Hammer Beam Roof Truss

Above these components is a rack of common rafters.

Hammer beam roof truss.

The hammer beam timber truss elegantly distributes the roof load extending weight down through the first floor system by way of heavy posts. A timber frame truss roof with ridge beam purlins and common rafters is a stunning combination that creates visual interest and structural complexity. A hammer beam truss is a cathedral roof truss with an open center. This truss is favored in heavy timber construction in situations where wide clear spans are required and where a different structural member would obstruct the view of gable end windows.

A truss system is a combination of beams braces and rafters that help support a roof s weight. In a hammerbeam roof a series of short wooden horizontal beams curved support beams and wooden. This truss has the appearance of a hammer beam truss and when placed over a high nave the effect of the rods is not objectionable. Hammer beam roof english medieval timber roof system used when a long span was needed.

This truss behaves much more like an actual truss with the ability to have a tension line along the hammer beam up into the web down the other side and or up into the king post. The tie rods should extend through the hammer beams to their outer end. For a truss of 32 feet span a 1 1 4 inch square bar will be ample and it may be twisted to give a more pleasing effect. A hammerbeam is a form of timber roof truss allowing a hammerbeam roof to span greater than the length of any individual piece of timber in place of a normal tie beam spanning the entire width of the roof short beams the hammer beams are supported by curved braces from the wall and hammer posts or arch braces are built on top to support the rafters and typically a collar beam.

There is a hierarchy of timber framing at work here with trusses supporting the ridge and purlin beams. A true hammer beam truss like the one shown here relies on exterior buttresses reminiscent of the flying buttresses of notre dame cathedral to hold it in place and keep the roof planes from spreading apart.