Using grout to fill the gap between a tile and a skirting board is a very common DIY mistake — and unfortunately, it almost always leads to cracking, lifting, or moisture problems down the track. The short answer is: no, you should not use grout here. Instead, a flexible sealant or silicone is the correct product for this junction. Read on to understand why, and how to do it properly.
Why Grout Fails at This Junction
Grout is a rigid, cement-based material designed to fill the narrow joints between tiles where movement is minimal. The gap between a floor tile and a skirting board (or wall) is what tilers call a movement joint — a deliberate gap that allows for the natural expansion and contraction of different building materials.
In New Zealand homes, timber framing, concrete slabs, and tile substrates all move at different rates due to:
- Temperature and humidity changes — especially relevant in our varied NZ climate, from humid Northland summers to cold South Island winters
- Building settlement — particularly common in newer homes or those on timber subfloors
- Foot traffic and vibration
Because grout is rigid, it cannot absorb this movement. The result? Cracking within weeks or months, which then allows moisture to penetrate — a serious concern in wet areas like bathrooms and kitchens where NZ Building Code clause E3 (Internal Moisture) — note that E3 relates to internal moisture more broadly; the specific wet-area waterproofing requirements are also addressed under E3, but confirm the applicable clause with a professional or MBIE requires surfaces to be adequately waterproofed and sealed.
What You Should Use Instead
The correct product for the tile-to-skirting junction is a flexible, paintable acrylic sealant or, in wet areas, a neutral-cure silicone sealant. These products are specifically formulated to flex with building movement without cracking.
Dry Areas (Hallways, Living Rooms)
In dry areas, a flexible acrylic gap filler/sealant works well. It can be painted over once cured, which makes it ideal where the skirting board will be painted to match the wall. Look for products labelled as flexible or gap-filling sealants at your local Bunnings or Mitre 10.
Wet Areas (Bathrooms, Laundries, Kitchens)
In wet areas, use a 100% silicone sealant or a hybrid silicone-acrylic sealant rated for wet area use. Silicone is waterproof, mould-resistant, and permanently flexible. Choose a colour that matches your grout for a neat, professional finish. Brands like Sika offer a range of suitable sealants for tiling applications.
Note: In wet areas, the waterproofing membrane behind the tiles is critical. If you're retiling or renovating a bathroom, make sure the membrane complies with NZ Building Code clause E3 — this is work that benefits from a professional eye.
How to Apply Sealant Neatly
A tidy sealant joint takes a little preparation but is well within DIY reach:
- Clean the gap — Remove any old grout, dust, or debris. A grout rake or oscillating tool works well for this.
- Mask both edges — Apply painter's tape along the tile edge and the skirting board to keep lines crisp.
- Apply the sealant — Cut the nozzle at a 45° angle and run a smooth, consistent bead along the gap. Don't overfill.
- Tool the joint — Use a wet finger or a sealant tool to press the sealant into the gap and create a slightly concave profile.
- Remove the tape — Pull the tape away while the sealant is still wet for clean edges.
- Allow to cure — Follow the manufacturer's curing time before exposing to water or foot traffic.
Matching Your Grout Colour
One common concern is getting the sealant to match the grout colour. Many sealant manufacturers offer colour-matched products to popular grout ranges. Check with your tile supplier or visit PlaceMakers for advice on colour matching. Brands like Ardex and Mapei both produce grout and matching sealant ranges, which makes colour coordination straightforward.
What About Tile-to-Tile Joints?
It's worth clarifying: grout is absolutely the right product for the joints between tiles on the floor or wall. It's only at the perimeter junctions — where tiles meet a different material or a change of plane (floor to wall, tile to skirting, tile to bath) — that a flexible sealant must be used instead. This is standard practice in line with tiling best practice guidelines from BRANZ.
A Quick Comparison
| Location | Correct Product | Why |
|---|---|---|
| Between floor tiles | Grout | Rigid joint, minimal movement |
| Tile to skirting board | Flexible sealant | Movement joint, different materials |
| Tile to bath or shower tray | Silicone sealant | Wet area, significant movement |
| Tile to wall (internal corner) | Silicone sealant | Movement joint, change of plane |
When to Call a Professional
If you're dealing with a bathroom, laundry, or kitchen renovation where waterproofing is involved, it's strongly recommended to engage a qualified tiler. Waterproofing in wet areas is closely tied to the NZ Building Code, and getting it wrong can lead to costly structural damage from moisture ingress. A licensed tiler will ensure the correct products and methods are used throughout.
You can find experienced, local tilers in your area through tradedirectory.co.nz — it's always worth getting a professional opinion before starting any wet area tile work.
For building consent questions — for example, if you're doing a full bathroom renovation — check with your local council or visit MBIE Building Performance for guidance on what work requires consent.
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