Can your chosen Lead Flashing contractor install the flashing correctly? In many cases this will be your chosen Roofing contractor whether they are installing slate , concrete tiles or clay tiles and unfortunately many are not capable of this and rely on mastic and the roof underlay to keep the roof weathertight and not their skill at installation. This area is often overlooked but it is a vitally important part of the roof and needs to be done correctly or can cause major problems. Flashings are often where two roof faces meet and this is where water is getting channelled so it need s to be correct and not reliant on mastic. Choose your tradesman carefully. Please view my Gallery for a number of lead welded flashings that will be watertight and are not reliant on any mastic.
Lead sheet should be carefully worked or lead welded/burned so that the lead is not thinned by more than 25% or weakened by creasing or stretching. Bossing and welding/burning lead should be carried out by experienced (preferably registered) lead operatives using the proper tools and equipment.
Joints in leadwork are weathertight but not watertight. Joints in leadwork are designed to keep water out whilst allowing for thermal movement. It is therefore important that the type of joint used is appropriate for the type of application or situation.
Lead sheet must be adequately supported on a smooth base sufficient to take the weight and to allow for thermal movement to take place. It may be laid on timber, plywood, concrete or masonry together with a suitable underlay.