Will OSB Make Me Sick? Is it Strong?

Hi Tom.  My parents are considering a new home in retirement community. My question is what are the pros and cons of a home built with particle board, and specifically OSB?  OSB was used throughout the house and my parents worried about the glue that the glue used could have negative health side effects.  Also, what is the longevity of using OSB vs plywood?  We don't want a house  that will fall down!
LDefino 5-16-07  12:16am

OSB, or "Oriented Strand Board," is one of many engineered wood products used in home construction.  Many of these products are less expensive as they are easier to produce and hence popular amongst builders looking to slice pennies off projects.  First, let me respond to your structural concerns and then we'll tackle the health issues.

For the most part, I have no concerns about the use of OSB in a home.  As a sidewall sheathing and when properly nailed (8 nails at the seam, 6 nails in the field), it is just as functional as plywood at preventing "racking" which is a sideways movement of the framed wall.  For floor sheathing it also works just as well, so long as it is thick enough and tongue and groove, so that each board locks together. 

The one area that I really don't like to see OSB used is as roof sheathing.  In my 20+ years of experience as a professional home inspector, I frequently noticed that OSB roofs were very wavy.  Since OSB is not as stiff as plywood, it would flex around every roof rafter or truss.  If one of these ended up being high or sagged, you'd see an obvious hump or sag in the roof right over that spot.  I also felt very uncomfortable walking on an OSB-sheathed roof as it was much weaker than, say, the cheapest half-inch plywood.   Finally, I also noticed that roofing shingle nails don't seem to have the same holding power in OSB compared to plywood.  As a result, you'd see a lot more roof shingles blown off an OSB roof, than a plywood one.

As for health effects, there have always been concerns about off-gassing of glues.  But the research shows that this is so minimal, it should not have an effect.  That is, unless your parents happen to be super chemically sensitive, in which case all bets are off.

More detail on the topic is published by TECO, a USA-based third-party certification and testing agency of structural panel products. TECO evaluate and certifies OSB, plywood, particleboard, MDF and agrifiber panels produced throughout North, Central and South America, as well as Europe. 

According to TECO's experts "Structural panels, such as OSB and plywood, manufactured with exterior type phenol formaldehyde and isocyanate adhesives do not "off gas" like other types of wood-based panels and therefore do not require certification for formaldehyde emissions. Phenolic-based adhesives are specifically exempted in Section II.C.3 of HUD Rule 24 CFR 3280 (of the August 9, 1984 Federal Register), which states that HUD "has decided to exempt products that are formulated exclusively with phenol-formaldehyde resins and surface finishes from the testing and certification provision of the rule." The amount of formaldehyde emitted from panels using phenolic-based adhesives is considered too small to be significant and has therefore been exempted. Isocyanate resin panels do not contain formaldehyde so no risk of formaldehyde emissions exists."

For more information and an in-depth explanation of this topic, please refer to TECO's TECH TIP "Formaldehyde Emissions from Wood-Based Panels."

Reaching Tom:  If you have a home improvement question or comment on this topic, please post it below.  For answers to other home improvement questions, please email Tom at tomsmoneypit@aol.com so your question can be used in future blog entries, or search Tom's home improvement articles at moneypit.com.

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