17-1112 v3.0/The Living House/Glulam Beams and I10-E10 2/2008 - A Clarification

QUESTION

The desire of the Living House project to use sustainably sourced materials led the project to specify exposed timber beams for the roof structure. The loads of the green roof on the project then led to the HYNE 17C glulam beam being the only beam strong enough to take the loads of the designed roof over the requisite span.

During the requisite Red List vetting process we found that the HYNE 17C beam uses the following products and materials:

         Pine timber (mix of PEFC/FSC certifications - subject of a separate dialogue post)

         Resin

         Hardener

Subsequent investigation into the resin and hardener determined that they are comprised of the following:

Resin

Phenol 0-10% 108-95-2
Methanol 0-10% 67-56-1
Resorcinol 0-3% 108-16-6
Sodium Hydroxide 0-2% 1310-73-2

None of these CAS numbers appear on the red list and this product therefore appears to be compliant.Hardener

Formaldehyde 10-20% 50-00-0
Kaolin 10-15% 1332-58-7
methanol 0.1-0.2% 67-56-1

We initially felt that this meant that this beam was not red list compliant as it contains formaldehyde which is banned on the Red List. However a search of the dialogue revealed this answer to a question:

“We understand that there are certain life-cycle and design benefits to using glulams over other available structural solutions (e.g. steel or concrete), despite the dependency on phenol resorcinol formaldehyde. Due to current market realities – there are no glulams made without formaldehyde available today – the product may be used. This exception only applies to glulams made using phenol formaldehyde; no glulam products made with urea formaldehyde are acceptable......”

We interpreted this to be that as long as the Glulam product did not contain urea formaldehyde then it was ok to use, if there were no other compliant options. However subsequent reading of the formal exception has now led us to query our initial interpretation. I10-E10 2/2008 states that:

 “Added phenol formeldehyde is allowed in composite structural members such as glulam beams."

As stated in a previous dialogue post we are trying to reduce our project’s footprint as much as possible. We therefore are trying to use timber roof beams instead of steel or concrete. Salvaged beams were the first choice but are not currently possible to get past New Zealand Building Code due to a lack of NZ structural testing information on reused structural beams. LVL beams do not meet the red list requirements, but are covered by the I10-E10 2/2008 exemption. However it is not possible to source these in NZ in the 17c strength category that we require, according to all our current sources. We are therefore currently left with the glulam beam option and thus far there is only one beam that we have investigated that meets the 17C level AND the structural strengths that we require for the spans in our building. This is the HYNE beam.

We have approach HYNE and asked them if it would be possible to be use a different hardener that does not contain formaldehyde, however they have advised that this is not possible as their beams are only certified when this hardener is used.  We will continue to advocate with them that they make a change to their hardener and recertify using a different compliant hardener. However due to a lack of other options at this time we are seeking either 1) a clarification that only urea-formaldehyde is banned for use in composite structural wood products and other formaldehyde containing chemicals are acceptable for use at this time or 2) if this is not the case an exemption to use the HYNE beams 17c for this project.

We enclose a copy of our advocacy letter to HYNE Timber. 

ANSWER

Teams using I10-E10 Structural Composite Wood Members must confirm with the manufacturer that any formaldehyde used in the product is phenol formaldehyde or is not on the Red List. If the product contains any other formaldehyde on the Red List,such as 50-00-0 in this case, the team must instead.show due diligence to find a compliant product (glulam or alternative) for this specific application in order touse I10-E1 General Red List. 


Post ID 6803

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