Shiplap · ceilings
Shiplap ceiling calculator
Ceilings are where shiplap calculators usually give up. This one just asks for width and depth, then does the same honest maths as the wall version — rows, boards, waste, shopping list.
- Ceiling-ready inputs
- Joist-friendly row count
- Works in feet or metres
Your ceiling in three answers
Left to right, wall to wall.
Front wall to back wall.
How long the boards are at the store. Longer boards mean fewer joints.
No calculate button — the numbers follow your typing.
Ceiling preview
Final row needs cutting, leftover width: 1.75 in
12 ft × 10 ft = 120 sq ft total.
What you need
10% waste includedBoard rows
23rows
5.38 in face each
Total linear
276 ft
120 sq ft covered
Boards to buy
39boards
about 13 packs of 3 · exact fit
39 boards needed with cutting waste. Each board covers 5.38 in once the reveal is taken off.
23 rows, 276 ft of board, 39 boards to buy.
Your shopping list
39 boards (about 13 packs) · 120 sq ft · 10% waste built in
- 1
Buy 39 8ft 1x6 shiplap boards (about 13 packs of 3)
- 2
Buy 1 box of 1.5-inch 18-gauge brad nails
- 3
Buy 2 tubes of Liquid Nails construction adhesive
39 boards needed with waste, and 13 packs of 3 covers it exactly. Always round up — a second trip costs more than a spare board.
What will it cost?
Pop in the shelf price. 39 boards (about 13 packs of 3) at the store.
- Shiplap boards39 × $12.98 each
$506.22
- Brad nails1 box × $9.98
$9.98
- Construction adhesive2 tubes × $6.48
$12.96
Project total
Fixings: $22.94 · $4.41 per sq ft
$529.16
Excludes paint, caulk, primer and tools. Prices are estimates you can edit above.
Ceilings: the two things that actually trip people up
The maths is easy. The install is where ceilings earn their reputation.
- 1
Measure depth, not height
Depth is front wall to back wall. Width is side to side. Enter them as a wall would be entered and the row count comes out right, because a ceiling is just a wall lying down.
- 2
Plan around the joists
Boards across the joists means you can nail every 16 in into real wood. Boards along the joists means furring strips every 16 in first — add that lumber to your list.
- 3
Budget one extra row
Ceilings are rarely square. Out-of-square rooms eat an extra row on the last course, which is exactly what the 10% waste is there for. Do not drop it to 5% up there.
Ceiling install notes worth reading twice
Everything below is cheap advice compared with redoing a ceiling.
- Weight matters. 1x6 boards in 8 ft lengths are the sweet spot for solo work — 16 ft boards overhead are a two-person job.
- Glue plus brads, not one or the other. Ceilings rattle and flex; adhesive is what keeps them quiet.
- Check the ceiling for sag before you start. Shiplap follows whatever the joists are doing, including the dip.
- Leave a 1/16 in expansion gap at each wall and cover it with trim or caulk.
- If the ceiling has a light in the middle, work outward from the light so any error ends up at the edges instead of the middle.
Questions people actually ask
Straight answers to the ceiling questions that show up in every search bar.
How much shiplap do I need for a ceiling?
Same maths as a wall, different words. Measure the ceiling width and depth instead of length and height, then treat the result exactly like a wall — rows, boards, waste and all. A 12 ft by 10 ft ceiling with 1x6 boards lands around 23 rows and 39 boards with 10% waste.
Should ceiling boards run along or across the joists?
Run them across the joists and you can nail straight into framing — that is the easy version. Run them along the joists and you will need furring strips or a plywood backer first. The calculator does not care which way you go, but your arms will.
Do I need to subtract lights and vents?
Only the big holes. A recessed light or a small vent barely changes a board count, so we leave them in. If you are cutting a large hatch or an AC bulkhead, put the area into the window and door box and the count adjusts for you.
What is the best board size for a ceiling?
1x6 is the crowd favourite: fewer rows than 1x4, less weight than 1x8, and boards are still light enough to hold overhead. Use 1x4 for a busier, more cottage look, or 1x8 if you want a clean modern plane with fewer seams.
Can I install shiplap on a ceiling by myself?
Yes, with a helper and a deadman prop. Cut the first row to fit, screw a temporary T-prop under it while the adhesive sets, then work outward. Loads more useful than any calculator: mark your joists before the first board hides them.