For small, non-structural decorative brick projects, a quality construction adhesive can absolutely do the job — but only in the right situations. Whether you're building a garden feature wall, a decorative indoor panel, or a faux-brick accent, understanding the difference between adhesive and mortar will save you time, mess, and potential headaches down the track.
What's the Difference Between Adhesive and Mortar?
Mortar is a cement-based mix (typically sand, cement, and water) that bonds bricks together and fills the joints between them. It's the traditional choice for structural and semi-structural brickwork, and it's what most bricklayers use for anything load-bearing or exposed to the elements long-term.
Construction adhesive (sometimes called brick adhesive or masonry adhesive) is a pre-mixed, polymer-based product that bonds surfaces together without the need for mixing or curing time. It's faster and easier to apply, but it has real limitations.
When Adhesive Works Well
Adhesive is a practical option for decorative projects where:
- The bricks are lightweight or thin (such as brick slips, veneer bricks, or split-face tiles)
- The project is non-structural — nothing load-bearing, no retaining walls, no freestanding walls over a low height
- The surface is indoors or sheltered from direct rain and freeze-thaw cycles
- You're bonding to a solid, stable substrate like concrete, fibre cement sheet, or existing masonry
- The finished look doesn't require traditional mortar joints (or you'll add a separate grout/pointing product after)
Common examples where adhesive works well include indoor feature walls using brick slips, decorative garden edging with lightweight pavers, or small outdoor ornamental projects in sheltered spots.
When You Should Stick with Mortar
Don't reach for the adhesive tube if your project involves:
- Full-sized, heavy bricks in a freestanding or structural arrangement
- Outdoor exposure to NZ's variable weather — UV, rain, and temperature swings can degrade many adhesives over time
- Any load-bearing application, including garden walls over a certain height (which may also require a building consent — check with your local council)
- Wet areas like around water features, unless the adhesive is specifically rated for that use
- Fire surrounds or BBQs — heat-resistant refractory mortar is required here, not standard adhesive
NZ's BRANZ research highlights that moisture management is one of the biggest causes of building failure in New Zealand. Using the wrong bonding product in a wet or exposed situation can lead to delamination, efflorescence, and structural failure over time.
Choosing the Right Adhesive Product
If adhesive is appropriate for your project, look for products specifically labelled for masonry or brick bonding. Brands like Sika offer construction adhesives and tile-setting products suitable for masonry applications. Always read the technical data sheet to confirm:
- Substrate compatibility (what surfaces it bonds to)
- Weather and UV resistance rating
- Load capacity (shear and tensile strength)
- Open time (how long you have to position the brick before it sets)
You'll find a range of suitable products at Bunnings, Mitre 10, and PlaceMakers. As a rough guide, construction adhesives suitable for masonry typically range from around $10–$30 per cartridge, though prices vary by brand and formulation.
Surface Preparation Is Everything
Regardless of whether you use adhesive or mortar, proper surface prep is critical:
- Clean the substrate — remove dust, grease, loose material, and any old paint or sealant
- Check for moisture — adhesive won't bond well to damp surfaces (check the product specs)
- Prime if required — some adhesives recommend a primer coat on porous surfaces
- Dry-lay first — plan your layout before committing, especially for feature walls
Do You Need a Building Consent?
For most small decorative projects (a garden edging feature, an indoor accent wall), a building consent is unlikely to be required under Schedule 1 of the Building Act. However, if your decorative wall is freestanding and over a certain height, or forms part of a retaining structure, consent may be needed. Always confirm with your local council before starting — requirements vary by region and site. The MBIE Building Performance website has helpful guidance on what work is exempt.
Tips for a Professional Finish
- Use spacers or tile wedges to keep joints consistent if you want a traditional brick look
- Apply a separate pointing mortar or grout to fill joints after the adhesive has cured — this gives a much more authentic appearance
- Seal the finished surface with an appropriate masonry sealer if it's outdoors, to protect against moisture ingress
- Work in moderate temperatures — most adhesives don't perform well below 10°C or in direct hot sun
When to Call a Professional
If your project involves anything structural, load-bearing, or over about 600mm in height, it's time to bring in a qualified bricklayer. Freestanding walls, retaining walls, and anything connected to your home's structure may require a building consent and should be built to relevant masonry standards — check with your local council or a qualified professional. A licensed bricklayer will know the right materials, methods, and consent requirements for your situation. You can find qualified local bricklayers on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
