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The Saga of the Living House Basement Roof and The Living Building Challenge Red List

February 2, 2018

The Building Consent drawings for the Living House call for the use of either Tray Dec or Dimond Flatdeck. Both great construction systems that would allow us to easily pour a concrete roof to the basement (which is also the floor of the garage)........except for the fact that these products are manufactured from galvanised steel and that steel has a protective coating added to it which uses Chromium V! – which is on the Living Building Challenge Red List.   


 ​​It turns out that it is possible to manufacture the steel that the Tray Dec and Dimond use to form the products without the Chromium VI protective coating (they just apply an oil instead) however this oil doesn't protect the product as well during storage and if it gets wet it would form a type of white coating (I guess a type of oxidation). Apparently it doesn't affect it structurally but just doesn't look very nice.  This is all still fine and we can easily use this product, except for the fact that the steel mill will only take a minimum order of 4 ton which is about 400 times that amount that we require for the Living House. And we can't really ask either Dimond or Tray Dec to place this minimum order for us as they would then end up storing a whole lot of extra product, that isn't their normal stock, that wouldn't store as well since it doesn't have the normal protective coating on it. 



Therefore we could not use Tray Dec or Dimond Flatdeck for the roof of the basement and had to spend around three to four months scrambling around trying to find a cost viable alternative! The options that were on the table were:

  • Rib and timber infill (structural engineers first choice)

  • Formwork and a solid slab (not pretty to put the formwork up on site!)

  • Precast perhaps

Somewhat surprisingly we actually ended up going down none of those routes and have instead opted for a suspended timber floor to the basement. We have done this for a large number of reasons but probably the two strongest are:

  • To reduce the amount of concrete that use in the Living house. To be clear we have nothing against concrete and we think it is a beautiful material plays a vital part in the construction industry. However apparently the world is starting to run out of sand ( https://www.smithsonianmag.com/science-nature/world-facing-global-sand-crisis-180964815/ ) and we want to be good global citizens and play our part by only using resources that we have to use. And in this instance there ended up being an alternative to concrete that we could use – so we have.

  • Construction detailing. As you know we are building the Living House ourselves and since building is not actually our trade we were concerned about how we were going to manage the more complicated detailing and formwork that we would have had to use with all of the concrete options. The timber detailing is much more straightforward and we feel like we will be able to manage it ourselves onsite.

So we merrily placed an order for HYNEBeams from our wonderful IBuilt supporters as well as some 135 x 45mm topping timber from our other wonderful supporters ABODO. I mention these two suppliers because as you can see being Red List compliant is very important to us, and both of these companies can provide Red List compliant timber products and there are not many companies out there that can do this! Most trip up at the timber treatment step tending to use the common CCA (Chromated copper arsenate) timber treatment. However Arsenic is on the Red List so that is a no-go for us.


However the Living Future Institute's Living Building Challenge enjoys throwing up challenges at every possible turn! We thought we were all good as the HYNE beams were Red List free and FSC. HOWEVER..... it turns out that the FSC certification for the HYNE beams is only for the forest where the pine is harvested and that the chain of custody is broken when that pine goes to the mill and glulam plant as they hold PEFC certification (which the LBC doesn't recognise).


What a disaster.  We only found this out when we were paying the invoice for the deposit for these timbers and noticed PEFC notated on the invoice. Cue immediate and frantic questions to Ibuilt and Hyne Timber as well as an official dialogue post to the Living Building Challenge by our wonderful sustainability consultants The Building Excellence Group to find out if this mix of FSC and PEFC would be acceptable.


THEN the Red List struck again! When originally researching whether or not we could use the Hyne beams we found that they used a hardener that contains formaldehyde (CAS #50-00-0). Now for those of you that do not know formaldehyde is on the Red List. However there was also an answer to an official dialogue question that said:

 "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 read this that as long as the products didn't contain urea formaldehyde then we could use them. HOWEVER after the issue with the PEFC we thought that perhaps we should really look into this a little further and I found that the official exemption states:

"I10-E10 2/2008 Added phenol formeldehyde is allowed in composite structural members such as glulam beams. " Hmmm, not quite the same as my interpretations above. So it looked as though perhaps our preferred glulam beams had 2 issues that we needed to get resolved!


Thankfully we received confirmation from the Living Future Institute just before Christmas 2017 that we could go ahead and use the HYNE beams, even though they were a mix of FSC and PEFC and contained formaldehyde as all other glulam beams on the market that have the strength that we require also contain this red list substance.

However the Red List wasn’t finished with us yet! When trying to research the joist hangers that we would require to hold up the HYNEbeams I discovered that all of these hangers suffered from the same problem as the Tray Dec or Dimond Flatdeck.



Basically all galvinised steel in New Zealand is pretty much produced by either NZ Steel or Pacific Steel. Mitek who makes a lot of these joist hangers just purchases gavlanised steel coils from Fletcher Steel and shapes them and punches holes in them. Fletcher Steel don’t do much but just purchase 1.55mm g300 Z2752 steel  coils from NZ Steel and mechanically shape it, which they then sell to Mitek. NZ Steel produces and galvanises the steel and they apply that lovely Chromium VI protective coating. So we thought that we couldn’t use joist hangers. This then required us to go back to the structural engineers and come up with another way to put the structure together for the basement roof. Quite a simple solution in the end which was to drop the timber stringer that the joist hangers were going to attach to and instead of using joist hangers we are just going to sit the HYNEbeams on the stringer and skew nail them in place.  So we managed to eliminate an entire material! And we then found out that hangers/bolts/nails etc are all exempt from Red List compliance due to market limitations!!!! So all of that design change for nothing – however it has saved us some money, so not really for nothing.


You would think we would now be done. However the Red List still had another surprise for us on the basement roof! This time it was around the timber stringer. Joel headed off to the local Mitre 10 to pick up the required untreated, FSC, SG8 190 x 45 timber for this stringer, only to find out that Mitre 10 don’t have  FSC timber in stock. A call to Bunnings determined that they only stock SG8 in 190 x 25mm (which may or may not have been FSC) and would be treated with CCA (which is not compliant with the red list). ITM don’t stock any FSC timber and we didn’t even bother trying to call Carters. Instead we called our wonderful supporters at Ibuilt who had some smaller HYNE beams in stock so those ended up being used as the stringer as we already knew that they were Red List compliant and FSC/PEFC acceptable!




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