Description
Renders World lists this profile as the third of four anthracite over sill depths, and every figure below was read live this session or is named as an omission. It belongs to the window sill extensions and over sills range, alongside the matched verge trims and end caps.
Where the 170 mm Anthracite Over Sill Sits on a Rendered Wall
The over sill anthracite 2.5m 170mm depth profile carries a window's drip edge out past a newly rendered wall face, priced at £27.90 per 2.5 m length as at August 2026. Insulating and rendering an elevation pushes the finished face beyond the original masonry sill, and an over sill restores the shed line across each opening.
This is the second-deepest of the four anthracite depths, and the practical consequence is a wider margin of error than the shallower profiles allow: where a build sits between two depths, the deeper one still sheds water clear, while the shallower one may finish level with the render face.
- Certain from the range itself: four anthracite depths at 110 mm, 140 mm, 170 mm and 220 mm, each on a 2.5 m length.
- Read live this session: the price above, and stock showing as available at the time of the fetch.
- Confirmed on ordering: profile geometry and depth against your own build-up, checked by the technical desk against current stock.
Why Installers Order Matched Anthracite Profiles Together
The case for a matched profile over a generic one is practical, and it holds at every depth in the range.
- One piece per opening: a 2.5 m length spans most domestic window widths without a joint, and a joint in a trim face reads more plainly on a dark finish than a pale one.
- Continuity across the elevation: anthracite reads as a single line only where sills, verge trims and caps come from one colour family, so specifying them in one order is the straightforward route.
- Caps pair to their own trim: the anthracite cap pair closes an anthracite run, and caps are colour-specific — a mismatched cap shows at the most visible point of the detail.
- Colour costs nothing: anthracite and white are priced identically at this depth, both at £27.90, so trim colour follows the window frames and fascia rather than the budget.
- One counter, one order: profiles, trims and caps come from the same trade desk, which closes every opening on an elevation in a single transaction.
Checking the 170 mm Depth Against Your Own Build-Up
Depth is chosen against the finished wall rather than the insulation alone. Measure the total added build outward from the original masonry face — board thickness, adhesive, the reinforced basecoat and the decorative finish — then take a depth that projects past that finished face rather than stopping level with it. The method is sound and needs no document behind it.
What this page will not publish is a depth-per-insulation-thickness chart, and the reason is worth a buyer's attention. The previous version of the over sill anthracite 2.5m 170mm depth page claimed a 90–120 mm insulation band, and the 140 mm profile's own description claims the same 90–120 mm band — two different projections, one stated band, so at least one was wrong. A minimum drip projection is a manufacturer figure, and no document for these profiles was retrievable this session by pointer, page or search. The over sills and verge trims collection takes the same position, so the pages now agree.
- Send the build-up to the desk: board type, thickness and the render system going over it are enough to confirm the depth against current profile geometry.
- Measure the cured basecoat, not the drawing: as-installed build-ups drift from specified ones, and the finished face is what the drip edge has to clear.
- Measure each opening separately: reveal depths on older housing vary along one elevation, so a single template carried across a wall fits poorly somewhere.
- Where two depths look plausible, this one is the safer of the pair against the 140 mm for £4.00 more, and the desk call settles it before the order goes in.
How to Fit the Profile Into the Render Sequence
Sequence is what makes these profiles read as one continuous line, and it belongs inside the render programme rather than before or after it. Fixing centres, fall angle and the sealant specification are real specification questions that sit in a manufacturer document this session could not obtain, so they are confirmed on ordering rather than stated here.
- Fit after the boards, before the reinforced layer: the profile goes on once insulation is bonded and fixed, so basecoat and mesh return up to its edge and lock it into the system.
- Set an outward fall: the profile drains forward, clear of the wall, rather than letting water track back toward the substrate.
- Bed the rear upstand in one continuous run of sealant rather than intermittent dabs — an uninterrupted line is what keeps driven rain out at the frame junction.
- Cut with a fine-toothed blade and deburr, so an end cap seats without being forced onto a rough edge.
- Leave any protective film in place through basecoat and topcoat and peel it once the render has cured, which keeps cementitious splash off the visible face.
- Check the fall before the fixings pull tight: a level held at the front edge takes seconds, and adjusting a profile after it is drawn down against a sealant bed is the fiddlier job of the two.
The sill extension fitting guide works through measuring and cutting in order, and the reveal and opening detailing guide sets this profile alongside the beads at the same openings — render stop beads at jamb terminations and render corner beads at external angles. The finish going over the whole detail comes from the thin-coat silicone render range.
The Four Anthracite Depths and What They Cost
All four anthracite profiles share the 2.5 m length and differ on projection, so depth, price and stock are the honest comparison. Every figure below was read from the product's own page in August 2026 and is material cost only.
| Profile | Price, August 2026 | Stock at fetch |
|---|---|---|
| 110 mm anthracite over sill | £20.90 | Available |
| 140 mm anthracite over sill | £23.90 | Available |
| 170 mm depth, this profile | £27.90 | Available |
| 220 mm anthracite over sill | £30.40 | Out of stock |
The four depths span £30.40 − £20.90 = £6.50 end to end. Two things follow for a buyer sizing an order: the step from this profile up to the deepest is £30.40 − £27.90 = £2.50, the smallest gap in the range, and with the 220 mm currently out of stock this is the deepest anthracite profile actually available.
What It Costs and How It Reaches Site
At £27.90 for the 2.5 m length in August 2026, no VAT treatment was displayed alongside the figure. The price covers the profile alone: end caps are a separate line, one pair per continuous run, in matching anthracite.
Renders World processes orders the same day where stock is available, and delivery is priced after the order rather than at checkout, because profile lengths and pallet weights vary too widely to calculate automatically. Small parcels up to 25 kg and pallets up to 1200 kg both move next-day by courier, with a two-business-day economy option, and all deliveries are curbside. Free local van delivery runs to 15 miles of the Southampton base above the order value stated in the shipping policy, with a per-mile charge beyond that to a limit of 60 miles.
Is the 170 mm Depth the Right Call Here?
Four points settle it, and the last is the fastest route to certainty.
- Deeper build or an exposed elevation, dark trim line: the second-deepest projection gives the wider drip margin on a wall that takes driving rain.
- Lighter builds: the 140 mm anthracite over sill at £23.90, or the 110 mm anthracite over sill at £20.90, avoid projecting further than a thin build needs.
- Deepest build-ups: the 220 mm anthracite over sill is £2.50 more but showed out of stock this session, so check availability before specifying it across an elevation.
- Not certain yet: send the build-up to the technical desk and order the confirmed depth with its matching cap pair in one go.
FAQ — Quantities, Caps, Depth Bands and Care
How many profiles and caps does one opening need?
One 2.5 m length covers most domestic openings in a single piece, and one cap pair closes that run at both ends. Count caps by runs rather than by windows: a bay built from three separate sections takes three pairs, while one wide opening formed from a single profile takes one.
Do the anthracite caps suit this depth?
Caps are supplied colour-matched and pair to their own trim, so an anthracite run takes anthracite caps. Cap-to-depth fit is confirmed by the desk at the point of order, since no manufacturer compatibility document for these profiles could be obtained this session.
Why does this page no longer state an insulation thickness?
Because the same 90–120 mm band was published against both this profile and the 140 mm one, and two different projections cannot share a band. The figure rests on a manufacturer's minimum drip projection that no available document carries, so the measuring method plus a desk confirmation replaces it — a firmer answer than a band that contradicts the page next door.
Is this the deepest anthracite profile available?
At the time of this session, yes in practice: the 220 mm showed out of stock while this one showed available. On paper the 220 mm is deeper for £2.50 more, so on a deep build-up it is worth a stock check with the desk before the order is placed.
How is the profile looked after once rendering is finished?
Periodic rinsing with clean water to clear airborne deposits covers it, avoiding solvents and abrasive pads. Keeping cementitious runoff off the face during the build pays off most, since marking on a trim face usually comes from render residue rather than the finish itself.