Build the Roof — Pitched and Slate or Flat and Membrane, the Decision Is Half Planning, Half Budget
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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/
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