One of the most common things a buyer wants to know about the house is, “How old is the roof.” This is code for, “How much longer will the roof last.”
These questions are not all that easy to answer—especially the later one.
While I do my best to give some “general” guidance regarding these questions, I make it very clear that whatever I say should be considered a “guesstimate” at best. There are many factors that can contribute to the condition of a roof: color, type, style, installation methods, exposure, maintenance, factory defects etc.
For example take your typical “15-20 year,” three-tab, composition roof. Exposed to full sun, a light colored roof will tend to last longer than a dark black roof. Protected from full sun all colors will last longer but if this protection results in the roof staying covered with moss the roof can be damaged anyway. Frequent pressure washing will take years off the life of a roof, as will installing it over other layers of shingles. Shingles that are stapled as opposed to nailed are more vulnerable to wind damage.
Roofs can be subject to other forms of mechanical damage such as from overhanging trees, shoveling off snow in the winter, hail, water from upper roofs beating down on lower roofs, and downspouts from upper gutters flooding across lower roof surfaces. Even pigeons and seagulls, hanging out on the ridge pecking at the roofing granules, can damage a roof. Installing shingles when it is too hot can cause mechanical damage that will later result in a shortening of the life of the covering.
Of course using the roof for sunbathing and star gazing can cause damage to the roof—-as well as uncontrolled falls to the bather/gazer.
These indicators also have to be adjusted for different conditions in different parts of the country.
So when a buyer asks me how long is the roof going to last, these are the kinds of things I must consider in giving any kind of an answer.
A roof that has few visible signs of aging is the hardest to predict in some ways. We often have sources of information to give us clues as to when the roof was installed and then we can use rough rules of thumbs to give an “approximate” idea of how much longer the roof might last. For example if the seller tells us that the roof was replaced when he bought it and we know he bought it ten years ago it is a “fairly” safe bet it is 10 years old. That info, coupled with what it “actually” looks like at the time of inspection, one could reasonably expect to get another 5 years out of the roof—-assuming that it is a 15-year-roof—-and it looked like it might last another 5 years. Again, I always warn my buyers that these are “best guesses” and that there are many factors to take into account.
No home inspector is likely to “warrant” a roof and most are pretty careful to make their predictions “necessarily” vague. The reality is, that predicting the life of a roof is very difficult and if one is accurate within 5 years one is probably pretty close.
On the other hand, some roofs speak very clearly when they are past their expected life, as the following picture will attest.
There are no maintenance questions here.
There are no questions as to how much longer the roof will last.
This roof was likely past its expected life 20 years ago—and the buckets in the attic agreed with me.
By Charles Buell, Real Estate Inspections in Seattle
If you enjoyed this post, and would like to get notices of new posts to my blog, please subscribe via email in the little box to the right. I promise NO spamming of your email
One more variable to include would be the condition of the underlayment. But you wouldn’t know anything about that, would you 😉
Reuben, well I DO vaguely remember something about underlayment 🙂
No mention of adequate and balance ventilation? It’s the #1 installation mistake and makes up 90% of asphalt roofing systems in existence. Of the dozen shortcuts we see on roofing installs it’s the easiest to see.
And 15 or 20 year shingles? The lowest lifetime I’m aware of is a 20 yrs shingle, even thought he average roof lasts about 15 yrs..(see issue #1)
And it is the most difficult Home Improvement to get an honest job on. Roofers are notorious for hit-n-run short-cutted work and tail light warranties. Have you heard the Angie’s list ad’s lately? That ad begins with “Are you looking for a good roofer?” for a reason.
A competent Home Inspector should be able to gauge the service-able life of a roof within 5 years +/-, but should ALWAYS temper any client expectations with some hard facts and the usual HI disclaimers. An asphalt roof is like an engine. It can look clean on top, but the number of nails, placement of nails, possible use of staples, correct flashing, use of ice and storm shield (rubberized polyastomer) is “a hidden” and plays a large role on how a roof will hold up regardless of it’s outward appearances.
Anyone who would give a warranty on a roof they did not install or oversee/view the installation of, is crazy.
I refer to “20yr” shingles as 15-20 year shingles because in my experience, that is the window of time a 20 year shingle will last. As far as the “issue” of ventilation goes, color affects life more than ventilation and should not really be much of a consideration in relation to the life of the roof. Now the health of the roof “structure” can be an entirely different matter in terms of ventilation.
Interesting.
It’s fully understood that the average lifetime is below the Mfgr’s rated time. This goes to show the average roof is mis-installed. Installation & ventilation exceeds shingle color in it’s impact on life expectancy. That’s factual.
And I had to smile at the concept of “Frequent pressure washing”. While I know some people have done that, the practice reads in your blog like it’s an acceptable normal thing. That’s not good. One should NEVER pressure wash an asphalt shingled roof. They have products like Spray and Forget for mildew and moss.
Pressure wash your roof wrong and you easily take 5-10 years off of it’s life.
Most of an integrated roofing system cannot be seen. That’s the HI’s challenge. But -If installed properly by a Professional some warranties are rather lengthy in duration. Covering mildew and moss for the first 10 years due to the copper in the products. Some shingles guarantee a lifetime of no mildew or moss. Many warranties (IF A ROOF WAS INSTALLED CORRECTLY) can be picked up for a few hundred dollars by the buyer. It’s a suggestion your customer might appreciate if he is working with a seller and Realtor who can locate such information.
And then there’s storm damage; Hail craters and torn shingles. But that’s a whole other quagmire.
Enjoyed your blog!
Thanx.
In General, knowing that the average roof material, compostion shingles being installed today is warrantied for 20 to 25 years, minus the installation date, what roof material, i.e. composition, or others like slate, metal or terra cotta tile, life span are 30 to 40 years along with considering the “installed by manufactures installation clause, guidlines, weather condiditons, etc, then you tell them your best guesstimate, is plus or minus a few years, statisfies a professional response for an inspector.
Most buyers understand and appreciate a general response based on the scope of the inspection standards we go by, your expierence and training. All their concerns must be answered professionally and honesty to the best of your skills. They understand we are generalist, not the manufacturer or installer of the roof and material, and are not liable for unknowns. Best guesstimate is a good word used when speculating. If you are writing it in the report, you should state best guesstimate, due to Murphy’s law, the inspection is good for the day of the inspectoin, and not technically exhaustive. Remeber there are pre aging roofing materials due to manufacturer defects, bad installers not installing to per manufacturers requirements, etc, remaining life expectancy my buddy says tell them, Not My Job, But my B