Flat Roof Joist Construction

The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls.

Flat roof joist construction.

The most important thing to know about a flat roof says tom is that it s not flat to prevent water from pooling and eventually invading the home flat roofs are always built on a slight incline at least 1 8 inch per foot. The standard construction of interior framing in a home uses 16 inch on center oc spacing for ceiling joists. It is the responsibility of the designer of record to address items like ponding snow drift loads lateral loads wind loads bracing ventilation and insulation when adding a slope to roofs. Maximum clear span of flat roof joists in metres for sc3 timber spacing between joists size of roof joist 400mm 450mm 600mm 47 x 97 1 84 1 81 1 74 47 x 120 2 43 2 39 2 27 47 x 145 3 08 3 02 2 87 47 x 170 3 75 3 67 3 42.

Many slope in several directions like squashed hip roofs toward scupper holes that connect to downspouts. Flat roofing under construction plywood decking is then used to cover the joists with the width in between also determined by the weight being placed upon them. Flat roof joists. Joist spacing in this design mode incorporates different types of wood used in ceiling construction including 2 grades of southern pine douglas fir and hemlock fir types which are the most common.

The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. For additional stability you can also use steel joists that are built into one or both of the walls. This will give additional stability to the roof structure.

1 enter joist details 1 1 span and joist spacing. The construction of the flat roof is similar to that of the timber upper floor. Getting the balance right here is crucial as too much weight will inevitably lead to an unstable roofing structure. Flat roof joist calculator.

Ceilings and roofs excluding trussed rafter roofs for dwellings or ask your lbc surveyor for advice. Suitable for uk building regulation approval. Flat roofs with a slight slope can be achieved using trus joist tji joists and solid section products.