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Repair and Replace Lead Flashing

Skill Level: Beginner



Anywhere a tile or a slate roof meets brickwork or masonry; there will be lead flashing to seal the joint. Lead flashing must withstand fluctuating weather conditions, year in, year out. Extreme temperatures, do in time take their toll; making repair or replacement necessary. Lead is used because it is a tough, durable material which has the ability to expand and contract with fluctuating temperatures. This quality is essential on a roof which must tolerate the seasonal elements. Lead is also very malleable, and can be formed and shaped with relative ease.



The first thing to keep in mind is safety! With flashings you will invariably be working at height, and so must ensure you are always working from a safe and stable, platform or footing. When using a ladder, tie it off from a secure anchor location, or have someone foot it for you. Never work in windy conditions. There will be a bit of chipping out to do, so wear eye protection.

Fine Cracks

It’s worth catching cracks in flashing in the early stage if you can. Repair is so much easier. Repairing cracks at this early stage requires simply the injection of a bituminous sealer into the crevices, using an applicator gun. Some commercial sealants are available in a range of colours, making matching up to an existing colour scheme easier

Small Holes and early Signs of Corrosion

Small holes and areas of slight corrosion are best repaired using self –adhesive, metal backed flashing strip. Again, very simple; cut a piece of flashing strip to the required size, peel the backing off and apply the tape. Smooth and flatten down, Job done.

Repairing Flashing Mortar

The top edge of lead flashing is always bedded into the brickwork between two courses of bricks. With time, and the effects of the elements, the mortar holding the flashing in place becomes loose, and therefore vulnerable to water ingress.

Where mortar has become loose and is crumbling, you will need first to rake out this damaged area in order to obtain a good fixing point for the flashing. When you have raked back approximately 13mmor so, feed the flashing back into its slot, and re-point with a suitable mortar mix

Replacing Lead Flashing


Where the flashing is so badly corroded or is damaged beyond repair, then the most effective thing to do is; remove the old, and replace with self-adhesive metal backed flashing strip. The sequence of stages in the removal and replacement are as follows;
Remove the old flashing. Chip out the old mortar using a club hammer and cold chisel.
Clean out thoroughly the crevice between the bricks using a wire brush.
Re-point the whole of the length to be fitted with new flashing. We shall be using self adhesive flashing here, so will not be bedding it into the brickwork. Allow to dry.
Paint a band of flashing primer on the wall and roof where the flashing is to be attached. Allow to dry as per the manufacturers recommendations.
Cut TWO pieces of flashing strip to the correct length.
Peel off the backing and lay the strip half on the brickwork, half on the roof. Roll out and smooth the strip down using a wallpaper seam roller, making sure it is well stuck down.



Corners are a little tricky, but are important!
For internal corners simply make a snip at the lower edge of the strip, and overlap the edges. Smooth and flatten down.
For external corners, fit a square patch of flashing around the corner, before attaching the main piece. Use a craft knife to trim and cut the patch to suit the contours of the corner. Smooth and flatten down.

The Final Strip

The second strip of flashing cut is positioned so that its top edge is about 50mm above the first strip laid. Apply it in the same way as the first strip especially the corners. Finally, paint or coat the flashing to the desired method

Tools you will need:
Faithfull 1.8Kg / 4Lb Fibreglass Handled Club Hammer
Faithfull 1.8Kg / 4Lb Fibreglass Handled Club Hammer
- Stanley 4-18-298 3 Piece Cold Chisel Set
Stanley 4-18-298 3 Piece Cold Chisel Set
- Marksman Retractable Safety Utility Knife - Red
Marksman Retractable Safety Utility Knife - Red
- Rolson Wire Brush with Scraper
Rolson Wire Brush with Scraper

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