Repointing ridge capping is one of those roof maintenance jobs that a capable DIYer can tackle — but it comes with real risks and some important caveats. Working at height on a sloped roof is inherently dangerous, and using the wrong mortar mix or technique can cause more problems than it solves. Read on to understand what's involved before you decide whether to grab a trowel or call a professional.
What Is Ridge Capping and Why Does It Need Repointing?
Ridge capping refers to the curved or angled tiles that sit along the apex (ridge) of a pitched tile roof, sealing the join between the two roof planes. They are bedded and pointed in mortar to hold them in place and keep water out.
Over time — typically 15–25 years depending on exposure and mortar quality — this mortar cracks, shrinks, and crumbles. New Zealand's variable climate, with UV, frost in cooler regions, and driving rain, accelerates this process. Once the mortar fails, water can enter the roof space, leading to timber rot, insulation damage, and ceiling leaks. Catching it early with a repoint is far cheaper than a full repair later.
Can a Homeowner Legally Do This Work?
Repointing ridge capping is not restricted building work under the NZ Building Act, so you don't need to be a Licensed Building Practitioner to do it yourself. It also generally falls under Schedule 1 of the Building Act as routine maintenance, meaning a building consent is not usually required — but always confirm with your local council if you're unsure, as rules can vary.
There is no electrical, gas, or plumbing work involved, so no licensing restrictions apply from EWRB or PGDB.
The Biggest Risk: Working at Height
Before anything else, take the height risk seriously. Falls from roofs are a leading cause of serious injury and death in New Zealand. WorkSafe NZ requires that anyone working at height — including homeowners doing their own maintenance — takes practicable steps to prevent falls.
Minimum safety measures:
- Use a roof ladder (one that hooks over the ridge) to spread your weight and give you something to hold
- Never work on a wet, frosty, or windy day
- Have a second person on the ground at all times
- Wear rubber-soled footwear with good grip
- Consider hiring scaffolding or a roof edge protection system for anything beyond a small patch — these can be hired from most tool hire companies
- If your roof pitch is steep (over about 25°), seriously consider leaving it to a professional
What Materials Do You Need?
Using the correct mortar is critical. Standard builders' mix is too rigid and will crack quickly with roof movement. You need a flexible, polymer-modified mortar or a dedicated roof tile bedding and pointing compound.
Look for products specifically labelled for roof tile bedding and pointing at Bunnings, Mitre 10, or PlaceMakers. Sika and Ardex both manufacture suitable products — always check the manufacturer's datasheet to confirm suitability for your tile type and exposure conditions.
Basic materials list:
- Polymer-modified roof bedding mortar
- Pointing compound or flexible pointing mortar (can be a separate product)
- Stiff brush and water for surface prep
- Cold chisel and hammer for removing old mortar
- Pointing trowel and margin trowel
- Bucket and mixing paddle (or pre-mixed product)
- Safety gear (gloves, eye protection)
Step-by-Step: How to Repoint Ridge Capping
1. Inspect First
From the ground with binoculars, or carefully from the roof, identify which sections need attention. Look for cracked, hollow-sounding, or missing mortar. Tap gently — a hollow sound means the mortar has separated.
2. Remove the Old Mortar
Using a cold chisel and hammer, carefully rake out all loose and cracked mortar to a depth of at least 15–20 mm. Don't lever against the tiles themselves — they can crack. Remove any ridge tiles that have shifted and re-bed them properly.
3. Clean and Dampen
Brush away all dust and debris. Lightly dampen the surface with water — this prevents the substrate from drawing moisture out of the new mortar too quickly, which causes premature cracking.
4. Apply Bedding Mortar (if re-bedding tiles)
If any ridge tiles have lifted or shifted, apply fresh bedding mortar to the tile below and press the ridge tile firmly back into position. Check alignment before it sets.
5. Point the Joints
Apply the pointing compound to all exposed mortar joints, pressing it firmly in and finishing with a smooth, slightly angled surface that sheds water away from the joint. Avoid feathering the edges too thinly — thin edges crack first.
6. Cure and Check
Keep the mortar damp for the first day or two if conditions are hot and dry. Avoid working in direct summer sun if possible. Once cured, inspect your work from the ground.
Colour Matching
If aesthetics matter, try to match the existing mortar colour. Some pointing compounds come in a range of colours. Resene and Dulux offer exterior masonry paints that can be used to paint over cured mortar if an exact colour match isn't available — though this is a cosmetic fix only.
When to Call a Professional
Call a qualified roofer if:
- Your roof pitch is steep or the ridge is difficult to access safely
- Multiple ridge tiles are loose, cracked, or missing
- You find damaged or broken tiles elsewhere on the roof
- There is evidence of water ingress into the ceiling or roof space
- You're not confident working at height
- The roof is older and may need a full re-bed rather than just a repoint
A professional roofer will have the right equipment, experience, and insurance. You can find qualified local roofers on tradedirectory.co.nz. For peace of mind, look for tradespeople who are members of the Roofing Association of New Zealand (RANZ).