Wood fiber insulation boards

Louis Koehl

Director of Sustainable Design

Handel Architects

LEEDuser Basic Member

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October 12, 2023

Hello everyone,

Wondering if anyone has evaluated/considered/specified wood fiber insulation for use in lieu of mineral wool as the exterior wall insulation? Am mostly looking to better understand domestic availability, r-value and fire/combustibility.

We have a multi-family building in DC where the client is interested in using wood fiber insulation board on our precast concrete cladding – it would be installed on the interior face of the panel.

In my research so far, I’ve found TimberHP which I understand will be available this fall offers a board product like rockwool comfortboard. All the rest seem to be European, most without representation or sales staff in the US, and none with published domestic test information.

The TimberHP has a lower r-value per inch (around 3.8/inch) compared to mineral wool, and does not appear to be considered ‘non combustible’ - still trying to confirm this, but is stated by the manufacturer that it passes ASTM E84, as a Class B product with a Fire spread index of 50 (no smoke developed index provided).

Is anyone aware of other domestically available products? or had experience using European products on US projects?

Thanks!

Louis

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Anne Hicks Harney

Founder and Principal

Long Green Specs

LEEDuser Basic Member

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Thu, 10/12/2023 - 14:42

I know Tim Lock who is a part of the ownership team of Timber HP, so i forwarded your email and here is his response: It is Class B rated, but unless you are going over 7 stories, this should still be viable. Class A version coming, but not sure when yet. Board is available Q1 2024. As with any board insulation, mounting it under a siding like seems to be proposed here, should be assessed structurally - TimberHP (and all wood fiber) have higher compressive strength than mineral wool board, so if that’s the comp, they should be completely fine. It is true that is it not “non-combustible” by code definition. We are working on more testing to dispel this for larger buildings. TimberHP remains the only North American wood fiber insulation. I am not aware of any others even in the development stage.

Mike Fowler

Sustainability Integration Leader, Associate Principal

MITHUN

LEEDuser Basic Member

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Thu, 10/12/2023 - 16:52

Hi Louis -

475 High Performance Building Supply in Brooklyn, NY stocks Gutex Multitherm wood fiber insulation boards. 3 1/8" board thickness at R-11.4.
https://475.supply/products/gutex-multitherm-stock-sizes

I'm also very impressed with the work Tim Lock and TimberHP are doing. For others, here is a video overview of their product: https://passivehousema.org/video-library/wood-fiber-insulation

Steico is another wood fiber insulation product that is an import but have heard there has been some used here in the US. https://www.steico.com/en/products/insulation/ventilated-facade-insulation-systems/closed-facade-timber-frame-construction

I have proposed Gutex and Steico on a few projects with low embodied carbon goals, just learned of TimberHP last month, but so far each project has stayed with using Rockwool.

Good luck in your efforts!

Mike

Sarah Wood

Senior Sustainability Specialist

Jacobs

LEEDuser Premium Member

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Mon, 10/23/2023 - 22:37

CLF Seattle Hub Meetup included Gutex in their emerging material discussion last week. Annelise Aldrich & Mark Keller from Typical Works - Building Science Architecture shared their experience using it for the construction of their home they recently built in Rosyln, WA. This was a single-family residential application but it may be worth reaching out to them as they had a lot of info to share on their experience working with the product, including some comparisons on embodied carbon, r-value, cost, etc. (Post-Coal (typ.works)) And as Mike mentioned, I'd also recommend reaching out to your local product consultant with 475 High Perofrmance Building Supply re: more info on Gutex as they do stock it.