How to install PVC guttering

However well they are maintained, old metal gutters and down pipes may eventually begin to show signs of decay. If decay is far advanced, it is well worth replacing the system with PVC guttering.

PVC rainwater systems have several advantages over the various metal types. They do not corrode, nor do they require painting for protection — though they can be painted to suit colour schemes. Because PVC guttering is light, sections of it are easier to handle than their metal counterparts—an important consideration when you are working on a ladder. Being cheaper than cast iron, PVC has virtually replaced it for home building and renovation in Britain.

Planning the new assembly

Sections of PVC guttering can be joined together in a variety of different ways. But with all types of half-round guttering, you fix the system to the exterior of the house in more or less the same way. The gutter sections are clipped into brackets screwed to the fascia boards beneath the eaves of the roof. The downpipes have wrap-around pipe clips which are screwed directly to the walls. Some other systems require no brackets for the gutters because they are screwed directly to the fascias.

You can use sections of guttering in full lengths where there is enough space for fixing, or cut it to any length required using a fine-toothed hacksaw.

Before you take down the existing guttering, measure it carefully to give you the lengths for the new gutters and pipes. Count and measure, the stop-ends, outlets, shoes, swan necks, and internal and external angles to work out the number and size of each part you will require.

When you are calculating the number of support brackets and pipe clips needed, bear in mind that the existing system may not have been fitted with an adequate number. Gutter support brackets should be spaced no further than 1m apart, and ‘pipe clips a maximum of 2m apart.

Make a rough sketch of the proposed layout of the new assembly. This will help when you come to calculate the parts required and is also useful when you are carrying out the actual installation.

Removing cast or galvanized iron guttering

When you have bought all the replacement PVC components, you can start to dismantle the existing system. If your house adjoins another property, start at the joint nearest the dividing line between the two houses. If not, start at any convenient point along the run.

Remove the bolt holding the first joint together, using a junior hacksaw if necessary. Repeat the process for the joint at the other end of the length and then remove the section. When removing a long piece of guttering, take care not to let its weight catch you off balance while you are on the ladder.

When you have removed a section and taken it to the ground, unscrew the supporting brackets from the fascia board. If the fixing screws of a bracket are too corroded to unscrew, use a claw hammer to lever them away. Do not knock upwards with the hammer when you are trying to dislodge a stubborn support or you may crack the tiles immediately above.

If you are dealing with Ogee-section guttering, either unscrew the fixing screws holding the lengths to the fascia board, or, if they are corroded, cut through them with a junior hacksaw. If these methods fail, use a bolster to lever between the gutter and the fascia boards.

Some cast iron systems are supported by brackets which are screwed to the roof rafters. To gain access to the fixing screws on such brackets, you may have to remove the slate or tile immediately above it with a slate ripper. In this case, it may be easier to saw through the brackets and fit the new system directly to a fascia, if you can add one.

When you come to dismantle a downpipe, start by removing the outlet section at the top and if fitted, the swan neck. You should be able to dislodge these by hand by pulling upwards but if not, use a hammer to knock them from place. Remove the downpipe brackets by levering out the pipe nails with a claw hammer. Where necessary, hold an offcut of timber against the wall so that you get more leverage on the hammer.

Assembling the new system

Before you erect the new guttering, check that the fascia boards are in a sound condition. It is well worth taking the opportunity to repaint the fascias before fixing the new guttering.

Scrape off any paint that has formed in ridges around the old guttering, then wash down the fascia and when dry apply primer to any bare wood. When this has dried, key the surface by rubbing it over with a medium grade of glasspaper. Paint the boards with two undercoats and one top coat then leave them to dry out before erecting the new guttering.

Boards in particularly bad condition may have to be replaced altogether. This is not always a particularly easy job, and you may find it involves disturbing the lowest course of slates or tiles on the roof.

To assemble tbe system, begin by fixing the supporting brackets. Place one bracket at the top end of a run to correspond with the old one, and one at the bottom end in a similar position. Attach a length of string between the two brackets and make sure that it is taut. Check the string with a spirit level to make sure that it slopes towards the outlet position—the correct slope need be as little as 25mm in a 15m run—then use it as guide for positioning the intervening brackets. It may be that you can fix all the new brackets in the positions of the old ones. But check constantly that both the spacings and the fall are correct.

When you come to an internal or external angle at the corners, hold the appropriate part in place and mark the appropriate bracket positions: these vary according to the brand of system that you are installing.

When you have marked all the bracket positions, drill holes for the mounting screws into the fascia boards and screw each bracket home. With all the brackets in place, you can start to position the guttering lengths within them.

Cutting and fitting

When you are cutting new gutter lengths, it is important to make sure that the cut ends are square. You can do this by fitting a spare section over the piece to be cut and using it as a template to draw the cutting line. Once you have sawn through a section, smooth the cut edges with a medium file.

Start fitting the guttering at the top end of a run. Clip the lengths into position in the brackets and join sections together, following the manufacturer’s instructions.

Because PVC tends to expand and contract, even with quite small temperature variations, some systems make allowance for movement at each joint. In this case, the union clips holding sections together have marks on either side with which the ends of adjoining gutter sections are aligned. The resulting gap between sections allows for maximum expansion and contraction without weakening the new seal.

If you are faced with the problem of connecting the new guttering to a neighbour’s iron system, special adaptor fittings are available for joining the two materials. Dry out and clean the end of the iron section, using a wire brush to remove any traces of rust. Apply sealing compound to the area then press the adaptor into place. You can now join the PVC section, following the manufacturer’s instructions.

Fitting a downpipe

Unlike cast iron systems, the swan necks for PVC guttering are not manufactured in one piece. Instead they are made up of an offset socket, an offset spigot and an offcut of pipe. The length of pipe determines the angle of the bend, thus giving you more flexibility in positioning the downpipe than you would have with cast iron or galvanized metal.

To erect the downpipe, fix a plumb-line with a nail or drawing pin to the fascia board behind the outlet. You can then use the string as a guideline down which to mark the pipe clip screw positions.

Place one of the clips around the bottom of the offset spigot, hold it temporarily in place on the wall, and mark its screw holes. Next, measure and cut the length of pipe to fit between the socket and spigot. To make sure that the cut end of the pipe is square, mark the length to be cut then wrap a paper template around the pipe at the mark. Bore the holes for the pipe clip screws into the wall , plug the holes with wall plugs, then fit the swan neck in position.

Fit the downpipe down the wall, joining the sections according to the manufacturer’s instructions, and fix a pipe clip at each joint to support the pipe. Finally, fit the shoe piece that lets into the drain or soakaway at the bottom of the pipe a’nd attach the last clip.

Once the whole assembly has been fitted and joined, test the system by emptying a bucket of water into the gutter at the highest point of each run to check that there are no leaks.

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