Pratt Truss Roof Details

Fan truss it is made of steel.

Pratt truss roof details.

It used wood for the vertical members. In a conventional pratt truss diagonal members are in tension for gravity loads. It can be used for spans from 6 10m. Vertical members are tension and diagonal members are compression.

The ones in the photo above are in a heritage building of around the 1950 s fannie bay gaol darwin nt. Pratt trusses are commonly used in long span buildings ranging from 20 to 100 m in span. Pratt truss pratt truss is made of steel. The roof truss structure and design is integral to roof structural integrity and shape.

It offers a new alternative in prefabrication and field assembly methods without basic departures from established. This type of truss is used where gravity loads are predominant see below left. Pratt truss this is one of the most popular steel roof truss types and it is quite economical. These can vary a lot.

A way of making a larger truss out of pre fabricated elements of smaller trusses these roof trusses are simple in design but very effective and cheap to build. There are many types of roof trusses as wall as many types of roofs more types than there are parts. Flat truss with cantilever pratt configuration top chord bearing flat truss pratt configuration fl att rus w e nc of ig s l op i ngp are ch ds h w f u t sloping top chord howe configuration floor truss system 42 modified warren configuration mono trusses scissors mono mono parts of a truss framed roof gable end valley set gi rde. I think this does give the pratt an advantage but read my best bridge design article more for information.

These are very economical form of roof trusses. This particular type of truss offers some interesting features mainly thanks to the fact that the vertical members provide tension while the diagonal ones are bringing in compression. Roof truss span tables alpine engineered products 15 top chord 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 bottom chord 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2 12 24 24 33 27 27 37 31 31 43 33 33 46 2 5 12 29 29 39 33 33 45 37 38 52 39 40 55 3 12 34 34 46 37 39 53 40 44 60 43 46 64 3 5 12 39 39 53 41 44 61 44 50 65 47 52 70. There are six main types of roof trusses as listed below.

The roots of the pratt truss involved using iron not wood for the angled members. For further details on how the loads are calculated on a truss and other design details please read this. A roof truss based on two pratt trusses and a bottom chord. This article and series of illustrated diagrams shows you all the parts of a basic roof truss king truss and queen truss.