Roof Flashing Mistakes That Cause Leaks on Northern Sites

Most flashing leaks are not mysterious. They come from rushed laps, missing fillers, or fixings in the wrong place. Below are the problems we hear about most from roofers and building owners across the North East, Yorkshire and the North West, and how to avoid them.

1. No foam fillers under the ridge

On box profile sheets, open troughs under the ridge invite wind-driven rain. Fit 32/1000 foam fillers before the ridge goes on. Exposed sites in Northumberland, the Pennines and western Yorkshire punish this shortcut quickly.

2. Screws in the water path

Drive TEK screws through the high points of the profile into solid support. A screw in the trough creates a puddle at the washer. Use a proper socket driver so you do not dish the washer and break the seal.

3. Laps facing the wrong way

Every flashing lap should shed water downhill, same rule as sheet end laps. A ridge or barge joint facing up the slope will take water inwards in heavy rain. Aim for 150mm minimum lap, more on exposed elevations.

4. Abutment stuck on with sealant only

Silicone alone against brick is not an abutment detail. Use a proper upstand flashing and chase it in or cover it so movement and frost do not open a gap. Lean-to roofs on terraced property in Newcastle, Sunderland, Leeds and Manchester fail this way all the time.

5. Ignoring drip trays on long sheet runs

When sheets join on the slope, fit a drip tray underneath. Skipping it to save a few pounds is a false economy on factory and farm roofs.

6. Mixing colours and leaving cut edges messy

Clients notice a Merlin Grey roof with a random Anthracite barge. Match flashings to sheets, and use colour caps on visible screws. Wipe swarf off coated steel so it does not rust-stain the face.

7. Ordering the wrong angle

A 130° ridge will not sit right on a roof that needs a different apex, and a 90° barge will not fix a non-square verge. If the drawing is odd, order custom flashings instead of forcing a standard piece.

Get the right kit before you start

We stock the flashings and sealing accessories for these details from our Newcastle workshop, with delivery across Northern England. See the flashings range and accessories, or phone 01912 853848 if you want a second pair of eyes on a detail before you strip out a leak.