Restoration of lantern roof – Wythenshawe Hall, Manchester

Restoration of lead covered lantern roof – stripped roof

The stripped lantern-light roof. New perimeter gutter was fixed at this stage as brackets will be beneath lead bays once fitted. The four existing hip rolls were too short so were cut back and new sections added. The wood rolls now finish flush with eaves corners. The existing timber boarding was in good condition and was retained without need for alteration.

Bossing & forming of lead roof bays

Once the roof had been prepared a geotextile underlay was laid over the boarding and wood rolls fixed to allow correct setting out of leadwork. Lead bays were cut to size and formed by bossing into shape.

Setting out of wood rolls & fixing of bays

Lead bays were fixed to the boards with copper clout nails and preliminary bossing carried out to set in position between rolls. The new roof layout increased the number of bays, allowing the use of smaller pieces of lead and reducing the risk of fatigue due to oversizing. They were also lighter than the originals and easier to handle.

Fixing of lead roof bays

The roof pitch of 6 degrees required bays to be fixed through their base in order to prevent creepage.

Sealing over roof bay fixings

Fixing through the base of roof bays created potential points of water penetration via the nail holes. Nail heads were sealed over by leadburning in order to obviate this risk.

Fitting lead roof bays

Once the lead sheets had been fixed, dressing of the bays around the wood cored rolls was carried out. The undercloak roll end was bossed and trimmed to allow fitting of the adjacent panel.

Forming roll ends

Lead bays were dressed around the wood cored rolls and overcloaks formed to create a splashlap onto the adjacent panel. Finally, roll ends were neatly bossed to form a weathertight expansion joint at intersection of bays.

Completed roll end

The finished roll end terminates at the very edge of the roof eaves to form a watertight drip edge into the perimeter gutter.

Hip flashings & roll cappings

Once all of the roof bays had been fixed and bossing completed, weathering of junctions at hip intersections was carried out. These flashings were formed by cutting lead and folding around the lead covered hip rolls. Capping pieces were then bossed and trimmed to fit snugly around the rolls at intersections with the hips. The caps were then lead-welded to the flashings and finally dressed neatly into the undercut of the rolls to prevent windlift.

Clips & securing of flashings

Flashings are always prone to the effects of high winds if not adequately secured. Lead clips were leadburned to the surface of the lead roof bays to overcome such problems.

Securing flashings & weatherings

Hip weatherings not only protect intersections from water penetration, but in this case also serve to conceal the sealed over nail head fixings of the roof bays. The lead-welded clips were turned to secure the free edges of the hip weatherings and an expansion gap left to allow for thermal movement.

Weathering at centre of roof

The completed roof was topped with a central capping piece at the intersection of all of the lead covered rolls. This was bossed from 4 pieces of lead and dressed around the rolls. The fitted pieces were then leadburned together to form a weathertight flashing at the roof apex and clips welded and turned to secure against windlift.

The completed lead roof

The leadwork was treated with patination oil during progression of the works. Final touching-up of bossed areas with patination oil completed the job. The finished lead roof will last for many years to come and is truly in keeping with the appearance of the building.