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Example of Large Slate & Lead Roof

House Slate & Lead Roofing

The slate and lead roof of this large house required extensive renewal, replacement and refurbishment.

The house is located in Bowden, nr. Altringham, Greater Manchester.

The roof was also susceptible to further damage and leaks due to:

• The lack of a breathable felt membrane under the slates on roof - as a result there would be no secondary roof to capture wind blown spray or there would be an immediate leakage if slates were lost
• Leadwork was at the end of it's life and byonde repair - flashings, soakers, aprons and capping pieces were of variable thickness and showing evidence of damage caused by thermal movement
• Nail fatigue and decay was evident under the slates because galvanised nails had been used to fix slates to the battons
• There were multiple isolated areas of defective slating - broken, damaged, poorly seated slates
More about our residential:
Slate roofing
Lead roofing
• Timber sofitts - the horizontal & flat timbers that sit under the slate eaves were defective (see image 6)
• Timber fascia the vertical timbers under the slate eaves were rotten and defective
• Chimneys were soiled, had missing mortar between the brickwork and misshaped lead aprons and flashings
• Lead flat roof was of uneven thickness and not constructed to LDA regulations

Slate Roof Preparation

• Scaffolding was erected around the building up to the level of the roof
• The roof slates were carefully stripped from the roof, lowered to the ground and stacked according to size
• Ridge tiles were to be replaced with a dry fix system and so were disposed of
• Existing roof battons were stripped away from the rafters and disposed of
• The existing lead flashings, chimney aprons, soakers, eave gutters, gutters and flat roof were stripped and disposed of

Slate Roofing

• A waterproof breathable membrane was positioned onto the rafters to provide a secondary roof system
• The roof membrane was mechanically fixed to the structural timbers with 25x50mm wood battons, positioned horizontally.
  • Battonning uses softwood cut to dimensions that prevent bounce when driving in the slate nails. battons are secured at each end and along their length and are butt-jointed at rafter centres, never spliced between supports or allowed to cantilever
• Slating started at the verge overhang, from the eaves up.
  • Reclaimed Welsh slates, rather than synthetic slates were chosen for their like-for-like replacement, aesthetic qualities - they sit well on older roofs, long life span, and price
  • Replacement slates were graded by thickness, the thickest at eaves and thinner to the ridge, to minimise dead loading on the roof.
  • Slates were holed to the right gauge with the thicker end as the tail.
  • The first course begins at the eves, being aware of the verges and abutments to reduce redressing or cutting of slates.
  • Neighbouring slates were given a 3-4mm gap between them and fixed using two slate nails so they don't protrude above the face of the slate which could cause wind chatter (rattling) or allow wind blown spray of debris under the slate.

Leadwork

• The roof makes extensive use of leadwork
  • as a long term protective timber covering
  • on the dormer flat roof and cheeks
  • to channel rain water runoff
  • to protect abutment joints

• Once the chimney brickwork was cleaned the stacks were 'ground-out' and repointed with 3:1 sand/cement ratio and new lead flashing and aprons were fitted
• The small lead flat roof system was completely renewed
• Lead flashing and capping piece were fitted along the eaves to provide full weather proofing to the lead soakers
• Lead valleys were fitted the dual pitch areas so run-off is channeled into the gutters
  • each lead section is no longer than 1.5 metres.
  • length restriction allows thermal expansion and contraction by solar heating
  • lead sections were fixed using copper nails to avoid corrosion and chemical reaction
  • the first, bottom section was nailed at the top and subsequent sections overlap by 150mm, preventing water ingress
• protective lead was custom made and fully welded to the eaves
  • Eave gutters were formed to channel water from the eaves
  • timber pieces were used to form upstands which were then clad in lead sections which allow for thermal expansion

Timber Eaves, fascia, Soffits

• new tongue and groove eaves were fitted and the brickwork repointed underneath these
• replacement timber sofitts and fascia were installed under the slate eaves

Roof Ridge System

• To ensure maximum roof life and to meet the requirements of the location a dry ridge system was fitted to the slate roof
• The ridge system used Redland Uni-Angle tiles which were mechanically fixed
• Along the ridge a dry membrane was fitted and the ridge tiles mechanically fixed using screws, batten straps and clamps