I-Joists | Structural Timber & Framing | Birak Building Products

Category Structural Timber & Framing

Type Engineered Wood

Variants 8 available

Availability In Stock

Delivery Australia-wide

Variants

8 of 8

400x58 Spec Joist 70 Series H2-S Request
300x47 Swelite I-Joist H Series UT Request
240x70 Swelite I-Joist HI Series UT Request
300x70 Swelite I-Joist HI Series UT Request
360x70 Swelite I-Joist HI Series UT Request
300x97 Swelite I-Joist HB Series UT Request
360x97 Swelite I-Joist HB Series UT Request
400x97 Swelite I-Joist HB Series UT Request

Frequently asked questions

What spans can I-joists achieve compared to solid timber joists?

I-joists deliver substantially longer clear spans than equivalent solid MGP joists because the deep flanged web concentrates structural depth efficiently. A 300mm-deep I-joist typically spans further than a 240x45 MGP10 with less floor deflection and reduced bounce. Birak stocks I-joists from 240mm up to 400mm deep, including the Spec Joist 70 Series H2-S at 400x58 and the Swelite range from 240x70 through 400x97 — letting designers tune span and centres to suit each room.

What's the difference between Spec Joist H2-S and Swelite UT I-joists?

Spec Joist 70 Series is supplied in H2-S termite-protected grade, suitable for use in BCA termite-risk zones — generally most of mainland Australia. The Swelite I-Joist H, HI and HB Series are supplied untreated (UT) and suit applications outside termite-risk areas, or where a separate termite management system is in place. Both ranges deliver the same dimensional stability and long-span performance — selection comes down to project location and termite management strategy.

Why are the Swelite I-joists offered in three series — H, HI and HB?

The H, HI and HB designations reflect different flange widths. The 47mm H Series suits standard residential floor and roof joist applications. The 70mm HI Series provides increased bearing area and stiffness for higher loads or longer spans. The 97mm HB Series — supplied at 300, 360 and 400mm depths — is the heavy-duty option for commercial floor structures, large residential builds and heavier loading conditions where extra flange capacity is required.

How do Birak I-joists ship across Australia?

I-joists ship from Birak's distribution network direct to site nationwide. Lead times for typical residential orders are 5–10 business days, with scheduled deliveries available for staged commercial projects. Most state-bound competitors require interstate buyers to coordinate freight separately — Birak quotes delivered to your site in any state or territory on a single PO, with care taken to handle the long flanged sections without damage.

Do I-joists count toward Indigenous Procurement Policy spend?

Yes. Birak is Supply Nation Registered, so every dollar spent on Spec Joist and Swelite I-joists — and any other product we supply — counts toward your IPP 4% Indigenous procurement target. Audit-ready procurement documentation is supplied automatically with each invoice, which simplifies reporting for Tier 1 builders, Commonwealth-funded projects and head contractors with Reconciliation Action Plan commitments.