The 3 Different Types of Lead Flashing
The term lead flashing is used to describe many aspects of leadwork however technically speaking a lead flashing is where lead is used to weather the junction between a roof and an abutment. Lead flashings can be used on most roofing materials and are the preferred choice due to the longevity of lead. There are 3 main types of lead flashings:
- Apron Flashing
- Cover Flashing
- Step Flashing
Lead Apron Flashing
A lead apron flashing, also known as an abutment flashing is where a piece of lead is bent into an L-shape and fitted on either the side or the top of a roof that meets a wall or another type of abutment. The upstand of the lead will have a minimum height of 75mm and wouldreturn on to the roof 150-200mm. When installing lead apron flashingsit is very important to consider the wind exposure as the lead flashing will lift in the wind if not secured correctly. Lead clips and continuous clips can be used to securely hold the lead down in place without restricting the lead movement. It is very important not to fix the lead anywhere else other than the top edge of the 75mm upstand as this will impair the leads ability to expand and contract which will cause the lead to split and fail. Lead clips should be installed a minimum of every 450mm to suit the wind exposure.
Lead Cover Flashing
A lead cover flashing is where a piece of lead is used to weather the junction between the wall/abutment and the upstand of the roof flashing. To create a weatherproof seal the lead is turned 25mm into the joint in the wall and dressed down over the roof flashing. The lead cover flashing can be used to weather all roofing materials, however, it may be necessary to use a separation barrier if there is potential for the material to react with each other. The lead flashing should lap the upstand of the roofing material by a minimum of 75mm to ensure that no capillary action takes place.
Lead Step Flashing
Lead step flashing does the same job as lead cover flashing however the design is different and it is generally only used when the abutment is made of brick and on the side/slope of the roof. There are 2 types of step flashing:
- Continuous Step Flashing
- Single Step Flashing
Both types of step flashing weather the upstand of the roofing material and have the same minimum requirements such as lapping over the upstand a minimum of 65mm. However, continuous slept flashing uses a long length of lead which is cut out to suit the brickwork joints.Single-step flashing is where small pieces of lead are cut to shape and used in each brick joint and lapped over each other to create a weatherproof seal. In both scenarios, the lead is turned into the brick joint 25mm and wedged in with either lead wedges or stainless steel hall clips. The joint can then be filled with mortar however, it is generally preferred to use a mastic that accommodates thermal movement as when the lead expands and contracts mortar joint can crack and fall out.
Installing Lead Flashing
Whilst the method of installing lead flashings is relatively simple it is still recommended that they are installed by a professional. The main reason for lead flashings to fail is due to incorrect installation, this could be down to them being incorrectly lapped, under fixed or over fixed.
At Bespoke Leadwork we are a team of experienced lead workers who specialise in installing lead flashings. We guarantee that we install the lead flashings to the highest standards and the correct specifications to ensure that no water will ever penetrate your roof.
Contact us today for more information or your complimentary quote.