Apron flashing
What is a lead apron flashing?
The short answer
A lead apron flashing is the sheet of lead that covers the front, or downhill face, of a junction where a roof meets something upright, such as a chimney, dormer or the front of a window. It lies over the tiles below, turns up the vertical face and is tucked into the brickwork, so water that runs down is carried over the joint and out.
Where the apron sits on a typical roof, how it is made and fixed, and the signs that yours has failed.
What the apron does
An apron is the part of the flashing at the foot of an upstanding feature. Water running down the roof meets the front of a chimney or dormer cheek and has nowhere to go but sideways or into the gap. The apron closes that gap. Its lower edge lies over the roof covering, its upper edge turns up the face of the brickwork or timber, and the water slides over the top of it and carries on down the slope.
It is only one part of a set. The sides are covered by stepped flashings or soakers, the back by a gutter or back flashing, and the apron joins them. The set works as a whole, so a failed apron is rarely the only fault on the stack. Our guide to lead flashing shows how the pieces fit together, and why the order they are laid in matters as much as the metal.
How an apron is made and fixed
The leadworker cuts a piece wide enough to cover the face and reach well over the roof, then bosses and folds it to the shape. The top edge is turned into a chase, a slot cut in the mortar joint, and held with lead wedges, then pointed. The lower edge is dressed down over the tiles, shaped to the profile of the roof covering so there are no gaps for wind-driven rain to find.
Along its lower edge the lead is held with clips, so that gales do not lift it. Our answers on lead wedges and lead clips go into those details. Royston lists lead codes 4, 5 and 6 as suited to flashings, and the code is chosen by the size and exposure of the piece. Longer, more exposed pieces on a tall stack often call for a different code from a short piece on a small dormer, and we set that out in the quote. The apron should also be cut to suit the roof covering it lies on, whether that is plain tile, slate or concrete interlocking tile.
Signs that an apron has failed
You can often spot a failed apron from the ground. Look for lead that has lifted along its foot, split on a fold, pulled out of the joint above, or been buried under a smear of sealant. Mortar missing from the chase is another sign. Indoors, the usual alert is damp on the chimney breast or a brown stain spreading across the ceiling beneath, and it often shows after driving rain from one direction. In the loft, check the brickwork for dark marks and the timbers beside it for softness.
A small crack does not always mean the whole piece is finished. A short split can sometimes be repaired, and a lifted edge can be refixed. But if the lead has thinned, been patched several times or no longer matches the shape of the roof, it is better to replace the apron than to keep patching. On the survey we take photographs of the apron from several angles and tell you whether it is a repair or a replacement, and why, before any price is given.
Typical costs and published lifespan
Typical UK figures come from MyJobQuote, in a chimney leadwork guide dated 22 September 2026. It gives a patch repair at £150 to £250, and a full replacement at £350 to £460 without scaffolding or £700 to £920 with it. The same guide says lead flashing can last for over 80 years in good order. These are national guide figures, not our prices.
What counts most is how big the chimney or dormer is, how many pieces need replacing, and whether scaffolding is needed to reach the job. A stack on a three-storey house with a steep roof costs more to reach than a bungalow dormer. Look at whether any quote you are given covers VAT and scaffolding. Once we have surveyed, our quote reaches you in writing with one overall price for the job. For the wider picture of what chimney leadwork costs, see our page on chimney lead flashing cost.
Look at the whole junction, not only the apron
If the apron has failed, check what it was protecting. Water that has been getting in around a chimney for some time can leave rotten battens, damp brickwork and stained plaster. The apron is the visible repair, but the work underneath may matter more, and it is cheaper to find it now than after the next winter.
It is also worth checking the neighbours: the soakers, the back gutter and the pointing around the stack. Doing one piece of the set while the rest is worn can mean a second visit and a second scaffold. The lead roofing and leadwork page explains how we treat a junction as a whole. If the stack has not been inspected in a long time, have it looked at before the winter gales arrive.
Related questions
Apron flashing questions
Is an apron flashing the same as a cover flashing?
Not quite. An apron sits at the foot of an upstand and lies over the roof covering. A cover flashing hangs down over a joint to shed water across it. A chimney usually has both, with different names for each piece.
Can I seal a lifted apron with silicone?
Sealant can hold for a short time, but it dries out and it hides the fault. A lifted apron usually means the fixings or the clips have failed, and that wants refixing, not smearing over.