Following recent P21 bracing tests, we've updated the substitution table on page 14 of the GIB® Site Guide. The limitation of a 900mm minimum element length when switching to 13mm and thicker GIB Fyreline® used in place of 10mm GIB Braceline® is gone.

What's changed

The substitution table in the GIB® Site Guide lets builders swap one GIB® plasterboard for another in the range of boards we have to offer.

Until now, one substitution came with a catch.

You could use 13mm or thicker GIB Fyreline® in place of 10mm GIB Braceline® in a BL type brace element, but only if the element was at least 900mm long. By comparison, a minimum element width is 400mm.

That rule has now been removed.

13mm and thicker GIB Fyreline® can be used as a direct substitute for 10mm GIB Braceline® in BL elements, with the same 400mm minimum element length.

Why the restriction was there

When a substitution hasn't been proven by testing across the full range of element sizes, we take a conservative position.

The 900mm minimum reflected what we could confidently stand behind at the time.

It was a sensible safeguard, but it also meant builders and designers lost flexibility on shorter bracing walls. This limitation became a real issue when an installer needed 16mm GIB Fyreline® on a section of wall but also to achieve a BL type brace in the same area.

What the testing showed

We ran a series of P21 bracing tests (the industry-standard method used to establish bracing ratings in New Zealand) on BL elements lined with 13mm GIB Fyreline® at the 400mm width.

The results confirmed that 13mm and thicker GIB Fyreline® performs at least as well as 10mm GIB Braceline® in a BL element, in both strength and performance, including at shorter element lengths.

With that evidence in hand, there was no longer a reason to keep the 900mm rule.

What it means on site:

• If a BL element is specified in GIB Braceline® but the wall also needs a fire rating, you can line it with 13mm or thicker GIB Fyreline® without worrying about element length.
• Fewer board types on site means less ordering, less sorting and less chance of the wrong sheet going on the wrong wall.
• Designers get more freedom to combine fire and bracing requirements on shorter walls.

What hasn't changed

The substitution covers the board type only.

All other requirements for a BL element still apply, including fastener type and spacing, hold-downs, and framing, as set out in GIB EzyBrace® Systems.

Make sure you're working from the current edition of the GIB® Site Guide. If you have an older printed copy, the page 14 table is the one to check.

The fire rating equivalence of GIB Braceline® GIB Noiseline® remains the same, (but remember we don’t make a 16mm thick GIB Braceline® GIB Noiseline®).

Testing to make building easier

This change is a good example of why we keep testing.

Our systems are only as useful as they are practical on site, and when a rule is making life harder for builders, we want to know whether the evidence still supports it.

Sometimes testing confirms a limit needs to stay. This time it showed we could remove one. Either way, you can be confident that what's in our literature is backed by real test data.

If you have questions about this change or any GIB® bracing or substitution detail, call the GIB® Helpline on 0800 100 442.