Rafters And Roof Ridges Are Normally Under Tension

A tension tie in the upper third of opposing gable rafters that is intended to resist rafter separation from the ridge because of wind or unbalanced roof loads.

Rafters and roof ridges are normally under tension.

Roof vents are required for roofs with unconditioned attic spaces. Under the roofing paper felt along the rake edge. The roof framing mock up below shows a standard rafter tie. A horizontal timber uniting two opposing rafters at a point below the ridge usually in the upper half of the rafter length.

A ridge board with the ceiling framing below acting as a tension tie is nearly non structural and of nowhere near the importance of a a true ridge beam. A guarantee by a surety company that a roofing manufacturer will repair a roof membrane or covering under the conditions listed in the bonding contract. A pair of rafters is called a couple in home construction rafters are normally made of wood exposed rafters are a feature of some traditional roof styles. If you see sagging rafters recommend stabilization by a qualified contractor.

Roof sag or roof collapse forces. We include photographs of collapsing wood framed roofs and photo sequences. An attic with an area of 600 square feet with ridge and soffit vents should have a total vent area of square feet. Flat roofs normally have venting systems.

That s true for horizontal ties in the lower third of the roof. It s an indication that you should look carefully for other problems in the roof framing. Mathematicians and engineers discussing collar ties and rafter ties explain that collar ties and rafter ties or ceiling joists under a gable roof are in enormous tension and that the mathematics of the roof forces are the same for collar ties and rafter ties. This article describes explains the directions of forces in roof structures illustrating downwards force horizontal thrust and the causes of rafter sags rafters that disconnect from the ridge or top plate and why a sagging roof pushes the building walls outwards at the wall top.

Collar tie is a colloquial term for collar beam. In many situations you ll find that ceiling joists installed parallel to the rafters are intended to function as rafter ties. Rafter tie a tension tie in the lower third of opposing gable rafters that is intended to resist the outward thrust of the rafter under. A ridge board was not always required and the photo above of the attic in a 1920s era house shows a roof framed without one.

That said i recommend having a local structural engineer come out and review the situation if you are not such an engineer yourself. Also called collar tie. Rafters are typically installed on 24 inch centers. A rafter tie is a tension tie in the lower third of opposing gable rafters that is intended to resist the outward thrust of the rafter under a load.

As such i don t see significant risk here.