Traditionally, sloped roofs have been more popular than flat ones. The reasons for this are apparent, as a sloped roof generally does a better job of shedding water, snow, and ice. Due to these factors, they have traditionally had a shorter service life.
At the same time, who doesn’t want the opportunity to install a little bit of extra living space? Thanks to new and innovative methods, it is possible to enjoy the benefits of a flat roof while still retaining adequate levels of weather resistance. Unlike the simple flat roofs of the past, today’s version can also compete with the sloped roof in terms of longevity.
The Benefits Of A Flat Roof
As we already mentioned, a flat roof gives you some extra living space that you can customize in whatever way you like. Many people enjoy planting rooftop gardens, and these may be the only gardening option for those with small yards. A rooftop patio also makes a great place to relax and enjoy the fresh air.
On a more practical side, a flat roof allows for much easier access to the roof area. While a person can climb on a sloped roof, it is not recommended to do so without a safety harness. With a flat roof, it is very easy to inspect your roof for damage, and it is easier to repair as well. This ease of is access is great because it usually means lower bills on maintenance and repair.
The Drawbacks Of A Flat Roof
A flat roof will never shed water as well as a sloped roof, but it should be noted that most flat roofs are not entirely flat. The vast majority of them will have a very slight pitch, but you wouldn’t notice it unless you look very closely. This small slope keeps rain and other moisture from accumulating on top of the roof. However, it isn’t recommended to have a flat roof in cold northern climates that see a lot of snow. You may have noticed that flat-roof houses are far more common in hot-weather areas.
The Three Types Of Flat Roofing
Let’s start by looking at the three basic types of flat roofing. Although there is a wide variety of products on the market, you can classify most of them into one of these three categories:
This type of roofing is so named because it consists of only one layer. Single-ply roofing consists of sheets that are typically 6-18 feet wide, with ten feet being the most common size. These sheets are laid down and secured in place with glue, screws, or both.
Single-ply roofing is made of plastic, and there are many varieties of plastic. Not surprisingly, the most durable available material is PVC, the same plastic that is most often used for underground pipes. It is much better able to resist moisture and weathering than most other plastics and is thus a natural choice.
Of course, there are some good alternatives. EPDM is the most popular choice these days, and TPO plastics are also popular and should be effective for any flat roof. Whichever material you choose, proper installation is essential. Thus, you should make sure that your roofing contractors follow instructions and refrain from cutting corners.
It is best to have your singly-ply roof installed with both screws and glue. Either one or the other may not do the job. Some contractors will try to take a shortcut by using glue alone, as this is the easiest method. However, there is one problem with this method: The seams.
There will always be seams in between each piece of roofing, and these will always present a potential leak point. Unless the job is done very thoroughly, a glued-on roof will be more prone to leaking. On the other hand, a flat roof that is fastened only with screws will have to be installed with special joiners at the seams, and that is also problematic. Play it safe and use both whenever possible.
Single-ply roofing might be a little more expensive than our other two choices (in general), but it offers an opportunity for some extra savings. Most of the materials used in single-ply roofing are highly energy-reflective, which means that your roof will not absorb as much heat or cold from the outside air. This will translate to a little bit of savings on your electric bill.
These are the old-school tar/gravel roofs that used to be the most common style for flat roofing. You can also use asphalt, and there is nothing wrong with that. Most roof shingles are made of asphalt anyway, so it’s a natural choice. Built-up roof coatings are so named because they are added in layers. You add one layer, let it dry, and then add another until it is thick enough.
These flat roof coatings are less common today in spite of their high durability. Apart from the fact that they are less attractive, they also don’t offer very good insulation and are much heavier than most other roofing materials. Worst of all, these roofs will require maintenance more often than our other choices, as the tar will not last more than ten years without needing to be replaced. Sure, ten years is a long time, but most other roofing materials will last far longer.
Despite these difficulties, built-up roofing continues to be used in some homes because of its one significant upside: Low cost. A bucket of tar is much cheaper than buying all those single-ply sheets and the fittings that they require, and it’s usually less expensive than the spray-on or painted-on coatings. Thus, you will see roofs like this on some low-cost homes and trailers.
Tar and asphalt coatings are quite tough, and they do an excellent job of repelling water over their service life. However, they provide a surface that is somewhat hard and inflexible. Further, these materials tend to dry out over time, making them even less flexible and more likely to crack. When a crack forms, it will often be hard to pinpoint the location because it only takes the tiniest of cracks to cause a leak. That which is unable to bend is always more likely to break.
This type of roof coating offers a lot in terms of convenience. Like a built-up roofing material, it can be applied easily as a solid layer, and you can use multiple layers for extra durability. At the same time, these coatings are much more durable and effective than tar, bitumen, or asphalt.
The best thing about this type of flat roofing is the fact that you have no seams. Seams will always represent the weakest point of a flat roof, so eliminating them is a major plus. You also eliminate the need to use special fittings or flashing when you go with a coating of this type. That being said, there are still plenty of ways in which the installation can go wrong, so there is still a need to find the right person for the job.
These types of coatings are not made of rubber, but they do give a thick and rubbery coating to your roof. This coating is flexible enough to absorb impact, which means that it won’t be as prone to cracking as a tarred roof. This benefit is especially useful for those who want to use their flat roof as an extra porch. You want something that can handle lots of foot traffic, as well as the weight of whatever items you may wish to place up there.
Spray-on coatings are a little more challenging to apply than the painted-on versions. That’s because the spray-on coatings require two additional layers on top of them. You are supposed to spray the material directly on the roof deck, and once it dries, you apply a coating of acrylic or urethane to seal it against moisture. A layer of crushed stones or sand is also added to make it look nice and to act as an indicator layer: When the grit is gone, you know it’s time for repair.
That brings us to one of the best aspects of these elastomeric coatings: It is easy to repair a small patch, and you don’t always need to consult a professional. If your roof has only a small leak, you can purchase a small container of this stuff and patch it yourself with minimal effort. As mentioned before, these coatings are not cheap. However, materials alone will usually be less expensive than materials and the labor of a professional.
As nice as these materials are, they do come with a few problems apart from their high price. First of all, this rubberized coating can be prone to peeling and cracking if the edges are not properly secured. Once the edges start to go, the rest will follow. Also, you must install these coatings under certain conditions of temperature and humidity, and those conditions may not always be present.
Finally, there is the fact that these coatings release a lot of harmful vapors as they dry, exposing both the roofing crew and those in the home to the possibility of exposure. In mild cases, a person might get a headache or a slight ache in the stomach. At worst, a roofer could pass out and fall from a roof by breathing those vapors too deeply.
Signs That Your Flat Roof Needs Repair
If your home has this type of roof, or if you are considering a house with a flat roof, you will need to familiarize yourself with the common signs of wear and tear. By doing this, you can ensure that you get a head start on any potential problems and head them off before they become disasters.
The following are some of the more common signs of a flat roof in need of repair:
- Cracks, especially in seam areas
- Surface flaking
- Bubbling and blistering
- Visible thinning of the material
- Loose flashing/fittings
- Bowing of the roof surface itself (extreme cases)
- Weather-induced contractions
- Grease or other buildup
You should understand that nothing lasts forever, and any roof will require at least some maintenance. That’s why it pays to be on the lookout for warning signs and to take action immediately when you detect a problem. Of course, that’s where it helps to have the number of a good roofing contractor that you can trust.
Which Kind Of Flat Roof Will Last The Longest?
PVC and TPO are the most long-lived options out there. Both of them have a feature that all the other options lack: Heat-welded seams. Both of these plastics can be melted in place so that there is almost no seam at all. You can’t do that with all types of plastic, but these two are suited for the task.
A PVC or TPO roof will often have a manufacturer’s warranty with a term of 25 years or more, which tells us that they are confident in the ability of this material to stand up for at least that long. Thus, you can reasonably expect thirty years of life from a roof like this. In contrast, a built-up roof requires maintenance at least every ten years, and sprayed on/painted-on coatings won’t last much longer than that.
You might have noticed that large buildings are more likely to have a flat roof than traditional residential buildings. This is no accident, as a flat roof usually presents less weight than a sloped one. As such, it puts less strain on a large building, which certainly does not need any more than it already has!
We should also mention that cost is a highly relative factor. While we can base price ranges on certain trends, it is difficult to predict just how expensive a roofing job might be. Every roof is different, and because some problems are far more costly than others, prices will vary. Either way, you should always make sure that you find the best deal that you can. If you would like to know more, you can start by filling out the contact form below.