Sunday, September 9, 2012

Metal Roofing Versus Tiles?

Tile Roof manufacturers, installers spreading the green theme.

There has been a large amount of publicity in all media of Australia lately on spruking the advantages of tile roofing over metal roof systems. At BPN (Building Product News) they have a classic example of this "New Roof Tile Research Highlights Energy Efficiency Performance" on 21st August 2012.
Many of the tile manufacturers have the same type of claims on their websites and even tile roof contractors advertising the fact the - "studies in the USA" & "testing at University of Newcastle" etc have proved the above statements of ENERGY EFFICIENCY!

Lets look at some of these claims by the Tile groups:
  1. Comparing (white) roof tiles and (white) metal roofing showed that roof tiles have significantly higher reflectivity than metal roofing, reflecting a total of 75.4 per cent of solar energy. This is 7.8 per cent more reflection than metal roofing which reflected a total 67.6 per cent.
  2. Concrete and terracotta roof tiles were found to cause the strength of energy being transmitted to dissipate significantly.
  3. The roof is one of the largest external facing surfaces of a home and the choice of roofing material has a major role in determining internal living temperatures and household energy usage.
Basically they are saying that tiles are a better alternative to metal roofing because of the temperature and hence eventual energy used by the household to regulate this less with tiles. They are grabbing on ONE point only of many, that are required in measuring energy efficiency. But the advertising above works because most people just read about this one aspect and in reality it is only one tiny portion of the whole energy cycle employed in building. As one commenter stated - the main aim of a roof is to keep the rain out! Let's look at the overall advantages of tile versus metal.

1. Embodied Energy.
This is the base embodied energy of each roof system at time of manufacture. The less the MJ/sqm the better
Timber frame, concrete tile, plasterboard ceiling    251 MJ/sqm
Timber frame, terracotta tile, plasterboard ceiling  271 MJ/sqm
Timber frame, steel sheet, plasterboard ceiling  330 MJ/sqm

So here - the tiles win on average but only just.

2. Solar reflectivity.
This is simple energy reflected by the roof system and based on results from the USA?
Tiles (White) reflect a total of 75.4 per cent of solar energy.
Metal (White) reflect a total of 67.6 per cent of solar energy
So here we have the tiles ahead again on average but not much.

3. Re-cycle Capabilities.
The is simple again and roofing materials are measured in their ability to be recycled and here is a list of waste disposal in landfills in Australia.
WASTE DESCRIPTIONWASTE QUANTITY
WEIGHT % OF TOTAL
Paper / cardboard1
Garden / vegetation3
Wood / timber10
Textiles / rags1
Hard plastic1
Ferrous2
Soil rubble (<150mm)34
Soil rubble (>150mm)2
Concrete-based masonry16
Clay-based [eg. bricks, tiles]16
Plasterboard2
Other / unknown11
Total100

The tiles on average are 8 times less likely to be involved in recycling whereas the steel roofing is nearly 100% recycled.
Huge loss for the tiles as an unfriendly "green" product.

4. The Construction Stage.
With no actual statistics available on the impact of tile roof over metal roof installation - but any observation of a tile roof in progress - the on site disturbance is extremely waste intensive with large area of ground disturbance.
Tiles here lose again heavily as metal roofing is simply delivered, located & fixed. Also more time efficient.

5. Transportation.
Again no available statistics but metal roofing with a lighter frame requirement is much more efficent in transport costs to deliver than tile systems.
Another big loss for tiles over metal.

6. Construction Light or Heavy.
These two systems are at exact opposites - with tile roofing requiring extra heavy design structues from the footings up. The metal roofing system offers a much lighter overall building structure for support.
Huge loss again for Tiles.

7. Final Score
Metal Roofing 4 beats Tile Roofing 2.
The winner is metal roofing.

If a Life Cycle Analysis was done on two houses next to each other on the total "Green" acceptability - the metal roofing systems wins every time.

Metal Roofing is much more environmentally suitable for residential housing systems in general and this latest information by the Tile Groups is almost untrue when looked at in total context. Let's get the ASI etc to publish some data that reflects the true nature of metal roofing, its affordability, LCA favourable outcomes and generally more "GREEN".

12 comments:

  1. This is typical of an industry wide "Green Wash" over virtually everything in the world today. Of course nobody wants to be harmful to the environment so an angle must be taken on everything.

    Just look at the 'sustainability of timber' dribble that gets around.

    ReplyDelete
    Replies
    1. So true PB:
      Now days the more money you spend on a bigger, heavier building system - the GREENER you become.

      Nothing beats the old tin roof Queenslanders in the tropics! Nowdays its blocked, insulated and double glazed so your A/C is more efficient to run.

      In some houses today, they don't even know if its raining outside?

      Delete
    2. What about wear and tear on the transport system roads vehicles etc Tiles are not the way to go in the building industry - and time is the other factor as $ just add up

      Delete
  2. Very nice post. Really choosing tile roof is always better than metal roof. Thanks for sharing the advantages of tile roofing. Colorado spring roofing companies provides quality tile roofing service.

    ReplyDelete
  3. James: You really have to read the post before commenting.
    Here - I've fixed your comment below:

    "Very nice post. Really choosing a tile roof is always WORSE than a metal roof. Thanks for sharing the DISadvantages of tile roofing."

    ReplyDelete
  4. Healthy debate and democracy, don't we just love it !

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  5. Nice comparison between the two,As a roofer i totally agree with you.Thanks for sharing.

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  6. I would chose metal to be put in my roof.Saves me a lot of things.
    colorbond roofing brisbane

    ReplyDelete
  7. http://forums.whirlpool.net.au/archive/1949961 is a really good read.

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  8. Of course, I'd hate to have to work with tiles... http://www.hse.gov.uk/construction/silica-dust-article.htm

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  9. If I had to choose between asphalt shingles versus metal roofing, I would probably more then likely choose asphalt shingles. Solely for a few purposes, asphalt gravel shingles look more natural on a home as tiles as opposed to the long and sleek shiny metal that looks all indented and what not, its just ugly. Sorry, but asphalt shingles for life foo'

    -Adam Ahmed

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  10. The metal roof is an all-time and all-around type of roof. But I think in this current time, roof tiles are proving to be more promising. Moreover, sound insulation can also be a point of comparison here. Roof tiles, however, is still the favored party. A tiled roof offers better sound insulation qualities and does not produce creaking sounds, unlike metal sheets.

    ReplyDelete