Chapter one
Flint gables and the lead that seals them
Flint and brick walls are only as dry as the lead strips where roofs meet them.
The Victoria County History describes cottages in Funtington built of flint and brick, alongside others with seventeenth-century timber framing. A larger house at the west end is flint with seventeenth-century brick dressings and a porch gable carved with the date 1655. A wall like that is a patchwork of different materials, and each one takes in and releases water at its own rate. Flint cobbles are dense and shed water, but the mortar between them is porous, and where a roof slope meets such a wall the junction has to be sealed with lead. The flashing, the answer to that, is a folded lead strip pushed into a cut joint in the wall and laid down across the tiles, so rain follows the metal and not the gap. Sealant smeared along that joint will stop working within a few winters, because the wall and the roof move at different speeds.
At a glance
- Flint walls hold water in their joints
- Lead flashing is cut into the wall, not stuck on
- Code 4 lead suits most everyday flashing

1.1 Gables, verges and chimneys
On a gabled cottage the verge, the sloping edge of the roof at the gable, is the most exposed line. If it has been bedded in mortar alone, a gale can lift the end tiles and leave the wall top open. A chimney stack gets a flashing on every side, plus a back gutter, a small lead channel behind it that sends water round the stack. When we find water coming in near a stack, the fault is as often at the back gutter as at the stack itself.

1.2 What the lead is made of
Lead sheet is sold by code, which refers to its thickness. Leadworx calls code 4 the standard for everyday flashing, code 5 the step up for general and vertical work, and code 3 a soaker grade only. A flashing in a sound code can outlast the tiles around it, with published figures of over 80 years. Our lead roofing page covers the choice of code, the width of the laps and how long we expect each piece to hold. Sun and rain wear lead at different rates on different slopes, so we photograph every run we replace, and the record stays with the house. Where an old flashing was only caulked, we cut a proper chase and set new lead into it, because a joint that holds only on the day it is made does not suit a wall exposed to the Downs.
Lead sheet codes for a flint-and-brick house
- Code 3 (1.32 mm)
- Soakers only
- Code 4 (1.80 mm)
- General flashing work
- Code 5 (2.24 mm)
- General, vertical and pitched use
- Flashing life
- Over 80 years, over 100 for higher codes
Source: Leadworx; MyJobQuote, fetched October 2026





