Description
When a house gets external insulation and a new render coat, the window sills are left short of the finished wall. The Over Sill White 2.5m 170mm Depth goes over the old sill and brings a clean white edge out beyond the render. In the white range it is the third of four depths — 170 mm deep, supplied in 2.5 m lengths.
Four Reasons to Consider the White 170 mm Depth
- A white sill for white frames. It keeps the window line in one colour with the white verge trim above.
- Depths either side. 140 mm sits just below and 220 mm just above, so a change in your site figures still has somewhere to go.
- 2.5 m per piece. Cut on site to the width of each sill.
- Caps to match. The white end cap pair closes both ends in the same colour.
The Over Sill White 2.5m 170mm Depth: What You Get
Known in the trade as an oversill or an external window sill extension, the profile is a flat board with a short upstand on its back edge and a front edge bent down. The white product photo shows this shape with caps on the ends; the same photo is used on all four white depths.
| Property | This over sill |
|---|---|
| Colour | White |
| Depth | 170 mm, third of four |
| Length | 2.5 m per piece |
| Shape | Flat board, upstand at the back, front edge bent down |
| End caps | Separate item: white end cap pair |
| Matching trim | White verge trim with upstand, 2.5 m, 140 mm |
Four Depths in Each Colour
Find your depth, then choose the column that matches your frames.
| Depth | White | Anthracite |
|---|---|---|
| 110 mm | White 110 mm over sill | Anthracite 110 mm over sill |
| 140 mm | White 140 mm over sill | Anthracite 140 mm over sill |
| 170 mm | This over sill | Anthracite 170 mm over sill |
| 220 mm | White 220 mm over sill | Anthracite 220 mm over sill |
Working Out Whether 170 mm Fits
A middle depth is not a safe default for a wall that seems to fall in between. The answer comes from two site measurements at each window:
- the total thickness of insulation and render around the opening;
- how far the present sill sticks out from the wall today.
Give both to the counter on 023 8200 2442 and the depth is agreed before you order. If the windows on one side of the house are different, measure each one.
Lengths and Caps for Each Window
Divide each sill width by 2.5 m and round up to the next whole length.
- A 1.5 m sill: one length, cut down.
- A 4.6 m sill: 4.6 ÷ 2.5 = 1.84, so two lengths.
- Caps: one white pair for each sill with two open ends.
For a sill made of two lengths, agree with the counter how the joint is made before you order.
The Rest of the White Set
- White verge trim with upstand — the matching profile for the top of the wall.
- White end cap pair — finishes the ends of a sill or verge run.
- Every depth in both colours: the window sill extensions page.
White or Anthracite
Choose by the window frames. White frames go with this sill, the white verge trim and white caps. Dark frames go with the anthracite 170 mm over sill in the table, which has the same depth and its own anthracite caps.
Installation Guides
- How to install window sill extensions explains measuring, cutting and capping the sill.
- Render detailing around windows and doors explains how the sill, beads and render meet at the reveal.
Ordering, Delivery and Returns
- Dispatch — Renders World processes orders the same day when the stock is there; order the caps alongside the sills.
- Delivery — quoted by the team after the order; parcels up to 25 kg arrive next day at the kerbside.
- Collection — at the counter, Unit 9A, Central Trading Estate, Southampton SO14 5JP, open Monday to Friday 7am to 5pm and Saturday 7am to 12pm.
- Returns — up to 14 days, in original condition, on goods bought directly from Renders World; special orders and promotion purchases are excluded.
FAQ
Which insulation thickness suits 170 mm?
Your wall decides. Ring 023 8200 2442 with the insulation and render thickness at the window and the projection of the current sill, and settle the depth first.
Is the photo the 170 mm profile?
It shows the shape all four white depths share. The depth you receive is the one in the title, 170 mm.
Is it aluminium or uPVC?
Where your specification names a material, check with the counter on 023 8200 2442 before ordering.
Can it be used as an internal window board?
No. It is fitted outside, over the old sill, on an insulated and rendered wall.
My wall falls between 140 and 220 mm — is 170 mm the one?
Not automatically. Give the counter your two site measurements and the depth is settled before you order.
Is 170 mm also sold in anthracite?
Yes — the anthracite 170 mm over sill, with the anthracite end cap pair.