Stick Framing
Loading Development
Roof Framing
Although truss-designed roofs
are predominant throughout
most of the residential
construction industry, there are
regions where building with
stick-frame roofs is still
common.
There are several reasons for
this. One of the most common
is that with a site-built roof,
it’s easier to customize the
roofline. Builders sometimes
also prefer this construction
method when they want to
provide a large attic space or
high, vaulted ceilings (often
called cathedral ceilings).
VaultCeiling
The load-resisting concepts of
the vaulted ceiling are
completely different. Without
the tie at the bottom, the
rafters must be supported at
their upper end to prevent the
rafter thrust at the lower
end. Since half the load is
now supported at the ridge,
the ridge member becomes a
ridge beam that is a loadcarrying element, and must be
designed to bridge the span
between the supports, which
carry the vertical load to the
ground. This requires a secure
connection of the rafters to
the ridge beam at the top.
Typical Dead Load on a Roof
Typical Dead Load on a Roof
Typical Dead Load on a Roof
Stick Framing
A ridge beam supports vertical roof loads while a ridge
board does not. Both are roof framing members that are
located at the peak formed where two sloped roof areas
intersect. However, a ridge beam is a structural member
that receives a vertical load from roof rafters and transmits
the load to structural supports. A ridge board is not a
structural member; its primary purpose is served during
construction to make it easier to install the rafters.
Strutural Roofs
Kite Method
The load on valley in joist
and beam systems is
developed exactly the same
as the hips in the previous
example.
The reactions are reversed
so the high-end reaction is
smaller.
Stick Frame Roofs
Rafter span
Bracing arrangement
Convention Roof-Braced
Stick Frame Roof
Preliminary Design Consideration
What is the allowable Span for the specified rafter?
Is there intermediate support (purlin and brace) of the roof rafter required?
Can the rafters be braced to an interior wall or to the ceiling joist?
IRC Code Summary
Minimum Slope of 3/12 (R802.2)
Maximum Slope of 12/12.
Rafter framed to a ridge board (R802.3)
Rafter framed to a ridge board (R802.3)
Hips & Valleys are supported (R802.3)
Rafter tie is continuous
Collar ties required @ 48” O.C
Stick Frame Roof-Linear load
Purlin Placement
Braces from ridges, hips and valleys at the high
end should be located to a support generally
within a 4’ radius to make it as plumb as
possible.
Shaded area indicates the preferred direction of
brace.
Intermediate braces from hips and valleys should
be located to a support generally within a 4’
radius.
If bracing to ceiling joist, orient brae in the same
direction as the joist members.
Do not orient the brace towards the lower
support.
Purlin
Installation
Purlins at least same size as rafters.(often
overlooked).
Support Purlins 4’ o.c with 2”x4”:
minimum brace.
Unbraced length of brace ≤ 8’
Braces must be 45 from horizontal
ceiling plane.
Typical purlin location may be 10’ to 12’
from the exterior wall.
Draw the purlin lines continuous until
they intersect a hip, valley or an exterior
wall.
Example
Thank U.