Silicone Joint Movement Capacity Calculator

Thermal Movement  ·  Wind Load Stress  ·  Pass / Fail  —  ASTM C1401 / C1472 / C1193  ·  ETAG 002  ·  Dow SSG Manual

1 — Joint Geometry

mm — face width of joint opening
mm — sealant depth with backer rod
Preset fills Panel Width below
mm — c/c spacing between joints; drives thermal movement
mm — storey height / panel height
Backer rod assumed — 2-sided adhesion only (no 3-sided bond).  Ideal W:D = 2:1 per ASTM C1193.
SSD (Short Span Dimension) is auto-set to the shorter of Panel Width or Panel Height for wind stress.
Panel Width is used as the length of substrate (L) contributing thermal movement to the joint.

2 — Climate & Temperature

°C — surface temp (add ~15°C for dark / south-facing cladding)
°C — lowest expected surface temperature
× 10⁻⁶ per °C — auto-fills from material

3 — Wind Load

kPa — service-level design wind pressure
Wind stress formula (Dow SSG Manual / ASTM C1401):  σ = (q × SSD) ÷ (2 × Bite)
SSD = shorter panel dimension. Bite = joint width (W). Allowable = 138 kPa standard.

4 — Sealant Properties

Non-staining silicone is assumed fully cured before movement exposure. Movement capability is the ± % of the joint width the sealant can accommodate without cohesive or adhesive failure.
Results — Joint Geometry
Width : Depth Ratio
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Short Span (SSD) Used for Wind
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Results — Thermal Movement
Temperature Range ΔT
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Thermal Movement ΔL
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Required Movement (with Safety Factor)
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Sealant Can Accommodate
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Thermal Movement Verdict
Results — Wind Load
Calculated Wind Stress (σ)
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Allowable Stress Limit
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Per ASTM C1401 / ETAG 002
Wind Load Verdict
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References: ASTM C1401  ·  ASTM C1472  ·  ASTM C1193  ·  ETAG 002  ·  ISO 11600  ·  Dow SSG Technical Manual (Asia)  ·  Sika Structural Glazing Guidelines