Built-up roofing is the most popular option for commercial roofing projects because of its many benefits, especially on flat roofs or those with low slopes. Built-up roofing is sometimes referred to as tar and gravel roofing because of the way it's constructed. Multiple layers of felt roofing fabric material are bonded with coats of bitumen or tar and then topped with gravel. It's almost like turning the roof into one giant seamless shingle. With so many commercial roofing materials available, it can be difficult to choose the best material for your building or project. If you're considering built-up roofing as an option, here are the essential pros and cons.
One of the most desirable characteristics of built-up roofing is that it will last for many decades. When properly installed, a built-up or gravel and tar roof will last about 15 to 20 years, especially if it's at least 4-ply, meaning there are at least four layers of roofing felt and bitumen. Many commercial roofers estimate that a built-up roof will last 5 years for every layer added.
Another advantage of this type of roofing is that it creates a roof surface with no seams and that means fewer areas for leaks and water damage. It's just one continuous, solid surface that stretches across the entire length of the roof. Since seams are the most vulnerable areas for water penetration, it increases the roof's waterproofing significantly.
Built-up roofing has very little maintenance. In fact, the only maintenance involved is keeping an eye on the gravel layer to make sure it's even and consistent and adding more gravel if it gets low on any section of the roof. Other than that, once the roof is installed, you can virtually forget about it.
The biggest enemy of a built-up roof is wind because it can blow away the gravel layer over time. If you live in an area with high winds and a tendency for windstorms with high mile per hour gusts, another roofing material might be more suitable.
The gravel layer blocks most UV rays from reaching the layers underneath. In fact, the gravel does a wonderful job of reflecting those rays and keeping the building underneath well insulated. However, once the gravel starts to deteriorate, the UV rays can reach the layers underneath and start to break them down. That's why it's so important to consistently check the gravel layer.
To find out if a built-up roof is suitable for your building, contact a commercial roofing contractor.