Choosing the right material and specification for leadwork in Mattishall makes the difference between a repair that lasts and one that fails within a few years.
When a roofer tells you they will replace your flashings, the detail that matters most is not how quickly they can do it - it is what they intend to put up there. Lead is not the only option, and even within lead there are several specifications. Understanding what is available, and where each option is genuinely appropriate, means you can have a more useful conversation with whoever you hire.
This page explains each material honestly, including the situations where a cheaper alternative is a reasonable choice and the situations where it is not.
Milled lead is the material that has been used on British roofs for centuries. It is heavy, dense, and completely impermeable. When correctly dressed and fixed, it conforms tightly to complex shapes - the stepped sides of a chimney, the curved head of a bay - in a way that no other material matches.
Lead is classified by code, which refers to its weight per square metre and therefore its thickness:
The honest case for milled lead is that, installed correctly at the right code, it is extremely long-lasting. It is also the only material that a skilled roofer can dress into complex shapes on site using traditional bossing and welting techniques. For chimney and dormer work on older properties, it remains the best choice.
The drawbacks are straightforward: lead is the most expensive option, and it has some scrap value, which means on isolated properties it can occasionally be targeted by thieves - though this is a relatively rare problem on domestic flashings rather than large flat church or commercial roofs.
Pre-formed aluminium flashings with a grey coating are sold as a lower-cost alternative to lead. They come in rolls and are designed to press into a chase in the brickwork in a similar way to lead.
The honest assessment: aluminium flashings can be a practical solution for straightforward repairs where the junction is simple and the exposure is not severe. They are significantly lighter and cheaper than lead. Some products are self-adhesive, which speeds up installation.
The limitations matter, though. Aluminium does not dress as tightly as lead around complex shapes. It is more prone to cracking if overworked. The adhesive backing on self-adhesive products can fail in high UV or very cold conditions, and unlike lead, aluminium cannot be bossed or welted - so it cannot be formed into the same watertight details that a skilled lead worker can produce. For a chimney with multiple faces and awkward geometry, lead is the appropriate choice. For a simple straight flashing on a low-pitch lean-to roof, a quality aluminium product can do the job at lower cost.
Zinc flashings are less commonly specified on domestic properties but are worth knowing about. Zinc is lighter than lead, has a long service life when correctly installed, and weathers to an attractive grey-blue patina. It is more commonly used on new-build or architect-designed properties where the aesthetic is a consideration.
Zinc requires soldered joints rather than lapped and dressed joints, which means the skill set needed is slightly different from traditional lead work. It is generally priced between aluminium and lead. For a standard re-flashing job on an existing older property, lead remains more practical - zinc is more relevant where a specific aesthetic or a full valley replacement on a new extension is being planned.
Self-adhesive flashing tape (butyl or bitumen-based) is sold in DIY sheds and is widely used as a quick fix. It has a legitimate place in roofing: as a temporary seal while waiting for materials or in emergency situations where water needs to be stopped immediately. It is not a long-term replacement for properly dressed lead or metal flashings.
Flashing tape degrades in UV light. The edges lift within a few years and water tracks underneath, often making the underlying problem worse. If you can see flashing tape on your chimney or dormer, treat it as a sign that the underlying leadwork needs proper attention, not as evidence that the problem has been fixed.
Silicone and mastic sealants applied over the top of lifting lead are similarly a short-term measure. They block the visible gap but do not address the reason the lead lifted, and they make subsequent proper repairs more time-consuming because the old sealant has to be removed first.
For most domestic properties - particularly older homes with chimneys, dormers, or bay windows - milled lead at code 4 or code 5 is the right specification. It is the material that performs best over the long term and can be properly formed to seal complex junctions.
For a simple lean-to or straight flashing on a modern extension, a quality pre-formed aluminium flashing is a reasonable and cost-effective alternative, provided it is correctly fixed into a proper chase and not just stuck to the surface.
If a contractor proposes to use code 3 lead or self-adhesive tape as the primary repair for a chimney flashing, that is worth questioning. The right material for the job should not change based on what happens to be on the van.
Regardless of the material chosen, the method of fixing matters. Lead and metal flashings should be tucked into a raked-out mortar chase in the brickwork - typically 25mm deep - and secured with lead wedges or appropriate fixings before the chase is re-pointed with mortar. Lead should be fixed with copper clips at regular intervals to allow for thermal movement, not nailed rigidly or adhered along its full length.
The individual sections of a chimney flashing should be lapped correctly - step flashings overlapping soakers by a minimum of 65mm, with each step section lapping the one below it. Back gutters should have an adequate fall and a proper upstand height to prevent water backing up in heavy rain.
When looking for a roofer for leadwork in Mattishall, ask which code they propose to use and how they intend to fix it. If you want to know which material is right for your particular job before committing to anything, call us and we will come and take a proper look.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
