There is currently an arguement to remove wood from SIP panels. The foam industry is showing how foam may act as a shear panel to replace the OSB. That would leave the only reason for OSB’s inclusion is as a base for attachment. Well OSB is lousy to screw to. We need to reinvent the SIP quickly. Can we get rid of the foam instead? Wood is a great insulator. Wood is a great shear panel. Wood is breathable. Wood is light. Wood is easily machinable. Wood is easy to bond. Wood is…well…… a list of great things, biodegradable, renewable, not to mention the fuel of our economic engine. We can create buildings with more wit than stick frame.
Hi Mark, I think that might be a good approach. At the end of day, it would be nice to use environmental friendly and renewable mateirals for buildings and replace some of petrolium based products.
To meet the challenge, we also need to consider the actual function of the material in relation to the building structure and try to improve the properties of biomaterial, such as moisture and fungal resistance.
Hi Mark, I am skeptical about “structural” properties of foam and its ability to replace shear panels in wall systems… I assume you hinted towards replacing the foam in a SIP system with wood fibre insulation, which is a viable idea, although likely more expensive than SIPs with foam insulation.
Regarding the ability of OSB to hold fasteners, here is a journal paper about AOSB (advanced OSB), an FRP-reinforced OSB which significantly increases fastener strength and energy dissipation under monotonic and cyclic loading.
Free draft available at: http://www.pathnet.org/si.asp?id=1079
Full paper available at: http://cedb.asce.org/cgi/WWWdisplay.cgi?150221
Thank you for the link.
The SIP panels that I have designed with in the past would be tested under a very different mode. I like the OSB/EPS/OSB sandwich, thus no load transfer to framing. In fact, the OSB carries most of the static loads while the ESP help to absorb the dynamic loads. Screws into the OSB are mostly to hold exterior or interior finishes (rain barrier or fire barrier).
The OSB that I am familiar with is mostly poplar, and of varying quality. It seems that the product looks much like it did in the 70’s. I love the idea of composing OSB to create better performance (AOSB). Perhaps it is already being made here locally. I just don’t understand a push for quantity over quality.
The “structural” foam is not on the market, that I am aware of. However I understand that the testing, and an argument, is currently underway. If you are interested, I could get you some more info.
What I want to do is just make a panel that makes sense, rain barrier, air barrier, structure, thermal barrier, acoustic barrier and finally fire barrier. Within the next week or so, l’ll upload a section detail that may hypothetically show it all done with wood products……in a practical and cost effective way. The devil is in the details and the details are where materials meet.
Wouldn’t it be nice if change was as subtle as bending a branch, rather than hitting your head on a stump?
Hi Mark, I am quite interested in your approach and feel that you will have a good approach. In building system and the materials used, the most important considerations are the cost and how easy to use. There are many discussions recently on the multi-functional panels and new insulation materials to meet new requirement for building energy efficiency. Some discussions were on the subject what methods would be the most practical, economical and best practice in obtaining an Energy Star label for our houses. One suggestion, as an example is to go with a 2×6 wall with R19 batt and a XPS rigid panels laminated with a thin OSB (for example 5/16” OSB or even 3/16″ OSB). The system might be able to provide the insulation required while meet the strength requirement. This also will shift the dew point to the exterior side comparing using OSB sheathing alone. The design also can consider different combinations as well such as (OBS+XPS+OSB) or (interior size OSB+exterior size XPS).