Construction Flat Roof Joist Layout

If you re trying to reinforce a shed or gable roof use a simple king post truss design which has a single vertical joist running through the center of the triangular frame.

Construction flat roof joist layout.

Hot tar and gravel. Old asbestos roofs are often replaced with flat roofs. Although flat roofs are cheaper to build than pitched roofs they have a shorter life span. Continuing on from part 3.

For pitched roofs flat roofs and ceiling joists. For that reason cold flat roof construction needs to keep in mind the need for unblocked airflow. Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof. The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial.

Structural calculations for timber joists timber beams glulam beams flitch beams using the latest design codes. Flat roof joist calculator. Sizes of joists needed for flat roof construction. Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

For larger structures like floors roofs or decks try a fink truss design which has internal joists arranged in a w shape for extra support. Ceilings and roofs excluding trussed rafter roofs for dwellings or ask your lbc surveyor for advice. The 3 most common materials used for flat roof construction. Let s consider a basic gable wood roof framing design.

There are several methods and materials for the design of the exterior surface of a warm or cold flat roof. 1 enter joist details 1 1 span and joist spacing. 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. As you may imagine there is a fair amount of weight involved here in terms of boards felt etc.

A flat roof usually consists of the following. Suitable for uk building regulation approval. A roof is considered to be flat when it is of a slope of 1 5 o to the horizontal. Here we have a wood framed gable roof.

Of course you don t need to live in a modern house to deal with a flat roof. Waterproof membrane to prevent water penetrating the structure and interior of the. Surveyors span tables for designing roof rafters. Boarding to be fastened on top of flat roof joists with a depth to width ratio greater than 4 the allowable clear spans have been calculated in accordance with bs 5268 2 2002 structural use of timber part 2.

Flat roof construction for residential. 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.