Excerpt from my regular column in the Santa Barbara News-Press.
Question: The back patio at our Mesa home has a very nice arbor that was built by the previous owner of the house but it doesn’t provide much shade or any protection from rain. My husband and I would like to know what type of roof could be put on it that would make the patio more pleasant to use on hot days and give some shelter to our dogs and patio furniture in rainy weather.
Your Handyman: There are several issues that need to be considered to determine what type of roof if any can be correctly installed over your arbor, which are adequate slope for drainage, strength of the structure to safely support the weight of a roof, and the spacing of the support pieces that the roofing will need to be fastened onto.
Most baby boomers who grew up in the Sun Belt will remember the wavy corrugated fiberglass panels that covered countless patio roofs in the 60’s and 70’s, but after 30 years of exposure to the sun became brittle and cracked. These fiberglass roofing panels were very popular because when installed correctly they provided a weather tight, light weight, inexpensive roof that was relatively easy to install, and only filtered out about 1/3 of the sunlight. This same style of corrugated roofing panel is now made from poly carbonate (PC) and PVC, available in many different colors and levels of light transmission, and now are virtually inert from ultra violet damage caused by exposure to sunlight. These PC and PVC panels have all the benefits of the old style fiberglass panels but will far outlive the homeowner if installed correctly per the manufacturer’s instructions.
All roofs must have a minimum slope to provide drainage, otherwise rain will pool eventually causing damage to the roof or house, and your arbor was probably constructed without any slope. However there may be an easy way to unfasten the cross members of your arbor and then reinstall them with a positive slope draining away from the house. The roofing panels typically are available with a width of 26” which allows for a 2” overlap horizontally when supported by rafters that are placed every 24”. If the spacing of your rafters is greater or less than 24” then the job may still be possible but will require some special efforts to ensure that the roof is rain proof. The connection where the patio roof and house meet needs to be sealed in a correct way depending on if the panels meet the house at the roof edge or at the siding, and you may want to consult with a roofing contractor to get this important detail correct to avoid expensive water damage to your home.
Most arbors are constructed with larger dimensional lumber for appearance and also to provide support for vines and hanging plant baskets so it probably is of adequate strength to support PC or PVC panels, both of which are very light in weight. You can take a look at these panels at most any of the building supply stores in Santa Barbara and be sure to go online to read the manufactures requirements for installation if you are planning to tackle this job as a “do it yourself” project. Otherwise you should not have any problem finding a local contractor with experience installing this type of patio roof.
Owner, YourHandyman & Construction
CA License #935259