What Is a Chimney Damp-Proof Tray?

Brick is porous, and the part of a stack above the roof is wetted on every side. A damp-proof tray, often shortened to DPC tray or just tray, is the barrier that stops that water travelling further into the house.

Where is it in the stack?

In a typical build the tray is laid into the brickwork a little above the roof line, where the shaft is still outside. It runs across the full width of the stack, usually in lead or a damp-proof membrane, with the edges turned up at the back and sides and left to run out through the face of the brick at the front. Small gaps in the joint line, called weep holes, let the water drain away.

Without a tray, rain soaked into the top of the stack finds its way down through the brick, past the roof, into the loft and on down the chimney breast. The tray cuts that path short and gives the water an exit to the open air instead.

Think of it as a gutter built inside the wall, sloping outward, which hardly anyone knows is there.

No. A tray belongs to better, later building. Many old stacks went up without one, and their brickwork dried through the flue and the warmth of an open fire. When the fire stopped being lit, the damp could stay.

How can I tell if mine has a tray?

Sometimes a line of weep holes, or a thin strip of lead poking from a joint on the shaft, gives it away. Often nothing shows, and the only way to find out is a close look from the roof, or when the stack is opened up. A roofer can check and show you a photo of what is there.

If there is no tray and the breast is damp, the tray may be missing, it may be failing, or neither. Flashing, the lead strip joining stack to roof, and the crown on top can leak into the same wall. The guide to the parts of a chimney shows which fault points to which part.

A damp patch is therefore a reason to survey, not to guess. A wrong guess means paying for work that leaves the leak running, and the stain keeps coming back.

A tray cannot be pushed in from outside. It has to sit within the brickwork, which means taking the stack down to the level where it will lie and building it back up on top.

Can a tray be added to an existing chimney?

Only by dismantling the stack above that point and rebuilding it. That is a larger job than repointing, so it normally happens when a stack is being rebuilt anyway. The page on chimney rebuilds describes how a stack comes down and goes back up.

A rebuild is the natural moment to fit one. Scaffold is up, the brick is off, and the new tray and the new flashing can be fixed together so they work as a pair. Lead flashing "can last for over 80 years" (MyJobQuote, Sep 2026), which makes it worth building the tray and the lead in as a set.

On a stack that is otherwise sound, simpler repairs often cure the damp. Check the crown, the pointing and the lead first, because damp in a breast can come from several places, and a cheaper repair may be all that it needs.

A tray fails quietly. Its signs appear indoors, not on the roof.

What should I look for?

Brown or yellow staining on the breast is the classic sign. Paint blisters, wallpaper lifts, and white salt marks bloom on the plaster. The patch often sits at roof level or in the room above, and it comes and goes with the weather, worsening after long spells of rain.

Outside, green staining or moss on the shaft around the line where the tray sits suggests water is leaving there and running down the face of the brick.

The first job is to track the leak, and that means looking at every route in turn. A leak at the flashing, a cracked crown and a failed tray can all look the same indoors, so a roofer checks them one at a time and shows you the photos. If it does prove to be the tray, rebuilding the stack with a new one is the lasting repair, and the price is written down once the survey is complete.

The full list of stack work is on the chimney repairs page.