A slate roof is the pinnacle of roof covering choices. Almost impervious to the elements, a properly installed slate roof can last for 100-plus years. In fact, there are slate roofs in parts of Europe that are still in good condition after 4 centuries. However, longevity is not the only factor that draws people of refined taste to slate — it is the timeless beauty, the undeniable curb appeal, and the increased value that a slate roof will add to your home. Slate roofing will not rot and is the most fire-resistant roof covering on the market. It is also an eco-friendly product due to it’s long service life. An asphalt shingle roof gets replaced about every 20-30 years and the resulting debris has to go into a landfill. A slate roof gets replaced every 100 years or so, which means disposal wastes from roof replacements are reduced by ⅔ every time a slate roof is installed. Natural slate has its limitations, however — primarily in the structural requirements that must be met in order to carry the load of the roof tile weight.
Drawbacks To Natural Slate Roofing
1. Slate roof weight
A slate roof can weigh between 800 and 1500 hundred pounds per hundred square feet. Compare that with an asphalt shingle roof that weighs between 230 and 430 pounds per hundred square feet. That makes slate potentially 6 times heavier than asphalt.
A standard roof structure is not built to hold the weight of slate. In fact, the normal roof is engineered to support a dead weight (the weight of the shingles and occasional snow load) of 15 pounds per square foot. A slate roofing system would need to be engineered to hold 27 to 50 pounds per square foot — a substantial difference — in order to avoid collapse.
If you are building a new home, this additional strength requirement can be engineered into the framing from the start of construction. However, if you are replacing an old shingle roof that was not designed to carry the weight of slate, you will have to get a certified engineer involved in the process and that can add thousands of dollars to the cost of your roof. If you decide to guess at what would be needed to brace your existing framing, you may end up with your roofing system sitting in your lap.
The additional slate roofing weight requires that you are diligent with regular maintenance checks. If you purchased a home with a slate roof already installed, you need to periodically check the roof structure in the attic to make sure that excessive bowing is not occurring in any of the truss members as a result of this weight.
2. Maintenance concerns
Slate is stone and stands up under most adverse circumstances, but it is dangerous to walk on because it can be very slippery. Not to mention, slate roofing is extremely brittle and can be cracked or broken just by walking on it. This means that maintenance must be done by experienced professionals or your entire roof could be damaged or destroyed. It also means that maintenance costs can add up. The biggest concerns when caring for a natural slate tile roof are broken tiles and flashing that is failing. By ignoring these issues you may be allowing water to seep below the tile roof onto the wood supports below, eventually inviting wood rot that can weaken the structure and lead to a total roof collapse. "Having a regular maintenance of your slate roof should be done at least twice during the fall season and right after the winter season is over. Make sure to check for any damaged slates due to weather conditions and have them replaced immediately if possible. Aside from that, a scheduled inspection should be done by a professional every 4-6 years." ~ Jeff Guthrie, Phoenix Roofing & Repair.
3. High installation costs
Once a slate roof has been installed, it is fairly easy to keep up with. The road to a complete installation can be long and expensive, however. A typical slate roof can cost up to 5 times as much as a regular shingle roof. In addition, locating a sufficient quantity of slate for the roof may be difficult and it may not arrive all at once. Some jobs have experienced delivery times that extended for months while waiting for the product to arrive. Unlike a standard asphalt shingle installation which can take 2-3 days at the most, a professionally installed slate roof can take months to install after all the materials are on the job. If there is extra support that must be added, this will also increase the cost of the job as well as the time needed to complete it.
4. Installers are difficult to locate
Installing a slate roof is not a DIY project by any stretch of the imagination. There are special tools required and the individual slate tiles must be handled delicately in order to avoid breaking them. The tiles cannot be walked on during installation without extreme care or they will break.
While searching for an installer, you may run into roofers that say they can handle the job, but you want to be sure that they have verifiable references before you turn this job over to them. If the tiles are not installed correctly you can experience a myriad of issues in the future that can cost you thousands of dollars in repair work and may require the roof to be redone if the mistakes are severe enough.
Is it possible to get the traditional beauty of slate roofing tile without the negative issues associated with slate roof weight and the special handling requirements required to avoid damaging the tiles?
Brava’s Synthetic Slate Roofing Products Offer the Best of Both Worlds
Brava Old World Slate is a beautiful synthetic slate roof tile that can be installed over most existing roof decks without any additional support. The tiles are all matching so there is no waiting period while sufficient quantities of slate are found to finish your roof and there are no special tools required to install our tiles. Brava Old World Slate tiles are available in a variety of standard colors as well as unlimited custom colors. They are available in Class A and Class C fire rating as well as a Class 4 impact rating for hail prone areas. Our tiles can be walked on without fear of breakage and come with our 50-year limited warranty to give you peace of mind after the purchase. Our website contains pdf drawings and videos to ensure that your job is installed correctly and our customer service experts are available to answer your questions. Contact us today to get a free sample of our Old World Slate tile or one of our other synthetic roof tile options.