Curtain walling for main contractors: what to include in a tender package
For main contractors and bid teams
Curtain walling prices vary more than most packages because so much depends on information that is often missing at tender: fixing details, design responsibility, interfaces and programme. The more of that a tender package contains, the closer the returned prices will be to each other and to the final cost.
This guide lists what is most useful to include. It is general guidance; the requirements for any project come from its own specification and design team.
1. Drawings
Subcontractors price what they can see. Include:
- Elevations showing the full extent of the curtain walling
- Plans and sections through slab edges, heads, sills and junctions
- Any door, window or vent schedules within the façade
- The revision status of each drawing
2. Specification and performance
State any named system or finish, and the thermal, acoustic, safety and weather requirements. If the specification is performance-based rather than naming a system, say so, so tenderers know they can propose one.
3. Design responsibility
Say clearly who is responsible for the design of the curtain walling, its fixings and its interfaces. This is one of the biggest sources of difference between prices and of disputes later.
4. Interfaces and package boundaries
List who provides each of these, or ask tenderers to state their assumptions:
- Fixings and brackets to the frame or slab edges
- Cavity closers, membranes and flashings
- Fire stopping at slab edges
- Sealant lines to adjoining trades and making good
5. Programme and site
Give the tender return date, the target start on site, key milestones and any phasing. Include access, storage, crane or hoist availability and working-hour restrictions, as these affect installation cost.
6. Commercial information
Include the subcontract conditions, preliminaries that affect the subcontractor and any pre-qualification questionnaire, so these can be returned with the price rather than chased later.
General guidance only. Requirements for a specific project are set by its specification, design team and the applicable regulations.