Fire safety is a critical but often overlooked aspect of roof design. Technical Guidance Document Part B (Fire Safety) sets strict requirements for roof coverings, fire resistance, and escape routes in Irish buildings.
TGD Part B: Fire Safety Requirements
Section 14: Roof Coverings
Primary requirement: External roof surfaces must resist fire spread from outside the building.
Classification system:
- Class AA, AB, AC: Highest fire resistance (slates, tiles, metal)
- Class BA, BB, BC: Moderate resistance (some membranes)
- Class CA, CB, CC: Lower resistance (requires fire-rated substrate)
- Class DA, DB, DC: Not permitted on dwellings
Source: housing.gov.ie Technical Guidance Document Part B
National Annexes to I.S. EN 13501-5
Test method: Roof coverings tested for:
- External fire exposure (burning brands, radiant heat)
- Fire penetration (time to breach roof assembly)
- Fire spread (flame propagation across surface)
Irish requirement: Roof coverings on dwellings must achieve Class B ROOF (t1) minimum.
Common Roof Material Fire Ratings
Class AA (Highest Fire Resistance)
✅ Natural slate – Non-combustible
✅ Clay tiles – Non-combustible
✅ Concrete tiles – Non-combustible
✅ Metal roofing (steel, zinc, copper) – Non-combustible
Compliance: Automatically compliant with Part B. No additional certification needed.
Class AB/AC
✅ Bituminous felt (multi-layer with mineral surface)
✅ EPDM membrane (on fire-rated substrate)
✅ GRP fibreglass (with fire-retardant resin)
Compliance: Manufacturer must provide fire test certificate (I.S. EN 13501-5).
Class CA–CC (Restricted Use)
⚠️ Single-layer membranes (without fire-rated deck)
⚠️ PVC/TPO (without Class A substrate)
⚠️ Timber shingles (not permitted on dwellings)
Compliance: Requires fire-rated substrate (e.g., 18mm plywood + Type X plasterboard ceiling).
Special Case: Thatch Roofs
Part B Section 13: Thatch requires:
- Minimum 1m separation from boundaries
- No habitable rooms in roof space
- Electrical wiring in steel conduit
- Chimney flues lined and swept annually
Insurance: Specialist thatch insurance required (higher premiums due to fire risk).
Fire Resistance of Roof Structure
Roof Deck/Sarking
Requirement: Provide 30 minutes fire resistance (minimum) for dwellings.
Compliant systems:
- 18mm OSB/plywood deck + 12.5mm plasterboard ceiling
- Concrete slab (flat roofs)
- Timber joists with fire-rated insulation
Non-compliant:
- Exposed timber rafters (no ceiling)
- Sarking felt only (no deck)
Insulation Materials
Fire safety concern: Some insulation is combustible.
Compliant materials:
✅ Mineral wool (Rockwool/Knauf) – Non-combustible
✅ Glass wool – Non-combustible
✅ PIR boards with foil facings – Fire-retardant (Class B/C)
Restricted materials:
⚠️ Expanded polystyrene (EPS) – Combustible (Class E)
⚠️ Spray foam – Fire rating varies (check certification)
Compliance: Use non-combustible insulation in fire-sensitive areas (attached dwellings, multi-unit).
Fire Safety in Multi-Unit Developments
Apartment Buildings (>3 Storeys)
Part B Section 6: Roofs must provide 60 minutes fire resistance.
Requirements:
- Concrete roof deck (flat roofs)
- Fire-rated separating walls extended through roof
- No timber roof structure unless fire-rated
Inspection: Fire Safety Certificate required before construction.
Terraced/Semi-Detached Houses
Part B Section 3.7: Party walls must extend 375mm above roof covering.
Purpose: Prevent fire spread between dwellings through roof space.
Compliance:
- Brick/block wall through roof line
- Cavity barriers at eaves
- Fire-stopped penetrations (pipes, cables)
Fire Escapes & Roof Access
Dormer Windows as Escape Routes
Part B Section 2: Dormer windows can serve as escape routes if:
- Minimum 450mm × 450mm opening
- Sill height ≤1,100mm from floor
- Opens directly to outside (not into roof valley)
Typical use: Attic conversions, room-in-roof bedrooms.
Roof Lights (Velux/Skylights)
Not acceptable as primary escape route (unless horizontal, e.g., flat roof exit).
Reason: Climbing onto pitched roof is not a safe escape method.
Compliance & Certification
For Homeowners
Replacing roof on existing house:
- Use Class AA materials (slate/tile) = automatic compliance
- Keep Fire Safety Certificate (if original build had one)
- Ensure roofer doesn’t remove party wall fire barriers
Building an extension:
- Architect/engineer designs fire-rated roof assembly
- Building Control inspects before roof covering installed
- Commencement Notice submitted 14 days before work
For Contractors
Documentation required:
- Manufacturer fire test certificates (membranes, insulation)
- CE marking (roof coverings)
- Fire Safety Certificate (multi-unit/commercial buildings)
Inspection checkpoints:
- Party wall continuity through roof
- Fire-stopped penetrations (chimneys, pipes, cables)
- Roof covering classification
FAQ: Fire Safety & Irish Roofs
Q: Are slate roofs safer than tile roofs?
A: Both natural slate and clay/concrete tiles are Class AA (non-combustible). Fire safety is equal. The difference is structural (slate is lighter).
Q: Can I use a green roof (sedum) on my house?
A: Yes – the substrate (soil/growing medium) is non-combustible, but the waterproof membrane must be Class B ROOF (t1). Check manufacturer certification.
Q: Do I need smoke detectors in the attic?
A: No – smoke alarms are required in circulation areas (hallways, landings) and rooms where people sleep. Uninhabited attics don’t require detectors.
Q: What if my roof has solar panels?
A: Solar PV panels are combustible (Class C/D). Building Regulations allow them if:
- Mounted on Class AA roof covering (slate/tile)
- Minimum 1m from roof edges/ridges
- Electrical installation by registered electrician
Q: Is spray foam insulation legal in Ireland?
A: Yes, if fire-rated. Some spray foams achieve Class B/C fire rating. Always request manufacturer certification. Avoid cheap non-certified products.
When to Get a Fire Safety Certificate
Required for:
- New builds (all dwellings)
- Extensions >40m²
- Material changes of use (e.g., house → apartments)
- Multi-unit developments
Not required for:
- Like-for-like roof replacement
- Attic insulation upgrades
- Roof repairs
Process: Architect/engineer submits application to Building Control Authority → inspection during construction → Certificate of Compliance on Completion.
Fire Prevention Best Practices
- Chimney maintenance – Sweep annually, repair cracked flues
- Electrical safety – Repair damaged cables in attic, avoid overloading sockets
- Clear debris – Remove leaves/moss from valleys (fire risk in dry weather)
- Solar panel installation – Use registered SEAI contractor
Need a roofer who understands fire safety regulations? Get quotes from certified professionals
Official Sources
- TGD Part B (Fire Safety) – https://www.housing.gov.ie/housing/building-standards/technical-guidance-documents
- I.S. EN 13501-5:2016 Fire Classification – https://www.nsai.ie/
- Building Control Act 2007 – https://www.irishstatutebook.ie/eli/2007/act/21/enacted/en/html
- Fire Safety in Purpose-Built Blocks of Flats (DHLGH 2023) – https://www.housing.gov.ie/
Tags:
Share this article
Need Professional Roofing Services?
Our expert team is ready to help with all your roofing needs across Ireland.
Get Your Free Quote