How to remove old gutters and rain pipes and replace with a new plastic rainwater system.
Plastic gutters and downpipes
By far the most common form of rainwater system for domestic use is now made of plastic. This has many advantages – lightweight, easy to cut, easy to fit, durable and maintenance free.
It is essential to use a suitable and stable means of access when working above ground level.
Removal of old rainwater goods
When dismantling an old system, great care should be taken. Many are particularly heavy.
To be safe, it is best to have an assistant help you with this and use a rope to lower the old sections to the ground.
Choice of new rainwater system
There are many different sizes available and you should select one at least as big as the old system. For new work, you will need a system whose capacity is sufficient for the size of roof being drained. Your merchant will be able to advise on this. An undersized gutter will overflow in heavy rain.
Measure the overall length of gutter required. Divide this by the standard gutter length. Always round your answer up so that you will have sufficient for the job.
Do the same for the total length of the downpipes required. Then make a note of the number and type of fittings needed: brackets, joining pieces, stop ends, outlets, stopend outlets, pipe clips, bends.
Installing new gutters and downpipes
Inspect and, if necessary carry out repairs and redecoration of the fascia boards – they are much easier to work on without gutters in the way.
Take an offcut of guttering and mount it on a bracket. Hold this against one end of the fascia board as close to the tiles as practical. Mark the top of the bracket. If this is too awkward, mark the bottom, but remember this when you are fitting the rest of the gutter. Tap in a nail and attach a piece of string. Now move to the other end of the fascia and, pulling the string taught, use a spirit level to position the string horizontally. Tap in another nail to secure it.
This process should be repeated for all the fascias.
Now, use a plumb line to mark a positions on the fascia which are vertically above the gullies or other rainwater drainage points on the ground. These are the positions at which the gutter will need to be lowest.
The fall or incline of a gutter will need to be at least 1:600. This means that for each 3m length a fall of 5mm is needed.
Where there is one outlet at the end of the fascia, calculate the fall needed for the length and lower the string line at the outlet end.
Where there are outlets at both ends, tap a nail in to hold the string at the middle. Lower both ends to suit the length from the middle to the end of the fascia.
Where the outlet is to be part way along a fascia, lower the string at this point to suit the longest length and support with a nail.
Fitting the outlet
Always use non rusting screws for fixings.
The easiest way to install the system is to start by fitting the outlet piece. Mount this on the fascia at the sting level. Now, mount a bracket 100mm in from the furthest point (end or corner). This will allow space for the last fitting. Fix gutter brackets at regular intervals between, not more than 1 metre apart, taking care that they will not foul any join pieces.
Fitting the gutter
Starting at the outlet, lay the first length of gutter on the brackets. Position it so that the end is about 5mm from the stop end inside the outlet piece to allow for expansion. Tip the back edge of the gutter under the clip at the back of the brackets, then pull the front edge down gently into the front clip. Mount a jointing piece at the end and continue in the same fashion. Always allow 5mm clearance from the gutter stop within fittings for expansion. The last length will need to be trimmed. This is easily done with a hacksaw. To cut it square, use a straight edged piece of paper wrapped round the gutter and back on itself to provide a guide. File off any rough edges. The last length will fit either into a corner piece which will need to be mounted at the string level, or a stop end. With stop ends, allow the gutter to run past the end of the fascia by about 50mm.
Fitting the downpipe
At the outlets, fit an offset bend pointing back towards the wall. Hold a second offset bend at a position a little off the wall to line up with the downpipe which will be held on brackets. Measure and cut a length of pipe to connect these two offsets in a ‘swan neck’ arrangement. Now hold a length of downpipe onto the bottom bend and place a pipe bracket over it. Mark the fixing holes and drill and plug the wall accordingly. Fasten the first section of pipe with the bracket. Mark and fit further brackets at 2m intervals adding new lengths of downpipe as required.
At the gulley
At the bottom, the pipe will need to be cut to length in the same fashion as for the gutter.
If the downpipe is to be fed into a gulley underground, cut it to length so that it reaches sufficiently into the gully housing, then assemble. Make good around the pipe where it feeds into the ground.
Where the downpipe feeds over an open gully, trim it 50mm above the grid, and fit an outlet shoe.
If desired, the downpipe assembly may be welded using the appropriate solvent in a similar fashion to that for plastic waste pipes.
Follow the manufacturer’s instructions and pay particular attention to the safety precautions.