Question 1

Are NeXTimber glulam and CLT suitable for wet areas?

Accepted Answer

Yes. NeXTimber can supply both glulam and CLT in H3-treated timber, drawn from Timberlink's H3-treated feedstock. The treatment is clear, not the green tint of framing pine. Ben Cox's preferred approach is to design the water risk out first, using waterproofing build-ups such as cement sheet and tanking above the CLT. H3 treatment adds cost and can slow the production line, so it is reserved for cases that need it, such as a covered balcony soffit exposed to airborne moisture.

Question 2

How does mass timber compare with a steel frame and suspended concrete on cost and program?

Accepted Answer

You pay more upfront for the timber, but the saving shows up in site labor and program. Ben Cox described concrete floors that take one to two months per level, once propping, formwork, reinforcement, pouring, curing, and stripping are counted. A smaller crew can install the equivalent CLT and glulam floor in one to two weeks per level. With skilled labor scarce across Australia, he argued the comparison should not stop at the higher material price.

Question 3

What R-value do CLT walls provide, and roughly what do they cost?

Accepted Answer

CLT gives roughly R1 for every 100 mm of thickness, so external walls still need added insulation to suit the climate and state requirements. Ben Cox put a 90 mm CLT panel at approximately AUD $200 per square meter. That price reflects far more fiber than a stud wall. In return you get a designed model, walls to 2 mm tolerance, and sawn openings. Air leakage is low, and the surface can be left exposed, often with a whitewash finish.

Question 4

How does CLT compare with structural insulated panels (SIPs)?

Accepted Answer

Both reduce the number of parts on site compared with stud framing, but CLT reduces them further. SIP panels arrive around 2.4 m wide, up to wall height, so a build needs more panels and extra detailing such as headers over openings. Ben Cox's main point was thermal bridging. A SIP has a spline roughly every 2.4 m that conducts heat. CLT can be wrapped in continuous external insulation for a bridge-free wall.

Question 5

Does the adhesive in NeXTimber timber off-gas formaldehyde?

Accepted Answer

No. Ben Cox confirmed there is a trace of formaldehyde in the structural adhesive, but it does not off-gas. NeXTimber's radio frequency press cures and locks the resin into the bond line during manufacture, so the finished panel does not release it. Technical notes are available for clients who need the detail.

Question 6

Is there long-term creep deflection in NeXTimber glulam, and how is it handled?

Accepted Answer

Yes. Long-term deflection is present in timber, and in Calcs.com it is handled through the deflection limit, the same way as other timber products. Specifying a cambered GL13 section is the practical lever. In Ben Cox's worked example, a straight 336 x 65 section showed around 13 mm of long-term deflection. The cambered version of the same section dropped under 10 mm and passed.

Question 7

Can I get NeXTimber GL13 glulam through a retailer, and how quickly?

Accepted Answer

Yes. NeXTimber offers a single glulam grade, GL13, and stocks every listed section size at its Australian distribution centers in Perth, Adelaide, Melbourne, and Sydney. Once an engineer specifies a GL13 size, a builder can order it through a retailer and receive it within a day or two. That availability is the point. It avoids specifying a grade or size that sits out of stock for weeks.

Question 8

Is there free software for designing CLT and glulam sections?

Accepted Answer

Yes. Ben Cox demonstrated Spec Toolbox, a free CLT design tool that lets engineers select NeXTimber panels and check deflection, vibration, shear, and bending. Calcs.com covers the glulam side: the NeXTimber GL13 sections are built into the Calcs.com timber calculators, available on the basic plan or through a 14-day free trial.

Specifying Glulam and CLT for Australian and New Zealand Projects

About this event

In this webinar we covered

Speakers

Frequently asked questions

Are NeXTimber glulam and CLT suitable for wet areas?

How does mass timber compare with a steel frame and suspended concrete on cost and program?

What R-value do CLT walls provide, and roughly what do they cost?

How does CLT compare with structural insulated panels (SIPs)?

Does the adhesive in NeXTimber timber off-gas formaldehyde?

Is there long-term creep deflection in NeXTimber glulam, and how is it handled?

Can I get NeXTimber GL13 glulam through a retailer, and how quickly?

Is there free software for designing CLT and glulam sections?

Related webinars

Engineered Wood Products (EWP) specifications for Australian projects

Expert hours with David Hourdequin: heavy timber design (Pt. 2)

Loft renovation - additional storey

Try the calculations from this session yourself