This project involved lead welding a neoprene movement joint to a stone gutter on the church roof. Lead T-Pren expansion joints are specifically designed to overcome the problem of laying Lead-lined gutters where the building construction prevents the recommended drip detail being used.
Recommended by the Lead Sheet Association where it is not possible to incorporate the recommended drip and fall joint details when refurbishing Lead-lined parapet or eave gutters.
Traditionally in applications such as lead lined gutters, lead sheet lengths are joined by overlapping them at drips that stand at least 50mm high. However, if the fall is insufficient for this to be possible, a length of lead expansion joint may be welded between the upper and lower sheets. A weather tight joint is thus effected that is sufficiently flexible to absorb strains by the thermal expansion and contraction of the adjoining lead sheet.
Lead expansion joints are able to operate satisfactorily at temperatures between -40C and 100C, They carry a manufacturers guarantee of 10 years and have an expected life of greater than 20 years, if correctly installed.
The changes in length that lead sheet undergoes during expansion and contraction are absorbed by the neoprene insert in the lead expansion joint. The neoprene is vulcanised at elevated temperature and pressure whilst in contact with the lead wings, forming a very strong rubber bond. The metal wings of the joint are manufactured from BS EN 12588 Code 5 rolled lead sheet.
Lead expansion joints have been designed to overcome the problem arising when laying lead lined gutters with restricted falls, and to provide a lower cost alternative to the restructuring of existing gutter detail.