The photograph above shows that when the covering was removed, there were four membranes instead of one. If there’s a subject that you hear a lot about in our field (and many others), it is the social awareness that we must have with respect to how our daily activities affect our environment, and we, like most of you, consider that to be a true and very important fact.
HOWEVER, there are situations where you must stop and ask a few questions before and ideology that might lead us to make the wrong decisions.
Some companies offer to install a new roofing membrane on top of the old one. Of course, they tell you that this is good for the environment, because you’ll be reducing the amount of waste that goes into landfill. Yes, you will avoid adding to the landfill but at what cost? And what risk?
This roof is three membranes thick instead of one.
You must understand that, when you install a roofing membrane on top of another one, this can cause a lot of problems, and the most frequent and obvious one is weight. Maybe the new membrane that is being installed is lighter, such as a TPO or EPDM membrane, but if you had 3 or 4 membranes already in place, like our clients above, and then another light membrane is placed on top of that, you can see that you now have several thousand kilograms, or even tons of weight too much on your decking.
Here there are 2 membranes and one wood fibre. It is not rare to see decking start to sag, so why expose yourself to such a high level of risk?
Above, we had to partly redo the decking structure and the decking, because there were already 4-layered membranes. If we recommend removing snow from the roof due to the surplus weight caused by snow, imagine what happens with the additional weight of several layers of membrane!
What You Need to Know
For a contractor, the process of removing the layers is expensive, and requires more equipment and greater organization. That is why some roofers will try to avoid this step, and in doing so, keep their prices looking competitive, which is not really the case at the end of the day. Of course, there can be times when you cannot remove an existing membrane, but such cases are rare, and should not be considered before verifying a number of factors. Above all, this method of doing things should not be the first suggestion that is made, especially knowing that there can be other problems related to a situation where there are membranes left in place. We believe that the environmental question in this particular case is only a sales argument, and should not be considered.
Published July 10, 2013
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