Build the Roof — Pitched and Slate or Flat and Membrane, the Decision Is Half Planning, Half Budget
On this page
Slate pitched: 30°+ pitches, €150–€220/m², 100+ year life. Flat warm roof: 0–10° pitch, €120–€180/m², 25–40 year life.
When this matters most
You're at detailed design or just passed weathertight. Either way, this is the choice stage.
When this doesn't apply
Roof is on, tiles/slates fitted, we're past weathertight.
Frequently asked questions
How much does a roof cost in Ireland for a self build?
Pitched slate or tile roof on a 150 m² house: €22,000–€40,000 installed. Flat warm roof: €18,000–€28,000.
How long does a slate roof last?
Natural slate: 100+ years. Concrete tile: 50–80 years. Clay tile: 60–100 years. Zinc standing seam: 60–100 years. Felt flat roof: 20–30 years; single-ply membrane: 25–40 years.
Can I plant solar PV on a slate roof?
Yes, with slate-compatible brackets and a competent roofer. In-roof PV (panels form the roof) is also possible but requires planning and warranty alignment.
Do I need a roof window?
Not, but it's the cheapest light source on a 1½-storey house. Budget €1,200–€2,500 per Velux installed, including flashing.
Pitched or flat for BER?
Flat roof needs more detail to avoid thermal bridging at the eaves; pitched is simpler. Both can achieve A1.
Sources
Irish Slate Quarries, Technical data and lifespan. https://www.irishslatequarries.ie/
NSAI, I.S. EN 490:2017 Concrete roofing tiles. https://www.nsai.ie/
Frequently asked questions
How much does a roof cost in Ireland for a self build?
Pitched slate or tile roof on a 150 m² house: €22,000–€40,000 installed. Flat warm roof: €18,000–€28,000.
How long does a slate roof last?
Natural slate: 100+ years. Concrete tile: 50–80 years. Clay tile: 60–100 years. Zinc standing seam: 60–100 years. Felt flat roof: 20–30 years; single-ply membrane: 25–40 years.
Can I plant solar PV on a slate roof?
Yes, with slate-compatible brackets and a competent roofer. In-roof PV (panels form the roof) is also possible but requires planning and warranty alignment.
Do I need a roof window?
Not, but it's the cheapest light source on a 1½-storey house. Budget €1,200–€2,500 per Velux installed, including flashing.
Pitched or flat for BER?
Flat roof needs more detail to avoid thermal bridging at the eaves; pitched is simpler. Both can achieve A1.
When this matters most
You're at detailed design or just passed weathertight. Either way, this is the choice stage.
When this doesn't apply
Roof is on, tiles/slates fitted, we're past weathertight.
Briefs in this stage
11 in-depth answers for this stage of the build. Pick the one that matches your question.
Concrete Tile Roof in Ireland — Cost, Lifespan, and When It's the Right Choice
Concrete tile: 50–80 year lifespan, €90–€140/m². Cheaper than slate, less durable, less planning-friendly in rural areas.
concrete tile roof IrelandRead brief →
Fascia, Soffit, and Gutter in Ireland — uPVC, Timber, or Aluminium, and What Lasts
uPVC fascia/soffit/gutter: €30–€60/m linear. Timber: €50–€90/m. Aluminium: €80–€150/m. uPVC is standard; timber needs repainting.
fascia soffit gutter IrelandRead brief →
Flat Warm Roof in Ireland — Construction, Cost, and Avoiding Condensation
Flat warm roof: 0–10° pitch, €120–€180/m². Continuous insulation above the deck. 25–40 year lifespan.
flat warm roof IrelandRead brief →
Pitched vs Flat Roof in Ireland — Cost, Lifespan, and Which Suits Your Build
Pitched slate: 30°+ pitches, €150–€220/m², 100+ year life. Flat warm roof: 0–10° pitch, €120–€180/m², 25–40 year life.
pitched vs flat roof IrelandRead brief →
Rainwater Harvesting in Ireland — Cost, Rules, and Whether It's Worth It for a Self-Build
Rainwater harvesting: €1,500–€3,500 installed for a 2,000–3,000 L tank. Irish water is cheap, so payback is 20+ years.
rainwater harvesting IrelandRead brief →
Ridge Ventilation in Ireland — Why It Matters, What It Costs, and the Building Regs
Ridge ventilation: €20–€40/m linear. Required for cold attic and warm roof. Prevents condensation and timber rot.
ridge ventilation IrelandRead brief →
Roof Insulation in Ireland — Part L 0.16 W/m²K, A1 0.13, and Where to Put It
Part L 2022 backstop: 0.16 W/m²K. BER A1: 0.13. Ceiling level (mineral wool 300–400 mm) is cheapest.
roof insulation IrelandRead brief →
Roof Structure in Ireland — Truss vs Cut Roof, Cost, and When Each Applies
Truss roof: factory-made, fastest, cheapest. Cut roof: site-cut, more flexible, more expensive. Engineer specifies either way.
roof structure IrelandRead brief →
Roof Windows in Ireland — Velux, Keylite, and Fakro, Cost and Where to Use Them
Roof window (Velux): €1,200–€2,500 installed. Cheapest daylight on a 1½-storey house. Cheaper than a dormer.
roof windows Velux IrelandRead brief →
Slate Roof in Ireland — Natural vs Man-Made, Cost, and the 100-Year Lifespan
Natural slate: 100+ year lifespan, €180–€260/m² installed. Man-made: 50–80 year, €120–€180/m². Irish slate quarries still active.
slate roof IrelandRead brief →
Solar-Ready Roof Design in Ireland — South-Facing Pitch, No Shade, and the Right In-Roof Kit
Orient the roof south. No shade. Design the structure for 4 kWp of PV (~28 m²) and the inverter location.
solar ready roof IrelandRead brief →
Where to go next
Next decision
The next step in your build sequence.
Branch into
Adjacent decisions at the same stage.
Watch out for
Common mistakes, hidden costs, gotchas.
- Concrete Tile Roof in Ireland — Cost, Lifespan, and When It's the Right Choice →
- Flat Warm Roof in Ireland — Construction, Cost, and Avoiding Condensation →
- Pitched vs Flat Roof in Ireland — Cost, Lifespan, and Which Suits Your Build →
- Rainwater Harvesting in Ireland — Cost, Rules, and Whether It's Worth It for a Self-Build →
- Ridge Ventilation in Ireland — Why It Matters, What It Costs, and the Building Regs →
- Roof Structure in Ireland — Truss vs Cut Roof, Cost, and When Each Applies →
- Roof Windows in Ireland — Velux, Keylite, and Fakro, Cost and Where to Use Them →
- Slate Roof in Ireland — Natural vs Man-Made, Cost, and the 100-Year Lifespan →