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WINDOW SILL EXTENSIONS & OVERSILLS
12 products
Showing 1 - 12 of 12 products
How to choose
What colour are the frames?White: the white over sills, trim and capsDark grey or black: the anthracite over sills and anthracite caps.
How far out is the new wall?Measure the insulation and render at the window and how far the old sill sticks out, then ring 023 8200 2442 to agree the depth: 110, 140, 170 or 220 mm.
Window sill extensions — also sold as oversills or window sill extenders — carry an existing sill out past the new face of a wall once external insulation and render have thickened it. The range here has twelve products for these openings: over sills in four depths and two colours, a verge trim with upstand for the top of the wall, and end cap pairs to close every run. They sit alongside the Renders World render systems, so the whole façade can be ordered in one place.
How to Choose a Window Sill Extension Depth
A window sill extension has to reach past the new wall face at each window, so two measurements come first.
The build-up — the thickness of insulation and render going on at the opening, measured on site.
The old sill — how far the existing sill stands out from today's wall face.
Ring Renders World on 023 8200 2442 with both figures and the counter agrees the depth with you before you order. Windows on the same wall can need different depths, so measure each one.
Every Over Sill, Trim and Cap in White and Anthracite
All over sills and verge trims come in 2.5 m lengths. Pick the depth, then the colour that suits the frames.
Each end cap pair is listed for the sills and the verge trim of its own colour, so a white run takes the white pair and an anthracite run the anthracite pair.
Over Sill, Verge Trim or Bead
Below a window — a window sill extension (over sill), laid over the old sill so water runs off past the new wall face.
At the top of the wall — the verge trim with upstand, which finishes the system at the wall head.
At the reveals and corners — the beads: render stop beads at the edges of an opening and render corner beads on external corners, so the whole opening reads as one detail.
At the open ends — an end cap pair in the matching colour.
Fitting the Profiles
The sills, trims and caps go on as part of the render work around each opening. Two guides take you through it:
For the finishing coat over the wall, see the thin-coat silicone render range.
Before You Order
Measure every opening — width for the number of lengths, build-up and old sill for the depth.
Count the lengths — divide each sill width by 2.5 m and round up.
Count the caps — one pair for each run with two open ends, in the run's colour.
Wider than 2.5 m? — agree with the Renders World counter how two lengths will meet before the order goes in.
FAQ
How many lengths and caps does one window need?
Divide the sill width by 2.5 m and round up for the lengths. Caps go by runs, not windows: a bay with three separate sill sections takes three pairs, a single opening one pair.
Can white and anthracite parts be mixed?
Each end cap pair is listed for the trim of its own colour, so keep one colour per run. Choose that colour to suit the window frames.
What is the difference between a verge trim and an over sill?
Where it goes. An over sill sits under a window, over the old sill; the verge trim with upstand finishes the top edge of the wall. Both come in 2.5 m lengths, in white and anthracite, and take the same end cap pairs.
Are the end caps sold separately?
Yes. The end caps are their own item, one pair per colour, listed for both the over sills and the verge trims.
Does a deeper sill matter on a listed building?
A deeper sill changes how a window looks from the street, so on a listed building or in a conservation area, check with the local planning authority before work starts.
