How to Tile a Bathroom Wall: Starting from the Bottom or Middle

For most bathroom wall tiling jobs, the best starting point is the middle of the wall — or more precisely, a carefully planned horizontal datum line that ensures your tiles are level and symmetrical. However, there are situations where starting from the bottom makes more sense. The right choice depends on your tile size, the room layout, and whether you have a full row of tiles at the top or bottom.

Why Your Starting Point Matters

Getting your layout right before you stick a single tile is the most important step. A poor starting point leads to awkward slivers of tile in prominent places — like a thin strip along the top of the bath or beside a window — which looks unprofessional and is harder to cut and fix neatly. Taking time to set out your tiles dry (without adhesive) before you begin will save you a lot of frustration.

Starting from the Middle vs. the Bottom

Starting from the Middle

Starting from the centre of the wall is the most common approach for feature walls or walls where both sides are equally visible. Here's why:

• It keeps the layout symmetrical, so any cut tiles at each end are equal in size.
• It avoids a tiny sliver of tile on one side.
• It's the preferred method when tiling around a window or niche.

To find your centre, measure the wall width and mark the midpoint. Then do a dry lay along the floor or a batten to see how the tiles fall. If the tiles at each end would be less than half a tile wide, shift your centre point by half a tile so the cuts are larger and more balanced.

Starting from the Bottom

Starting from the bottom works well when:

• You have a bath, shower tray, or tiled floor that provides a flat, level reference point.
• You want full tiles to sit at eye level and are happy with cuts at the top (often hidden by a ceiling or cornice).
• The floor or bath edge is confirmed to be perfectly level — if it's not, you'll need to account for this.

Important: Never use the floor or bath rim as your starting line without checking it with a spirit level first. NZ homes, especially older villas and bungalows, often have floors that are out of level. If the floor isn't level, establish a horizontal batten at the height of your first full tile row instead.

Step-by-Step: Setting Out Your Bathroom Wall

1. Check the walls and surfaces. Walls must be clean, dry, flat, and structurally sound. In wet areas (showers, around baths), GIB Aqualine or a similar moisture-resistant substrate is required under your tiles — standard plasterboard is not suitable.

2. Find your datum line. Use a long spirit level or laser level to draw a true horizontal line across the wall. This is your reference for everything.

3. Do a dry lay. Hold or lean tiles along your datum line to see how they fall at the edges, corners, and top and bottom. Adjust your starting point until you have the best balance of cuts.

4. Fix a temporary batten. Nail or screw a straight, level timber batten to the wall along your datum line. This supports the weight of tiles as the adhesive sets and keeps your first row perfectly straight.

5. Mix and apply adhesive. Use a polymer-modified tile adhesive suitable for wet areas — products from Ardex or Mapei are widely used by NZ tilers. Apply with a notched trowel, combing in one direction for good coverage.

6. Lay your tiles. Press each tile firmly into the adhesive with a slight twisting motion. Use tile spacers to keep grout joints consistent. Check frequently with a spirit level — both horizontally and vertically.

7. Work upward from your batten. Once the tiles above the batten have set (usually 24 hours), remove the batten and fill in the bottom row, cutting tiles to fit as needed.

8. Cut tiles carefully. A wet saw (tile saw) gives the cleanest cuts, especially for porcelain. Angle grinders with a diamond blade can work for straight cuts but require care. Always wear eye protection and a dust mask — tile dust is a health hazard. Check WorkSafe NZ guidance on silica dust if cutting engineered stone or certain porcelain tiles.

9. Grout and seal. Allow adhesive to cure fully before grouting (check the manufacturer's datasheet). In wet areas, use a waterproof or epoxy grout. Once cured, apply a grout sealer to protect against moisture and staining.

Waterproofing in Wet Areas

Under the NZ Building Code (specifically Clause E3 — Internal Moisture), wet areas like showers must be properly waterproofed before tiling. This typically means applying a membrane system behind the tiles. BRANZ provides good guidance on acceptable wet area construction methods. If you're unsure whether your substrate and waterproofing meet code, check with your local council or a licensed building practitioner.

Tools You'll Need

When to Call a Professional

Tiling itself is not restricted work under NZ law, so homeowners can tile their own bathrooms. However, there are important exceptions:

• Plumbing connections (moving or installing waste pipes, water supply) must be done by a licensed plumber or drainlayer.
• Electrical work (adding or moving lights, fans, heated towel rails) must be done by a registered electrician.
• If you're unsure about waterproofing, substrate condition, or the scope of your project, consult a Licensed Building Practitioner.

For large or complex bathrooms, awkward layouts, or high-end tiles, hiring an experienced tiler will save time and deliver a better result. You can find qualified local tilers on tradedirectory.co.nz.

Sources & Further Reading

• BRANZ – Wet Area Construction
• MBIE Building Performance – NZ Building Code
• Ardex NZ – Tile Adhesives & Waterproofing
• Mapei NZ – Tile Installation Products
• WorkSafe NZ – Silica Dust Safety
• GIB – Wet Area Plasterboard