Chapter 14: Roof Sheathing
1. Introduction
Roof sheathing is exciting as it is the last major step in "closing in" the house. This likely can be started the same day as raising the trusses. It prepares the house for the roof shingles. It also involves working at heights and walking on pitched surfaces so appropriate safety measures should be taken.
2. Safety Issues
- Review the Morning Safety Huddle Talking Papers for Roof Work and Ladders with the Volunteers.
- Other workers should not be working below the crews installing the sheathing as falling materials can cause injury. If they must work below, they must wear hard hats at all times.
- Ladders should be on secure surface, appropriate angle, and have a person to stabilize the bottom when mounting or dismounting the ladder.
- Any member of the sheathing crew working beneath the others (such as someone holding a ladder) should wear a hard hat.
- Safety glasses and other appropriate safety precautions should be used when using power tools.
- 2 x 4's nailed together to form "L"s will be nailed over the sheathing to reduce risk of sliding off the roof and to prevent materials from sliding off. (see Safety Huddle Talking Papers for Roof Work for details)
3. Prior Tasks to have been completed prior to starting
- Roof trusses raised and secured.
- Materials ordered and present.
- Fascia board installed.
4. Recommended Staff/Crew Assignments
- One volunteer to be safety supervisor.
- A crew of 3 to be the saw crew.
- A crew of 2 to mark truss locations on sheathing.
- Two or three crews of 4 for sheathing.
5. Order/Tasks to be Completed
____Put chalk or pencil lines every 24" on sheathing.
____Sheathing transported to roof.
____Sheathing nailed in place.
____Plywood clips installed between sheets of sheathing.
____2 x 4 "L"s nailed over sheathing for safety.
____Excess cut off.
____Sheath inside of exterior walls extending above the roof (on two story house)
____Ridge vent in place (if applicable).
____Cleanup.
6. Tools/Equipment List
- Circular saw
- Chalk line
- Pencils
- Hammers
- Extension ladders
- Hard hats
7. Material List
- Nails 8d, 16d
- ½" sheathing
- Plywood clips
- 2 x 4's
8. Quality Checkpoints
____Sheathing marked every 24"
____Plywood clips between sheathing between each truss
____Nailing pattern correct
____Sheathing staggered on consecutive rows
____Sheathing applied above to inside of exterior walls extending above roof on two story house
____Ridge vent in place
____Excess cut off
9. Construction Drawings and Text
NOTE: The following drawings, diagrams, and text are to be used on the job site when a question arises as to methods and procedures associated with the task. The notes on the drawings have been geared toward use as a quick reference. If a more in-depth explanation is needed, please read the text description. But most importantly, consult your Habitat Site Supervisor and Construction Manager for advice as needed.
To start, the ½" sheathing is marked every 24" with either a chalk line or pencil line.
The first sheet of sheathing is begun at the rear of the house on the bottom row. Measure up 48 1/2" from the edge of the house on each end. Snap a chalk line the entire length of the house. Keep the chalk line taut as a sag will result in the sheathing being out of alignment. Line up the top of the first course with this chalk line, not necessarily the edge of the roof. The bottom edge should extend to but not beyond the plane of the outside of the fascia board. If it extends past this point the aluminum fascia may not be able to be installed properly. A square or straight edge can be used against the face of the fascia to ensure proper placement. The first sheet will be cut so that it falls on a truss. It may be cut before it is installed or a small overhang may be left and cut off after it is installed. If an overhang is left, all workers should be made aware so that no one walks on it. Overhangs should be small, preferably less than 24". Sheathing is then transported to the trusses. It can be slid up a ladder, lifted by tall workers, or fed from the inside up through the trusses. The sheathing is nailed with 8d nails every 6" around the edges and every 8" over the rest of the sheathing. Continue the first row until completed. Each piece of sheathing should be nailed to at least three trusses. If the last one does not, the previous sheet should be cut back to the previous truss so that the final piece will be nailed to three trusses.
When the first row of sheathing is complete, long 2 x 4's are nailed together in an "L" and the "L" is nailed through the sheathing into the roof trusses. They are nailed into the trusses with 16d nails. The workers will use this for footing so it must be securely nailed to prevent falls. Additional rows will be needed as subsequent rows are installed. This step will not be necessary on a flat roof.
After the first row is complete, the second row is begun. The first board is measured and cut. It will be staggered so that the edge will fall on a truss 4' from the edge of the first board on the first row. This will ensure that seams are staggered. If this is not done, the roof will be weak at consecutive seams. Before installing the sheathing, a plywood clip is placed over the upper edge of the sheathing of the first row between each truss. The next row of sheathing is slid down into the plywood clips and the sheathing is nailed as previously described. Continue until all rows are finished.
On the one story house, a ridge vent will be installed so the peak will need to be open for ventilation. The sheathing should be cut so that there is a 1-1/2" to 2" gap on either side of the peak and the sheathing the entire length of the peak except for the last 24" on either end, which should have sheathing to the peak.
If any overhang has been left, a chalk line is snapped along the end of the gable ends and the cut is made with a circular saw. This cut requires more skill than other tasks during this project and should only be done by someone who has demonstrated sufficient skill and safety awareness. The area below the cut should also be cleared, as there will be falling lumber.
On the two story houses, there may be unsheathed inside surfaces of exterior walls extending above the roof. Cut and nail sheathing using 8d nails every 8 inches, every 6 inches on the perimeter.
Page last updated Saturday, May 3, 2008 at 6:39:57 PM
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Page last updated Saturday, May 3, 2008 at 6:39:57 PM
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