How to Frame and Finish a Wall

Building a wall is four estimates stacked on each other, and each one depends on the one before it. Done in order they are all straightforward. Done out of order — buying drywall before you know your stud spacing, say — and you end up cutting sheets that did not need cutting.

1. Studs, and the off-by-one

The Wall Stud Calculator gives stud count at 16 or 24-inch spacing, plus the plate timber, and it handles the mistake everyone makes.

A 16-foot wall at 16-inch centres is not 12 studs. It is 13. Spacing counts the gaps; the wall needs a stud at both ends. Dividing length by spacing gives you the gaps and quietly loses the last stud — and it is the same off-by-one whichever spacing you use.

Then add corners, openings and blocking on top of that number.

2. Sheets

The Drywall Sheet Calculator works from wall and ceiling area with a waste allowance for cuts.

Do this after you know your stud spacing, because spacing decides whether sheets land on a stud or need cutting back to one. Sheets are sized to suit standard spacings; a wall framed to something else generates offcuts everywhere.

Count the ceiling separately from the walls, and remember it is the harder half to hang.

3. Joint compound — the number that is finally settled

The Joint Compound Calculator uses USG's own submittal sheets: 9.4–10 gallons per 1,000 sq ft of panel, which works out to about a third of a gallon per sheet for the whole three-coat finish.

That figure is worth trusting because published advice on it has been genuinely contradictory — widely repeated numbers differed from each other by a factor of three. This tool is built on the manufacturer's own data rather than a rule of thumb.

Note it covers all three coats. People estimate the bedding coat, buy for that, and run out during the finish coats when the job is nearly done.

4. Trim, and the lengths you can buy

The Baseboard & Trim Calculator works out baseboard once doorways are taken out, with an allowance for mitre cuts and — the useful part — the lengths you can actually buy.

Trim is sold in fixed lengths. A 13-foot wall from 12-foot stock is two pieces and a joint, not 13 feet of material, and every mitre consumes a little more. Running total linear feet and dividing by stock length understates it.

The short version

1. Studs first — and add one. Spacing counts gaps, not studs.
2. Sheets after spacing is settled, ceiling counted separately.
3. Compound at about a third of a gallon per sheet, for all three coats.
4. Trim by buyable lengths, not by total footage.

Each tool has a printable with its own assumptions, and the compound sheet carries the USG figures so you can check them against whatever the merchant is trying to sell you.