Here we have a wood framed gable roof.
Construction flat roof joist layout.
Drawing legend attached flat roof 6a.
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.
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.
Structural calculations for timber joists timber beams glulam beams flitch beams using the latest design codes.
Roof deck framing unlike for decks at ground level doesn t entail a ledger attached to the rim joist of a house.
Instead a pair of beams rest on supports called sill plates to create a frame for the deck.
Awning frame width or rafter span χ.
Span tables allow for a maximum allowable overhang of 25 of purlin spacing p or 600mm.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure.
Maximum purlin spacing ro.
Attached flat roof 6a cont w.
Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof.
Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls.
In most cases an existing flat roof will be used to create a roof terrace.
1 enter joist details 1 1 span and joist spacing.
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.
Frame the roof one important and perhaps not so obvious fact is that a flat roof is not actually flat.
Add the plywood once you ve added the framing it s time to add a layer of 5 8 inch plywood sheathing.
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.
Joist is a term used in construction for load bearing planks that run horizontally or nearly to horizontally to ground.
Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
Continuing on from part 3.
Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading.
Suitable for uk building regulation approval.
The 8 step process for diy installation step 1.
The construction of the flat roof is similar to that of the timber upper floor.
Maximum post spacing maximum rafter spacing maximum purlin span p.
