PreConstruct AIOn an interior set, the floor plans tag every wall with a partition type — a mark like P1, 3A or W-4 in a small symbol on the wall. The partition schedule (or legend, or wall types sheet) says what each mark means. It is usually on an A-500 or A-600 series sheet, sometimes on the first floor plan. A drywall takeoff is the length of each type off the plans, multiplied out by what the schedule says.
What a partition type says
A typical commercial schedule looks something like this:
| Type | Framing | Board | Insulation | Height | Rating |
|---|---|---|---|---|---|
| P1 | 92 mm (3⅝") steel stud @ 400 (16") o.c. | 1 layer 16 mm (⅝") Type X each side | — | To underside of ceiling + 150 | — |
| P2 | 92 mm steel stud @ 400 o.c. | 1 layer 16 mm Type X each side | Acoustic batt, full height | To deck | STC 45 |
| P3 | 152 mm (6") steel stud @ 400 o.c. | 2 layers 16 mm Type X each side | Acoustic batt | To deck, deflection track | 1 hr, listed design |
Read every type for the same five things:
- Framing — stud depth, gauge (thickness) and spacing. Spacing is a maximum and depth a minimum in most listed designs.
- Board — how many layers on each side, the thickness, and the kind: regular, Type X, moisture-resistant, abuse-resistant, shaft liner. One side can differ from the other.
- Insulation — acoustic or thermal batts, and whether they run full height.
- Height — to the ceiling, a set distance above it, or to the deck (underside of the structure). Walls to the deck often need a deflection head track.
- Rating — a fire-resistance rating with a listed design number (ULC or UL), and a sound rating (STC). Ratings bring sealant, firestopping and head-of-wall details with them.
Turning a type into material
Measure the length of each type on the plans. For every type, per linear foot:
- Studs —
LF × 12 ÷ spacing + 1per run, plus the jambs and cripples at openings and a stud at each corner or tee. The metal stud calculator does this. - Track — top and bottom,
LF × 2, or deflection track at the head where the type calls for it. - Board —
LF × height × layersfor each side, less openings. Two layers each side is four times the wall area in board. - Insulation —
LF × height, less openings, in the batt the type names. - Finishing — tape and compound on the exposed face only; the inner layer of a two-layer wall is usually fastened, not finished.
Height matters as much as length. A type “to deck” on a floor with a 4.2 m (14 ft) structure takes more than half as much board again as one at 2.7 m (9 ft) — read the building sections and reflected ceiling plans, not just the schedule.
Where schedules trip estimators
- Types that change mid-run — a corridor wall that becomes rated at a stair, or a wall that goes to deck only above a door.
- Notes that apply to every type — “all partitions at washrooms to be moisture-resistant board” lives in the general notes, not the schedule.
- Furring and shaft walls — often shown as their own types with one side only.
- Unmarked walls — the notes usually say what an untagged wall is. If they don't, ask before bid close.
- Addenda — a revised schedule changes every wall with that mark. See how to read an addendum.
Doing it on the drawings
PreConstruct AI reads the partition legend's text — P1, P2, P3 and what each line says — and turns each into a wall type carrying your own rates, which you check before using. You click along the walls on the plan, pick the type, and it lists studs, track, board, insulation, tape and compound with the arithmetic beside each. It reads text: a legend drawn only as pictures gives nothing, and the assembly is always the drawings' to decide.