Flat Roof Joist Construction

Flat roof joists.

Flat roof joist construction.

Suitable for uk building regulation approval. Joist is a term used in construction for load bearing planks that run horizontally or nearly to horizontally to ground. 1 enter joist details 1 1 span and joist spacing. Flat roof joist calculator.

Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. What is the process of building a flat roof. For additional stability you can also use steel joists that are built into one or both of the walls.

Strutting is fixed between the joists to. Yet for historic modern style buildings like this old house s cambridge tv project flat roofs are at the core of the architecture meant to reflect the broad horizontal lines of the natural landscape. There are key differences between constructing a flat roof compared to a pitched roof and it s important to understand the basic criteria. Having a manual for warm flat roof construction with details and a summary of rules to follow helps.

Ceilings and roofs excluding trussed rafter roofs for dwellings or ask your lbc surveyor for advice. The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls. Flat roofs with a slight slope can be achieved using trus joist tji joists and solid section products. 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.

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. The starting point involves laying roofing joists across the two upright items which in most cases will be the walls of the structure. Of course you don t need to live in a modern house to deal with a flat roof. Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof.

This demo version is fixed at 1m. If you have a low sloped roof or flat roof of less than 2 in 12 these evenly spaced planks will be called roofing joists. Rolled steel joists or rsj s are used to support joists in flat roofs. On a basic level flat roof construction comes in the form of roofing timbers or joists as they are more commonly known or steels that are laid across two uprights walls in most cases.