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. Ceilings and roofs excluding trussed rafter roofs for dwellings or ask your lbc surveyor for advice. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. The standard construction of interior framing in a home uses 16 inch on center oc spacing for ceiling joists. Flat roof joist calculator.

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. 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. This demo version is fixed at 1m. Flat roof joists.

1 enter joist details 1 1 span and joist spacing. Many slope in several directions like squashed hip roofs toward scupper holes that connect to downspouts. The construction of the flat roof is similar to that of the timber upper floor. Flat roofs with a slight slope can be achieved using trus joist tji joists and solid section products.

The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. This will give additional stability to the roof structure. 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.

Getting the balance right here is crucial as too much weight will inevitably lead to an unstable roofing structure. For additional stability you can also use steel joists that are built into one or both of the walls. Suitable for uk building regulation approval.