Category: Roofing Work

The methods for tying in and flashing various roof penetrations and structures are similar for an over-lay or a tear-off. The difference is that the overlay often requires only the final few steps of the several that would have been required if you were working on a complete tear-off (or new roof).
If you are overlaying your roof, it is helpful for you to know what is underneath your old shingles. The knowledge of how the work was done originally will help you understand why you are doing certain things on your overlay.
Let’s review the reasons an old roof should be torn off:
1.    There are already two complete roofs on the house, the original plus one overlay. If your home is in the forty-year age range, chances are good it already has two roofs.
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A metal chimney, power ventilator, skylight, brick chimney, dormer, etc., will cut the courses off from the original base and offset lines. The courses below the obstruction continue across the roof uninterrupted to the far rake. You want the keyways of the courses broken by the obstruction to line up exactly with the keyways of the continuous courses. Let me show you two obstruction situations and how to establish new verticals in each case.

POWER VENTILATOR

Your baseline and offset line are to the left side. The size of the unit breaks the continuity of six courses. Lay the six courses up the left side of the unit and cut and trim them as shown. Carry the seventh course on across the top of the unit, nesting the tops of the new shingles to old shingles. Once you get to the top of the unit, nail the shingles in course 7 high. (“Nail the course high” by driving the nails at the top of the shingle, keeping the nails in a line directly above the keys.) Carry course 7 on beyond the power ventilator two (or three or four) shingles and stop laying in that course. When you stop laying in that course “leave the end loose.” (“Leaving the end loose” means you don’t drive the fourth nail at the end of the shingle.) Now bring the eighth, ninth, tenth, and eleventh courses on across, stopping them when you have laid the same number of shingles you laid in the seventh course. Nail courses 8,9,10 and 11 in their normal positions above the keys, but leave the ends loose on each of these courses. Drive a nail directly above the end of the last shingle on course 11. Hook a chalk line to the nail and run the line down across the gap the power ventilator caused in the courses. Hold the chalk line down several courses into the courses that continued uninterrupted below the power ventilator. Make sure it lines up with the ends of courses 9 and 7 above the power ventilator. Pull the line tight and pop it. You have the new baseline. Now lay the same number of shingles for course 12 as you did for the others coming across the top of the power ventilator. Nail directly above the end of the last shingle on course 12. Hook the chalk line, centering the line on the appropriate keyways on the uninterrupted courses, and pop a new offset line across the gap. Lay the shingles back toward the power ventilator and trim them in. You “nailed high” on course 7, so you can slide the shingles for course 6 directly under the shingles of course 7 and set them on the offset line to trim them into the power ventilator. Nail the shingles in course 6 normally. As you continue courses 7, 8, 9, 10,11and 12, you can butt the next shingle into its proper position because you “left the ends loose” on these courses. Of course, if you are overlaying the old roof, you nest the new shingles to the old shingles to carry the horizontal courses. If a tear-off has a big obstruction, just measure and pop lines for 5-inch courses up both sides of the obstruction. Going up as many courses as possible above the power ventilator before you nail above the end of the shingle, and going down several courses on the uninterrupted shingles (to hold on the keyways) gives you more accurate lines than just holding the line across one or two shingles at the top of the gap and one or two shingles at the bottom of the gap. When you use this method of redoing the verticals, the keyways will turn out straight—as if there had never been a power ventilator in the way at all.

OBSTRUCTIONS AT THE RIDGE OF THE ROOF

An obstruction such as a brick chimney can reach the ridge of the roof. In a case like that, lay uninterrupted courses across the bottom of the roof. Go several courses down from the last uninterrupted course you laid and find the end of a shingle in one course down from a baseline course. Carefully set the nail hook under the full tab, making sure it is centered exactly below the joint where the two shingles in the base course above are butted together. Pull the chalk line gently straight up the roof and lay the line down. Now weigh the hook down under the tab with a bundle of shingles and pull the chalk line directly up the roof. Pull it snugs, centering it over the keyway of the several courses above where you have it hooked. Hold it up at the ridge and pop the new baseline. Set the nail to hook up or down one tab, centering it directly below the butted joint of shingles in an offset course. Repeat the process and pop the offset line all the way to the ridge. Lay the courses back from the new verticals and tie the shingles into the obstruction. Then continue on across the roof. If the bottom edge of a tab gets nicked when you pull the chalk line against it, push it down smooth with your finger or tap it smooth with a hammer. (Someone else holding the chalk line makes all this easier: he can hold the chalk line directly over the butted joint. I have described the method for setting the nail hook to pop a chalk line when you are working singlehanded. You will probably have to set and weigh the nail hook more than once to get the chalk line to pull right over the joints.)

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We did one roofing job on two large townhouses that shared the same roof. The front of the roof was two stories up, had an 18/12 pitch, and rose 18 feet from the gutter to the caps. There were six protruding dormers with individual peaked roofs and metal valleys. In addition, the old roof was asbestos shingles so we had to wear very restrictive face masks while tearing the old roof off. One of my men quit and the remaining man had only done a couple of roofs before we tackled this monster. Frankly, I didn’t want the project and bid it high in an effort to avoid it. I didn’t know until we finished the job that the other roofing companies would not bid on it at all.

I always used adjustable roofing jacks that nail right into the shingle roof and can take up to a 2 x 10 scaffold board. You can adjust the support leg on the jack so that the board stays level on various pitches. On this monster roof, the adjustment was on its last notch.

You start the steep roof working from a ladder. It is extremely tedious, but lays the first three courses across the roof. Place the scaffold jacks no more than 8 feet apart (count eight keys). I routinely used a 16-foot scaffold board supported by three jacks. If the roof is especially steep or dangerous, put the jacks closer together and go to a 2 x 10 plank. On the monster roof, I had the jacks 5 to 6 feet apart and used unfinished (untrimmed) 2×10 planks.

Each scaffold jack is centered over the keys of the last course of shingles you laid. When you are starting a roof, you set the jacks on top of the third course. There are three nail slots in the upper part of the jack, and the bottom nail should be driven approximately 72 inch above the top of the key. Drive the remaining two nails at varying angles to keep the jack from jumping loose. Use 8d or lOd nails.

Nail: Some roofers hold their jacks in place with a couple of roofing nails. The results are sometimes disastrous. The nails should be galvanized because they stay in place when the scaffold is removed.

You will notice that since the jack is over the key, the tab of the next course of shingles up the roof will cover the nails. Lay the scaffold boards in position on the jacks. The arm that the board sits on has a vertical end piece to hold the board in place. That vertical end piece has a nail hole in it. Nail through the hole and into the scaffold board. You don’t want your scaffold board jumping loose either.

When you overlap scaffold boards, make sure there is a jack supporting the overlap. Don’t overlap a scaffold board onto another unsupported scaffold board. Charlie Chaplin made millions laugh doing that type of thing, but nobody will be filming you. Drive a nail through both boards of the overlap. You don’t want a board to slip.

Nail: Some roofers who do use jacks and scaffold planks instead of the 2 x 4 toe boards (chicken ladders) just lay the scaffold planks up there without nailing through the jacks into the planks.

Use good quality planks that are in good condition. Don’t use painted planks. The paint gives the planks a slick surface and covers up flaws. You don’t want to suddenly discover that the only thing between you and eternity is one weak knothole.

The scaffold will support you and enough bundles to lay the roof up as far as you can reach from the scaffold. Stock the bundles on the scaffold plank and walk on the bundles too. The bundles are a tripping hazard. The overlaps of the scaffold planks are a tripping hazard. In addition, if you are using an air gun, the hose can get caught and unexpectedly jerk you. Move slowly and easily along the scaffold. (If you start to feel like an expert, get back on the ground fast!)

You will scaffold up the roof in stages. Work from your first scaffold to build the second stage of scaffold. Repeat the process on up the roof. When the roof is complete, you bring your scaffold down in stages, too. Remove the scaffold planks. Lift the tab covering a jack. Use your hammer to tap (some-times pound) the base of the jack up the roof until it slides free of the three nails. Drive the three nails down flush and mastic over the heads. Press the covering tab down flat over the three nails. TIP: If the jacks are going to stay in place and are going to get wet, they can leave a rust stain. Raise each jack up slightly and slide paper from a bundle wrapper between the bottom of the jack and your new shingles. The paper can protect your new shingles from rust for weeks if necessary.

I scaffold everything right and still had one jack pull partially loose on me on a very steep roof. I sidestepped until another jack was supporting me and then I hustled down the ladder. It turned out that the sheathing underneath the jack was weak. The only reason the jack didn’t pull completely loose was that I had varied the angles of the three nails holding the jack. I was only one story up, but it was a sickening feeling when that jack started to let go.

Nail: The shortcuts roofers take by not scaffolding or by just using “toe boards,” warrant a Nail. If a roofer is doing stupid stuff and risking his own safety, you can guess what else he is doing as he lays your roof.

If you have hired an uninsured roofer, and he gets hurt, he has no choice but to sue you and your homeowner’s insurance. If an insured roofer gets hurt because of something dumb, he nails the entire industry because all insured roofing businesses end up paying higher insurance premiums. The cost of the increased premiums is passed on to the customer.

In Closing

If you are contracting the work for your new roof, you will not find a contractor who will do all these things exactly the way I have described them. Each roofing company develops its own characteristic methods. My goal is to prepare you to recognize and appreciate top quality workmanship when you check your contractor’s references. I want to make sure you are ready to negotiate in what can be a ruthless game. The next steps are yours.

If you are overlaying or tearing off the roof yourself, you know exactly how to do a top-quality job. You need to plan your strategy and your sequence of work. Don’t be overly concerned about the weather.

Just schedule your work around the weather forecast, and keep a “what if’ factor in your plans. You know how to handle sudden storms. When you reroof your home using this book, you will have a top-quality roof with an outstanding appearance. (You will also save a considerable sum of money.)

When you finish the roof, you will probably hear the kind of comment that was always music to my ears. More than once, prospective customers told me, “I want you to do my roof for me. I don’t know why, but your roofs always look so much better than any others I see being done.”

I have done everything I can to show you what to do and also to explain why you should do it that way. Now, it’s time to start talking to suppliers and their previous customers. Whether you are contracting or reroof mg your home yourself, I hope it is a pleasant experience for you and you achieve outstanding results. If my direction and insight helped you, it was my pleasure.

Now, go to it!