When to Replace a Roof on a Historic Building

They don't make buildings like they used to. While this is a phrase that implies durability and longevity for buildings made in previous eras, this does not mean that a historic building will last forever, at least not without the proper upkeep. When it comes to its sustainability, one of the most important parts of your historic building is the roof. Not only does it prevent an endless stream of water from pouring inside on a rainy day, but it also insulates the building, supports indoor ventilation and plays a critical role in the property’s structural integrity.

While regular roof maintenance will extend the life of your roof a great deal, you will eventually need to replace it completely. In the cases of a full restoration, roof replacement may be your only option to sustain the building at all. But how do you know that it's time to do so? Here is how you can figure out when to replace roof sections or its entirety for your historic building:

When to replace a roof made of metal

Metal roofing became extremely popular during the 19th century. Metal roofs are known for being durable and corrosion resistant, however the damage that they sustain is often irreparable. For example, erosion, corrosion and environmental damage should not simply be patched up. If your metal roof has suffered this type of damage, then you can temporarily extend the life of a metal roof by having a professional roofer coat it with an elastomeric coating. However, this needs to be redone every decade or so, and eventually your roof will have too many coats on it and will need to be replaced. If your historic building's metal roof has already been treated with multiple elastomeric coatings, or it is too badly damaged to receive an elastomeric coating, then it is time to replace it.

When to replace a roof made of slate

Slate roofs are so well-known for their durability that they have earned the nickname "hundred year roofs".  This does not mean that a slate roof is guaranteed to last you at least 100 years. Even if your historic building, and its slate roof, was originally constructed in the mid to late 1900s, there is a still a possibility that it needs to be replaced. So instead of using your roof's age as an indicator, consider the following factors:

1. Too many cracked, broken or missing shingles

In many cases, the primary damage that a slate roof undergoes will be extremely visible. Cracked, damaged and missing shingles can be spotted by an untrained eye. In most cases, shingle replacement will suffice. However, if too many shingles have been damaged, it is likely that the underlying structure has undergone irreversible damage due to the exposure. This requires a full replacement. A replacement is also more cost effective in this case.

2. The flashing has been worn down for too long

While a slate roof may be the "hundred year roof," not all of its components are designed to last so long. In particular, the flashing will wear down faster than any other part of the roof. Because of this, your flashing must be replaced more often than the other parts of the roof on your historic building. If worn down flashing is not replaced in time, then your roof will deteriorate faster than it should, requiring a full replacement.

Make sure that your historic building receives the proper care

If your historic building's roof needs to be replaced, do not wait. Significant roof damage affects the entire building and can shorten its life. For more information on when to replace a roof on a historic building, contact us today at Heather & Little.