Guide 106

White-cement concrete window sills

15 – 19 h of work · 3 weeks★★☆materials €216 – 600

Internal window sills made to measure for each window, cast face down in a melamine-faced chipboard mould. One mould, two finishes: terrazzo ground to a sheen, or a smooth white slab straight from the mould with no grinder. 2 mm clearance, composite reinforcement, a mix weighed to the gram for lengths of 600 – 2 400, and bedding in tile adhesive flush with the wall. Sample set of 5 windows.

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23 pages A4 mix to the gram dimensioned drawings shopping list

What's in this guide

Measuring the reveal in three places and casting length L = S − 4 (2 mm clearance each side)
Melamine-faced chipboard mould, face down, and a cutting plan for the sample set from one sheet
A mix to the gram for terrazzo (A) and the smooth slab (B), plus a weight table for lengths 600 – 2 400
Composite reinforcement, casting in two layers, compaction and three weeks of curing
Grinding to terrazzo 50 → 800 with pore filling, or a smooth face with no grinder
Bedding in flexible C2 S1 tile adhesive, splitting long pieces, and joints that don't crack

PDF, 23 A4 pages to print for the workshop · dimensioned drawings and illustrations · shopping list on a separate page so it can be torn out and taken to the store. You download it right after payment, access is for life.

Before you start building

This guide is informational material, not construction documentation or a professional assessment. Follow the instructions of tool and material manufacturers, safety rules and local building regulations. A piece built at home is not a certified product, even where the guide follows a European standard. Structures that carry people — beds, swings, decks, pergolas, children's equipment — should be checked by a qualified person before use. To the extent permitted by law, we accept no liability for the result of your build, property damage or injury arising from the use of this guide (Terms, section 9).