrosion – for example, copper guttering with galvanised steel inserts

Repair

  • galvanic corrosion can occur when two incompatible materials are in direct contact with each other in the presence of moisture, or water runs from one onto another

  • one of the materials should be replaced with a material compatible to the other. For example, if copper guttering is fixed with galvanized steel brackets, replace the steel brackets with brackets made of brass

  • ensure the gutters have a minimum fall of 1:500 (2 mm per metre) to allow water to drain and evaporate quickly (all metal corrosion, including galvanic corrosion, requires the presence of moisture)

  • repair or replace the rusted guttering as described above

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Cause

There is water flowing from copper (vent pipe or downpipe) onto galvanised or zinc/aluminium or aluminium/zinc alloy steel

Repair

  • the previous repair could be followed, with one other option possible – one of the surfaces could be coated. Properly-applied and maintained coatings provide a separation that prevents or reduces the risk of galvanic corrosion occurring
  • when working at height, always let someone know. Ensure the access ladder is in good condition and is securely set up on a solid level base. The correct angle for the ladder is 1 metre out from the wall for every 4 metres of height. 

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