Elective Units: Specialist Tiling Techniques and Finishes
What the elective units cover
Elective units extend the core into specialist work: waterproofing wet areas, laying large-format and stone tiles, installing mosaic and feature patterns, tiling stairs and curved surfaces, and setting out complex jobs. You should understand membrane systems and their curing and flood-test requirements, movement and construction joint placement, slip-resistance ratings for wet areas, and the handling and sealing of natural stone. Pattern setting-out is heavily examined: herringbone, chevron, basketweave and running bond each have different datum and cut rules, and feature strips or borders must be centred and balanced against the room, not just started from one wall.
Traps to watch
Questions often test whether a membrane must extend up walls and into showers, or whether a flood test is required before tiling. Large-format tiles need high-coverage adhesives, back-buttering and sometimes mechanical fixing; assuming standard coverage is a common error. Stone may need sealing before and after grouting, and some stones stain from cement-based grout. Pattern questions may ask for the cut size at a border, so know that balanced borders split the difference at both ends.
Worked example
A 3.6 m wall is set out with a 100 mm border each side and full tiles between. Full-tile span = 3600 - 200 = 3400 mm. With 300 mm tiles plus 3 mm joints, each unit is 303 mm. 3400 / 303 = 11.2, so use 11 full tiles (3333 mm) and absorb the remainder into the two borders, giving roughly 133 mm each. Always balance cuts rather than leaving one narrow sliver.
Rule of thumb
Set out from the centre of the visible wall or floor, balance cuts at both ends, and never leave a cut narrower than half a tile where it can be avoided.