Building structure

What this cluster is for

Two calculators that both answer "how much of a wall", in two different trades. Brick counts the masonry unit and the mortar that goes between the units; plasterboard counts the sheets, screws, scrim and jointing that cover a wall or a ceiling.

Both hinge on a module. Bricks are counted at about 60 per square metre for a 215 × 65 mm brick with a 10 mm joint — but that 60 is a module figure, with the joint included, so a thinner joint means more bricks per square metre, not fewer. Plasterboard has the same shape of problem in reverse: boards come in fixed sizes, so the waste sits in the offcuts rather than scaling with the area.

What usually goes wrong

• Treating 60 bricks/m² as exact. It is the module figure for one unit and one joint size. Change either and the count moves.
• Forgetting the cut course. A wall that is not an exact multiple of the brick height needs a cut course at the top, and cuts break.
• Guessing the mortar mix. The mix has to suit the unit and the exposure. A mix that is too strong is not "better"; it is a future crack path.
• Ordering plasterboard from floor area. Walls are a run × height, plus a ceiling if there is one, minus the openings — and the openings still need boards around them.
• Not allowing for the offcuts. A board is 2.4 × 1.2 m. A 2.5 m ceiling wastes more of a board than a 2.4 m one, and the waste is not proportional to area.
• Forgetting the fixings and the joints. Screws, scrim tape and joint filler scale with the boarded area; they are not optional extras.

What to order together

• Bricks or blocks, cement, building sand, wall ties, and a roll of damp-proof course
• Plasterboard, screws, scrim tape and joint filler
• Hire: a board lifter for a ceiling, and a brick jointer for the finish

Related clusters

Cross-links here are contextual, not a second home: each calculator belongs to exactly one cluster above.