There are key factors to consider when choosing the right material for your roof. These are climate, roof pitch (the degree of slope you have), how much weight your home can take on the roof, and budget.
Climate
The nastier the weather you experience, the more you should discuss this with your roofer, and ensure whatever they are proposing is compliant with your local building and safety. For example in icy climates they may require underlayment designed to resist ice, on coastal areas they may require materials that resist algae. There are roofing products that are more impact resistant than others (like versus hail). In very hot and sunny areas, you might want your roof to be white or light colored to reflect the sun better, or products that are considered reflective.
Roof Pitch
Roofers refer to pitch by how many feet vertical rise compared to twelve feet of horizontal travel but most readers are familiar with degrees of slant, so I’ll use degrees. The bottom line is around 15 degrees of slope, you have a big change. At 15 degree level you are really wanting to consider flat roofing materials, below 15 degrees definitely flat roofing materials (or metal, metal roof installations exist that are warrantied down as near flat as 2% slope). At 15 degrees or higher you can consider sloped roofing materials, but realize that in the 15 to 30 degree range, you can often run into needing increased/stronger underlayment systems (which can add a lot of cost) or even the implied material warranty being invalidated depending on the manufacturer and model of product you are having installed. Above 30 degree range you are firmly in the “sloped roofing material” range and you have less likelihood to need any underlayment more robust that what is normally called for.
Weight
You need to know how many layers of roofing you can install on your home according to building and safety. You can call your building and safety department and ask, it is their job to assist with this kind of information and most are helpful. If your home was not built for full weight tile, your only likely tile options would be light weight tiles. Most people in the building industry consider light weight tile to be tile that has an installed weight of 6 pounds or less per square foot. This can be important because if your home was built to take 2.5 to 6 pounds per square foot (i.e. just about any composition shingle model), realize that not only do full weight tile systems weigh more, they can weigh a LOT more than that per square foot installed, depending. Installing more weight than your structure can take can involve damage to the frame, collapse, and/or getting into trouble with your building and safety department. It’s very easy to be compliant on this so no sense asking for trouble. As a final note on this, a lot of building and safety departments allow two layers of some kinds of roofing material (flat systems or comp shingles are the two common examples), but you need a licensed roofer to inspect the existing and ensure it is prudent to add another layer on, and to discuss the various pros and cons of adding a layer or tearing off the old instead.
Roof Budget
There is a difference between a perfect world and the world you live in. In a perfect world, you could have the world’s most bullet-proof roof that looks like something out of a travel brochure for some wealthy beautiful neighborhood. In the real world, your decisions are mostly likely to come down to balancing longevity, appearance and quality. You can usually get good value on all three with a normal budget for a normal household. But your safety and the safety of your structure should take a paramount role in your decision process. A last factor on budget is longevity versus price. While the quality of the roofer plays a roll, certainly the material you pick does too. You can spend a fortune on a metal roofing system and possibly not have to pay a cent to maintain it for years and years! You should not expect to be dropping any serious money on maintaining any new roof, but there is maintenance on any of them to consider moving forward and some are easier to maintain than others. Some begin requiring maintenance sooner than others, some are by their nature more expensive in material costs to maintain than others.
The short checklist would be:
- What weight will my structure take (including do I need/want to tear off existing first)
- What does the weather/climate require of my roofing system, according to both building and safety and according to my roofer
- How long is the roof expected to last
- How much is this going to cost including what are my additional cost options and what value do they bring
- What kind of cost per year will we be looking at after installation
- Do I like how it looks
Building and safety can help you with a) and b). A good roofer should be easily able to help you with all of these points.
The good news is as long as you have a good roofer, most property owners are going to find good value for their situations.
