Roof cleaning guide
How do you fix a leaking roof?
A leaking roof needs to be addressed promptly. Water damage does not resolve itself and will worsen with each rainfall event. This guide covers the common repair types, what can realistically be done safely from inside the loft as a temporary measure, what requires a professional roofer and how to prevent recurrence.
The first and most important point about fixing a leaking roof is this: never climb onto a pitched roof yourself unless you have professional safety equipment, appropriate footwear, a safety harness and an anchor point. A wet pitched roof is an extremely hazardous surface. Falls from roofs are among the most common causes of serious injury and death in DIY accidents in the UK. The ground-level inspection and loft inspection described in the roof leak finding guide can be carried out safely. Any actual repair work that requires standing or walking on the roof surface must be carried out by a qualified roofing contractor with the correct equipment and insurance. With that stated clearly, there are some genuinely useful temporary measures a homeowner can take from inside the loft and some important context on what professional roof repairs typically involve.
Act fast
roof leaks worsen with every rainfall event. Timber saturation, mould growth and ceiling damage escalate quickly if left unaddressed
No roof access
never attempt to repair a pitched roof yourself without professional safety equipment. Falls from roofs cause serious injury and are rarely survivable
Address moss too
many roof repairs are made necessary by moss growth. Fixing the leak without cleaning the roof means the same damage mechanism continues
What a homeowner can safely do while waiting for a professional roofer
If you have identified active water entry in the loft space and cannot get a professional roofer to attend immediately, there are limited temporary measures that can help contain the damage. Place a waterproof tarpaulin or plastic sheeting under the area where water is entering the roof space, catching drips before they saturate the insulation or reach the ceiling below. Place a bucket or container on the tarpaulin and check it regularly during rainfall. Do not place the bucket directly on the plasterboard ceiling, use a board across two joists to support the weight safely.
Where the source of the leak has been identified as a tear or hole in the sarking felt visible from inside the loft, a temporary repair using roof repair tape or self-adhesive flashing tape applied to the dry side of the felt can slow water ingress until a professional repair is completed. This is a temporary measure only and will not substitute for the correct external repair. Do not apply roofing felt repair products to wet surfaces as they will not bond effectively.
Common professional roof repairsWhat professional roofers typically do to fix the most common leak sources
Replacing slipped or missing tiles
A roofer will use a slate ripper or tile lifter to access the area without disturbing surrounding tiles, replace the damaged or missing tile and re-nail or hook it into position. Matching replacement tiles for older clay or handmade tile roofs can require sourcing from reclamation yards. New concrete tiles may differ slightly in colour from weathered surrounding tiles.
Repointing ridge and hip tiles
Failed ridge mortar is hacked out, any displaced ridge tiles are repositioned and re-bedded in fresh mortar and pointed. On some properties flexible ridge systems using dry-fix clips rather than mortar are installed at the same time to eliminate future mortar failure. Ridge repointing is often combined with a roof clean and moss removal when moss growth has contributed to the mortar failure.
Reflashing a chimney stack
The existing lead flashing is removed, the chase cut into the chimney brickwork is raked out, new lead is cut and dressed to the profile of the tiles, wedged into the chase and the chase pointed with mortar. The step flashing at each tile course and the back gutter flashing behind the chimney are both replaced where necessary. This is one of the more involved roof repairs and is almost always carried out by a qualified roofer rather than a general builder.
Replacing failed soil pipe collars and vent flashings
Rubber or lead collars around soil pipes and roof vents are removed and replaced. Modern replacement collars are available in flexible EPDM rubber that conforms to the profile of the surrounding tiles and provides a long-lasting waterproof seal.
Why cleaning the roof after repairs matters
Many reactive roof repairs are either caused or significantly worsened by the presence of moss on the roof. Moss growing into ridge mortar joints is a major cause of mortar failure. Moss lifting tile overlaps creates the conditions for wind-driven rain penetration. Moss retaining moisture against tile surfaces accelerates freeze-thaw cracking that eventually leads to displaced or broken tiles. Carrying out the repair without addressing the moss leaves the same damage mechanism in place. A professional roof clean with biocide post-treatment at the time of, or shortly after, any roof repair significantly reduces the risk of the same type of failure recurring within a few years.
Roof cleaning London
Roof cleaning across London by Cloud Nine
Cloud Nine carries out professional roof softwashing across London and reports on tile condition and any structural concerns identified during the visit. Addressing moss before it causes further tile, mortar and flashing damage is significantly cheaper than reactive repair. Contact us for a free quote.
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Everything London homeowners need to know about roof cleaning.
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