Roof repairs and maintenance

Water shows up a long way from where it gets in. A stain on a bedroom ceiling can start at a chimney counterflashing three metres up the slope, run along a rafter, and drop at the first nail that interrupts the path.

Tracing starts above the stain and works upward: penetrations first, then valleys and wall junctions, then the field of the roof, then the attic side with the light off. Where access allows, the underside of the deck says more than the top surface does, because a stain there is dated and directional.

A repair priced without that walk is a guess with an invoice attached.

RCABC maintenance guidance is blunt about the basics: keep the roof clean and free from debris, keep overhanging branches trimmed away from the surface, and clear gutters and downspouts of anything that impedes their function. Zinc or copper strips are noted as a control for moss growth.

What does not help is pressure. Blasting an asphalt roof strips the granules that protect the asphalt and drives water up under the courses, taking years off a covering that was otherwise fine. Removal is done gently, and the conditions that grew the moss get dealt with — light, airflow, overhanging limbs — because moss taken off a slope that still sits in permanent shade under a fir canopy is moss that comes back.

The Roofing Contractors Association of British Columbia recommends inspection at least twice a year, spring and fall, and additionally after severe weather. On this coast the autumn one carries the weight.

A gutter that overflows in November is not a gutter problem for long. Water backs up over the fascia, runs behind the drip edge and gets into the sheathing at the eaves — the one part of the roof where the code's eave protection article would have helped, and the one place where nothing was required, because Appendix C puts Parksville at 3,200 degree-days and Article 9.26.5.1 exempts regions with 3,500 or fewer.

Clearing gutters, valleys and low-slope outlets before the wet season is the cheapest work on this list by a wide margin.

There is a point where repair stops being economical, and it is usually reached before the covering looks finished. The tests worth applying: whether the deck is sound, whether the flashings can be renewed without disturbing the field, whether ventilation meets the 1/300 of insulated ceiling area the BC Building Code sets, and how many separate repairs the roof has already had.

A roof with a sound deck, one failing detail and adequate venting is a repair. A roof with three previous patches, blocked soffits and split sheathing at the valleys is a replacement being paid for in instalments.

Both answers get given plainly, with the reasoning, whichever way the assessment falls.

• Leak tracing and diagnosis

  The roof and attic walked to find the entry point rather than the stain.

• Flashing and counterflashing repair

  Chimney, wall and skylight flashings renewed or re-let into the substrate.

• Valley repair

  Open and closed valleys rebuilt where fasteners, membrane or metal have failed.

• Vent boot and stack collar replacement

  Perished rubber collars replaced before a split becomes a ceiling stain.

• Moss and debris removal

  Growth removed gently, without pressure, and the conditions that grew it addressed.

• Gutter, downspout and outlet clearing

  Eaves, leaders and low-slope outlets cleared so water leaves the building.

• Sheathing and deck repair

  Localised rot and split sheathing replaced where the surrounding covering is sound.

• Post-storm assessment

  Lifted, cracked or displaced material assessed and reported after severe weather.

Moss is the dominant maintenance issue on this coast, and it is a north-slope and canopy problem rather than a whole-roof one. Growth lifts shingle tabs and holds water against the surface through a winter that BC Building Code Appendix C rates at 1,200 mm of rain for Parksville. RCABC maintenance guidance is to keep the roof clean and free of debris, keep overhanging branches trimmed back, and clear gutters and downspouts so nothing impedes their function, and it notes that zinc or copper strips can control moss growth.

Situation

A two-storey house at Qualicum Beach with a stain appearing on an upstairs ceiling only during prolonged rain, on a covering with roughly half its service life remaining.

Complication

The stain sat two metres downslope of anything obvious. Tracing from the attic found the entry at a bathroom vent boot whose collar had split, with water running along a rafter before dropping at a nail.

Resolution

The boot was replaced and the surrounding shingles re-laid. Nothing else on the roof was touched. Appendix C lists a one-day design rain of 96 mm for Qualicum Beach, and the failure only ever showed on the days that got near it.