Habitat Tutorial – Part 4 Roofing

This is the fourth part of a multi-part outline of what is involved in buildings a Habitat house.  This article covers the steps in installing roofing – felt and shingles and a few other roof line details such as building a “bird box”, installing the drip edge and vents.   The first part is Habitat Tutorial – Prepration for Build which covers some of the pre-build steps the Site Project Manger (SPM) and selected volunteers  go though just to get ready for the volunteers, the second is Habitat Tutorial – Part 2 which covers the first day where the walls go up and the third is Habitat Tutoial – Part 3 which covers raising the roof structure.    In addition, there are four sets of pictures with slide shows that have already been published that you may be interested in as they concentrate on people on the job site – volunteers.   The first is Habitat for Humanity – 2008 Dinner on the Slab consisting of 25 pictures including our future homeowner Nicole Combs and her son Elijah.  The second includes 115 pictures of the first day of the build – Habitat Build 2008 – First Day – Walls Go UP .  The third is: Habitat Build 2008 Second Day – Roof Goes On which has pictures and blog on the installation of the roof trusses and decking the roof.   The fourth is Habitat Build 2008 – roofing and siding.   If you want access to any of the tutorial pictures they are all in one place for all the tutorials to date.   Tutorial Slide Show – 146 pictures so far, including many not in this article.

Note: If you came here looking for the homeless veterans site, this is it!   If you came here looking for the homeless youth site, this is it!.   I’m just taking a break to help out on a Habitat House and once a year I post what I saw, experienced and learned.  Click on either of the two links in this paragraph or go to the side bar and select a category or search for what you want.  Also look above the banner or to the right for popular articles on Homeless Veterans.

Tutorial – installing roofing shingles

Roof Ready For Shingles

This is the way Habitat volunteers see the house when they arrive on the scene on roofing day.  Soon the roof will be covered front and back with volunteers.  It is essential that the roofing be done early in the day and that there is plenty of water available.  The felt and starter shingles are already in place.

 

 We need to start this tutorial a little earlier than that.

 

Drip Edge Installation

This drawing illustrates drip edge installation.  The drip edge must be installed in the order shown.  The drip edge is a metal extrusion that goes along the horizontal edge (eave) of the roof under the roofing felt and along the sloping edge (rake) of the roof above the felt.   Install the drip edge for the eave before the roofing felt is installed.  Install the drip edge for the rake after the roofing felt is installed.   Attach the edge using 7/8 ” roofing nails on 24″ centers.  Unlike shown in the drawing, the rake edge goes all the way down and overlaps the eave edge.   Trim the rake edge to match the eave using tin snips.   When two pieces of drip edge meet in a joint, overlap the joint by 1 to 2 inches by trimming the top of one as needed to allow them to overlap.   Joints on the rake drip edge should should have the upper one overlapping the lower one.

Also shown in this illustration is something called the “bird box”.  

Click here for the rest of this tutorial:

Bird Box

This is the “bird box” detail for the corners of the roof.   It is simply a 2 piece box that adds detail to the house and provides a place to mount corner lights.   It just adds to the overall looks.   Notice the rake drip edge is shown trimmed in this illustration and runs all the way to the facia.

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Once in a while our resident artist illustrates our work.

Roofing Felt Installation

Roofing Felt Installation

Roll out the roofing felt along the eave drip edge, trim it to the end of the house and nail using 7/8 roofing nails in plastic caps.   Nail on 24″ to 36″ (max) centers 3 across as shown.   Overlap each course by 3 to 4 inches.  Follow the lines on the felt for a uniform overlap.  Smooth out the felt as best as possible.  Any wrinkle that folds into a crease will show through the finished roof.   When finished, install the rake drip edges and trim top and bottom to match the eave drip edge (bottom) and the other rake edge (top).   Run the felt all the way to the roof peak and lap over to the other side.     The vent slot will be trimmed out later, after the shingles are on.

Starter Shingles

Starter Shingles

 The edge of the roof is outlined with starter shingles that are placed on the roof with the tabs turned inward.  This provides extra strength near the edge, higher wind resistance, and better resistance to water blowing under the edge of the shingles.   Before starting, snap a line 11″ from the drip edge on the eave all the way across the roof.   Have someone hold the line down in the middle of the roof and snap each side separately to minimize bounce and sag.  Repeat for the rake (sloping) edge.

The starter shingles are nailed along this line, allowing a uniform 1 inch overhang of the shingle over the drip edge on both the eave and rake (12″ shingle on 11″ line).    Notice that the eave edge starts with a shingle that has 1/2 tab cut off (6 inches) in the drawing, although that is optional in many areas.    Outline the roof completely with these shingles.  Butt the starter shingles end to end (do not overlap).  Each shingle gets 4 nails located near and opposite the beginning of the drip line.  See drawing “shingle layout below” if there is any doubt.

  

Starter Shingle Photo

This photo shows the start shingles installed and bundles of shingles on the roof ridge ready for installation.   

Shingle Layout

Shingle Layout

 

 The first step to a good looking roof is to lay it out carefully.   Find the center of the roof at the top and bottom and mark with a heavy pencil mark.   Measure out to each edge from the pencil mark and place a shingle on a 3 foot mark (measured from the center pencil mark) near the edge to see how the tabs will fit next to the rake edge.  Shift it left and right by 3″ to see how it fits with the edge.   It is important that at least one full 12″ tab and at least 3″ of the next tab lie on the roof on each end.  Adjust the marks made at the center left or right so that these rules can be followed.  Check with a shingle at both ends.   Shingles on the edge that are too short will not stay aleigned.  When tabs less than 3″ are left, they will often tear off when trimming the roof later, and will certainly fall off during high winds.

 

Make certain that any adjustment made at the bottom is matched by the same adjustment at the top.   Snap a chalk line top to bottom.   Snap two other lines 3″ on each side of this line.  

 

Snap a line 11 inches from the drip edge and the rake edge all around the house for the starter shingles if not already done.   Snap new lines 5″ above the horizontal 11″ line.     You will need to mark off 5″ all the way to the ridge on each end using the top edge of the starter shinges as a common reference.  However you should only snap 5 or 6 lines at a time or the roofing activity may erase them.   Notice in the photo of an actual roof, the lines have been snapped to the roof but many of them are already badly smeared/

 

Have your crews follow these guide lines carefully and always require them to work from snapped lines.   Volunteers and novices will try to eyeball the placement of the shingles if there are no snapped lines.  I guarantee that the shingles will drift off up or down from one edge of the roof to the other and the result will not be pretty from the ground later.

 

Place the first shingle edge on one of the 3″ marks and aleign the shingle top edge with the starter shingle.

The second course starts on the other 3″ mark, alternating on the 3″ marks for each new course.   Work from the center outward in both directions.   Each shingle should have 4 roofing nails placed just above the top of the drip groove as shown in the drawing. 

 

Shingle pattern for multiple crews

 

To ensure that the roof in uniform, many times Habitat crew chiefs will build a vertical set of shingles that allows two crews to work at different paces on each side of a roof surface, as shown in the drawing above.   The technique is to place shingles along the vertical lines all the way to the top.   The ends of the shingles are not nailed at this time, only the nails above the drip groove.

 

 Each course is expanded toward the edge by butting shingles to the center set and continuing to the edge of the roof.  Where necessary, the edge of the course above is lifted, the new shingle inserted below, aleigned with the chalk mark and then both edges are nailed.  Often the crew leader starts new courses. 

 

The shingles should overlap the roof ridge at the top.  This will cover the ridge vent slots.  Cut out the ridge vents with a shingle knife.

Trimming the Edges

Shingles Overhang Rake Edge

The shingles should overhang the end (rake) of the roof and droop down until the entire roof is covered.

Two people working together should first find the outside edge of the starter shingles at the top and bottom of the rake edges.   This may require cutting one or more shingles back enough to get a finger on it from the top of the roof.  Mark the location on the top of the shingles at the top and the bottom of the roof.

Then snap a line from top to bottom of each edge and carefully cut the excess off even with the chalk line which must match the overhanging starter shingles.    This should be done by someone experienced and comfortable working near the edge of the roof.

 

Pipe Flashing 

Pipe Boot

Shown above is the proper installaion around a typical vent pipe.  The flashing will already be there but not nailed down.   Lift the flashing up and run the course below up to the pipe and notch as necessary.   In the case shown above the pipe flashing has been dropped over the lower course and the follwing courses lap over the upper parts of the flange so that water sheds properly.   The boot is sealed to the roof with asphalt calking and nails below shingles.  Any nails are calked and located under shingles. 

Shingles for Valleys

Valley Weave

There are two ways to install shingles in valleys.   Both start with a 14″ wide aluminum sheet pressed into the valley from top to bottom.  Roll out the aluminum and form it to the shape of the valley down the center of the sheet.  Nail this sheet only on the long side edges.     No nails within 6″ of the center!

Valley Weave

The drawing above shows the valley weave technique that is usually used on valleys between two roofs on the front of a house, sometimes also on the back.  Shingles woven together both look better and hold up better to water dammed up from leaves on the roof.

Shingles from the shorter roof are extended to and lap over the valley but the ends on the other side are not nailed down at that time.   Shingles from the other roof are woven in by crossing over one shingle and slipped under a shingle in the next course and nailed down.   Form both sets of shingles snugly to the bottom of the valley.   It is best to trim the ends as necessary to not extend under more than one course at a time to avoid a lumpy appearance.    Do not put any nails within 6 inches of the valley from any direction!

Valley Weave Photo

 Standard Valley

Install the aluminum as described above.    Run the shingles from the shorter roof side over the valley and lap the other side by at least 12″.   Make certain that no end joints end up in or near the center of the valley, preferably end them near or past the edge of the aluminum.    Form the shingles snugly to the bottom of the valley.   Do not place nails within 6″ of the center of the valley at any time from any direction!

Snap a chalk line down the center of the valley.    Now extend the other side of the roof past the chalk line and cut it to match the chalk line.  Cut only the newer layer, not those from the short side.   The effect is one side is slightly higher than the other, forming a small step.   Apply a bead of asphalt caulk about 1″ back from the cut edges and press it in.  

Standard Valley Photo

You can see from this photo why this valley installation, if used, is usually on the back side of the house.

Compare it with the woven valley in the previsous photo.

Ridge Caps 

Ridge Cap Photo

 

Making Ridge Caps

 

These can be cut quickly with a shingle knife with 6 quick cuts on each shingle.   They can also be very efficiently gang cut by stacking a number of shingles neatly together, then carefully cutting the top one as shown using a straight edge.  Then use the top one as a pattern to cut through the ones below. 

 

Turn the cap shingles sideways, start at one end of the roof and lap each following cap over the first, leaving 5″ for the exposed part.   Place a 5″ mark on your hammer handle as a guide to ensure uniform placement.  Stop the last shingle at the beginning of the ridge vent slot at each end.   Then install the ridge vents. 

 

Ridge Vents

 

Ridge Vent Installed Photo

 

Ridge vents provide the vital service of siphoning off the enormous heat trapped in the attic on a hot day.  Rising hot air exits through the vent on the peak of the roof and pulls cooler air in through the soffets.

When the roof decking was put on, a slot was cut along the roof to provide for this air movement.   This photo shows the installed ridge vent with ridge caps alrady placed on top of it.

 

 

 

Ridge Vent, Top View

 

Bottom View Photo

 

It is necessary to look down into the cut slot and locate the roof truss locations.  mark them on the roof shingles below where the vent will be located, such that the marks can be seen after the vent is placed on the ridge.   Now place the roof vent over the cap shingles on one end such that the vent laps about 12 inches of the cap shingles beyond the start of the vent slot.  Nail the vents only into the roof trusses and not just into the OSB.   Butt the roof vents together until the last one overlaps the cap shingles at the other end by about 12 inches.    Follow the manufacturers instructions for proper installation.  You can see in the top view photo above that the instructions are embossed into the vent material on each vent.  Often the proper nails are clipped onto the vent on the underside.

Now install cap shingles over the roof vents beginning at the same end started for the regular roof cap shingles.  Work to the other end.  The last cap shingle will have exposed nails.  Caulk these nails before putting them in and caulk over the top of the nails. 

 

 

Slide Show of Tutorial Pictures.

This Roofing Tutorial slide show contains all the pictures shown here and quite a few more.

Here is a link to the Roofing Tutorial pictures

Here is a link to my Habitat Build Photo Sets  

 

There is at least one more tutorial coming, Hardi Plank siding.

Do you find these tutorials and pictures useful?  Please let me know!

Jim