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New roof with 3 tab shingles.

New Garage Roof:

Replacing Asphalt Shingles:
Part 2
Installation Details For Professional Results

In This Article:

Eaves-starter shingles are cut from 3-tab shingles. Row-starter shingles are cut. Special attention is paid to details at the end of the rows. After a dozen rows are done, imperfections are corrected in the shingle layout. Near the peak, the shingle rows are kept parallel with the ridge.

Related Articles:
Skill Level:
3+ (Intermediate)
Time Taken:
About 32 Hours
Project Date:
September 2008
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This article describes one common procedure for installing traditional 3-tab asphalt roof shingles. Architectural shingles, which have multiple layers to create the look of old-fashioned cedar shakes, don't have the same issues of tab placement and alignment.

For more information about roofing with architectural shingles, read Installing Architectural Roof Shingles (which covers a simple, low-pitch roofing project) and Old House Re-Roofing, Part 2, which describes a more complex re-roofing project on a two-story house with a steep roof and four valleys.


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Installing New 3-Tab Asphalt Shingles -
The Starting Point:

The old shingles had been stripped and the roof was covered with builder's felt (a.k.a. tar paper).

Click here to read about tearing off the old shingles.

Garage roof covered with tar paper or builder's felt.


Home-Made Eaves-Starter Shingles:

Cutting starter-strips for the eaves.

Since I was trying to do this re-roofing job as cheap as possible, I made the eaves starter shingles from some old 3-tab shingles I had saved from a previous roofing job.

I used a utility knife and a straightedge to cut the tabs of these plain black shingles.


As I installed the starter shingles, I applied a bead of roof cement (tar) to the drip-edge.

To avoid having tar squeeze out afterwards, I ran the bead about a half-inch back from the edge.

Using roof cement to adhere shingles to drip-edge.


Nailing starter shingles to the lower edge of the roof.

I nailed the starter shingles so they just barely hung over the drip-edge.

Like ordinary shingles, I drove 4 nails per shingle: One nail about an inch from each end, and the other two nails 12 inches from each end.

In the old days, many roofers would make their eaves-starter by simply using a full 3-tab shingle turned around so the tabs pointed uphill. The method I show provides a tar strip close to the edge of the roof, which will help secure the tabs of the first row of shingles. The turned-around method does save some time, but it also creates a slight bulge between the second and third rows of shingles. It took me about 15 minutes to cut the tabs off the 16 shingles I used.


Preparing The Starter Shingles For Each Row:

To make a row-starter shingle, I placed a shingle upside-down on a work table.

Then I cut the shingle with a sharp utility knife and a speed-square.

Cutting row-starter shingles from 3-tab shingles.


Small notch used to mark halfway point in shingle tab.

For each set of starters, there will be 3 shingles that need to be cut in the center of a tab.

Shingle manufacturers normally make a small cut in the top edge of their shingles to mark the center-point of each tab. I just curled the shingle material up to form a "stop" that I could place my speed-square against.

This makes it easy to cut the row-starter shingles because there is no need to measure anything... all the cuts are either made at one of these 3 points, or at one of the two notches between tabs.


Tip: I find it easier to cut the shingles if I let them sit in the sun for a few minutes to warm up.


A typical set of "row-starter" shingles. The shingle near the bottom is a full shingle, the other five have been cut.

These are cut on the left side, so I will need to place the cut edges against the left edge of the roof.

Set of row-starter shingles.

The 6 rows that are formed by each set of row-starter shingles will cover a swath of roof slightly more than 30 inches wide (which is 2-1/2 feet). My garage roof was just under 15 feet from the lower edge to peak, so I cut six full sets of row-starters, and I had a couple of pieces left over.

It's easy to get carried away and cut too many row-starters.

Row starter shingles nailed to the roof in stair-step fashion.

The South Side: Left-To-Right

The row-starters after being installed.

The first shingle was a 5/6th shingle, because I used a full shingle for the eave-starter.

When cutting the row-starter shingles, I made an effort to keep the pieces organized. Since the cut-off pieces were cut on the right, I saved them for use on the north side of the roof, where the shingles will be installed from right to left.

This brings up an important point:

I was tempted to use the off-cuts on the first side by switching to a right-to-left installation sequence, but then I realized that I needed to maintain the same left-to-right direction or else the shingle tabs wouldn't line up. This isn't a problem with "architectural" shingles, just with 3-tab shingles.


Spacing Adjacent Rows:

Each row of shingles should be placed 5-1/8 inches above the previous row, according to the instructions. That placed the lower edge of the shingle very close to the top of the notch in the shingle below.


After the first group of row-starters were installed, I shingled across the roof until I reached the far side. I used a pneumatic roofing nail gun to fasten the shingles.

When each row approached the end, I had to cut a shingle to reach the right side.

Then I installed another set of starter shingles and ran the rows across again, leaving this stair-step pattern.

Rows of asphalt shingles almost reaching the edge of roof.


Garage roof being re-shingled.

A view from farther away.

Note how the orange air hose comes from the other side of the roof. I find it easier to handle the air hose if it's draped over the peak of the roof instead of hanging over the edge on the side I'm working on.


Details At The End Of The Row:

A closer view of the pictures shown above.

As you can see, I need a narrow sliver of shingle to complete the the lowest unfinished row.

Edge detail: Terminating the rows of shingles.


Narrow strip of asphalt shingle used at end of row.

I cut a narrow strip of shingle and nailed it to the roof. This shingle was about 2 inches wide.

Actually, the shingle manufacturer instructions warn against doing this, but I did it anyways. I will apply some tar under every end shingle to keep the wind from peeling them up.


How To Avoid Narrow Shingles At The End Of A Row: If you want to avoid these skinny little shingles, you can use a 2/3 shingle (that's a 3-tab shingle with one full tab cut off) before the end of the row. Then the final shingle will be a full tab plus a little bit. The off-cut will be a little bigger than one-half of a full shingle. And that extra full tab you cut off earlier? You can use that on the ridge.


I installed another cut shingle on the next row. This shingle was about 8 inches long.

Each final shingle should be about 6 inches longer than the previous, but I measured the required length (instead of assuming), just to be sure.

I let each final shingle overhang the side about 1/8 inch.

Partial shingle at end of row.


Nail head below the shingle notch. Oops!


When I nailed that last shingle (shown above) I wasn't careful about where I put the nails, and there was a nail head right in the notch of the subsequent shingle.

I didn't make that mistake again.

This problem doesn't happen with architectural shingles because they don't have notches.


To prevent this from leaking, I applied a big gob of tar under both adjacent shingle tabs, and covered the nail head too.

I suppose I could go one step better and apply some shingle granules to the wet tar that was exposed, but I didn't get that extravagant on this garage, especially since this minor flaw is located on the roof overhang. If I was doing this job for somebody else, I would've taken that extra step.

Applying tar under shingle tabs near edge of roof.


Correcting Imperfections In Shingle Layout:

After I had finished the ends of the first 12 rows, I decided to check the shingle layout to make sure the rows were straight and parallel to the lower edge.

Measuring from edge of roof to top edge of shingle.

I measured from the lower edge of the roof to the top edge of the last row of shingles.

I did this at both the left and right sides of the roof. The measurements were very close, within 1/8".


I snapped a chalk line where the top edge of the next row of shingles normally should be.

Then I went along the roof and in several places I checked the distance from the top of the each shingle to this line. The measurements were not all the same.

Chalk line on roof used to help lay straight rows of shingles.


Measuring from shingle to line to check for straightness of row.

At each end of the row of shingles, my chalk line was about 5-1/8" from the top of the shingles, as it should be.


But in the middle of the row, the top edge of the shingle was 5-5/8" from the chalk line, a half-inch farther than it should be. This meant that the roof had a slight bulge (as viewed from above) and my shingle rows weren't perfectly straight.

That made sense to me, because I could detect a slight angle between adjacent shingles as I worked across the roof.

Measuring from shingle to line to check for straightness of row.


Another chalk line used too make straight rows of shingles.

So I snapped another chalk line one-half inch lower than the first line.

Why make the line LOWER? Because it's okay to make the shingles overlap too much, which will happen at the ends of the row. The shingle exposure on the previous row will be less at the ends, and that's fine. If I used the first chalk line as a layout guide, then the shingles in the middle of the previous row would have too much exposure, and the nails might not be covered.

Why A HALF INCH lower? Because the middle-of-the-row shingles are a half-inch farther from my first chalk line.


I nailed the next row of shingles with the top edges aligned with this new line.

From that point forward my rows of shingles were good and straight, and parallel to an imaginary line that connected the lower corners of the roof. (The actual lower edge of the roof is not straight.)

But that didn't mean the rows were parallel with the peak of the roof.

Installing asphalt shingles to guide line.


Keeping The Shingle Rows Parallel With The Peak:

After I installed a dozen more rows of shingles, I measured down from the peak of the roof to the top edge of the last row.

On this end I measured 49¼ inches.

Measuring from roof peak to edge of recent shingle row.


Nail used as base point for measuring when roof peak lacks clean edge.

A Baseline For Measurements:

The plywood at the top didn't form a good clean peak, so I couldn't get accurate measurements by measuring from the edges of the plywood.

However, the trim boards on the side of the roof made a nice clean peak. I just leaned over the edge and located the peak of the trim, and then I drove a nail through the drip-edge aligned with that peak.

Then I placed the end of my tape measure against the nail.


At the other (left) side of the roof, the top edge of the shingle was 50 inches from the peak.

In other words, the shingles on the left side were 3/4" lower than the right side. If I maintained my course, the last row of shingles will be tapered.

Measuring from roof peak to edge of recent shingle row.

It's debatable if 3/4 inch of taper would be noticeable... that depends on the width of the final row. If the final row ends up having 5 inches of exposure, then this taper will be hard to see. But if the final row has only 2 inches of exposure, 3/4 inch of difference will be obvious.

This is not a difficult problem to fix... it just requires some measurements and chalk lines.


Measuring from top edge of shingle to chalk line used for roof shingle layout.

I snapped a chalk line that had the proper spacing (5-1/8") on the left side of the roof.


On the right side of the roof, the chalk line was only 4-3/4" from the shingles, a difference of 3/8".

I decided to adjust my shingle rows by HALF of the error. Then I'll do another correction a few rows later.

Measuring from roof shingle to layout line.


A Brain Twister:

It's easy to get confused about which side of the roof needs to have the line closer to the shingles. The shingles on the left side are farther from the top. I'd like to simply start the next row 3/8" higher on the left... but that would be TOO HIGH and might expose the nail heads in the shingles below.

I can't have MORE than 5-1/8" of shingle exposed, but I can certainly have LESS.

So my solution is to make the next row 3/8" too low on the right. When my new row is done, the previous row should have an exposure of 4-3/4", at the right side. And a normal exposure on the left side.

Got that? This gives me a headache... and I like geometry problems.


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Guide line used to adjust layout of shingle rows.

After I snapped my chalk line (red arrow) for the adjustment row, I fastened the row of shingles so the top edges were on the line.

Like I said earlier, I only corrected for half of the error with this adjustment. I did another correction row after doing a few more rows of shingles.

After a full day's work, the south side was shingled almost to the peak.

I will need two more rows of shingles on this side before I can install the ridge cap shingles. I will also be installing a zinc strip to prevent moss and mildew from growing on the roof.

But first, I had to replace the shingles on the north side of the roof.

Garage with shingle job nearly complete.


Scenes From The North Side:

Shingle installation pattern.

After I tore off the shingles and covered the roof with with tar paper, I started shingling from the right-hand side of the roof, using the row-starters I had cut a few days earlier.


I fastened most of the shingles with a roofing nail gun.

I bought this tool a couple of years ago for about $250. Not everybody wants to spend that kind of money on a tool they won't use very often, but nail guns can be rented by the day or week.

My nail gun (Porter-Cable RN175A 7/8-Inch to 1-3/4-Inch Coil Roofing Nailer) can be purchased on for less money.

Nailing asphalt roof shingles with a coil nail gun.


Asphalt shingles near peak of roof.

Installing shingles was simple... until I reached the peak of the roof.

There are some special details for installing shingles at the peak of the roof.

See Part 3: Installation Details At The Peak


More Info:
Tools Used:
  • Basic Carpentry Tools
  • Speed Square
  • Utility Knife
  • Chalk Line
  • Pneumatic Roofing Nailer
  • Air Compressor
  • Ladders
Materials Used:
  • 3-Tab Fiberglass 25 Year Shingles, (23 Bundles)
  • Coil Roofing Nails, 1¼", About 22 Coils (Approx. 2600 nails)
  • Roof Cement in Caulk Tubes (4)
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