Roof

A-105 ROOF RIGID INSULATION LAYOUT.pdf

Rigid Foam Insulation on the Roof

This foam insulation installed on top of the rafters serves as the shelter's vapor barrier. Most houses will not have this in addition to the insulation installed in an attic because that attic insulation will come with a vapor barrier.

The printed plans provide a pattern to follow for both the insulation and roof sheathing so that joints on adjacent courses do not land on the same structural member. Refer to the drawings for the general layout for the insulation and sheathing, but take your own measurements and field-verify all dimensions

While this might be obvious, it is easy to forget not to stand on the insulation, once it is installed on the roof. If you stand on it between supporting rafters, it will break! Use 8D nails to temporarily secure the pieces of insulation in place first. If you need to get across the insulation, put a piece of plywood on top of the insulation across multiple rafters. You can step on the plywood between supporting rafters but be sure to not stand on the edges of the loose plywood that overhangs a rafter -- it will flip on you! Try and stand one foot a rafter under the plywood. It is helpful to have someone not on the roof to make sure that the insulation is flush to the facia.

Roof Sheathing

Do not trust the plans, measure to the rafters. Use 3 in screws. Install screws on 6" centers along all edges of each piece of plywood (when you can, don't screw into nothing), and 12" centers in the field. When the plywood is on the insulation, you can now step on it.

A-106 ROOF SHEATHING LAYOUT.pdf

Drip Edge

The metal drip edge protects the roof sheathing from moisture. Again, remember that water runs downhill. Therefore, install the dripedge on the lower wall first. Cut one flange at a 45 degree angle so that this edge can be bent and wrapped around both the front and rear facia boards about six inches. Nail the drip edge with the roofing nail gun. For the corners bend it by cutting a small slit in the top and bend it over a 2x4 to ensure a sharp joint.

All lapped pieces of drip edge should overlap at least six inches.

Remove the white sticker stuff (it is protective film).

Once the bottom piece is installed, install paper on the roof sheathing. Next, you can install the front and rear wall drip edge pieces, nailing through both the drip edge and the paper in the roof. The tall wall drip edge is installed last and should extend beyond the wall corner so that it can wrap around the facia at both ends by about six inches.

Roof Underlayment

Lay out the first course of paper starting at the low side wall. The paper (and the shingles) should extend at least 1/2" beyond the edge of the facia. Continue installing underlayment courses, making sure that pieces higher on the roof overlap lower courses of paper by at least 6". More is even better. Use the hammer tacker to secure the paper as necessary.

In this photo, the front and rear drip edge has been installed, but the drip edge on the tall wall (on the right in the photo) has not.

Proper drip edge lapping at the corner on the shorter wall.

Proper drip edge lapping at the corner on the taller wall.

Securing the taller wall drip edge at the corner of the roof.

Shingles

The asphalt shingles are very sensitive to heat. If hot, you do not want to be walking on them because you will damage them when they soften. While utility knives are often used to cut shingles, knives dull quickly. Tin snips are great for cutting shingles.

At minimum, you must use use four or five nails per shingle and use the roofing nail gun. (the trigger is really sensitive, be warned). While you only put four nails in a full shingle when you first lay it out for nailing, you will end up putting eight nails in each shingle because of the way courses will overlap.

The biggest thing to remember -- NEVER, NEVER allow a joint between two shingles in one course line up with a joint between shingles in an adjacent course. If you do this, the roof will not be watertight!

The First Row -- The Starter Course

Cut the shingles in half lengthwise, along the joint in the middle. Use the thicker half (the top half of the shingle) to lay a first course down. This starter course is necessary; wihtout it, the first course of shingles would not have anything beneath the joints at adjacent shingles in a row. Throw away the other half of the shingle. This first course should hang off the edge of the facia by 1/2".

The Pattern

Look at the shingle package for the correct layout instructions. In this picture, notice how the first shingle is a full shingle. Then, to start subsequent courses, the first shingle of each course is shortened by some pre-determined amount so that joints between shingles on subsequent courses do not line up.

DO NOT HAVE SHINGLE JOINTS LINE UP!! This cannot be overstated.

Once you lay whatever pattern piece per row continue to add full sheets of shingles until you reach the end. Cut the final piece to size using the tin snips. Do not throw away these pieces you cut off however -- likely you will be able to use them to start new courses.

Finishing At The Top

Repeat previous step until the entire roof is covered. Keep adding as long as the thicker half of the shingle is still visible. Once all of the shingles are covered, use tin snips to cut off the excess material. The final course of shingles will have some exposed nails that do not get covered with other shingles. Completely cover these nails with roof compound.

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