Project Snapshot
- Location: Castlegrey, Co. Limerick
- Property Type: Detached residence with concrete interlocking tile roof
- Primary Issue: Failing ridge cap mortar allowing water ingress, combined with perished underlay leaking at the lower roofline
- Service: Ridge Repointing & Localized Breathable Membrane and Batten Replacement
- Materials Used:
- Corotop® High-Performance Breathable Membrane: Heavy-duty, vapor-permeable underlay resistant to wind uplift and water penetration.
- Pressure-Treated Timber Battens: Rot-resistant laths to support tile spacing and proper airflow.
- Weather-Resistant Bedding Mortar: High-adhesion sand-and-cement mix engineered for external ridge lines.
- Corrosion-Resistant Nails & Fixings
- Existing Concrete Interlocking Tiles: Cleaned, re-laid, and aligned.
- Time on Site: Completed within 1 working day
The Problem
The homeowner in Castlegrey contacted Doherty Roofing after discovering water ingress along the lower section of their roof following sustained rainfall.
An inspection by Jim revealed two related points of failure:
- Deteriorated Ridge Mortar: The original mortar bedding along the apex ridge caps had cracked, separated, and crumbled over years of weather exposure. During driving rain, wind forced water directly beneath the loose ridge caps.
- Perished Eaves Underlay: Once rainwater bypassed the ridge line, it tracked down the rafters. The property’s original bitumen underlay had deteriorated, split, and failed completely across the lower courses of the roof. Unable to catch and shed secondary moisture into the gutters, water was pooling and penetrating down toward the fascia line and ceiling joists.
The Solution & Work Carried Out
Rather than recommending an unnecessary, disruptive full re-roof, Jim and the crew implemented a targeted structural roof repair to secure both the roof apex and the lower eaves:
- Stripping & Surface Prep: Carefully stripped back the lower rows of concrete tiles on the affected roof slope and stacked them securely on site. Removed the decayed timber battens and cleared away all brittle bitumen felt down to the bare timber rafters.
- Membrane & Batten Installation: Installed a fresh run of Corotop® high-resistance breathable underlay, sliding it securely beneath the sound upper membrane to form an unbroken waterproof run. Fixed new pressure-treated timber battens into the rafters to establish a rot-proof nailing grid and allow proper under-tile ventilation.
- Re-fitting Concrete Tiles: Cleaned and re-laid the original interlocking concrete tiles back over the new membrane, checking alignment and overlap to ensure complete mechanical weather resistance.
- Apex Ridge Repointing: Chipped out all loose, degraded bedding mortar along the entire ridge line. Re-bedded and neatly hand-pointed every ridge cap with fresh, weather-resistant mortar to seal the roof apex against high Atlantic winds and rain.
The Result
The property in Castlegrey now features a fully sealed ridge line and a reinforced lower eaves drainage system that safely channels rainwater away from timber fascias and internal ceilings. By addressing the damaged underlay locally and securing the ridge caps, the issue was permanently resolved without the expense of a full replacement.
