Construction Flat Roof Joist Layout

Drawing legend attached flat roof 6a.

Construction flat roof joist layout.

You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. Span tables allow for a maximum allowable overhang of 25 of purlin spacing p or 600mm. Let s consider a basic gable wood roof framing design. The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial.

1 enter joist details 1 1 span and joist spacing. Flat roof joist calculator. Suitable for uk building regulation approval. Maximum post spacing maximum rafter spacing maximum purlin span p.

Maximum purlin spacing ro. Joist is a term used in construction for load bearing planks that run horizontally or nearly to horizontally to ground. The 8 step process for diy installation step 1. 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.

Structural calculations for timber joists timber beams glulam beams flitch beams using the latest design codes. Of course you don t need to live in a modern house to deal with a flat roof. Can i turn my flat roof into a roof terrace. Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. Here we have a wood framed gable roof. Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof. The construction of the flat roof is similar to that of the timber upper floor.

Roof deck framing unlike for decks at ground level doesn t entail a ledger attached to the rim joist of a house. Attached flat roof 6a cont w. The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure. In most cases an existing flat roof will be used to create a roof terrace.

Continuing on from part 3. Awning frame width or rafter span χ. Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading.

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. Add the plywood once you ve added the framing it s time to add a layer of 5 8 inch plywood sheathing.