It’s a typical question we get, though it’s not one we can easily answer. How long your roof will last is dependent on a number of factors.
The biggest factor to the longevity of your roof starts with the type of material used.
- Composite shingles – The most common roofing material, asphalt or 3-Tab shingles typically last between 15-20 years. This can vary a bit in part to the quality of the tiles. You can go cheap or premium. Premium architectural asphalt shingles can last for 30 years.
- Wood roof shingles – less common and prone to decay and weathering, will generally last for 15 years.
- Wood shake shingles – much thicker and more common than standard wood shingles, they stand up to the weather and UV rays far better. Their life expectancy is between 35 and 40 years.
- Clay tiles – commonly found in the Southwestern US (Arizona, Nevada, Southern California), these tiles are extremely durable and will last 100 to 150 years.
- Metal Roofing – Metal roofing has become mainstream and is now one of the more common choices for many homeowners. Its strength and ability to withstand the elements leads to an average lifespan between 40 and 50 years (though they can last closer to 70 or 80 years).
- Slate roofs – Slate is particularly suitable as a roofing material as it has an extremely low water absorption index of less than 0.4%, making the material waterproof (http://utm.io/uh1). This also makes it less susceptible to breakage from freezing. One can expect to get 150 years or more from a slate roof.
Quality materials will only last if installed properly. It’s a simple concept. Proper installation applies to more than how the tiles are laid.
- Your roof is made up of more than just the tiles used. It is a complete system. It starts with the roof deck – the wood surface laid over the trusses/joists. If the decking is too thin, weak or damaged everything installed on it will be compromised. For a roof to last, like your house, the foundation needs to be solid.
- Over the top of the decking, there needs to be an underlayment – a water-resistant or waterproof membrane. Underlayment types range from the basic ‘felt’ paper (it’s really asphalt-saturated felt) in varying thicknesses or something highly advanced like SlopeShield.Its primary purpose is to protect the decking from any moisture which gets underneath the shingles (should they be damaged). Missing or installed incorrectly (how it was fastened, was it damaged by walking on it after installation?), there is an increased risk of leaks and damage to the decking.Over time, this will weaken your roof’s foundation. Even if your roofing material has another 10-20 years or more of life expectancy, if the deck rots below it, your roof could/will fail.
- Drip edge is metal flashing installed along the edges of the roof. Its primary purpose is to divert water running off the roof into the gutters. Without it, water could work its way back under the shingles damaging the decking or the fascia. During re-roofs, it can be overlooked or skipped by cheaper companies.
- Flashing around roof vents, chimneys, and skylights when improperly installed allow water intrusion and damage below the roof tiles or shingles.
A final note about installation – the roof ‘pitch’ matters. Pitch is a measure of the steepness of a roof. Your choice of roofing material (and the underlayment) must be matched to the pitch of your roof. Not all materials are suited for all pitches.
While most roofing material estimates likely account for varying environments, some materials will hold up better in different areas. Clay tile as strong and long-lasting as they are, are prone to breaking. While perfect in the hot southwestern climates, in Western Washington, with our trees and falling branches, you can expect increased tile damage. They are also more susceptible to damage from freezing (while coated, clay is still a porous material allowing water to be absorbed where the coating has worn).
When you buy a new car, you know it won’t last forever if you don’t change the oil, the air filters, your tires, and perform routine checks, you know at some point, your car will die…and long before it should.
The same applies to your roof. You cannot install it and forget it. Any damage which occurs impacts your roof’s longevity – regardless of the material used. Damage from falling branches and animals can crack or tear tiles, dislodge them, or create small openings water can easily access.
Moss, algae, and mold build-up are more than unsightly. Moss and lichen anchor their roots into the top layers of shingles and remove granule. They grow up into the keyways (slots) of the shingles and along the edges causing them to lift and make the roof more prone to wind damage and leaks. Their growth in valleys will obstruct water flow.
This weakens tiles (and their UV coating), can cause them to tear, allow water intrusion, and can create pockets of standing water.
Over time, caulking and sealants dry out and deteriorate. This leaves openings around the edges of flashing vulnerable to water gaining access. The same applies to chimneys. Exposed to the elements, bricks, and mortar will erode creating additional ways for water to get in below the tiles.
Clogged gutters prevent proper drainage. Water can get back behind the gutters damaging the fascia boards they are attached to, causing rot. This weakens the edges of the roof. It makes it possible for further water intrusion and damage to the decking.
We highly recommend a minimum of two roof inspections per year. This will not only help correct any issues you have, it will help prevent some new ones.
How Long Will Your Roof Last?
There is no simple answer. Some things are also beyond your control – especially when buying an older home. The best thing you can do to help make sure it lasts – take care of it!