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Dec 22, 2015 We have a 1900 Queen Ann that has sagging roof rafters and two of them are cracked. How can I repair this issue? Do I install a support wall in the attic? Do we sister the rafters? Can i lift the roof back to straight or leave it alone? The rafters are 2x4 and have a span of over 20 ft from peak to wall. It is a 12/12 pitch.
- 1 Install a Metal Roofing Edge
- 2 Fix a Crack in an Attic Rafter
- 3 Level Out Studs for Drywall
- 4 Fix a Rotten Floor Joist Under a Bathtub
Rafters can split as a result of excessive weight on the roof or damage from fallen objects, such as trees or power poles. Regardless of the cause, a split rafter must be repaired to ensure the integrity of the roof’s support system. In terms of repair, fixing a split is not particularly complicated, but the repair must be reliable. The most reliable repair consists of affixing a length of metal angle at the lower edge and one side of the rafter. The job starts with taking some measurements to determine the size of the metal angle that you will need.
Preparation
1
Inspect the roof from the outside of the house and note the area where the roof sags. Access the attic area through an access panel, pull-down stairs or attic stairs. If an attic light is not installed, carry a flashlight into the attic.
2
Locate the split rafter. Measure the length of the split and multiply this measurement by three to determine the length of the metal angle you will need to fix the rafter. Measure the width at one side of the rafter from the underside of the roof sheathing to the lower edge of the rafter to determine the size of the large side of the metal angle. For example, the large side of the angle is 5 1/2 inches wide for a two-by-six rafter and 7 1/2 inches wide for a two-by-eight rafter.
3
Visit a structural steel fabricator and obtain a piece of 3/16-inch-thick steel L-metal based on the length and side measurements. The smaller side of the angle is always 1 1/2 inches wide and the larger side is the same as the width of the rafter. Ask the fabricator to cut the piece to length.
4
![Building code for sistering rafters Building code for sistering rafters](http://www.mchenry-homeinspection.com/system/files/images/cracked_rafter%20new.preview.gif)
Set up a power drill with a 1/4-inch drill bit. Drill pilot holes for lag bolts at 6-inch intervals from end to end on the 1 1/2-inch side. Drill additional pilot holes for carriage bolts at 6-inch intervals on the wide side of the metal angle. Center each hole between the outer edge of the wide side and the corner where that side meets the 1 1/2-inch side.
1
Position the L-metal at the rafter with the wide side against one side of the rafter and the smaller side against the underside of the rafter. Move the piece either way, as necessary, so the ends extend equally at each side of the split.
2
Attach the smaller side of the metal at the underside of the rafter with 1/4-by-1 1/2-inch lag bolts at each of the pilot holes with a socket and ratchet. Start at the end that fits against the underside of the rafter. Push upward on the opposite end of the metal so it fits tight against the underside of the rafter at the other side of the split as you install the remaining lag bolts.
3
Use the pilot holes in the wide side of the metal as guides and drill 1/4-inch holes through the side of the rafter for carriage bolts at each hole.
4
Install the end of a 1/4-by-3-inch carriage bolt through each hole at the opposite side of the rafter and push them through the corresponding holes in the metal angle. Use a hammer to drive heads of the bolts, if necessary. Thread a nut onto the end of each bolt and tighten the nuts against the face of the metal with the socket and ratchet.
Things You Will Need
- Flashlight
- Measuring tape
- 3/16-inch-thick steel L-metal
- Power drill
- 1/4-inch drill bit
- 1/4-by-1 1/2-inch lag bolts
- Socket and ratchet
- 1/4-by-3-inch carriage bolts with nuts
- Hammer
Tips
- Apply drops of light oil onto the steel tip of the drill bit when drilling the pilot holes. This prevents dulling the drill bit.
- Use a piece of 3/4-inch plywood as a catwalk when fixing the rafter. Cut the piece 24 inches wide and long enough to span across the upper edges of four ceiling joists when laid flat.
- Ask an assistant to push upward on the end of the metal angle as you install the lag bolts, or cut a two-by-four brace that wedges between the upper edge of a ceiling joist and the outer end of the metal, if necessary.
- As an added measure, inject wood glue or polyurethane glue into the split before closing the split with the metal angle and bolts.
Warning
- Avoid stepping on air-conditioning ducts and electrical conduits when working in an attic area.
References (2)
About the Author
William Machin began work in construction at the age of 15, while still in high school. In 35 years, he's gained expertise in all phases of residential construction, retrofit and remodeling. His hobbies include horses, motorcycles, road racing and sport fishing. He studied architecture at Taft Junior College.
Cite this Article Choose Citation Style
Machin, William. 'How to Fix Split Roof Rafters.' Home Guides | SF Gate, http://homeguides.sfgate.com/fix-split-roof-rafters-47616.html. Accessed 25 January 2020.
Machin, William. (n.d.). How to Fix Split Roof Rafters. Home Guides | SF Gate. Retrieved from http://homeguides.sfgate.com/fix-split-roof-rafters-47616.html
Machin, William. 'How to Fix Split Roof Rafters' accessed January 25, 2020. http://homeguides.sfgate.com/fix-split-roof-rafters-47616.html
Note: Depending on which text editor you're pasting into, you might have to add the italics to the site name.
Related Articles
- 1 Sister a Wall Stud
- 2 Fix a Rotten Floor Joist Under a Bathtub
- 3 Construct Knee Walls in Attics
- 4 Replace Rotted Rafter Ends on a Gable Roof
Fixing a cracked or split rafter in your attic ensures that the roof will receive the necessary support. A rafter might split when heavier roof tiles are installed, or if the rafter has inconsistent grain or excessive knots. Fixing a rafter requires basic carpentry skills and the ability to work in an attic, where space is sometimes limited. Similar to many home repair projects, the job starts with taking some measurements and obtaining the necessary materials and fasteners.
1
Access the attic using attic stairs or through the ceiling using a stepladder or pull-down stairs. If an attic light is not available, use a work light to locate the cracked or split rafter.
2
Measure one side of the rafter from the upper edge to the lower edge to determine the size of framing lumber for the repair, such as two-by-six, two-by-eight or larger. Measure from the point where the lower end of the rafter rests atop a wall to the center of the crack or split, and add 48 inches. For a shorter rafter, measure the overall length from the wall to the ridge at the upper end of the rafter.
3
Measure, mark and cut the piece of framing lumber to length, using a circular saw. Position the piece flat alongside the cracked rafter, with the lower end at the wall. Attach the piece to the cracked rafter with several 16d framing nails and a hammer.
4
Set up a power drill with a 1/4-inch drill bit. Drill pairs of holes through both pieces at 12-inch intervals from the lower end to the upper end of the attached piece.
5
Install 1/4-inch-by-4-inch carriage bolts at each drilled hole. Put a 1/4-inch washer and nut on the ends of each bolt, and tighten the nuts securely with a socket and ratchet.
Things You Will Need
- Stepladder or attic stairs
- Attic light or work light
- Measuring tape
- Framing lumber, two-by-six or larger
- Circular saw
- 16d framing nails
- Hammer
- Power drill with 1/4-inch drill bit
- 1/4-inch-by-4-inch carriage bolts with washers and nuts
- Socket and ratchet
Tip
- Place a 24-inch-wide strip of 1/2-inch plywood atop exposed ceiling joists as a catwalk when fixing the rafter.
Warning
- Always wear eye protection and a dust mask when cutting lumber with a power saw and working in an attic.
References (1)
About the Author
William Machin began work in construction at the age of 15, while still in high school. In 35 years, he's gained expertise in all phases of residential construction, retrofit and remodeling. His hobbies include horses, motorcycles, road racing and sport fishing. He studied architecture at Taft Junior College.
Cite this Article Choose Citation Style
Machin, William. 'How to Fix a Crack in an Attic Rafter.' Home Guides | SF Gate, http://homeguides.sfgate.com/fix-crack-attic-rafter-73155.html. Accessed 24 January 2020.
Machin, William. (n.d.). How to Fix a Crack in an Attic Rafter. Home Guides | SF Gate. Retrieved from http://homeguides.sfgate.com/fix-crack-attic-rafter-73155.html
Machin, William. 'How to Fix a Crack in an Attic Rafter' accessed January 24, 2020. http://homeguides.sfgate.com/fix-crack-attic-rafter-73155.html
Note: Depending on which text editor you're pasting into, you might have to add the italics to the site name.