An overlay requires less labor, involves less risk, and generates less scrap material to be hauled and disposed of than a complete tear-off. Overlays are covered early in this book because you should check that option thoroughly before deciding you have to tear off.
You measure the roof and it is 37’6″ wide. 37’6″/3′ per shingle = 12 lh shingles. You want the lines near mid-roof, or about 18 feet from the rake. Pull from the left rake. We want 2 inches of shingle overhanging the rake so we can cut 1 inch off and get a perfectly straight cut when we trim the rake.

Your base line would be 18′ – 2″ = 17’10”

Your offset line would be 17’10” – 6″ = 17’4″

Let me show you what size tabs you will end up with at our right rake.

Base line: 37’6” – 17’10” = 36’18” 17’10” = 19’8″

Offset line: 37’6” -17’4″ = 36’ 18″ -17’4″ = 20’2″

Both of these measurements are to the face of the right rake. Remember, we want to have a 1-inch overhang, so add an inch to each measurement to get 19’9″ and 20’3″ Shingles have a key cut out every foot, so at the right rake you will have a 9-inch tab and a 3-inch tab. (You will have a lot of shingle, 1’4″ and 10″, sticking out over the right rake. Rough trim the shingles before you nail them in place. That much length will drop down and break the shingle right away if you don’t rough-trim it first.)

The reason for checking the tab sizes at the rake is that you don’t want to end up with a narrow sliver of a tab overhanging the rakes. If you have a 1-inch tab at the far rake, the key is directly above the rake edge, and the 1-inch tab has no strength. The 1-inch tab will gradually weaken and droop over the edge.

I call these “pigtail tabs” because they end up looking like a line of pigtails drooping down over the rake board.

Nail: Most roofers pull in 36″ – 2″ = 34″ and 34″ 6″ = 28″ for their base and offset lines. They let the tabs along the right rake end up whatever size they happen to be. That is the reason for so many homes with the weak, dangling “pigtail tabs.”

The shingle layout will not be centered on the roof if we lay it out as we computed it. To make it even, the tabs on the left should lose another inch, and the tabs on the right should gain an inch. In effect, we need to shift the whole shingle layout 1 inch to the left. This is easy to do. Just subtract another inch from the initial measurements you made for the baseline and offset lines:

Pull over 18′ 2″ 1″ = 17’9″ for the base line

Pull over 17’9″ – 6″ = 17’3″ for the offset line

Measure over 17’9″ from the left rake along the

Ridge of the roof, drive a nail at this measurement near the ridge. This is the base line nail. Now drive another nail at 17’3″ This is the offset line nail.

Hook the chalk line to the baseline nail and gently run the line out down the roof. Try to keep the chalk line out of the area where the finished lines will be. “Ghost” lines where the chalk line bumped the felt can cause you to make errors later. At the bottom of the roof, measure over 17’9″ and mark the felt with a vertical arrowhead, using the blunt back of your straight blade or a nail. Mark the 17’3″ measurement too. Pop the chalk line at the 17’9″ mark, and you have the base line. Re-hook the line to the offset nail at the top of the roof and pull it taut over the 17’3″ mark at the bottom of the roof. Pop it and you have the offset line.


If you have left shingles stocked at the ridge of the roof, chances are good that Murphy’s Law has come into play again, and the stockpile is right where you want to put your verticals. You want to pop the verticals all the way from the fascia to the ridge. Just vary the verticals 3 feet one way or the other. Instead of 17’9″ and 17’3″ use 14’9″ and 14’3″ or 20’9″ and 20’3″ to get to one side or the other of the stockpile. Then you can pop the verticals all the way to the ridge.


Now we need to set up our horizontal courses, and we are ready to start nailing shingles. You want the shingles to overhang the fascia board by between 174 inches and IV2 inches, so the water will run off the end of the shingle to the ground or into the gutter. You want the horizontal chalk lines to mark the tops of the shingles. The shingles are 12 inches high so 12″ IV21 = IOV2″ Measure from the front of the fascia board up the roof IOV2 inches and drive a roofing nail. Hook the chalk line. Go to the far end of the roof and mark the felt with a horizontal arrow IOV2 inches above the fascia. Pop a line. You now have the line for the top of the starter course.

Some styles of aluminum drip edge can extend 1 inch or more beyond the face of the fascia board. Extend the bottom edge of the shingles 1 inch beyond the outer lip of the drip edge. You don’t want the bottom edges of the shingles to extend more than 2 inches into the gutter and start blocking it. If you are using drip edge, measure up the roof 11 inches ( 12″ -1 ” = 11 “) from the outer lip of the drip edge. Pop the line for the starter course.

Open a bundle of shingles. There are a few ways you can make it easier to use the shingles. Bring the bundle down to the lower center area of the roof and hold one end while you drop the bottom of the other end of the bundle on the roof. Remember, you have self-sealing shingles: they tend to stick together in the bundle even with the protective tape. Dropping one end is called “breaking the bundle” because the impact causes the shingles to shift and separate from each other while they are still wrapped in the bundle. Pull the paper wrapping apart at its seam in the back and discard the paper. (I have watched some roofers shred the wrapper into five or six small pieces. Then they have a bunch of small wind-blown scraps to pick up.)

Some people with super-flex knees can squat and duck-walk along the lower edge of the roof and are comfortable. My knees won’t take that kind of abuse. I’m right-handed, so I’m more comfortable sitting with my right leg tucked up under me and my left foot down the roof as a brace and brake. Sitting is a little slower, but I can still walk the next morning.

Take a shingle and turn it so that the top edge overhangs the fascia and the bottom of the tabs is right on the line for the starter course. Slide it over until the end (not the side of the half-key cut) is centered on the base line. You are going to lay the starter course this way with the grit to the sky, the tabs facing up the roof, and the top edge overhanging the fascia. Nail this starter shingle in place, driving the nails slightly below the self-sealing strip.

Now lay the next shingle over toward the left rake of the roof. Butt it in against the end of the first shingle you laid. But it reasonably snug, but don’t jam it. The shingles will expand and contract. If they are jammed tight, they will tend to buckle. This second starter shingle should also have its tabs heading up the roof with its top edge dangling over the fascia.

Now lay the first shingle of the first course right side up and directly over the starter course. The end of this shingle should be in perfect line with the offset line, which has been covered over by the first starter course shingle. The top of this shingle can be set even with the bottom of the tabs of the starter course. The tabs on the shingles of the first course should be over the solid edge of the starter course. Nail this first course shingle in place. The nails go in the shingle above the keys and just below the self-sealing strip. There has to be a nail at each end of the shingle and a nail above each of the keys, a total of four nails.

The upside-down starter course provides a straight, unbroken, strong edge beneath the tabs of the first course. Water running down the keys of the first course is carried on over the edge by the upside down shingles of the starter course. This method gives the maximum protection against damage to the fascia board and the ends of the joists covered by the fascia board.

When you drive your nails just below the self sealing strip, it forces the strip to bulge slightly, so the shingle in the course above it can adhere firmly to it. If you nail right in the self-sealing strip, you pull the strip down and away from the shingle above it. (Plus, you end up with asphalt all over the head of your hammer. When asphalt does accumulate on the head of the hammer, rub the head vigorously on the top portion of a shingle. Shingles are like giant sheets of sandpaper.)

You will note as you lay shingles that nailing just below the strip catches the top of the course of shingles below. This means that each shingle is held in place by not just four nails, but eight nails. This makes for a very strong roof.

A nail gun doesn’t lend itself to the exactness of hand nailing. Just shoot the nails into the self sealing strip. If you try to stay below the strip, you are going to end up with some exposed nails on the new roof. You will also end up damaging, and removing, a lot of shingles. If you gun your nails in the self-sealing strip you will still be nailing through the top of the shingles in the course below.

Nail: I stressed four nails per shingle because that is the way the roof is designed, and that is what the building code calls for. Some unscrupulous roofers cut the corner by three-nailing or only two-nailing a shingle.

The code calls for six staples per shingle. Each end of a shingle should have a staple. There should be a staple on either side of the two full keys for a total of six staples. I have never, ever found a roofing company that six-stapled shingles. The most they do is four and not always that.

Some companies will fire one staple above each of the two full keys in the shingle. They will then fasten one staple across the butted joints of the shingles. In other words, one leg of the staple is in one shingle and the other leg of the same staple is in the next shingle. The company may try to convince you this is four stapling the shingle. Sorry, this is three-stapling the shingles, and it gives you half the fastening strength the code calls for!

Nail: Shorter staples are cheaper than longer staples, so guess which staples an uncaring roofer is going to buy. A short staple will penetrate the shingle and bite into the wood sheathing if your roof is a tear-off. In the case of an overlay, the shortest staples will just barely bite into the wood. In other words, the legs of the short staples don’t penetrate the old shingles and all the way through the sheathing. The new shingles are not fastened thoroughly to the wood sheathing, which is where the holding power is. If your roofer uses the shortest staples, he has, in effect, fastened the shingles of your new roof to the shingles of the old roof.

Nail: Short staples have a nasty habit of penetrating part of the length of their leg and then bending over and lying on top of the shingle. Staples like this might as well not be there.

Nail: The final problem with staples is that they give maximum strength or have maximum holding power in the direction perpendicular to the staple itself. On a roof, you want your maximum strength to be in a vertical direction. (Gravity is trying to pull your shingles down the roof, and high winds will try to tear the shingles up the roof.) This means that you want the staples to be horizontal; you want the exposed top of the staple to be running across the roof, parallel to the fascia board or gutter.

As roofers work, they are swinging the staple gun in an arc. The staple fired at the far reach of that arc is not horizontal across the roof. Depending on the roofer, that staple may be almost vertical (or perpendicular to the fascia). A vertical staple gives the roof the least strength possible, even if the staple legs fully penetrate the sheathing.

These tricks give you some insight into the bad rap on staples. Six-stapling shingles with long staples will generally work out fine. It’s easy to get confused on the starter and first courses, so nail the upside-down starter course all the way across the roof to both rakes. Now come back and nail the first course directly over the starter course. Just remember to start this first course at the offset line.

Rough-trim the overhangs as you finish each course so the shingles don’t sag down or break along the rake. Measure the courses up the roof in 5-inch increments above the starter course. Lay the end of the steel tape against the top of the starter course, and mark arrows up the roof in 5-inch increments. Do the same marking at the other rake. Drive nails in each mark up one of the rakes. It’s tedious, but keeps hooking the chalk line one nail at a time and pop the 5-inch course lines across the roof. After popping three or four lines you will start running out of chalk, and the lines will get faint. Reel the line back into the chalk box, then hook the nail clip. Un-reel the line, banging the side of the box on the heel of your hand and keeping the box nose down as the line reels out. This will keep the chalk loose and get the maximum amount on the line. Popping lines on horizontal courses is one of those times when another set of hands is most welcome.

Nail: Most roofers don’t mark every course. The better roofers will pop a line for every other course. A roofer may have a good feel for how far down the shingle he is laying should overlap the next course down the roof. He can keep the courses straight by popping a horizontal course line every 10 inches.

Unfortunately, too many roofers pop a line every five courses (25 inches) or even as much as every eight courses (40 inches). They take great pride in the time they shave off the job by taking such large skips. Unfortunately, their courses get increasingly wavy and often look like snakes before they get up to their next marked course, which is perfectly straight.

Your starter course began at the base line and the first course began even with the offset line. So the second course begins back at the base line again.

Lay the second course. Double nail the rakes. When you come to the rakes, nail the shingle in its normal place. Then nail the shingle again just inside the face of the rake board. Keep the nail far enough in from the face of the rake board that you don’t end up splitting the wood on the face of the rake board. Nail a second nail straight up the shingle from the first rake nail. Be aware of where the key of the next shingle up the roof will fall and keep nails away from that key. Double nailing gives an extremely strong edge to the roof and will help keep the roof on during very high winds. Keep laying courses until you complete the fifth course.

Keep checking to make sure you alternate each course. Starting two consecutive courses on the same vertical line is an easy mistake to make: you don’t want to lay half the roof before you discover it.

Now you can stock the roof. Let’s say this section of roof is 18 feet high. You computed the area to be:

37.5′ x 18′ = 675 sq. ft. = 6.75 squares

6.75 sq. x 3 bundles/sq. = 20.25 bundles

You have already laid three bundles in the first five courses, so you need to stock 20, 3 = 17 more bundles. Break the bundles as you drop them and un-wrap the bundles you stock on the lower third of the roof. Don’t get in the habit of unwrapping bundles until you are ready to use them. Remember that sudden storms or winds can blow the shingles from the roof.

You can place containers of regular roofing nails above the bundles, or you can spot a coil of nails for the nail gun above each bundle. The patterning on the shingles is designed to be random if you lay the shingles across the roof as described. This is particularly true if you are drawing from different bundles going across a stocked roof.

Now you have five solidly nailed non-skid courses of shingles to work from. The edge may make you extremely nervous, but it’s time to turn your back to the world and work up the roof. (If five courses still places you too close to the edge, lay two more courses, then turn and work up the roof. Don’t worry, you’ll get used to it and will probably end up turning after only four courses.) I found that standing and bending over using the gun was the easiest and quickest way for me to nail. (A gun is nice but too expensive to buy for a one-time effort. You also have to be extremely careful not to step on the hose to the gun. The hose will roll out from under you and throw you.) Most people who hand-nail either sits and scoot or work from the balls of their feet and their knees. It’s exciting to look back and see the progress you are making. Keep checking to make sure you have alternated every course.


Some roofers reinforce their rakes with a shingle running lengthwise up the rakes. It’s like a starter course for rakes. Lay the starter course along the fascia. When you get to the rake, turn a shingle so that its top is */4 inch out over the face of the rake.

The top of this shingle supports the protective overhang out over the rake board. Pop a chalk line up the rake 1IV4 inches from the face of the rake.

This is the line for the bottom of the tabs of the shingles. Lay the horizontal courses right over this rake shingle, allowing a 1-inch overhang as computed before. If you are using twenty-five-year shingles, let the rake shingle extend 1 inch over the face of the rake and let the course shingles overhang by IV4 inches.

The rake shingle is a nice idea, especially with a twenty-year shingle. However, I encourage you to pay three or four dollars a square more and go with a twenty-five-year shingle instead of the twenty year. A 1-inch overhang on a twenty-five-year roof shouldn’t droop down, even without the rake shingle.


It is not unusual to need a small portion of a tab of a shingle to complete a course. Often you only need a few more inches of shingle to complete a course at a valley, wall, chimney, or other obstruction.

When this happens, don’t just put in the small piece and nail it down. The small piece will be very weak and prone to blow off. In addition, you don’t want to drive nails through a small piece near the “V” of the metal valley.

You don’t want a small piece with its open, butted joint running close to the step flashing down a wall, chimney, or other feature on the roof. The butted joint could allow water to get in under the shingles. The last shingle before you would have needed the small piece has three full tabs. Nail the first two nails in the shingle and sit above the shingle using your foot to hold the loose end down. Start the hook blade at the center of the last full key way and cut up the shingle, angling the cut slightly back toward the center of the shingle. Remove and save the tab you just cut off and lay a whole new shingle in its place.

Nail the replacement whole shingle as appropriate. Now when you make the final trim cut on the replacement shingle, you won’t have a narrow, weak tab (where it can be blown off) or a joint in a leak prone location. Theoretically, when you cut off that last tab of the final whole shingle in the course, you should make the cut straight up from the center of the key way. I found I was usually off a little and had to trim the top of the shingle more to butt the top of my replacement shingle in, and to have the proper width on the key. By starting at the center of the key and angling the cut back very slightly toward the center of the shingle, you will eliminate a lot of lost time spent trimming. The end of the replacement shingle will butt right against the center of the key you cut, and the resulting key will be the perfect width.


Don’t try to felt in the entire roof if the wind is fighting you. Staple down one run of felt at a time, start the first run of felt above the fascia. Roll out a short length (5 to 7 feet) and staple it in place.

Weight it down with bundles of shingles. Roll out and staple another short length. Weight it down and continue toward the far rake. Mark the starter course. Mark the verticals in the felt at the bottom of the roof near the fascia. Mark the verticals at the ridge and as you did before, drive nails part of the way down at each of these marks. Hook the nail hook on the nails and pop vertical chalk lines down the roof. It will look funny to only have verticals on one run of felt, but don’t let it bother you.

Lay the starter course and first course of shingles. These will hold the first run of felt in place. Move the bundles up so they just cover the top of the felt and mark and pop the lines for the next four courses.

Lay the four courses of shingles. Move the bundles out of the way on up the roof and come across with the second run of felt, stapling and weighting it down as before. Now hook the chalk line on the nails at the ridge and hold the bottom of the chalk line exactly on the vertical lines on the top of the first run of felt. Pop the lines. Go on, up with the next courses of shingles. Keep repeating this process one run of felt at a time until they reach the ridge. It’s extra work to keep moving the bundles up and down, but it’s more work to have the felt blow off after you just finished marking all the courses.


On an extremely steep roof, hook a chalk line, and unreel the amount of free line you will need to reach down to the run of felt you want to mark. Slide the chalk box down the roof, keeping it a few feet away from where the verticals will be, so you don’t get “ghost” lines. Go back down the roof and pop the line.

Get back up on the ridge and repeat the process for the next vertical. This is another case where a second set of hands is welcome. Single-handed popping of verticals on steep roofs is time consuming (and strenuous), but it can be done. It seemed that when we came to a really mean, steep roof, no matter how good the pay was, my crew got sick or disappeared.


Occasionally you have to stop laying the horizontal courses of shingles before you can finish the courses all the way across the roof. At the same time, you need to continue the courses on up the roof. When this happens, don’t nail the end of the shingles in the courses you had to stop. By eliminating the fourth nail, you have “left the ends loose.” You can raise the loose ends up later and slide new shingles under them to continue the course on across the roof. After you have tied the course in, you go back and nail down the loose end.

You can leave the ends loose by just leaving out the last nail in either the base or offset courses, which ever extends 6 inches out in the direction the course is heading. It’s easy to lose track of where you are and mess this up. I just left the end loose on every course. Then I knew I had to nail the loose end of each shingle when I came back and continued the courses on across the roof.


You may have to carry the course over an obstruction, leaving a gap in the courses on the other side of the obstruction. Nail the shingles in this kind of course at the very top of the shingle, keeping the nails on a vertical line directly above the keys. This is called “nailing the shingles high.” The nails go in their normal position when you lay the courses above the course you “nailed high.”

Nailing high allows you eventually to tie in the next course down the roof by sliding the shingles for that course in under the course you carried across the top of the obstruction. The nails on the shingle you slide in will be in their normal positions on the shingle.

Then re-nail the course of shingles you “nailed high,” placing the nails in their normal position also. (Don’t worry about the nails you left at the top. They already did their job, and they aren’t hurting anything.)

“Leaving the end loose” and “nailing high” are both ways of allowing you to come back to tie shingles in later.


Shingling the roof should go without any major problems. However, sudden changes in the weather may force you to get everything as watertight as possible and then get off the roof. There are things you can do if you keep an eye on the sky and have a little warning before a storm hits.

Let’s suppose you have just finished felting in the roof and those towering, fluffy white, cumulonimbus clouds off to the west start to bunch together and turn gray. The section of roof has one plumbing vent and a wall rising above one end of the roof. Stock the roof, spotting the bundles along the overlaps of the felt. On a 6/12 roof, lock the bundles in place (by laying a second bundle on top, with one edge on the roof and the other edge on top of the first bundle).

Leave all the bundles wrapped, and don’t bother to break the bundles by dropping one end first. Weight the felt down at the ridge. Get light stuff off the roof or weight it down with a bundle. Get any trash off the roof.

Next, shape the all-lead flashing and bed the base of it in place in a bead of roofing cement, which you have caulked on top of the felt and around the plumbing vent. Tuck the top of the flashing in the vent pipe.

The storm is forming, so you still have some time. Figure the verticals on the roof so that they run close (one or two shingles away) to the wall you need to flash. Mark and pop the verticals. Mark the starter course and then mark the first several of the horizontal courses. Nail the starter and first course shingles from the verticals to the wall, but leave the ends of the shingles loose at the verticals. Install the lower step flashing. Lay as many of the rest of the partial courses from the verticals to the wall as you can; leave the shingles loose at the verticals. Tie the step flashing in as you do each course. Water accumulates as it runs down a roof, so every additional 5-inch piece of step flashing tied into the end of its partial course of shingles is critical.

You may see that you can’t get the wall completely shingled and step-flashed. Cut a length of felt off the roll and lay it up the wall, preferably getting the edge under the siding. Use bundles to weight the felt down in position up the wall.

Another option is to run a bead of roofing cement to tie the end of the felt into a brick or mortar wall. The step flashing will cover this, but it can be a mess when you come back later to finish the step flashing. It’s worth risking the mess to keep the water out. When the storm is definitely coming but it’s. Several miles away, get off the roof. Lightning will strike several miles in advance of the actual rain. Plus, wet shingles are slick, and wet felt is extremely slick.

You did the best you could, so just hope it won’t leak. I have been forced to carry more than one plain felt roof through a sudden totally unpredicted storm. Measures like these work very well. It helps to take a “what if’ approach to roofing, then you don’t panic and flounder if the horizon suddenly gets dark.