![]() Perfect Roof Rafters – Focus your efforts on the pattern rafter, and the rest of the roof falls into place easily.ĭon’t Fall Short on Shingles – How to estimate materials for roofing projects.ĩ Upgrades to Windproof Your Roof – Master these roof-installation details to keep asphalt shingles on and rain out of your house.Įxposed Rafter Tails – An architect offers advice for making roof details match the style of your home.Importance of Rafter Ties in Home Construction Roofing Resources – Take the mystery out of getting roofing done right. Laying Out a Common Rafter – For simple gable or shed roofs, you need to learn this basic building block of roof framing. ![]() Rafter ties or ceiling joists support the rafters and sidewalls under gravity loads, including the dead load of the roof structure and live loads such as snow (above drawing).ĭrawings courtesy of Christopher Mills More about building and repairing roofs: What we think they doĬollar ties (or ridge straps) prevent the ridge from separating due to uplift pressure from wind (top drawing, right). Installed in the top third of the roof structure, collar ties prevent separation of the roof at the ridge due to wind uplift. You may need to add reinforcement to the top plates of the walls in order to compensate for the wide spacing of this type of rafter tie again, consult an engineer to make sure this is feasible and that you get the details right. If this isn’t an option, the next best thing would be to space several large rafter ties out, using either attractive timbers–as you would see in a traditional timber frame–or wrapping them in order to make them architectural elements in the space. You can possibly remove them altogether of you include posts in the gable walls to support a structural ridge. If you are framing a cathedral ceiling, there are a couple ways to deal with the need for rafter ties. Rafter ties (or ceiling joists acting as rafter ties) are required by code unless the house is designed so that the walls or a structural ridge beam carries the full load of the roof. Located in the bottom third of the roof structure, rafter ties effectively resist the horizontal forces caused by gravity loads that would otherwise cause the roof to pancake, pushing the sidewalls out. If you’re unsure of whether you can safely remove collar ties, consult your local code official or engineer. If rafters are sized correctly, this shouldn’t be needed, though it might explain why collar ties have been a part of roof structures for a long time. In this scenario, the load on one side is partially transferred to the rafters on the other side across the collar ties. Some engineers theorize that collar ties may minimize deflection of undersize rafters, particularly under heavy loads, such as snow. ![]() Theoretically, no-if rafters are correctly sized and properly joined by rafter ties, and if other means to resist uplift, such as ridge straps, are present. If you’re not sure if you need collar ties, you should consult an engineer. That’s the job of the rafter ties or the ceiling joists. The proper thing to do, of course, hinges on knowing why they’re there in the first place.Ĭontrary to popular belief, collar ties are not there to support rafters or to keep walls below from spreading under the weight of the roof. Rafter ties are required by code, unless the house is designed so that the walls or a structural ridge beam carries the full load of the roof.īuilders have been installing collar ties for years, and for years, space-starved homeowners have been asking to have them removed, particularly if they plan to remodel their attic. Rafter ties resist the forces caused by gravity loads that would otherwise cause the roof to pancake and push out the sidewalls. Collar ties are necessary to prevent separation of the roof at the ridge due to wind uplift. In this “How It Works” article, managing editor Debra Judge Silber explains the role of collar and rafter ties in the framing of a roof. Synopsis: Collar ties may take up space in the attic of your home, but they are there for a reason.
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