Complex Cills That Fit First Time Bay, Curved, and Non-Standard Openings
Bay windows, curved walls, splayed reveals, and stepped openings cannot be cut from a standard cill on site. They require precision fabrication. We manufacture complex cills as a single welded piece, shaped to your exact opening, powder coated in your chosen RAL colour. No on-site mitres. No silicone joints. No guesswork.
3-5 day turnaround Made in Dublin Trusted by 1,000+ contractors Free delivery over €150
Standard straight cills can be cut and joined on site. Complex cills cannot. Bay windows have angles. Curved walls follow a radius. Splayed reveals taper inwards. Cutting these from a straight extrusion always leaves gaps, exposed cuts, and joints that need silicone to seal. In Irish weather, those joints fail.
We measure the geometry of the opening, fabricate the cill as a single welded piece in the factory, and powder coat after welding. The cill arrives on site ready to fit, with no field mitres and no sealant joints exposed to weather.
Single welded piece, no field joints to fail
Bay angles, radius curves, splayed reveals all supported
Welded end caps included as standard
Template service available for non-standard geometry
Powder coated after welding for a seamless finish
Manufactured in Dublin, delivered nationwide
Complex Geometry We Manufacture
Bay Window Cills
3-sided and 5-sided bay window cills welded as a single piece. Internal angles match your opening exactly. No field mitres required.
Curved Cills
Radius cills for curved walls and bow windows. Manufactured to your radius dimension or from a site template.
Splayed and Angled Reveals
Cills for splayed reveals where the opening tapers inwards. Each cill is fabricated to the exact taper of the reveal.
Stepped Openings
Multi-level cills for stepped openings, corner windows, and feature glazing. Welded transitions between levels.
Corner Cills
External and internal corner cills with welded mitres. The corner becomes one continuous sealed piece.
Heritage and Replacement
Replacement cills matched to existing openings on heritage and refurbishment projects. Templates accepted.
Recent Work
Complex Cills We Have Manufactured
A selection of bay, angled, and welded complex cills produced in our Dublin workshop. Every piece fabricated to exact site dimensions, powder coated, and delivered ready to fit.
Welded Bay Cill
Single-piece welded bay window cill in RAL powder coat finish.
Angled Bay Reveal
Multi-angle bay reveal cill fabricated as one continuous piece.
Bay Window Installation
Installed bay cill showing precise alignment and powder coat finish.
Manufactured for contractors across Dublin, Cork, Galway, Limerick, and nationwide.
External Wall Insulation
Bay Cills for External Wall Insulation Projects
External wall insulation changes the geometry of every window opening. The wall gets thicker. The reveal gets deeper. A standard 150mm cill no longer covers the wall build-up. On a bay window, the problem multiplies. Each face of the bay needs its own deep projection cill, and every angled junction must stay watertight.
Generic suppliers do not manufacture EWI bay cills. They sell standard straight stock that has to be cut, mitred, and silicone-sealed on site. Within two winters, those joints fail. Water tracks behind the EWI render and the entire detail has to be opened up.
We manufacture EWI bay cills as a single welded piece. The projection covers the full insulation depth, typically 100mm to 250mm. The angles are factory-formed to your exact bay geometry. The drip edge throws water clear of the render. No field joints. No silicone. No callbacks.
Deep projection from 150mm to 400mm to suit any EWI build-up
Welded bay angles for 3-sided and 5-sided bay windows
Integrated drip edge to throw water clear of the render finish
Welded upstand at the back to seal against the window frame
SEAI grant compatible specification for retrofit projects
Compatible with EPS, mineral wool, phenolic and PIR insulation systems
EWI Projection Sizing for Bay Cills
The cill projection must cover the full wall build-up plus a drip edge of 30mm to 40mm. Use this guide to specify the correct depth for your bay window EWI project.
EWI Insulation Thickness
Wall Build-up
Recommended Cill Projection
80mm EPS or mineral wool
Block + 80mm + render
150mm
100mm EPS or mineral wool
Block + 100mm + render
180mm
120mm phenolic or PIR
Block + 120mm + render
200mm
150mm EPS
Block + 150mm + render
230mm
200mm EPS (deep retrofit)
Block + 200mm + render
280mm
All projections include a 30mm to 40mm drip edge beyond the finished render face. Custom depths up to 400mm available on request.
Common Complex Cill Scenarios in Irish Construction
EWI Retrofit on 1970s Semi-D Bay Window
Original concrete bay cills cracked and cold-bridging. We strip the existing cills, fabricate a new welded aluminium bay cill with 200mm projection to cover 150mm EPS plus render, and powder coat in RAL 7016. Fitted in a single visit. SEAI grant compliant.
New Build Bay with Splayed Reveals
Architect-designed bay window with 22-degree splays on each face. Standard cills cannot handle the splay. We weld a single aluminium piece to the exact splay angles, with welded end caps and a continuous drip edge. No silicone joints anywhere on the detail.
Curved Bow Window on Heritage Refurb
Period property in Dublin 6 with a curved bow window. We take a site template, fabricate a radiused aluminium cill, and powder coat in a heritage RAL to match existing joinery. The cill follows the radius exactly, no segmented cuts visible.
Apartment Block with 80 Identical Bay Cills
Volume residential project with 80 matching bay window cills across four floors. Manufactured to one specification, batch powder coated for colour consistency, delivered in lifts to suit the install programme. Zero remakes across the order.
Frequently Asked Questions
Can you manufacture bay window cills for external wall insulation?
Yes. EWI bay cills are one of our most-ordered complex cill types. We fabricate to projections from 150mm to 400mm to cover any EWI build-up, with welded angles for 3-sided and 5-sided bays.
How do I measure a bay window for a complex cill?
Measure the length of each bay face along the back of the cill, the internal angle between each face, and the required projection from the back of the cill to the front edge. For curved or unusual geometry, we accept site templates.
Are your complex cills SEAI grant compatible?
Yes. Our deep projection bay and complex cills are specified on SEAI-funded retrofit projects across Ireland. Marine-grade aluminium, powder coated, with welded joints to meet long-term durability requirements.
What is the lead time for a welded bay cill?
Standard lead time is 3 to 5 working days from confirmed measurements. Larger volume orders or unusual radii may take 5 to 7 days. Delivery is nationwide and free on orders over EUR 150.
Why not just cut and silicone a standard cill on site?
Silicone is not a building material. Site-mitred and silicone-sealed bay cills fail within two to five winters. Water tracks behind the cill, into the EWI render, and damages the wall. A welded one-piece bay cill is the only permanent solution.
Order Complex Aluminium Cills
Submit your measurements or request a template. We fabricate, weld, powder coat, and deliver to site ready to fit.
