Pergola glossary of terms & specifications
15 technical terms, material grades and Irish standards explained in plain English so you know exactly what is on a written quote.
Sorted A to Z for quick reference when comparing specifications.
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Key pergola terms explained
10.8 mm Laminated Safety Glass Roof
Two sheets of 5 mm toughened or float glass bonded around a 0.8 mm tear-resistant PVB interlayer, required overhead on glass veranda roofs so that if a pane is struck by falling slate or hail it stays held in the glazing bars.
13.5% vs 23% VAT Two-Thirds Rule on Pergolas
When a registered Irish contractor supplies and permanently fixes a pergola to your house or patio footings, the 13.5% reduced building VAT rate applies if the trade cost of materials does not exceed two-thirds of the total ex-VAT price; flat-pack DIY kits carry 23% VAT.
16 mm Multiwall Polycarbonate Glazing
Lightweight structured polycarbonate roof sheets (clear, opal or bronze solar-control tint) with UV co-extrusion on the top face, spanning between timber or aluminium rafters at €1,000 to €2,200 less than laminated glass.
Beaufort Wind Rating (EN 13659 / EN 1991)
Heavy-duty aluminium louvred and glass pergolas installed in Ireland are engineered to Beaufort 10 to 11 (90 to 115 km/h) when bolted to concrete footings; on exposed Atlantic and Irish Sea coasts, louvres should be left slightly open during orange or red storm warnings.
Bioclimatic Rotating Roof Louvres
Interlocking double-skin aluminium roof blades that rotate up to 135 degrees by crank handle or Somfy motor to let low winter sun in, angle summer glare away, and interlock flat into a watertight roof deck when rain starts.
C24 Kiln-Dried Structural Softwood
Strength-graded European structural softwood ( typically 150x150 mm posts and 200x50 mm rafters) kiln-dried to below 20% moisture content to minimise twisting, splitting and deflection across wide patio spans.
Class 3 Exempted Development (30 m² Rule)
Under Class 3 of the Planning and Development Regulations (S.I. No. 338 of 2026, in force 27 July 2026), a rear-garden pergola or patio cover is exempt from planning permission provided all garden structures combined do not exceed 30 m², at least 25 m² of private open space remains, and roof height stays within 3.0 m (flat roof) or 4.0 m (pitched roof).
Galvanised Bolt-Down Post Shoe vs Concrete Pad
Pergola posts should never sit directly in wet soil. Installers cast a 350x350x500 mm C25/30 concrete pad footing beneath the patio slab and bolt down a heavy-duty hot-dip galvanised steel H-anchor or concealed aluminium base plate.
Infrared Patio Heater Clearance & RCBO Circuit
2 kW to 3 kW short-wave quartz infrared heaters mounted on pergola beams require a dedicated 16A or 20A RCBO radial circuit from the consumer unit and strict 300 mm to 500 mm clearance from timber rafters or polycarbonate roof sheets.
Internal Post Gutter Drainage
The concealed perimeter gutter channel integrated inside the top ring beam of an aluminium or glass-roofed pergola, which collects rainwater from the roof louvres or glass panels and discharges it down the hollow corner posts.
IP65 Outdoor LED Linear Perimeter Lighting
Low-voltage 24V warm-white (2700K to 3000K) weatherproof LED strip or recessed spot lighting rebated into the ring beam or roof louvres, switched via remote dimmer and fed from an outdoor IP66 junction box.
Motorised Zip-Track Wind Blinds
Vertical outdoor micro-perforated screen blinds where the fabric edge is welded to a zipper tooth that runs inside sealed aluminium side channels, stopping wind flap, driving drizzle and low evening glare across open pergola sides.
Powder-Coated Extruded Aluminium (Qualicoat)
Heavy-gauge 6063-T6 extruded aluminium box posts (120x120 mm to 150x150 mm) and ring beams finished in marine-grade Qualicoat Seaside powder coating (most commonly RAL 7016 Anthracite Grey or RAL 9005 Jet Black) that never needs painting.
UC4 Pressure-Treated Structural Timber
Use Class 4 kiln-dried softwood (or Douglas fir and larch) vacuum-impregnated with preservative for direct ground and freshwater contact, essential for pergola posts and footplates exposed to year-round Irish rainfall.
Wall Ledger Plate and Chemical Resin Anchors
On a wall-attached lean-to pergola, the rear wall plate is fixed into the structural masonry leaf using M12 stainless threaded studs set in two-part polyester or vinylester chemical resin, with distance sleeves where external wall insulation is present.
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Questions people ask
How much does a pergola cost in Ireland?
A timber pergola kit is €428 to €733. An aluminium louvred kit is €1,886 to €2,998 for 3 × 3 m to 4 × 3 m, and a motorised roof €3,395 to €7,420. Made to measure and fitted, aluminium starts from €2,500. See the price guide.
How long does it take?
It depends on the base and the roof. A kit going onto a sound, level patio is the quickest job. A made-to-measure aluminium pergola is made to order after the company measures up, so ask for the lead time and the fitting days in writing with the price.
Is there a grant for a pergola?
No. SEAI grants are for energy upgrades, and there's no council grant for garden structures. What you can control is the spec: a timber kit costs a fraction of a motorised roof.
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