The roof is the umbrella of the building. It protects you and your possessions from the elements.

While rain is the obvious thing we might think about here it doesn't stop with the rain. Often a roof is overhanging the external wall (sticking out further than the walls), protecting the wall from driving rain, snow, wind as well as giving us shade in summertime within the house and stopping the house from overheating.

 

New Zealanders became especially more aware of the importance of the roof after the leaky home issue of many houses with flat roofs built from the mid-1990s onwards. Sadly not all options at the time were completely weathertight, leaving building structures to rot and destroyed (6). Many hours, nerves and financial resources of the owners were lost. Luckily, the industry has learned and moved on and building codes have made improvements.

 

A roof is either flat or sloped. The decision on which one we choose tends to come back to which one we judge to look better and to fit for our purposes. From an environmental standpoint, flat roofs utilize fewer materials and are therefore more environmentally friendly if the same materials are used.

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As many materials can be used on either type of roof we will first explain the two roof types and following them the materials of roofs. As always we want to give you a complete picture and save you hours researching yourself. So we have included materials that we do not personally support at the moment out of environmental reasons. However, we believe in you being able to make the choice that fits you best by knowing all the pros and cons of all options.

 

Interesting fact: White roofs reflect most of the sunlight and thereby cooling the roof while reducing our carbon emission footprint. The Lawrence Berkley National Laboratory estimated that in 2009  24 gigatonnes of carbon dioxide emissions per year could be offset if all world cities had cool white roofs (1).

In 2009 the per capita carbon emission in New Zealand was 9.28 tonnes (2). Every 100sqm roof painted in white would offset 6 tonnes, greatly reducing our carbon footprint (1).

If you are interested, here is a link to the data comparing every country for carbon emissions:

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So why does not every house have a white roof? Right now in many instances, this would create a hazard for oncoming traffic, potentially blinding drivers and leading people to get hurt in accidents. 

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Sources:

(1) The Guardian, 'Cool roofs: beating the midday sun with a slap of white paint', Author: Dyani Lewis, 13.04.2017

(2) The Guardian Datablog, World carbon dioxide emissions data by country: China speeds ahead of the rest', 2016

(6) Building Performance, 'Signs of a leaky home', NZ Ministry of Business, Innovation and Employment, 08.03.2019