Drywall waste factors: what to actually add, and where

The single biggest source of drywall quote errors we see is people applying a flat 10% waste to everything. That works in a contracting handbook. It does not work on a real fit-out where the partition layout, ceiling height, and access conditions vary site to site.

This is what we have learned to add — and where.

Board

The waste figure depends on room geometry, not job size.

Layout	Suggested waste
Long straight runs, few openings	5–8%
Standard partition with doors / openings	10–12%
Curved walls, splays, lots of openings	15–18%
Bulkheads, soffits, shafts	18–25%

Why the spread? Boards come in fixed sizes (typically 1200 × 2400 or 1200 × 3000 mm). Every off-cut from a cutout is real waste. A 600 mm strip removed for a door head is not going back into a wall — it goes in the bin.

The longer the straight run, the closer your real waste gets to "just trim losses." The more openings, the more you are paying to install board you will throw away.

Studs and tracks

Different physics. Studs are linear — typically 3,000 mm or 3,600 mm pieces — and your real waste is dictated by stud spacing × stud height.

For a partition:

• Track: top and bottom rails. Linear metres = 2 × wall length. Waste 5%.
• Studs: number of studs ≈ (wall length / spacing) + 1, plus jamb studs at openings (2 per opening) and head/sill studs for windows. Waste 5–8% on stud quantity.
• Noggins / nogging: required for board joins on tall partitions. Roughly one row per 1,200 mm of height. Often forgotten in spreadsheet quotes.

Ceiling height changes everything. A 2,700 mm ceiling lets you use 2,700 mm studs uncut. A 2,750 mm ceiling forces you to either use 3,000 mm studs (waste 250 mm per stud) or 2,400 mm + an extension (extra labour). The cost difference is real.

Screws, tape, compound

These almost never come out of a spreadsheet correctly because the rate-of-use depends on board area, not partition length:

• Drywall screws: ~1 kg per 30 m² of single-layer board. 2× for double-layer.
• Tape: typical paper or fibre-mesh tape — about 1.4 metres of tape per square metre of board (joints + corners).
• Joint compound: 1 kg per 4 m² for finish-grade level 4. More for level 5.

Apply waste 8–12% on each. They are the cheapest line items in the quote and the easiest to under-order.

Acoustic and fire-rated work

Add 5–10 percentage points to your normal board waste figure on:

• Fire-rated partitions (the boards are heavier and crack at the corners, more breakage).
• Acoustic partitions with rockwool infill (the rockwool itself wants 10% over insulation calc).
• Shaftwall and lift shaft linings (board weight + access constraints).

A "10% waste, all in" quote on a fire-rated shaftwall job will leave you short on every line.

Where to apply this in Quotiqa

The platform does not auto-add waste — that is intentional. Different teams have different working assumptions, and we did not want to bake one team's defaults into another's quote.

The clean way to apply waste:

1. Set your cost rate on each item at the already-loaded figure (i.e., supplier price × your standard waste %). That way the cost field reflects what your delivery will actually cost.
2. Keep markup as your commercial lever, not your waste buffer.

The mistake is using markup to cover both waste and profit. When the supplier price moves, you cannot tell which part of the markup absorbs it. Separate them.

What about labour?

We are deliberately not addressing labour rates here — that is a separate calculation tied to crew composition, productivity rates, and local market. The waste figures above are for materials only.

If you want a labour-inclusive cost rate per item type, model it as:

cost_rate = material_loaded_cost + labour_cost_per_unit

…and feed that one number into the cost field. Quotiqa does not care which inputs you used to build it — it just needs the final cost-per-m or cost-per-m².

TL;DR

• Don't apply 10% to everything. Use geometry-aware figures for board.
• Studs and tracks waste differently from board.
• Fire-rated and acoustic work get a 5–10 point bump.
• Build waste into your cost rate, not your markup.
• The margin chip tells you whether the resulting sell rate is sustainable.

Better waste assumptions → tighter quotes → fewer surprises on procurement.