1. Article Body
Inspecting a historic roof is partly condition survey and partly record keeping. Both matter, because any future application for consent will depend on evidence.
Do not walk it
Slate, clay tile and aged metal are damaged by foot traffic, and slate in particular breaks under a misplaced step.
Inspect from the ground with binoculars, from the attic, from upper windows and from a ladder at the eave. Specialist access for a closer look is a job for someone equipped for it.
Start in the attic
Look for daylight through the roof covering, which on a spaced board roof is normal in places and elsewhere is not.
Check the sheathing type. Spaced boards or continuous deck, and the condition of each.
Look for staining on rafters, particularly at the eaves, at valleys and around chimney stacks.
Press timber at the wall head and at joist ends near the eaves. This is where built in gutter failure shows and it is the most important single check on a period house.
Check for condensation, frost on nails and damp insulation, particularly if any modern insulation has been added.
Built in gutters, specifically
Establish whether they exist. Many owners do not know.
Where accessible, check the lining for splits, corrosion, failed joints and previous bitumen repairs.
Check the outlets for blockage and the overflow provision.
Look at the cornice and the wall below from outside for staining, paint failure and rot, which indicate the gutter has been leaking.
From the ground, outside
Scan the roof plane for slipped, missing or displaced units. Count them. A rising count over inspections is the diagnostic for nail fatigue.
Check ridges and hips for failed mortar bedding or displaced units.
Check valleys for debris and for the condition of the metal.
Check every flashing: chimney, dormer, parapet, wall abutment.
Check chimneys for open joints, failed pointing and missing flaunching, since these deliver water into the roof.
Look for visible previous repairs in cement, mastic or mismatched material and record them.
Record to a standard
Photograph every elevation and every finding, wide, medium and close, with dates.
Keep a plan or elevation drawing marked with findings.
Record the material, profile and dimensions of the covering. If a slate or tile is ever removed, photograph and measure it before it goes.
This record is what supports a consent application, a grant application and an insurance claim, and none of it can be recreated once material is off the roof.
Cadence
Twice a year, plus after any storm.
Count slipped or missing units each time and track the trend. That number, over several inspections, tells you more than any single visit.
When to bring in a specialist
Where built in gutters are present and their condition is unknown. Where slates are slipping in numbers. Where original flashings are near end of life. Before any consent application.
