Be sun smart. Your Home Needs Protection from UV and Heat too.
In Christchurch and Canterbury in general, we have the most extreme weather conditions in New Zealand, and that means our poor roofs get a pretty hard time.
In over 20 years working on roofs of all types in the region, we’ve seen it all.
You might think that it’s the rain and wind that are the most unkind to roofs, but it’s actually our high UV and searing summer temperatures that do the lion’s share of the damage, followed very closely by the corrosive salty sea air along the coast.
In this article, we’re going to take a look at the environmental threats to our roofs and what to do to extend the life of your roof as long as possible.
- Long-term degradation caused by UV radiation
- The effects of extreme high temperatures
- The corrosive effects of sea air
- Simple ways to extend the life of your roof
Ultraviolet radiation – the long-term roof killer
The high number of annual sunlight hours we benefit from in Canterbury comes with very strong UV radiation that breaks down and degrades the performance of roofing components.
Polymer, plastic and rubber
Many modern roofs use a range of polymer membranes, plastic or rubber sealants, flashings, and fasteners. Over time UV exposure causes all these materials to lose their strength and elasticity over time and then fail.
- Roof membranes become brittle and crack
- Sealants around seams and penetrations shrink
- Rubber gaskets on fittings harden and crack
Painted Metal
Long exposure to harsh UV can also hammer painted and coated metal roofing. Fading, chalking looks bad, but worse it leaves the underlying metal exposed to accelerated corrosion.
Thermal Cycling
Thermal cycling isn’t about riding your bike on a hot day – it refers to the expansion and contraction of a material when it undergoes repeated heating and cooling.On a hot summer day in Christchurch the surface of your roof can easily exceed 50° which is easily hot enough to fry an egg. Then at night the temperature can fall to 20° or lower if a cool wind crops up. This daily cycle can lead to weakening of fasteners, micro-fractures, and deformations that can let water and salt spray in, speeding up roof corrosion and deterioration.
But there’s more! The sealants and adhesives used in flashings can dry out and lose their flexibility and adhesion due to thermal cycling, resulting in leaks around vents, skylights, chimneys and flashings.
Salt Spray and Corrosion in Eastern Christchurch
The sunny, beachside eastern suburbs are experiencing a very well-deserved resurgence with lots of new developments and renovations happening. But being close to the ocean, along with UV and thermal cycling, eastside roofs have to deal with fine salt spray carried by onshore winds. Salt attracts moisture and accelerates oxidation and degradation of metal sheets, fasteners, fittings and flashings.
How to protect your roof from UV, heat, and salt
The first thing to do is make a ground-level inspection of your roof to check for any obvious signs of deterioration or damage. The idea is to spot any areas of concern and have us address them for you before they turn into expensive problems. Make sure to pay attention to joins, flashings, fittings, and the overall appearance of the roofing sheets or tiles.
If you can’t get a good look at everything don’t be tempted to get up there yourself – stay safe and get us to inspect your roof for you.
Here’s what we recommend to help your roof last longer
- Make sure your roof is made using UV-resistant coatings and/or polymers
- Use corrosion-resistant metals (e.g. marine grade COLORSTEEL® and ColorCote roofs and stainless steel fixings, especially near the coast)
- Make regular roof inspections, especially after extended northwesterly heat waves to check for thermal cycling-induced damage.
- Good under-roof ventilation and thermal breaks will reduce heat stress on materials and minimise damage by thermal cycling.
DCM Roofing are your roof protection experts
We’ve been looking after people’s roofs in Christchurch for over 20 years, and we’re the local experts in roof maintenance, repairing and rejuvenating damaged roofs, and installing new long-lasting COLORSTEEL® and ColorCote roofs.
If you have any questions about roofing in Christchurch and how to prolong the life of your roof – or for advice on a new roof – we’d love to help. Please get in touch today for a roof inspection or free quote on a new roof.