How to fix and maintain gutters and downpipes

Gutters and downpipes play a vital role in protecting your house from the effects of rain. But unless guttering is regularly maintained it will deteriorate, causing leaks or overflows. The damp in turn causes structural damage which often costs a fortune to repair.

To clear a blockage in a straight downpipe, tie a rag firmly to one end of a long pole and poke it down the pipe. Once the blockage has been dislodged, flush the pipe thoroughly with a hose.

If the downpipe is fitted with a hopper head carefully clear by hand any debris which has collected. Try not to compress the debris, or it may cause further blockage in the downpipe.

With plastic hopper heads, wipe the inside with a cloth and soapy water once the debris has been cleared.

With some systems, the guttering is positioned some way out from the wall and water is directed into the down-pipe through an angled section known as a swan neck. To clear a blockage here, use a length of fairly stiff wire in place of the pole so that the bends may be negotiated.

If a blockage is beyond reach, the lower part of the downpipe will have to be dismantled.

Sagging gutters

If a gutter sags, water may overflow or the joints may crack and leak. A bucket of water poured in at the highest point of the system reveals any such defects.

The commonest causes of sagging are broken or bent brackets, or loose fixing screws or spikes. Most guttering is supported on brackets screwed either to the fascia boards underneath the eaves of the roof or to the ends of the roof rafters.

To rectify a sagging gutter, remove the defective sections and examine the brackets to see if they are firmly fixed. If they are not, use longer screws to secure them. Where brackets are bent or corroded, replace them with matching new ones.

Replacing a rafter bracket normally involves removing the roof covering directly above it, though this problem can often be overcome by fixing a fascia bracket adjacent to the faulty rafter bracket to give the necessary extra support.

Ogee section guttering differs from other types in that it is screwed or spiked directly on to the fascia. Sagging here is usually caused by the fixing devices rusting and then pulling away from the fascia. In this case, plug the holes and re-fasten with new screws or spikes.

A common fault with guttering occurs where the slope or fall towards the downpipe outlet becomes distorted —because of faulty installation or settlement of the house itself. Too steep a fall causes water to overflow at the downpipe outlet. Too shallow a fall results in a build up of water and sediment along the run.

To determine the correct fall for an incorrectly aligned section, tie a length of twine along the top of the gutter—from the high end to the outflow point—and use it as a guide to reposition the intervening supports. The gutter should fall 25mm for every 3m of its length.

Leaking joints in cast-iron

The joints in cast-iron gutter systems are held together by nuts and bolts which are usually screw-headed. A proprietary sealing compound—often a mixture of putty and red lead or a mastic sealer—is sandwiched between the two ends to make the joint watertight.

A leaking joint may be patched up by cleaning the area with a wire brush and applying one or two coats of bituminous paint. However, for a more permanent repair the section on one side of the leaking joint must be removed, cleaned and replaced. If the removed piece is in the middle of a run, two new joints have to be made—one at each end of the section.

Start by removing the bolts which hold the joints together. These may well have rusted and seized—in which case apply penetrating oil to loosen them. If this fails, saw through the bolts with a junior hacksaw.. With Ogee-section guttering, remove the screws holding the section to the fascia as well.

Lift out the loosened section— making sure as you do so that its weight does not catch you off balance —and take it to the ground. Returning to the guttering, chip off all traces of old sealing compound from the hanging end and scour it thoroughly with a wire brush. Repeat the cleaning operation on the removed section.

Apply fresh sealing compound to the socket section of the joint, spreading it in an even layer about 6mm thick. Relocate the removed

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I gutter section, screwing it to the fascia or laying it on its brackets and fitting the joints together.

Insert a new galvanized bolt into the joint from above. Screw on its securing nut, tightening gently so that the joint closes up and squeezes out any excess compound. Trim away the excess with a putty knife , wipe over the area with a damp rag, then repeat the operation for the other joint. Finally, repaint the joints with one or two coats of bituminous paint.

Leaking joints in plastics

Leaks from plastics guttering can be just as damaging as those from cast-iron and should be attended to as soon as possible.

In most plastics guttering systems, the sections are connected by union clips, lined with replaceable rubber seals. In some cases, the seal is positioned in the end of one section of gutter with a separate clip used to secure the joint. When the clips are sprung home, the gutter ends compress against the pad to form a watertight joint—but this can leak if silt finds its way in.

To replace a seal, undo the clip holding the ends together, lift out the old seal and thoroughly clean the surfaces which come into contact with it. Fit a new seal of the same type and clip the joint back together by squeezing the ends of the gutter slightly and snapping the union clip over each edge of the section.

On systems which use combined union brackets, silt bridged joints are used. The silt bridge clips into the union to prevent debris working its way into the joint and causing leaks. Leaks in such joints will be due to cracks—either in the bridge or in the union bracket itself—and can be remedied by replacing the defective part with a matching new one.

To fit a new silt bridge, hook one end under the front of the union clip and snap the other end under the lip at the back of the gutter.

Replacing a cast-iron section

If the whole system has eroded, it may be advisable to replace it with plastics guttering.

However, if the rest of the run is still in good condition, replacing a corroded cast-iron section is well worthwhile.

Where possible, take the old section to a builder’s merchant and obtain a matching replacement. As well as the shape and diameter, check that the new section matches the existing joints. If not, buy the appropriate union at the same time.

Cast-iron guttering is normally sold in 1.8m lengths, so the new section may have to be cut to fit. When measuring it up, take into account any overlap for the joints or new joint unions.

To cut it, lay the old section over the top of the new and use it as a guide. Mark the new section in pencil and lay a strip of masking tape along the mark, towards the waste side, to give a clearer guide. Cut the section with a large hacksaw.

Mark the positions of the joint bolt holes and punch and drill them to a diameter of 8mm before you fit the new section into place.

Cast-iron downpipe repairs

Cast-iron downpipes are usually attached to walls by pipe nails driven into metal, lead or wooden plugs. The nails run through cast metal brackets some of which have spacers behind to prevent contact between the pipe and the wall. Brackets often come loose, making the pipe dangerous.

To secure a loose bracket, start by removing the bracket nearest to the ground and repeat the operation up to and including the bracket that is loose. To remove a bracket, lever out the nails with a claw hammer. Use an offcut of timber held against the wall to obtain the necessary leverage. Withdraw the section of corroded downpipe. Where the joints have been sealed and do not fall away easily, heat them with a blow lamp to loosen the sealing compound or chip the compound away by hand.

Remove the loose plugs by digging them out of the masonry, and make up replacements—slightly larger all round than the holes—from pieces of 12mm dowel. If necessary, extend the holes with a 12mm masonry drill. Drive the replacement plugs into the wall until they are flush , check that they are firm, then refit the downpipe.

In many houses, downpipe joints are unsealed. If dirt collects in an unsealed joint, water may gather and freeze and crack the pipe. Avoid this by filling any unsealed joints with a mixture of red lead and putty or a proprietary mastic. Wipe it smooth with a rag then seal the joint with a coat of bituminous paint. Do the same with sealed joints that have become loose, having first chipped off the old compound.

Replacing an enamelled section

Gutters made from thin-section aluminium or galvanized steel, finished with white baked-on enamel, are less subject to rust than cast-iron gutters. But they are apt to dent sometimes just by your leaning a ladder against them.

The procedure for replacing a damaged section is much the same as for plastics. First, jam a block of wood inside the gutter while you draw the fixing spikes with a claw hammer, and disconnect the damaged section at the nearest joints. Cut the new section with a hacksaw, using the old one to measure the correct length, and file off the burrs on the cut edges. If you are using spike supports, drill holes through the new section to receive them.

Next, clean off the old sealing compound from the undamaged sections, as described above. Fill the joint connectors with sealing compound, slip them into place, and fit the new gutter section, spiking it into place. Finally, bend over into the gutter the top ends of the connectors if these are designed with fold-over tabs.

At external corners, as with other types of gutter, you need two fixing spikes—one into each length of fascia.

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