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A flat roof is a nice choice for homes, but it will require very specific maintenance. A home with a typical roof pitch uses a combination of shingles and gravity to keep moisture from entering the home. Water that sits on a roof for any length of time can lead to a leaky roof. In a traditionally roofed home, the pitch of the roof expedites the water running off the roof after a storm. The shingles prevent the water from penetrating until it can run off.
A flat roof, or even one with a low pitch, does not have the advantage of gravity to remove water from the roof. It is important, therefore, to have a covering that will provide a moisture barrier for your home, as well as a way to pull the water off of the roof after wet weather.
One way to keep the inside of your home dry if you have a flat roof is with rubber roofing. Rubber roofing is a single ply membrane that is made of synthetic materials. This roof coating is fastened to your roofing deck, either by fasteners or glue. The rubber roofing is available in wide widths, so that you can cover the roof completely, eliminating the need for seams. Any seam will automatically be an area where the membrane may fail.
Another way to keep your home dry if you have a flat roof is with the use of a siphon. It is possible to create a siphon that, when set on a timer, will run for one minute several times each day. If there is water on your roof, the siphon action will continue to drain the water from your roof after the motor kicks off. Eliminating standing water as soon as possible after rain is the best prevention against a leaky roof.
With all of the maintenance required in a flat roof design, it is easy to wonder if they are worth the trouble. In warm climates, flat roofs are a nice choice. They allow complete use of the space inside the home. You do not lose any head room due to the pitch of the roof. Many people use the flat roof as an extended living area, and create a terrace or garden on the roof. Some people even plant turf on their roofs. The plants absorb water from rain before it can reach the rubber roofing, helping to keep the roof dry.
In colder climates, flat roof designs are not as popular. Water that freezes in cold weather can create ice dams, making it difficult to prevent moisture from remaining on the roof. If you have a home with a flat roof design, it is important to get on it several times a year to make sure that your moisture barrier and roofing material are in good condition. Catching a problem early is the best way to prevent a costly roof repair later.
@anon109517 – You know, I had never thought of the benefits of having a flat roof. I had only ever thought about the potential problems with moisture run-off and such.
How cool would it be, though, to have a house with a garden on the roof? That would be quite amazing to me, an avid vegetable and flower gardener.
My husband and I are considering the possibility of building a home in the near future, and I think you may have given me some newer, less conventional ideas. Or at least, less conventional for the area that I live in!
Flat roof construction just might be in my future!
Well, I must say that I had a flat roof for some time, and it caused us a lot of problems! I think, though, after reading this article that it may the type of covering we had on our roof rather than the roof itself that was the problem.
We had your traditional single layer shingles, and apparently it should have been something more water resistant.
We didn’t have any kind of system to remove the water from the roof, either.
I wish we had known because that leaking flat roof caused us nothing but grief for years until we moved!
Pooling water on a TPO or EPDM roof does not cause leaking. Think about EPDM for example, is used to for lining pond and pools.
Likewise, flat top roofs handle snow just as pitched if the building is properly designed. The principal reason for pitched roofs today is generally a matter of style. The traditional rose covered cottage cannot have a flat top roof; it just won't do!
Input from immigrants from Asia is starting to change that perception as they well understand the advantages of flat top roofs.
First, why spend hundreds of thousands of dollars to buy a lot and house and then give up usable roof space (patio, gardening etc.) in order to have a pitched roof?
Back to drainage. The most effective system of roof drainage on flat top roof is to found in the parts of China, etc. And, they put a 12 to 16 inch down pipe in the center of the roof which drops down through the building and directly into the plumbing drains.
This system has been used on the West Coast of Canada with great success and they do not get blocked by leaves, etc.
North American residential roofing, flat and pitched roof are the most expensive, least effective and environmentally damaging roofs of all.
A recent article in Western Roofing Magazine reports the concern the citizens of Assisi, Italy have about finding replacements for five types that fell off a church roof due to an earthquake installed 700 years ago. A roof that lasts thirty five to forty years in North America is considered old and in need of replacement.