Keeps purlins straight between frames
Sag rods restrain the purlins at mid-span or third points so they do not twist or sag sideways under the sheeting.
Purlins & Sag Rods
Sag Rods
Sag Rods are round steel rods threaded at both ends that tie purlins or girts together between the main frames, keeping them straight and upright. They come straight or cranked, each with four nuts and two washers. Specify diameter, length, form, finish and the quantity you need.
At a glance
Sag Rods at a glance.
Straight or cranked
Straight rods run between purlins at the same level; cranked rods step between purlins set at different heights, such as at the ridge or eaves.
1/2 or 5/8 in, 3 to 10 ft
1/2 and 5/8 in (12 and 16 mm) diameters, 3–10 ft (900 mm–3 m) long, threaded both ends, plain, zinc plated or hot dip galvanized, with 4 nuts and 2 round washers per rod.
Also known as
Sag Rods are also called anti-sag rods; in other languages they are lierne (French) and tirante (Italian).
- English
- Français
- Italiano
Through the webs, nuts either side
The rod passes through holes punched in the webs of neighbouring purlins. A nut and washer either side of each web fix it in place and set the spacing. A line of rods runs up the roof slope, tied at the ridge or eaves, so the whole purlin run is held in line.
Common applications
Where it is used.
Roof purlin runs
Roofs with long purlin spans carry one or two lines of sag rods in each bay. The design sets how many.
Wall girts
Girts hung from the eaves on sag rods stay level under the weight of the cladding. The rods run down the wall between girts.
Canopies and lean-tos
Canopies and lean-to roofs use sag rods in the same way as the main building. Short straight rods suit the closer spacing.
Questions answered
Common questions.
What are sag rods called in other markets?
Sag rods are also called anti-sag rods in the UK and US, and Australian roll-formers include them under purlin bridging. In French a sag rod between purlins is a lierne, and in Italian a tirante. Corona supplies each rod with four nuts and two round washers.
When is a cranked sag rod used?
A cranked rod steps between purlins set at different levels, such as at the ridge or the eaves, where a straight rod cannot line up with both webs. Corona makes straight and cranked sag rods in 1/2 and 5/8 in (12 and 16 mm) diameters, 3 to 10 ft (900 mm to 3 m) long.
Part of the roof and wall systems
Sag Rods tie the C Purlin and Z Purlin lines together between the frames in both the roof purlin and wall girt systems.
Explore cold-formed systemsSag Rods specifications
Sag Rods configuration
ParameterUS / PrimaryMetric / Additional
Diameter1/2, 5/8 in12, 16 mm
Length3-10 ft900 mm-3 m
FormStraight or cranked; threaded both endsStraight or cranked; threaded both ends
FinishPlain, zinc plated, hot dip galvanizedPlain, zinc plated, hot dip galvanized
Assembly1 rod + 4 nuts + 2 round washers1 rod + 4 nuts + 2 round washers
Cold-Formed Profiles & Sections
Related components
Purlins & Sag Rods
C Purlin
Height (H): 3-14 in / 75-300 mm · Flange (B): 2.35-3 in / 60-75 mm
Specifications
Purlins & Sag Rods
Z Purlin
Height (H): 4-14 in / 100-350 mm · Flange (B): 2.75-3 in / 60-90 mm
Specifications
Strut Channels & Accessories
Universal Strut Channel / ‘C’ Strut Channel
Thickness: 12G 13G 14G 16G / 2.5 mm 2.3 mm 2.0 mm 1.5 mm · Size: 13/16" x 1-5/8" 1-5/8" x 1-5/8" 2-7/16" x 1-5/8" 3-1/4" x 1-5/8" / 21 mm x 41 mm 41 mm x 41 mm 61 mm x 41 mm 81 mm x 41 mm
Specifications