If it is obvious that your roof is in a state of disrepair (i.e. there is water leaking inside, roof shingles are missing and/or severely worn) or you have had several professional roofing contractors have a look at it and tell you that it needs replacing, the first decision you need to make will be to choose whether to have a tear-off job done and start again from scratch, or to opt for an overlay instead. A tear-off job involves completely stripping the roof right down to the wood decking and installing a brand new roof, while when an overlay job is done, new shingles are simply applied to the existing roof. Which option is better is a highly debated topic in the roofing industry, with most roofing contractors agreeing that it’s impossible to discover whether a roof has “weak” spots without completely stripping it down, and by simply overlaying it you are risking serious structural damage to the property in order to avoid the short-term investment a new installation would require. As the leading metal roofing installation experts in Toronto and Mississauga, this is something we are frequently asked about and during this article we are going to discuss the merits of opting for a new installation over an overlay.
Benefits of a Brand New Metal Roofing Installation
We of course specialize in metal roofing, but these benefits apply to any type of new roofing installation. Remember that the only real advantage of overlaying your existing roof is that you will save money in the short term. You should, however, never base your decision on the cost alone, and a new metal roofing installation will:
- Allow for a Thorough Inspection – By removing the existing roofing materials, roofing contractors are able to thoroughly inspect the deck, valley, the areas where the roof connects to the walls, and the areas that surround the roofing penetrations. It is possible that any of the materials used in these areas could have fallen victim to water damage and rot, which could compromise the stability of the roof if not replaced. It would not be possible to inspect this area if the roof was simply overlaid.
- Ensure Presence of an Underlayment – It could be possible that when your current roof was installed, the shingles were installed directly onto the decking without an underlayment. If your current roof is left in place it will be impossible to install the missing underlayment, which helps to keep moisture out of your home and helps to prevent shingles cracking and buckling as a result of the fluctuating Toronto temperatures.
- Avoid Adding Weight – While a metal roofing installation is known for its lightweight and strength, when an existing roof is overlaid the overall weight of the roof is doubled, exerting more pressure on the rafters. This means your roof is more likely to bow or sag. It would only take particularly heavy snowfall during winter, which is possible in Toronto, to cause the roof on your property to completely collapse. Remember that asphalt and concrete shingles absorb moisture too!
- Heat Shortens Roof’s Lifespan – A double layer of shingles will improve the insulation of your roof, which may sound like a good thing. However, this results in your attic becoming significantly warmer, and exaggerating the contraction and movement of shingles to such an extent that they don’t often reach their expected lifespan. The increase in your attic’s temperature could also cause your air-conditioning bills to skyrocket during the summer months, when temperatures can climb above 30 degrees Celsius in Toronto.
- Valleys Will Be Properly Flashed – Any roofing contractor in Toronto or Mississauga will tell you that the most vulnerable part of any roof is the valleys. The underlayment will offer a certain level of protection to valleys, but it’s vital that flashing is also installed to protect your home against leaks. If you opt for a new metal roofing installation, the roofing contractors you work with will be able to fit new flashing, but on an overlay job that isn’t usually possible.
If you are considering a new metal roofing installation and would like further information about the products and services that we offer,