Glass · Sealants
Silicone sealant calculator
A joint 6 mm wide and 6 mm deep takes 36 ml of silicone per metre, so a 310 ml cartridge does about 8.6 metres; 10 metres need 2 cartridges with 10 % waste. The volume is the joint's section times its length: width × depth for a joint between two edges, half the width squared for a corner bead. The second part sizes a structural silicone joint, its bite and its thickness, from the wind and the movement.
How it is worked out
A millimetre squared of section is a millilitre per metre of joint, so a 6 × 6 mm joint takes 36 ml/m and a 310 ml cartridge does 8.6 m. A corner bead round a shower tray, 8 mm on each leg, is 32 ml/m: 12 metres take 2 cartridges with the waste.
The depth follows the rule sealant makers print: as deep as wide up to 12 mm, half the width above that, and never less than 6 mm, with a backer rod behind so the sealant sticks to two sides and not three. For a pane 1200 mm on its short side under 1.6 kPa of wind: h = 1200 × 0.0016 / (2 × 0.14) = 6.9 mm of bite. With 2 mm of movement the thickness works out at 3.9 mm, so the 6 mm minimum governs: the joint is 6 mm thick.
What this page does not do
- It does not approve a structural joint. Structural glazing is checked by the silicone maker against the project (adhesion tests, the approval's σ, dead load on unsupported panes); this is the predimension to send them.
- It does not choose the sealant. Neutral-cure silicone for glass, sanitary grade in showers, and never acetoxy on insulating glass edges or mirrors.
Questions people ask
- How many metres does a tube of silicone do?
- A 310 ml cartridge does about 8.6 m of a 6 × 6 mm joint, 9.7 m of an 8 mm corner bead and 3.1 m of a 10 × 10 mm joint: divide the cartridge's millilitres by width × depth in millimetres.
- How much silicone do I need for a shower?
- Measure the corner beads in metres and multiply by the bead's leg squared over 2: an 8 mm bead is 32 ml per metre, so 12 metres take 2 cartridges of 310 ml with 10 % waste.
- How deep should a sealant joint be?
- As deep as it is wide up to 12 mm, half the width above that, and never under 6 mm, with a backer rod behind it. Your sealant's data sheet may say otherwise; it wins.
- How is the structural silicone bite calculated?
- With ETAG 002: bite = short side × wind pressure / (2 × 0.14 MPa). A pane 1200 mm on its short side under 1.6 kPa needs 6.9 mm, never under 6 mm, and the silicone maker checks it.