Curtain Wall Framing — Quick Reference

Stud Specifications

Item	Value
Steel grade	345 MPa (50 ksi) — ASTM A1003 Grade 50
Typical gauge	14ga (1.73 mm) or 12ga (2.46 mm)
Typical width	152 mm (6") or 203 mm (8")
Standard spacing	400 mm (16") o.c.
Corner/edge zones	Closer spacing or heavier gauge per P.Eng.

Cladding Type	Limit
Brick, stone, precast (rigid)	L/360
Metal panel, fibre cement (flexible)	L/240
Glazing systems	L/175 (or per glazing eng.)

Example: 3.6 m storey, L/360 = 10 mm max deflection under design wind load.

1. Cladding (brick, metal panel, stone, fibre cement)
2. Air space / drainage cavity (min. 25 mm for brick; varies for others)
3. Continuous insulation (CI) outboard of studs (EPS, XPS, mineral wool, or polyiso)
4. Weather-resistive barrier (WRB) / air barrier (self-adhered membrane or fluid-applied)
5. Exterior sheathing (DensGlass or exterior gypsum)
6. Steel studs + cavity insulation
7. Vapour retarder (warm side of assembly)
8. Interior drywall finish

Without CI outboard, a 152 mm wall with R-22 batt performs like R-8 due to steel thermal bridging.

CSA S136: CFS member & connection design
AISI S240: CFS framing systems
OBC Part 4: Structural design — wind loads, deflection
OBC Part 5: Environmental separation — air/vapour barriers, rain control, insulation
OBC SB-10: Energy efficiency — CI requirements
CSA A371: Masonry construction for buildings (brick veneer)
Ont. Reg. 213/91: Fall protection, scaffold requirements

P.Eng. shop drawings REQUIRED — no prescriptive path for church curtain walls. No drawings = no framing.
345 MPa steel only for curtain wall studs. 228 MPa (33 ksi) = 35% less capacity. Verify grade stamp.
Deflection clips: Bolts must allow vertical sliding. Never fully torque. Mark clips to prevent accidental tightening.
Air barrier continuity: Every joint, penetration, and transition must be sealed. One gap = condensation & mould path.
Fall protection mandatory for all exterior framing work at height (Ont. Reg. 213/91).
Window flashing sequence: Sill, jambs, head (shingled). Reverse order = water intrusion.

Pre-fabricate clip angles in bulk on the ground with a jig — faster, more accurate, less waste.
Spray-foam seal around window rough openings from inside before drywall — closes the air gap between frame and stud.
Mock-up wall section before production — verify all layers, CI attachment, cladding clips, and drainage path.
Photo document every concealed layer (WRB, flashing, CI) before cladding covers it. These photos are your warranty defence.