How To Repair A Leaking Gutter Joint

The seal in a PVC guttering joint is made when the gutter is clipped into place. The clips on the fitting and on each fascia bracket along the length of the gutter apply a downwards force, pushing the gutter down onto the rubber seal that is located within the fitting. This downwards force compresses the seal, creating a watertight seal.

There are several factors that can cause this seal to fail, all of which can be quickly identified and easily fixed. These are the most likely causes;

Expansion and Contraction of the Gutter System

All PVC gutter systems expand and contract with changes in temperature. Stand outside on a warm day just as the sun's rays fall onto the gutter and you will hear a clicking noise - this is actually the gutter catching on the brackets as it expands along its length.

All gutter fittings have an insertion mark on the inside, showing exactly where the gutter should be laid during the installation. This point is calculated to ensure that on hot days, the gutter can expand without pushing against the adjoining length, and on cold days that the seal is still covered and compressed when the gutter has contracted. Therefore if the gutter has been cut too long or too short, extreme thermal movement (either hot or cold) will weaken the joint by reducing the pressure that the gutter applies onto the seal. This effect is usually noticed soon after installation but it has been known to occur over longer periods, particularly in colder weather.

Dirt or Grit Caught in the Seal

This can happen in cold weather, when a contracting length of gutter draws a small piece of sediment or grit that has been washed off of the roof onto the seal as it moves. This prevents the gutter from seating correctly down onto the seal, allowing a small amount of water to pass through the gap.

Damaged Gutter Fittings

Damage to gutter fittings is usually caused by outside interference - often a slipped tile or perhaps a ladder being leaned against the gutter fitting. Less commonly it can also be caused by snow loading in the gutter. Once a fitting has broken, the compression on the seal is immediately reduced, allowing water to flow through the gap between the gutter and seal.

Wear and Tear

This is usually combined with one of the other factors above. Older PVC gutter systems were not as well engineered as their modern equivalents, and both the moulded plastic and the rubber material in the seals had a shorter life cycle than the guttering of today. On an old plastic gutter system, any type of outside force or interference on the gutter or fittings can cause a breakdown in the seals that will manifest itself as a leak.

Replacing the Joint

Fortunately, replacing a leaky gutter fitting is a relatively simple task. We would never recommend replacing just the seal rather than the whole fitting. This is because for a seal to work effectively it needs to be a perfect fit in the slot moulded within the fitting. With more than a dozen PVC gutter systems on sale in the UK, the chances of locating the correct seal for your fitting is low, and even if you do track down the correct type of gutter it is quite likely that either the seal or the design of the fitting will have changed since it was installed. Gutter fittings are relatively inexpensive, and many are interchangeable (the supplier will be able to tell you if their fitting will work with your system), so it is much more sensible to replace the whole fitting.

Once you have purchased the new fitting, the first task is to remove the length of gutter in question to gain access to the fitting. To do this, pull the retaining clips on the fittings and fascia brackets upwards towards you whilst pushing the gutter inwards, easing it out from under the front clips. Repeat this action on all fittings securing the front of the gutter, then when the front edge is free from the clips roll it away from you to release the back edge of the gutter. The piece of gutter can then be lifted out completely.

Now you can unscrew the faulty fitting, and replace it with the new one, screwing it back to the fascia board through the locating holes. With the new fitting secured in place, clean the gutter with a damp cloth to remove any dirt or grit, and double check the length against the insertion marks by laying it loosely in the fittings. If it is too long you will need to trim it with a sharp, fine-toothed saw - it is unlikely to be too short, although if it is you will need to replace the length of gutter.

Spray the seals of the new fitting with silicon lubricant (this improves long term performance) and insert the gutter. To do this, slide the back edge of the gutter up under the retaining clips at the back of the fitting and the fascia brackets and check that the felt protruding from the bottom of the roof is inside the gutter and not trapped behind it. Then, ensuring that the ends of the gutter are correctly aligned with the insertion marks on the fitting, pull the front of the gutter down until the fascia brackets and the clips on the fitting click in to place. Once all clips are in place, make a final check that the felt is sitting safely inside the gutter, and the job is done.