SF-100 is an FRP box purlin 100 mm tall and 50 mm wide with a 3.5 mm wall, weighing 1.95 kg per metre. It is the size most farms need: with rafters 2.5 m apart it works up to 1.25 kPa basic wind pressure, and the ammonia in pig and poultry houses cannot rust it.
| Item | SF-100 |
|---|---|
| Section | Box 100 × 50 mm, 3.5 mm wall, single cell |
| Weight | 1.95 kg/m (a 6 m length is about 11.7 kg) |
| Material | Pultruded FRP, no metal |
| Fittings | 304 stainless L-brackets, bolts, sleeves, screws and end caps |
How far can SF-100 span?
| Basic wind pressure W0 | 0.65 kPa | 0.95 kPa | 1.25 kPa | 1.55 kPa | 1.85 kPa |
|---|---|---|---|---|---|
| Maximum rafter spacing | 3.4 m | 2.9 m | 2.6 m | 2.4 m | 2.2 m |
For plastic roof sheets or ASA/PVC roof tiles, purlin rows 660 mm apart, deflection limit L/200.
Why do livestock farms switch to SF-100?
Manure gives off ammonia, which condenses with the humidity under the roof. In closed houses with fans and cooling pads the roof drips at night. Under ISO 9223 such buildings are often corrosivity class C4, and a Z275 zinc coating may last only about 2.5 – 9 years there. Rust starts at the screw holes and flakes fall into the feeders. SF-100 has no zinc to lose and no steel to rust.
Which rafter spacings need a bigger size?
- 3 m rafters: SF-100 only at 0.65 kPa; use SF-120 at 0.95 – 1.25 kPa and SF-160 above that.
- Eave, corner and gable rows: one size up.
- Crop wires, fans or lights hung from the purlins: calculate separately.
One person can carry a 6 m SF-100 onto the roof, so a farm can be re-roofed house by house while the animals stay inside.
Frequently asked questions
Is SF-100 the same as a 50x100 purlin?
Yes. SF-100 is 100 mm tall, 50 mm wide, with a 3.5 mm wall, and is fixed with the 100 mm side vertical.
Which size for a pig farm with 3 m rafters?
SF-100 at 0.65 kPa, SF-120 at 0.95 – 1.25 kPa and SF-160 at 1.55 – 1.85 kPa basic wind pressure.
Do farm disinfectants harm SF-100?
Most farm disinfectants and detergents at working dilution do not affect the polyester resin, and pressure washing does not damage it.
All six sizes with the full span table: FRP Composite Purlin – SF Series.
Contact: Santiago Import Export Co., Ltd, Vietnam. WhatsApp +84 935 391 495 (Mr. Quyen), hotline +84 965 437 316 (Mrs. Ly), email salessantiagoroofing@gmail.com.
Updated October 2026.
