The Built-up Roof
If there is one roofing option that is considered a classic, it would most definitely be the built-up roof system. Developed for over a century ago, this type of roof has a time-tested reputation that makes it almost an automatic choice for a lot of home builders. Of course, this is not a perfect roofing option as it can pose some considerable limitations, but a lot of those who chose this type have seen it work quite well.
The built-up roof is generally preferred in places of high traffic and when there is a possibility for the roof to be subjected to mechanical abuse. The built-up roof’s membrane is generally thicker and stronger compared to most other roofing options with its multiple layers and gravel surfacing. Since this is a popular choice, it is usually easy to find a contractor who can handle both installation and repair of this roof type in most locations.
The main disadvantage with built-up roofs is inflexibility. The roof may be subject to damage due to structural or thermal movement. A long building would need additional roofing support to prevent the roof from damage due to contraction. The compression due to cold temperatures or stretching due to hot temperatures may also take a toll on built-up roofs. Much care is needed if these factors are pronounced in a particular area.
Modified-Bitumen Roofing Systems
Modified-bitumen roofs have similar advantages and disadvantages as built-up roofs. However, one great advantage of this roofing option is that it performs significantly better during cold weather. This type of roofing has been developed to become flexible when the temperature is low. They can adapt to temperature changes better than the built-up roof.
There are two type of modified-bitumen roofs – the plastic-based ones (APP) and the rubber-based ones (SEBS and SBS). The plastic-based membranes are usually installed using torches while the rubber-based membranes are installed using cold adhesives or hot asphalt. Most modified-bitumen roofs already have granulated surfaces so they are lighter than built-up roofs that have gravel surfaces. Modified-bitumen roofs may also be added as cap sheets on top of existing built-up roofs. This adds redundancy to the roofing as well as some flexibility.
Single-Ply Roofing Systems
Singly-ply roofing, as its name suggests, is comprised of a single layer make of plastic or elastic material. Because there is only one layer, this type of roofing is thick. There are two types of single-ply roofs, first, thermoset membranes whose seams are sealed using adhesives and second, thermoplastic membranes whose seams are welded using heat or a solvent. There are three types of attachment for single-plys – ballasted, loose-laid and fully adhered. Because of its light weight, the single-ply is often used for re-covering. They are also quite inexpensive.
Single-ply roofs may be sensitive to certain substances and great care should be taken when choosing from different kinds of single-plys. EPDM and PVC-based materials can be damaged when exposed to oil, jet fuel, and cooking grease. When there are such emissions in the area, the chemical composition of the single-ply membrane should be checked carefully.
Metal roofing is no longer limited to those leaky sliding panels attached together rather insecurely and then screwed or nailed to a frame. Today, there are metal roofs that have more secure concealed clips that can be expanded or contracted. Perhaps the most important factor for choosing metal roofing is its life expectancy: metal does not decompose or break down even with exposure to extremes in weather. Some metal roofing may have warranties of up to 50 years. The disadvantage with metal however is the greater possibility of leaks compared to other roofing options. If metal is not installed properly, leaks are likely to occur.
There are several other roofing options these days. It is just important to choose the right type for the right structure. Whether it is new or a classic, good roofing should serve its purpose of providing good coverage.