Why is my conservatory roof leaking?

A lot of conservatory roof leaks are not caused by broken seals or failed panels. They are caused by water that cannot get off the roof. When the box gutter, the valley against the house or the conservatory gutter fills with silt, leaves and moss, rainwater backs up and finds its way into the frame. Clearing them is often the first thing to try before paying for a repair.

This guide covers the usual causes, what you can check from the ground and inside, and when it really is a job for a conservatory installer.

Where the water usually gets in

Box gutters

Many conservatories, especially the Victorian and Edwardian styles, have a box gutter where the roof meets the house or another roof section. It is a flat channel that collects water from two directions. Because it is shallow and out of sight, silt builds up quietly until it overflows into the frame below.

The valley against the house

Where the conservatory roof meets the house wall, rainwater from the main roof often lands on the conservatory as well. Moss and grit washed off the main roof collect in this joint, and once it holds water the flashing has to cope with far more than it was designed to.

The conservatory gutter and its downpipe

The small gutter along the front edge of the conservatory blocks just like a house gutter. Leaves from nearby trees and moss off the panels are the usual culprits. If the downpipe outlet is blocked too, the whole gutter fills.

Moss and debris in the glazing bars

Moss and lichen grow along the glazing bars and the edges of the panels, particularly on shaded roofs. They hold water against the seals for days after rain, which is not what the seals are designed for.

Why leaks show up in late autumn

Leaves fall straight onto the roof and into the gutters in October and November, and the first heavy winter rain arrives on top of them. A conservatory that stayed dry all summer can start dripping in the first proper storm. Wind-driven rain, which Torbay gets plenty of, pushes water sideways into joints that would cope with rain falling straight down.

What you can check yourself

• Where the drip is. A leak along the house wall points to the valley or flashing. A leak at the front edge points to the gutter. A leak in the middle of the roof is more likely to be a panel or glazing bar.
• When it leaks. If it only leaks in heavy rain and stops soon after, overflowing gutters are a strong suspect. If it drips for hours after the rain stops, water may be sitting somewhere on the roof.
• The downpipe. In heavy rain, check whether water is coming out of the bottom. If not, the outlet is probably blocked.
• The view from upstairs. From a bedroom window you can often see leaves and moss sitting in the gutters and valleys.

Please do not climb onto the roof to look. Conservatory roofs are not made to be walked on or to take the weight of a ladder, and polycarbonate and glass panels can crack. Everything we do on conservatory roofs is reached with a pole and soft brush from the ground for exactly that reason.

When it is not the gutters

Sometimes clearing the gutters and valleys does not stop the leak. Signs that it is a repair job include:

• Cracked or slipped panels
• Lead or flashing that has lifted away from the house wall
• Seals or gaskets that have shrunk, split or perished
• Water coming in at the same spot in light rain, with the gutters clear

In those cases the right person is a conservatory or roofing specialist. Clearing the roof first still helps, because it lets them see what they are dealing with.

Keeping it dry

Once a year is enough for most conservatories, ideally in late autumn after the leaves are down. Roofs under trees or on a shaded side of the house go green faster and may need more. Doing the conservatory at the same visit as the house gutters makes sense, because the main roof sheds onto the conservatory and the two are linked. Our guide to the signs your gutters are blocked covers the house side.

AbraClean cleans conservatory roofs inside and out, including the box gutters, valleys and finials, across Torbay, South Devon and Exeter. See our conservatory roof cleaning service and gutter clearing, or find your area, including Paignton and Newton Abbot. Call or text Mark on 07901 563000 for a free quote.