Doors and framed openings

Framed openings explained

Every door, window or louver in a pre-engineered building sits in a framed opening: a set of jamb members on each side, a header above and sometimes a sill, which interrupt the girts and transfer wind and door loads into the girts, eave strut, endwall columns or foundations. The door itself is a manufactured product mounted on this framing. Openings are defined at concept stage because they change the wall framing, the bracing layout and sometimes the frame design. Openings left "by others" or cut on site without framing are a common source of cladding damage and leaks.

Door types

Fire-rated doors, insulated doors for cold stores and dock doors with levellers and shelters are specified separately to meet local codes.

Framing and sizing rules

• Jambs are usually cold-formed C sections for small openings and hot-rolled or built-up members for large doors, spanning from slab to eave strut or to a header.
• Headers span between jambs and carry wall sheeting above plus the weight of the door coil or track.
• Clear opening = door size; framed opening is slightly larger to suit the manufacturer's guide and fixing details – obtain door data before detailing.
• Wind on a closed door is transferred to the jambs and header; a large door may need its own wind columns or a portal frame in the wall.
• Openings placed in a braced bay require portal bracing instead of rod bracing.
• Check whether a door may be open during a storm: in many codes a large opening changes the building to "partially enclosed", greatly increasing internal pressure on the whole structure.

Sliding doors, roll-up wind ratings and framed opening types

Sliding doors remain common on PEB because they need no headroom and can close very wide openings. A typical sliding door consists of a leaf framed from cold-formed members and clad with the wall profile, hung from trolleys running in an overhead track fixed to a header, with a bottom guide or floor channel to stop the leaf swinging in the wind. Single-leaf, bi-parting and multi-leaf telescoping arrangements are used; the wall area beside the opening must be long enough to receive the open leaves, and the track header must be designed for the door weight and wind reactions.

Roll-up and sectional doors are rated for wind like any other cladding element. Large curtains deflect inward and outward under wind, and windlocks or end-locks on the slats keep the curtain engaged in the guides. Ratings are established by test:

The required rating comes from the components-and-cladding pressure at the door location. In hurricane and cyclone regions, a door that fails lets the building become internally pressurised, which can overload the roof, so door ratings and the building enclosure classification must be consistent.

Personnel doors and frames are commonly specified to ANSI/SDI A250.8 in North America; fire doors are tested and installed to UL 10C and NFPA 80 (US), EN 1634-1 (Europe) or AS 1530.4 with AS 1905.1 (Australia).

Installation and detailing

Jambs are anchored to the slab with expansion or chemical anchors and bolted to the girts or eave strut. Head, jamb and base trims weather-seal the opening (see trims and flashings). Bollards protect jambs from forklift impact. Door guides and brackets must be fixed into framing, not into sheeting. Motorised doors need power and controls coordinated with the electrical contractor. In hurricane and cyclone regions doors should be rated for the design wind pressure and, where required, debris impact.

Maintenance and WSC supply

Check door operation, guides, springs and seals regularly, and repair dents in jambs immediately because they can weaken the opening. World Steel fabricates all framed openings – jambs, headers, sills and trims – as part of the secondary framing, and supplies roll-up and personnel doors in its doors and windows packages, coordinated with windows and louvers on the wall drawings.