Welcome to Watson's Journal! Issue # 16, September, 2000

HOME OWNERSHIP 101: The things everyone else forgot to tell you!

The subject this month is roofs. I couldn't do this very well without some pictures, and the pictures have to be pretty big so you can make sense out of the details. In case you are wondering why this looks different than what showed up in your mailbox: I didn't want to put a meg or two of photos into the newsletter itself, but the "WEBified" version your are reading now has them embedded right in the text.

Each week, I inspect about a dozen roofs. Most of them are the common 3-tab asphaltic shingle type, and many of them are nearly new. Almost all of them are done wrong. This doesn't mean that they are useless, or that they leak. It does mean that they won't provide the reliable lifespan they should, and that the manufacturer's warranty is probably not in force. In my opinion, it means that many homeowners are getting cheated when they hire a roofer, but they don't know it until a home inspector shows up, or until the roof starts giving them trouble a few years down the road.

Lets look at the first picture. This is a standard 3-tab shingle, made by Owens-Corning and available at nearly any builder-supply store. The yellow arrow points to a line of adhesive placed on the shingle by the maker. This product softens when heated by sunlight, and makes the next shingle above adhere to this one. This adhesive is what keeps the shingle from being lifted and torn off by high winds. The yellow dots represent the proper locations for nails. Note that the nails go above the cutouts and BELOW the line of adhesive. (I'm not making this stuff up. A photo of O-C's installation instructions is available at the end of the article.

Why is this so important? Read on! the second picture shows how the next shingle should be applied. Note that only 5 inches of shingle A is exposed. The remaining 7 inches of its height are covered by shingle B. Note also that if the nails in B are installed where they belong, they catch the upper edge of A. This effectively doubles the number of nails holding down each shingle. This is the reason the shingle makers are willing to warrant the product to stand up to 60mph winds. (Beyond 60mph, they have special instructions, and you have a lot of reliance on your homeowners' insurance.) Now, let's look at what happens in the real world.

The third photo shows where the nails usually end up; in or above the line of sealant. Exactly why is no mystery when you look at the 4th photo. Notice that shingle B is now up an inch or so, exposing about 6 inches of shingle A. Why? Because when we increase the exposure by 20%, we use 20% fewer shingles on the roof, and save on materials and labor! But then, the only way to make sure the nails are covered by B is to put them in or above the tar line, rather than below the tar line as specified.
Note what happens when we nail B the same way: Those nails no longer catch the upper edge of A. We have lost a lot of the holding power of the system. Also, if the nails are in the adhesive, they can keep the next shingle from sticking, leaving the whole roof very vulnerable to wind damage.

The majority of roofs I inspect have exactly this problem. How do the get away with it? Well, in a lot of cases, the adhesive strip works, despite incorrect nail placement. The whole assembly resists wind lift fairly well, just not as well as it should. Also, if a roof fails early, (anything less than 20 years is early.) most people just replace it. They can't remember who applied it, or they can't find the contractor, or they can't find the paper work. The stuff really hits the fan in those rare instances when the manufacturer screws up. I have seen shingles that were made badly, and started to fall apart after a year or two. This is what the warranty is actually supposed to cover, but if the nails are in the wrong place, or the exposure is wrong, or the venting is wrong, or the underlayment (tar paper) is missing, then the manufacturer has an excuse to void the warranty. They just send the unfortunate homeowner back to the roofer, who may or may not be findable. Some of these cases end up in court, and the lawyers are the only ones who win that game.

This is not the only problem I find on roofs, just the most common.

So, how can you protect yourself from a bad roof job? I suppose you can start by not hiring the lowest bid roofer. Check with the Better Business Bureau, to be sure your chosen contractor isn't somebody who just "appeared" in the business last week. Check with your City to see if a permit is needed. Most cities require permits for reroofing, and reputable contractors have no quarrel with getting the permit, and calling for inspection at the appropriate time. You can also let your roofer know that you expect all the products he uses to be installed according to manufacturer's instructions. "Up to code" is an easily misapplied term here. For instance, the some codes don't require using tarpaper under the shingles on a reasonably steep roof. However, the shingle maker probably does, so "up to code" isn't good enough to keep your warranty in force.

Then there is your ace in the hole: An independent home inspector. An experienced, knowledgeable inspector would be glad to check on that roof job, and make sure it was done right. He will need one of the paper or plastic shingle bundles, where all the instructions are printed, so be sure to grab one while the work is going on. It probably wouldn't hurt to let the roofer know that someone knowledgable will be checking his installation details.

Enjoy the Fall, it's Michigan's most beautiful season!

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copyright 2000 Matthew J. Bezanson .