What advantage do plastic vents have over ventilators made from metal, well you have cheaper production costs and they may be cheap for the consumer however cheap is the only advantage.
Sometimes you get a bargain for a cheaper price however getting a cheaper price may cost you a lot more in the long run.
The definition of cheap is – costing very little or of little value – youdictionary.com. It is not very wise to pay too much for a product however it is even worse to pay not enough – Jon Ruskin.
Well this BLOG is not about advantages, this BLOG is about the disadvantages of plastic roof vents. Myself, being in the roofing industry for almost 6 decades I have seen most roofing products and roofing accessories that come on to the market and seen how they perform. The worst accessories are those made of plastic – no matter how impervious to the solar rays and elements the manufacturers claim I have seen all the plastic roofing products absolutely destroyed by solar rays and hail etc. The temperature of concrete roof tiles can be so hot on 30° days you feel your feet burn through your shoes, if you touch them with your hand by leaning on them you will soon let go. This period lasts from 11am till 4pm, that’s 5 hours a day year in and year out, how long do you expect plastic roof vents to last under these circumstances. Then you have your freezing conditions in winter.
Polycarbonate roof sheeting when it first came out, they said it was almost bullet proof, after 6 or 7 years of the Australian extremes and constant solar rays hail will go through the sheeting like bullets and if you have a pergola with polycarbonate sheeting get ready for 5 or 6 hundred dollars + for new sheeting and $2,000 for labour and incidentals such as new screws etc, if you cop a hail storm. My experience with most plastic roofing products has seen the same results.
However getting back to plastic roof vents these are also vulnerable to hail damage and due to the harsh Australian summers they will only last about 7 years tops, then you will have to replace them – if you are smart you will replace them with metal roof ventilators for longevity and performance, if you are real smart you will use metal roof vents in the first instance.
In Australia using plastic roof vents you will not only have to worry about solar rays, hail etc. In Australia almost every home will have a bushfire BAL rating from BAL Low (bushfire attack level) to Flame Zone. The last things you need to be fixing into your roof are plastic roof vents. In the 2003 Canberra bushfires aluminium whirlybirds were sucked out of roofs like a piece of tissue paper, how long do you think plastic roof ventilators would last in these conditions before they go up in a puff of smoke, followed by your home. Plastic products have their place but please, not in your roof in our Australian conditions.
As I was approached by a plastics company in the early days I myself toyed with the idea of making my ventilators from plastic.
Well they couldn’t convince me as the only advantage was going to be cheap. However, an installer of our products in Sydney said these guys are talking about making your product in plastic, you can’t do that, you know you have reroofed many old homes in Sydney yourself, I said yes I have, he then said then you will know that valley and perimeter flashings made from metal are still in good condition after 100 of years of use, your ventilators made in metal will be the same. Even though I had made my mind up to continue manufacturing from metal, the installer’s words rang too true – definitely no to plastic for my products.