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How-to install a new asphalt shingle roof in one weekend

The new generation of asphalt shingles are a vast improvement. In addition to enhancing the appearance of all types of roof, they are easier to install and much more durable. These are laminate asphalt shingles made from a fibreglass mat, thicker and very wind-resistant. They are referred to as composition or architectural shingles.

Accurate measurements are essential for a successful installation. Safety ropes and harnesses are necessary, as is a roof scaffold system to ensure a safe working environment, particularly if you are installing shingles on a very steep roof.
Verification and preparation of the roof
1

Remove the old shingles

  • 1.1 - Remove the old shingles and roofing felt with a roofer's shovel. Pry out nails.
  • 1.2 - Sweep the roof as clean as possible and run a scraper over the decking to check for nails that might have been missed.
  • 1.3 - Inspect the plywood or particle board and replace any damaged or rotten boards. Panels must be at least ½" thick.
  • 1.4 - Nail down or screw in any boards that are raised or loose.
  • 1.5 - Install a metal or vinyl drip edge directly on the plywood the length of the eaves. Nail at 12" intervals and lap each section by 2". Use snips to cut the corners.
  • 1.6 - Verify that soffit and ridge vents are not obstructed.

Pro tips

Even if the installation technique is much the same, different shingles require different methods. Read and follow the manufacturer's instructions to retain your warranty.

Chimney, vent and step flashing is installed as part of the shingle installation process. However, roof valleys must be prepared and built before you begin.

This project proposes open metal valleys to facilitate water run off.
2

Install the eaves protection membrane and cover the valleys

  • 2.1 - Install self-adhesive waterproof membrane 36-72" wide (according to the applicable building code requirements) on all fascia boards.
  • 2.2 - Unroll and align the membrane so that it overlaps the metal drip edge by 3/8".
  • 2.3 - Temporarily attach the roof membrane at a few equidistant locations.
  • 2.4 - Fold back the lower half and peel off the release film.
  • 2.5 - Reposition and press down to ensure good adherence.
  • 2.6 - Remove the temporary installations and fold back the upper half of the membrane.
  • 2.7 - Peel off the release film, reposition and press down to ensure good adherence.
  • 2.8 - Repeat to cover the eaves and fascia.
  • 2.9 - Lap the end joins by 6" and the lateral joins by 3".
  • 2.10 - Install roof vents and other roof elements on the decking.
  • 2.11 - Cover valleys with self-adhesive waterproof membrane. Begin at the lower section of the roof. Center a 36" strip (of self-adhesive membrane down the centre of the valley) so that half of the strip (approximately 18") covers each side. Overlap each section of the membrane by 6-12".
  • 2.12 - Lay the self-adhesive membrane to extend 4" up the sides of the chimney and to form a 12" strip on the roof around the chimney.
  • 2.13 - Cover ridges and crests so that half a strip (approximately 18") covers each side.
3

Install the underlayment

  • 3.1 - Install a felt or synthetic roofing underlayment over the entire surface. Start at the bottom of the roof.
  • 3.2 - Attach the underlayment to the roof with nails or roofing staples, spaced at every 8" at the centre where sections overlap.
  • 3.3 - Advance the underlayment by 6" on the self-adhering waterproof membrane along the fascia board.
  • 3.4 - Cover the entire surface of the roof, taking care to lap each row by 4-6".
  • 3.5 - Advance the underlayment by at least 4" on the valley membrane and by at least 6" on the ridges and crests.
  • 3.6 - Extend 4" around the chimney and at the intersection of all vertical surfaces on the roof.
  • 3.7 - Cut the openings for the chimney and vents.
  • 3.8 - Install the metal drip edge over the membrane on the fascia board.
Assembly and installation of the open metal valleys on the roof
4

Build the open metal valleys

  • 4.1 - Install metal valley trim on the membrane, starting at the bottom of the roof.
  • 4.2 - Center the trim on the valley and secure the edge with roofing nails. The nail head must maintain the flashing in place. Do not perforate the metal.
  • 4.3 - Continue along the valley and lap sections of trim by at least 6". Coat each overlay with plastic cement.
  • 4.4 - Establish two lines on either side of the valley where the shingles will end.
  • 4.5 - Place a line at the top, 3" from the centre on both sides of the valley.
  • 4.6 - Deviate 1/8" per foot (from the valley) as you bring the line down to the drip edge, where the maximum deviation should be 8".
  • 4.7 - Snap the chalk line on both sides of the valley

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Roofing calculator
5

Lay out the starter shingles

  • 5.1 - Start in the lower left corner and work towards the valley. Read the manufacturer's instructions specific to the type of shingle.
  • 5.2 - Snap a horizontal chalk line 5-10" from the lower edge of the roof. Adjust the measurement according to the type of shingle.
  • 5.3 - Snap a vertical chalk line every 6ꞌ and horizontal lines at regular intervals to ensure the rows of shingles will be straight.
  • 5.4 - Use a starter strip or cut the tabs off the shingles to be used.
  • 5.5 - Cut 3-5" from the left side of the shingle to stagger joins.
  • 5.6 - Install the starter shingle with the adhesive strip on the edge of the roof. Overlap the fascia boards by approximately 3/8".
  • 5.7 - Align with the chalk line. If necessary, move and snap another line according to the width of the starter strip
  • 5.8 - Secure the starter strip with 4 nails equally spaced. Do not nail closer than 6" from the fascia board, 1" from the lateral edges, and ½" above each notch. Do not nail into the self-adhesive strip. Nails must be perfectly straight and flush with the surface of the shingles.
  • 5.9 - Install starter rows the entire length of the eaves.
  • 5.10 - When you come to a valley, place the starter strip on top of the flashing and cut along the chalk line.
  • 5.11 - Nail 2" from the chalk line.
  • 5.12 - Make a 2" bevel cut in the upper corner of the strip and coat the valley side with asphalt sealant.
Le bardeau d'asphalte : pose des autres rangées sur la toiture
6

Lay the subsequent rows

  • 6.1 - Start off the first row with a whole shingle.
  • 6.2 - Place the shingle in the starting corner in such a way that the last shingle will overhang the fascia board by 3/8".
  • 6.3 - Drive in 4 straight nails only until the nail heads make contact with the asphalt. Avoid tearing.
  • 6.4 - Stagger each new row by a half-tab.
  • 6.5 - Align the lower edge of the shingle with the top of the notches on the preceding row.
  • 6.6 - Repeat for every row.
Laying asphalt shingles at the junction of an open valley
7

Shingle open valleys

  • 7.1 - Place the shingles on top of the metal valley flashing.
  • 7.2 - Verify that the shingle is at least 12" wide. If necessary, cut the width of the preceding shingle
  • 7.3 - Cut shingles, respecting the angle of the chalk line.
  • 7.4 - Make a 2" bevel cut in the upper corners so that water will be directed to the centre.
  • 7.5 - Nail in the shingle no more than 2" from the chalk line.
  • 7.6 - Coat the ends of each shingle with a 3" strip of asphalt sealant from the flashing to the upper corner. Cover all the nails along the length of the valley flashing.
8

Install wall flashing

  • 8.1 - Ensure that the self-adhesive membrane covers 4" up the wall and a 12" strip on the roof.
  • 8.2 - Place the first piece of flashing on the starter strip at the junction of the roof and the wall. If necessary, install a drip cap to the gutter below.
  • 8.3 - Nail in the flashing at the top through the shingle, using two nails. These will be covered by the next row of shingles. Do not nail to the wall, only the roof.
  • 8.4 - Install step flashing when shingles are being cut and installed the length of the wall. Pre-bent 8" x 8" flashing must extend up the wall at a height of 4", cover 4" of the asphalt shingle, and overlap.
  • 8.5 - On the wall, cover the step flashing with an adhesive waterproofing membrane.
  • 8.6 - Install an air-barrier on the wall
Flashing the chimney for asphalt shingle
9

Étanchéifier la cheminée

For large chimneys, build a chimney saddle on the roof support before installing flashing. Situated above the chimney, the saddle redirects water away from the chimney, thereby preventing any accumulation.
  • 9.1 - Ensure that the self-adhesive membrane extends 4" up the chimney and a 12" strip on the roof around the chimney. Install shingles up to the front of the chimney.
  • 9.2 - Install metal flashing at the base of the chimney. This must cover 4" of the shingles and 12" up and around the chimney.
  • 9.3 - Nail both bottom corners of the flashing to the roof, over the lower shingle, and seal with a layer of plastic roof cement at the junction with the chimney.
  • 9.4 - Seal all joints with plastic roof cement.
  • 9.5 - Continue to install rows of shingles.
  • 9.6 - Install step flashing when you cut and install shingles around the chimney. Pre-bent 8" x 8" flashing must rise 4" along the chimney, cover 4" of the asphalt shingles, and overlap.
  • 9.7 - Nail in flashing at the top through the shingles with two nails, which will be covered by the next row of shingles.
  • 9.8 - Secure the step flashing to the chimney with plastic roofing cement.
  • 9.9 - Glue the edge of the shingles to the flashing with plastic cement.
  • 9.10 - Insert the counter flashing into mortar grooves and cover the step flashing. If it is not possible to reuse existing grooves, groove out approximately 1 ½" using a masonry blade. The counterflashing must lap 3" over the step flashing.
  • 9.11 - Cover the saddle with single-piece metal flashing. Cover at least 6" of the sides of the chimney wall and extend at least 6" on the roof underlayment.
  • 9.12 - Seal joins with plastic roof cement.
  • 9.13 - Continue installing shingles over the flashing.
  • 9.14 - Insérer le contre-solin dans les engravures du mortier pour recouvrir le dos d'âne.
  • 9.15 - Seal joins with plastic roofing cement to improve the watertight integrity.
Install roofing around vents to ensure watertightness
10

Waterproof the vent pipes

Flashing around a vent pipe is installed on top of the lower shingles. The bottom section will be exposed, whereas the upper section will be covered with shingles.
  • 10.1 - Install shingles right up to the vent pipe.
  • 10.2 - Trim shingles so that they fit around the pipe, then nail.
  • 10.3 - Insert pre-formed flashing (vent pipe boot) around the vent, then glue with plastic roof cement. The boot should extend 4" over the lower shingles, rise 8" on the vent, and extend 6" on both sides.
  • 10.4 - Colmater l'espace entre le tuyau et le solin avec du ciment plastique.
  • 10.5 - Continue installing shingles, taking care to completely cover the upper edge of the flashing.
  • 10.6 - Glue all parts of shingles overlapping the flashing with plastic cement.
  • 10.7 - Coat exposed nails with plastic roof cement
11

Install a metal ridge vent

The metal vent is not shingled. Most new roofs are installed with a ridge vent to help ventilate the attic.
  • 11.1 - Snap a chalk line 7/8" from the ridge on both sides of the roof. If roof trusses are evident, the gap should be 1 ¾" the length of the ridge. Leave 8-10" along a wall or chimney.
  • 11.2 - Measure the thickness of the sheathing and adjust the circular saw to that measurement.
  • 11.3 - Cut the sheathing and be sure not to cut down to the rafters. Follow the two chalk lines along the ridge.
  • 11.4 - Use a wood chisel to complete the cut at the ends
  • 11.5 - Remove the sheathing panel with a pry bar. Remove all nails along the cut.
  • 11.6 - Install the shingles up to the ridge so that they cover the sealed strip on both sides of the ridge.
  • 11.7 - Cut the shingles covering the vent opening.
  • 11.8 - Center the vent on the ridge.
  • 11.9 - Nail at the top of the opening every 6", alternating from side to side.
12

Shingle a hip roof

  • 12.1 - Start from the bottom edge of the ridge.
  • 12.2 - Depending on the type of shingle, use a perforated ridge shingle or cut three-tab shingles into squares.
  • 12.3 - Bend the shingle piece over the crest and nail it through the top corners, 1" from each side.
  • 12.4 - Lap and center the second shingle.
  • 12.5 - Cover the entire crest.
  • 12.6 - Use plastic roof cement to glue the last shingle.
  • 12.7 - Coat all exposed nails with roof cement.
13

Shingle a ridge without a vent

  • 13.1 - Install the last row of shingles. The granule surface should be at least 6" from the ridge
  • 13.2 - Fold back the upper part of the shingle and nail.
  • 13.3 - Cover the other side in the same way.
  • 13.4 - Start at the end of the roof that faces the prevailing winds.
  • 13.5 - Depending on the type of shingle, use a perforated ridge shingle or cut three-tab shingles into squares, then cut the upper corners at a 45o angle.
  • 13.6 - Snap a chalk line on both sides of the roof as guides.
  • 13.7 - Bend the piece of shingle on the ridge, following the angle of the roof.
  • 13.8 - Nail on top of the tab, 1" from the edge of both sides.
  • 13.9 - Drive the nails through the shingle and decking.
  • 13.10 - Lap subsequent shingles by 5 5/8" and nail on both sides.
  • 13.11 - Shingle the entire ridge.
  • 13.12 - Glue the last shingle with plastic roofing cement.
  • 13.13 - Coat all exposed nails with roofing cement.

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