Roof Replacement Guide: Signs, Materials & What to Expect

Replacing a roof is one of the biggest jobs a home will ever need — and most homeowners only do it once. This guide covers how to tell when you genuinely need a re-roof, which materials suit Irish weather, and exactly what happens on site. Wondering what it'll cost? See our Roof Replacement Costs breakdown, or get an instant figure from the roofing cost calculator.

Do you actually need a full re-roof?

Most homeowners ringing us about a leak don't need a full re-roof — they need targeted roof repairs. But there's a tipping point, usually around the 25-year mark for concrete tiles, or when more than 20% of the slates are slipping, cracked, or delaminating, where patching becomes throwing good money after bad. Here's the plain test we use on every survey:

• Slipped or missing slates in multiple areas (not just one storm-damaged patch) — points to nail sickness across the whole roof.
• Sagging ridge or visible dips in the roofline — battens or rafters are failing.
• Daylight visible from the attic in several spots.
• Flashing failure at multiple chimneys, valleys, and abutments — not just one weak point.
• Underlay (sarking felt) torn or perished — visible when you lift slates at the eaves.
• Repeated leaks in different rooms after fixing the last one.
• Concrete tiles spalling (surface flaking) — common on estates built 1975–1990.
• Roof over 60 years old with original natural slate and rusting nails (nail sickness).

If you've got three or more of those, a re-roof works out cheaper over ten years than chasing leaks every winter.

Materials: what works on Irish roofs

Ireland's weather is the deciding factor. Most of the country sees 1,000–1,400mm of rain a year, with persistent south-westerly driving rain along the western and southern coasts. Material choice has to respect that.

Natural slate

The default for older and period homes — Victorian and Edwardian terraces and most pre-1960 builds. Spanish slate (SVA, Cupa) is the workhorse: 80–100 year lifespan and handles salt air on coastal exposures. Welsh slate (Penrhyn, Cwt-y-Bugail) is the premium choice for protected structures and heritage properties.

Fibre cement slate

Marley Eternit Thrutone or Cedral — a solid mid-range pick for re-roofs on 1960s–80s housing. Lighter than concrete, lasts 50–60 years, and looks close to natural slate from ground level.

Concrete tile

Tegral, Marley, or Sandtoft profiles. Most Irish estates built 1975–1995 are concrete tile. Cheaper to replace like-for-like, but the surface coating fails around year 30–40 (green algae and surface spalling), so a re-roof often makes sense around year 40.

Flat roof systems

For extensions and dormer cheeks, EPDM rubber (Firestone, single-piece up to 15m) is our default — seamless, with a 25-year warranty, and it handles UV and rain. GRP fibreglass suits smaller areas. We avoid felt on anything new.

What a re-roof actually involves

A typical 3-bed semi re-roof runs 4–7 working days, weather permitting. Here's the sequence:

1. Scaffold up — independent scaffold to all elevations, plus a chimney lift if needed.
2. Strip the existing covering — slates, battens, and old underlay into a skip on the drive.
3. Inspect rafters and ridge — replace any rot or woodworm damage (priced separately if found, and we tell you first).
4. New breathable underlay and treated battens to manufacturer spacing.
5. Slate or tile the roof — coursed from the eaves up, with copper or stainless ringshank nails.
6. Lead flashings to chimneys, abutments, and valleys — code 4 minimum, code 5 on exposed elevations.
7. Ridge, hip, and verge — dry-fix systems on new work (no more cracked mortar).
8. Gutters, fascia, and soffit if part of the quote.
9. Strip scaffold, sweep up, skip away.

We work in dry windows. If a storm rolls in mid-job, the roof is temporary-covered with tarps and battens before we leave site — never left open overnight.

Why Irish roofs fail earlier than you'd think

1. Nail sickness on natural slate (1900–1960 properties). Iron nails rust through after 80–100 years. The slate is still perfect — the fixings are gone. You'll spot it as random slipped slates with no obvious storm cause; re-roofing salvages the original slates where possible.

2. Concrete tile coating failure (1975–1995 estates). The factory paint wears off, the tile underneath soaks up rain, freezes, and spalls.

3. Underlay perishing. Old bitumen felt (pre-2000) goes brittle and tears. Modern breathable membranes (Tyvek, Klober) last 50+ years. If your underlay is torn, even good slates leak in driven rain.

Planning, winter work and disposal

Planning permission: not needed for a like-for-like re-roof (slate for slate, tile for tile) — that's exempted development. You will need permission to change the roof profile, add dormers, or work on a Protected Structure.

Winter: yes, we re-roof through Irish winters, working in dry windows and never leaving a roof open overnight. The only stop is sustained heavy rain or wind above 40km/h.

Disposal: skip hire, strip-out, and licensed disposal are included. Concrete tiles are recycled where possible; salvageable slate can earn a credit.

What will it cost?

Costs depend on size, pitch, access, and material. See the full breakdown in Roof Replacement Costs, or get an instant estimate from our roofing cost calculator.

Try the Roofing Cost Calculator →

Book a free roof survey

Not sure whether you need a repair or a full re-roof? We'll tell you straight on a free survey — and give you both prices so you can decide on real numbers. Request your free survey.