How to Install a Roof Anchor Into Framing and Seal the Roof After

Step by Step

1. 1Step 1: Read the anchor manual and confirm the load rating

   Anchors are not interchangeable. Some are rated for one person, some for two. Some are approved only for wood framing of a minimum size, some for metal roofs, and some only for a particular pitch range. The fastener type matters as much as the plate: a shorter nail or the wrong head will not reach the rafter or will pull through under load.

   Look for the compliance mark, usually CSA Z259.15, and any expiry or inspection tag. If the manual is missing, the anchor is not ready to use. Buy or borrow a documented one.

2. 2Step 2: Locate the rafters or trusses

   Most residential roofs are framed at 16 or 24 inches on centre, so once you find one rafter you can measure to the next. From inside the attic you can see the underside of the sheathing and mark where the nail lines run. From outside, the existing shingle nails show as a faint line, and a stud finder works on many roofs.

   Confirm the framing is sound. A rafter that is cracked, rotted or undersized, or truss chords that have been cut, will not hold an anchor. If you see staining or soft wood, stop and use a different anchor point or a different method.

   Tip: Mark the rafter with a chalk line running down the slope so you can see exactly where the nails will land once the anchor is on the roof.

3. 3Step 3: Choose the location high on the roof and in line with the work

   An anchor set high means the lifeline is as short as possible, which keeps the fall distance down and stops you swinging sideways if you slip. If the anchor is at the eave, a fall from the ridge would pull you across the roof in a long pendulum swing. An anchor directly above the work gives the shortest, straightest line.

   Most manufacturers also set a minimum distance from the ridge and from hips and valleys so the plate can lie flat. Keep the anchor clear of vents, skylights, flashing and any places you need to later remove roofing.

4. 4Step 4: Lift the shingles and position the anchor on the deck

   Some temporary anchors sit on top of the shingles. Others go directly on the sheathing, with the shingles cut or lifted around them, which gives better holding but means more patching later. Follow the manual. Whichever it is, the plate must lie flat without a gap or rocking.

   Orient the D-ring as the manufacturer shows, normally so it can pivot and the load pulls along the line of the nails.

5. 5Step 5: Drive every fastener into the rafter

   Use every hole. Leaving some empty reduces the capacity dramatically, and the count in the manual is the minimum that the rating was tested with. Drive the nails flush and straight, without over-driving or bending them. A nail that misses the rafter and only goes into the sheathing gives a false sense of security, so check by feel and by the sound of the hammer.

   If the rafter spacing does not line up with the plate, add blocking between rafters from the attic or choose another anchor. Do not add nails in other positions to make up the difference.

   Watch out: If any nail hits a knot, splits the rafter or misses the framing, pull it, fill the hole and reposition the anchor. Do not leave a doubtful nail and count on the others.

6. 6Step 6: Test the anchor before you rely on it

   Put a steady pull on the D-ring with your full weight while your other protection is still in place, such as standing at the ladder top or on the flat part of the roof. Watch the plate and feel for any movement or popping. Any movement means the anchor is not seated properly.

   Note the date, who installed the anchor and where, and report any damage. On a crew site, a competent person should sign off the anchor before anyone relies on it.

7. 7Step 7: Connect the lifeline or lanyard and work within its range

   Use a locking carabiner or snap hook, never an open hook. Keep the line clear of sharp edges and do not let it run across the eave or a metal ridge cap, which can cut it. For the clearance needed below in a fall, see how to set up a lifeline and rope grab.

8. 8Step 8: Remove the anchor and seal every hole

   Pull the nails with a flat bar, working slowly so you do not tear the shingles. Fill each nail hole in the deck with roof sealant. Where the anchor sat on the sheathing, lift the course above, apply sealant to the tab and press it down, and slip a matching patch shingle under the course if any tab is torn.

   Finish by nailing the repaired shingles in their normal positions and covering the heads with sealant. Anchor holes are a classic source of small leaks that show up a year later, so the repair deserves the same care as any other penetration. The patch methods in how to replace a damaged shingle apply.

Fall Arrest Versus Fall Restraint

Permanent Anchors

Fraser Valley Notes

Common Mistakes

• Nailing into sheathing only. The anchor holds until the load comes on, then the nails pull straight out of the plywood. Always hit a rafter or truss chord.
• Leaving out fasteners. A plate with half its nails driven is not half as strong, it is an unknown.
• Using the wrong nail. Short roofing nails or drywall screws do not reach the rafter or snap under load. Use the fastener the manufacturer specifies.
• Setting the anchor too low. An anchor near the eave gives a long line, a long fall and a long swing.
• Reusing an anchor that took a fall. It may be bent or cracked in ways you cannot see. Take it out of service.
• Skipping the patch. Unsealed nail holes are the most common source of leaks after a job that used temporary anchors.