Guides
How to read a window and door schedule: a guide for aluminium estimators
Sizes, opening symbols, glass notation such as 4-16Ar-4 and 44.2, Ug and Uw, RC and EI classes: what each part of a window and door schedule means and what to check before pricing.
The window and door schedule is the closest thing a tender has to a bill of quantities for aluminium work. It lists every unit type with its size, divisions, opening types, glass and performance. Read correctly, it saves hours. Read carelessly, it builds errors into every position. This guide explains what each part of a typical schedule means and what to check before you trust it.
What a schedule contains
Layouts differ between architects and countries, but most schedules have the same parts: a header with general notes, and one column or sheet per unit type with an elevation drawing and a table of properties. The elevation shows the outline, the divisions and the opening symbols. The table gives the numbers.
| Field | Typical notation | What to check |
|---|---|---|
| Type mark | W-01, D-03, L1, CW-A | The same mark on the plans and elevations |
| Quantity | 12 pcs, sometimes split by floor | Count on the drawings independently |
| Size | 1500 × 1800 (width × height, mm) | Opening or frame size, and which comes first |
| Opening type | Symbols on the elevation, or text | Viewing side and hand |
| Glass | 4-16Ar-4, 33.1, Ug 1.0 | Every pane of every field |
| Performance | Uw, Rw, RC2, EI30 | Whether the value is per unit or per system |
| Finish | RAL 7016 / RAL 9016 | Outside and inside colours |
| Hardware and notes | Handle type, closer, motor, restrictor | Items that change the price per unit |
Read the general notes first
The notes at the top or bottom of the schedule set the conventions for everything below them. Look for three things. First, the viewing side: whether the elevations are drawn as seen from outside or from inside. It decides which way every sash opens and which colour is outside. Second, the size convention: whether dimensions are structural openings, frame sizes or finished openings. Third, general requirements that apply to all units, such as a thermal target, a colour, a hardware line or a safety glass rule.
Sizes: opening or frame
A size of 1500 × 1800 can mean the hole in the wall or the outer edge of the frame. The difference is the installation gap around the frame, and it changes every profile length and every glass size. If the schedule does not say, compare it with a section drawing, where the frame and the wall are shown together. If that does not settle it, ask. Also confirm the order: most schedules give width first, but not all.
Opening symbols and hand
On European drawings, an opening sash is usually shown by lines from the corners that meet at the hinge side, forming a triangle. Lines meeting at a side mean a side-hung sash. Lines meeting at the bottom mean a bottom-hung (tilt) sash. Both together mean a tilt-turn sash. Arrows usually show sliding. Many drawings also use line style to show direction: a solid line for a sash opening towards the viewer, a dashed line for one opening away. These conventions vary, so always check the legend.
Decoding the glass
Glass make-ups are written from outside to inside, in millimetres. A few common patterns:
- 4-16Ar-4: a double-glazed unit with a 4 mm pane, a 16 mm cavity filled with argon, and another 4 mm pane.
- 4-14Ar-4-14Ar-4: a triple-glazed unit with two 14 mm argon-filled cavities.
- 33.1 or 44.2: laminated glass. The first two digits are the thicknesses of the two panes in millimetres. The digit after the point is the number of 0.38 mm interlayers. So 44.2 is two 4 mm panes with two interlayers.
- T, ESG or “toughened”: thermally toughened glass. VSG or “laminated”: laminated safety glass.
- Coatings such as low-e and solar control are usually named by the coating position or by product, for example “low-e on face 3”.
Next to the make-up you will often find performance values for the glass alone: Ug, the thermal transmittance of the glass centre; g, the total solar energy transmittance; and Lt, the light transmittance. Do not confuse Ug with Uw, the value for the whole window, which also includes the frame and the spacer.
Performance values
- Uw (W/m²K): thermal transmittance of the whole window. It depends on the frame, the glass and the size, so a target set per type may need a different series for small units.
- Rw (dB): weighted sound reduction. Higher values need thicker or asymmetric glass and sometimes a different system.
- RC2, RC3: burglar resistance classes under EN 1627. They require tested combinations of profile, hardware and glass.
- EI30, E30: fire resistance, integrity (E) and insulation (I) in minutes. Fire-rated units are separate, certified systems.
- Wind load, watertightness and air permeability classes, which we cover in our guide to EN 14351-1 and EN 13830.
Cross-check the quantities
A schedule is often prepared early and updated less carefully than the drawings. Count each type on the floor plans and on the elevations, and compare. Watch for mirrored units, which some schedules list under one mark and some under two, units that appear only on courtyard or roof plans, and doors listed in a separate door schedule. List every difference as a question. The method is covered step by step in how to estimate an aluminium tender from drawings.
What to do with gaps
Missing values are normal: a type without a glass make-up, a door without hardware, a colour marked “to be confirmed”. Do not guess silently. Either price a stated assumption and write it into the proposal, or send a question. Both protect you. A silent guess does not.
Frequently asked questions
What is a window and door schedule?
It is a document, prepared by the architect, that lists every window, door and glazed unit type in a building with its mark, quantity, size, divisions, opening types, glass, performance requirements and finish. Estimators and fabricators use it as the basis for the position list.
What does 4-16Ar-4 mean?
It describes a double-glazed unit from outside to inside: a 4 mm pane, a 16 mm cavity filled with argon gas, and a second 4 mm pane.
What does 44.2 mean in a glass specification?
It is laminated glass made of two 4 mm panes bonded with two 0.38 mm interlayers, 0.76 mm in total.
What is the difference between Ug and Uw?
Ug is the thermal transmittance of the centre of the glass only. Uw is the value for the whole window, including the frame and the edge of the glass, and it also depends on the window size.
Which document wins if the schedule and the drawings disagree?
The one named in the contract’s order of precedence. If no order is given, ask the client in writing and state your assumption in the proposal.
