Description
For a light-retrofit extension or accent wall where anthracite trim meets a deliberately thin 50–70 mm insulation layer, the Anthracite Oversill 2.5 m × 110 mm delivers the right drip projection without the visual mass a deeper profile would cast on a shallow build. It is the shallowest profile in the anthracite family, finished in RAL 7016 powder coat with factory-applied film, and stocked for trade self-collection from our Southampton counter.
What the 110 mm Anthracite Oversill Does in a UK Render or EWI System
For a partial-fill retrofit adding 60 mm of external EPS behind an anthracite trim line, the 110 mm Anthracite Oversill carries the original window sill outward across the light build plus basecoat and topcoat, restoring rainwater shedding without projecting further than the build actually requires. This is the shallowest depth in the anthracite range, occupying a specific niche where contemporary dark trim meets modest insulation thickness — partial-fill retrofits, conservation-zone work permitting anthracite but constraining depth, and thin-layer EWI over already well-insulated structural envelopes. The profile sits within the wider window sill extensions and oversills range for coordinated dark-trim detailing.
The anthracite finish corresponds to the RAL 7016 family that defines current UK contemporary specification, pairing the oversill with anthracite window frames and fascia on the same elevation. The factory-applied PVC film stays in place through rendering and peels away only after surrounding work has cured to taping-clean, with a single 2.5 m length typically serving openings up to around 2.0 m wide once end-cap clearances are deducted. For the standard 90–120 mm builds typical of most modern specifications, the 170 mm anthracite oversill is the workhorse projection, with the 110 mm reserved for the lighter band.
Why Trade Specifiers Choose the 110 mm Anthracite Oversill
- Sized for light EWI builds: the 110 mm depth accommodates 50–70 mm insulation plus basecoat and topcoat, covering partial-fill retrofits, cavity-pre-insulated upgrades, and conservation-zone work with restricted insulation thickness.
- Right visual proportion on shallow builds: on contemporary architecture with a light external layer, the 110 mm profile reads as a quiet horizontal line rather than the heavier shadow a 140 mm or 170 mm depth would cast on a thin build.
- Industrial powder-coat anthracite finish: the factory-applied coating delivers consistent colour density and bonded surface protection across a service life matching the typical 25–30 year EWI design horizon.
- Factory-applied PVC film: safeguards the dark powder-coated face through transport and handling, particularly on a shallow projection where the visible face sits closer to the render plane and splatter contact during install is more frequent.
- 2.5 m unit length: a single profile covers most UK domestic window widths in one piece, removing the visible joint line that reads more prominently on dark trim.
Technical Specifications — 110 mm Anthracite Oversill Data Sheet
| Property | Value |
|---|---|
| Profile type | Window oversill extension for render and EWI systems |
| Material | Powder-coated aluminium extrusion, exterior grade |
| Colour | Anthracite (RAL 7016 family) |
| Length | 2.5 m |
| Projection (depth) | 110 mm |
| Insulation build accommodated | 50–70 mm sheltered, up to 80 mm on protected elevations |
| Recommended drip-edge projection | 30–40 mm beyond finished render face |
| Fixing centres | 300 mm (countersunk screws along back upstand) |
| Finish | Industrial-grade powder coating |
| Surface protection | Factory-applied PVC film, removed post-install |
| Compatible end caps | Anthracite end-cap pair (sold separately) |
| Delivery | Self-collection from Southampton — courier transit excluded |
| Storage | Flat, dry, protective film retained until install |
How to Fit the 110 mm Anthracite Oversill — Build-Up Match, Fall, Sealing
To confirm the 110 mm depth is right, add the insulation thickness to a basecoat-and-topcoat allowance of typically 10–15 mm combined, then add a 30–40 mm minimum drip projection beyond the finished render face. A 60 mm partial-fill EPS build with 12 mm of render totals 72 mm, so the 110 mm oversill leaves about 38 mm of projection — within the recommended drip-clearance range for sheltered elevations. For builds approaching 80 mm or above, or any exposed weather-facing wall, step up to the 140 mm anthracite oversill for the safer projection margin.
Fit the oversill after the basecoat and reinforcing mesh have cured but before the decorative finish coat. Set the profile with a slight outward fall, typically 5–10 degrees, so rainwater drains clear of the wall rather than tracking back toward the substrate. Bed the back upstand into a continuous neutral-cure silicone seal against the original masonry sill, fix mechanically at 300 mm centres along the back upstand, and pair with the matching anthracite end-cap pair at each reveal to close the watertight termination. For the full installation sequence — measurement, cutting, sealant routing and basecoat integration — the window sill extensions installation guide walks through the trade method with worked examples.
Installation Notes — Splatter Discipline, Film Retention, Dark-Finish Care
Retain the protective PVC film on the visible face throughout render application and surrounding finishing. Anthracite shows render splatter and basecoat residue more visibly than white profiles, and on a shallow 110 mm projection where the face sits closer to the render plane, splatter contact during install is more frequent than on deeper profiles — the film prevents the additional cleaning step exposed dark surfaces would otherwise require. Peel only after all render work around the window has cured to taping-clean.
Shallow projections are less forgiving on the fall angle than deeper profiles, because a smaller margin of drip clearance means a smaller margin for water that tracks back rather than drains forward. Verify the 5–10 degree outward fall on the wet bed before the mechanical fixings drive home, not after, since corrections at the fixing stage distort the powder-coat surface and dark finishes reveal those distortions within a few weeks of service. Oversill detailing sits within the broader window reveal treatment that also includes stop beads at jambs and corner beads at external arris points; the render detailing around windows and doors guide covers the full junction-by-junction coordination of profiles around openings.
How the 110 mm Depth Compares to Deeper Anthracite Oversills
The anthracite oversill family runs across four projections on the same 2.5 m profile and RAL 7016 finish, so choosing between them comes down to insulation build and exposure. The 110 mm is the shallowest, with the deeper depths above it covering standard and deep-retrofit builds.
| Variant | Key Spec | When to Choose |
|---|---|---|
| 110 mm anthracite oversill | 110 mm projection | Light retrofit, 50–70 mm insulation |
| 140 mm anthracite oversill | 140 mm projection | Shallow refurbishment EWI, 70–90 mm |
| 170 mm anthracite oversill | 170 mm projection | Standard workhorse EWI, 90–120 mm |
Pro Tips From UK Installers Using the 110 mm Anthracite Oversill
The 110 mm anthracite is the niche profile in the dark-trim range, and the discipline that separates a clean install from a marginal one sits in resisting the always-step-up instinct and respecting the projection arithmetic on the lighter builds where this depth is genuinely right.
- Resist the always-step-up instinct on light retrofit: a 140 mm or 170 mm oversill on a 60 mm build creates the visible step that overspecified profiles produce, so treat the 110 mm as the correct answer here rather than a cheaper second choice.
- Measure the cured basecoat, not the drawing spec: on shallow builds the small absolute difference between 50 mm and 70 mm insulation creates a proportionally larger swing in projection margin, so tape against the cured basecoat before committing to depth.
- Order kit-complete for single-elevation jobs: the 110 mm anthracite often appears on extensions, accent walls or single elevations, so order profile, end-cap pair and anthracite neutral-cure silicone for one self-collection visit and finish in a single trip.
- Brief the client on the projection logic for conservation work: where planning has constrained insulation depth and permitted anthracite, the shallow projection is the right answer, and a clear explanation up front pre-empts the "shouldn't it stick out more?" question after install.
- Cap the cut ends immediately after trimming: a bare aluminium cut edge on anthracite reads as a bright silver line under raking light, so tool a thin bead of anthracite silicone along the cut edge before the end cap goes on, especially where the cap-to-oversill junction sits close to the eye.
Is the 110 mm Anthracite Oversill Right for Your Project?
- Light retrofit with contemporary aesthetic (50–70 mm insulation): the right projection for partial-fill EWI, cavity-insulated upgrades adding a thin external layer, and modern new-build EWI over highly insulated structural envelopes where anthracite trim is specified.
- Conservation-zone work with permitted anthracite: the shallow projection pairs with the restricted insulation depths typical of heritage planning consents that allow contemporary trim but limit external thickness.
- Shallow contemporary EWI (70–90 mm insulation): step up to the 140 mm anthracite oversill, since for builds approaching 80 mm and above the 110 mm projection narrows the drip clearance below the recommended 30–40 mm range.
- Standard EWI (90–120 mm insulation): step up to the workhorse 170 mm anthracite oversill for typical graphite EPS, standard EPS and mineral wool specifications above the shallow band.
- White facade schemes: the matched 110 mm white oversill is the right specification where the facade calls for white trim throughout, with identical geometry and only the powder-coat colour differing.
FAQ — 110 mm Anthracite Oversill Coverage, Compatibility, Ordering
How do I verify the 110 mm depth is right for my project?
Measure the total finished build from the original masonry face outward — insulation thickness plus adhesive layer plus basecoat plus decorative finish. The oversill projection should exceed that measurement by 30–40 mm to deliver proper drip clearance past the finished render face. For builds totalling around 65–80 mm, the 110 mm depth gives the right overhang on sheltered elevations; above that, the 140 mm or 170 mm depth is the safer specification.
Why is the 110 mm depth less common than deeper anthracite oversills?
Anthracite trim is most often specified alongside graphite EPS or mineral wool at 90 mm and above, where the contemporary dark aesthetic aligns with modern EWI performance specifications. The 110 mm depth covers shallower 50–70 mm builds — a smaller but genuine slice of the project mix where partial-fill retrofits, cavity-insulated upgrades and conservation-zone work intersect with permitted anthracite trim.
Are end caps included with the oversill?
No, end caps are sold separately as a matched anthracite pair. Order the anthracite end-cap pair alongside the oversill so both arrive ready for the install sequence in one self-collection visit. One pair closes both ends of one oversill run.
Why is delivery limited to self-collection?
Powder-coated extrusions of this length sustain corner damage during courier transit at a rate that makes shipping uneconomic for a visible facade product, particularly in anthracite where edge chipping shows clearly against the dark finish. Self-collection from our Southampton counter ensures the profile arrives with the powder-coat edge intact and ready for install, and trade buyers collecting larger orders regularly can arrange scheduled pickup in advance.
Should the protective film stay on through the full render install?
Yes, keep the film in place throughout surrounding render work and peel only after the system has cured to taping-clean. The film protects the dark powder-coated face from render splatter during basecoat and finish application, and on a shallow 110 mm projection the face sits closer to the render plane where splatter contact is more frequent than on deeper profiles.
How does the anthracite finish age on UK coastal and exposed facades?
Powder-coated aluminium is the standard specification for UK coastal and exposed-elevation work because it does not corrode like steel and resists the UV and salt-spray loading that degrades softer finishes. The factory coating provides the long-term colour and surface stability these conditions demand, subject to manufacturer guidance, with routine facade washing supporting appearance across all elevation orientations.