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Author Message Cynie Linton Intermediate Member Username: cynie_linton Post Number: 4 Registered: 10-2010 Posted on Thursday, January 05, 2012 - 02:41 pm:    So I will now post some long rambling questions on the topic of particleboard. I have a spec section (issued and on the street) with panel products and it says: Grade M-2-Exterior Glue. This appears to make no sense. It seems that nobody makes it. Or at least it is not referred to as such. Most of the FSC NAUF board manufacturers make a board that is MR – moisture resistant which is what I think is what exterior glue is trying to get at... Should my specs for particleboard simply say Grade M-2, moisture resistant board? And while I am at it, I see that Grade M-3 has slightly higher screw holding capacity than M-2. Does anyone have opinions about any of this? Also I am working with people who still want all of the boxes (div 6 and div 12) to be made of plywood... Thanks for any commentary on this. ken hercenberg Senior Member Username: khercenberg Post Number: 130 Registered: 12-2006 Posted on Thursday, January 05, 2012 - 03:08 pm:    Is this a substrate for plastic laminate? I've had numerous fabricators tell me to never use plywood as a substrate but they can't tell me what to use at countertops adjacent to sinks so I continue to specify marine grade plywood at those locations. When I'm lucky, we switch to solid surfacing at tops with sinks. As to the Grade, M-2 has pretty much been the product most often used from what I've seen. Take a look at http://pbmdf.com/cpa30/files/ccLibraryFiles/Filename/000000002143/FINAL-BuyersGuide-2011_PB.pdf for a quick side-by-side comparison of products without buying the standard. Lynn Javoroski FCSI CCS LEED® AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1367 Registered: 07-2002 Posted on Thursday, January 05, 2012 - 03:10 pm:    On page 80 of Architectural Woodwork Standards is a comparison table (for plywood panel cores, but the comparative properties should still apply). That should help you make a choice. Exterior glue is made with phenol-formaldehyde adhesive, and is more expensive than that made with urea formaldehyde. ANSI 208.1 gets into more detail regarding the relative strengths, screw-holding ability, etc. Someone else may have more information on that. Cynie Linton Advanced Member Username: cynie_linton Post Number: 5 Registered: 10-2010 Posted on Thursday, January 05, 2012 - 04:36 pm:    Thanks all. I have been scrutinizing the buyers guide. The Architectural Woodwork Standards comparison chart is useful. Ken - yes we are talking PLAM. If you use marine grade plywood for tops, what do you use for boxes? (This is public sector work - durable but not highend.) ken hercenberg Senior Member Username: khercenberg Post Number: 133 Registered: 12-2006 Posted on Thursday, January 05, 2012 - 05:18 pm:    Typically Grade M-2 particleboard and Grade 130 MDF have been good enough substrates for most conditions. Lisa Goodwin Robbins, RA, CCS, LEED ap Senior Member Username: lgoodrob Post Number: 159 Registered: 08-2004 Posted on Friday, January 06, 2012 - 08:47 am:    Cynie, I agree with Ken on this. And that buyer's guide is pretty nifty. If you also need info on green attributes of particleboard and plywood, the folks at Sterritt Lumber in Watertown can be very helpful. - Jim Sliff Senior Member Username: jim_sliff Post Number: 114 Registered: 08-2010 Posted on Saturday, January 07, 2012 - 02:57 pm:    I use a lot of particleboard outside construction and that comparison was really helpful. I knew there were different grades but not the specifics. Thanks! Steve Taylor (Unregistered Guest) Unregistered guest Posted on Tuesday, January 10, 2012 - 10:49 pm:    M-2 particle board is the default requirement of the AWS for core for casework and counter tops (and just about everything else.) As I recall there are two "Water Resistance" standards incorporated into ANSI 208.1. The lower level of water resistance involves a test requiring a sample be soaked for a period of time and the amount of swelling measured. The higher level test requires repeated boiling of the sample. As far as I know, no one makes particle board that passes the second test, but it is in the standard in case someone figures out how to make it. The AWS recommends particle board or MDF as core for casework because veneer core plywood tends to warp. For many cabinet components this is a minor problem, because those parts (sides, tops, bottoms) are fastened on three edges. Doors, however, are a problem. If you insist on veneer core for cabinet doors the manufacturer need not warrant them against warping. The AWS requires water resistant core at LP Tops if they contain a sink. The sink cutout is also required to be sealed with a water resistant sealer. Hardwood plywood with exterior glue remains a reasonable choice for wet tops. Regarding the difference between M-2 and M-3 particle board: The problem is that there is no easy way to tell them apart. You can specify M-3, and it is marginally better than M-2, but I have no way to tell which they provided without either destructive testing or documentation. Woodwork Institute will review millwork specs and make suggestions at no charge. We do always recommend Woodwork Institute Certified Compliance though. Steve Taylor ken hercenberg Senior Member Username: khercenberg Post Number: 139 Registered: 12-2006 Posted on Wednesday, January 11, 2012 - 09:32 am:    Thanks Steve, that's very helpful. I knew that using plywood as a PLAM substrate was a problem at cabinets and doors but wasn't sure about using it counter tops. Still, with all the problems we've had at sinks, marine plywood seemed like the best way to go. To my knowledge we haven't had any problems over the years. At wall panels we use MDF core with good success. What would you suggest? Is there any way to tell the difference between water-resistant core and M2? Are there any VOC compliant sealers on the market that work well at sink cutouts? As to the boiling, maybe someone was looking to add M2 fiber to their diet by making soup. Seems like an odd test to create; I can't imagine a condition requiring use of particleboard in a boiling water or steam cleaning application. steve Taylor (Unregistered Guest) Unregistered guest Posted on Wednesday, January 11, 2012 - 03:41 pm:    Ken, MDF core is what I would specify at wall paneling. Originally Water Resistant particle board was supposed to have some dye in the glue; blue I think. Unfortunately the manufacturer's are not doing so. There are two options to verify that water resistant PB has been used; have them send you the waste pieces from the sink cut outs and perform the soak test (no equipment beyond a caliper is required) or ask for copies of the material invoices. These are pretty much the same options you have for determining that Marine Grade Plywood was used. I think the test for Marine grade may be more technical. I do think the plywood spec is a good choice. Any plywood made with exterior glue will be better than even water resistant particle board. I usually recommend an exterior primer as the sealer for the sink cut outs. Silicone sealant is fine too as long as it is spread so it covers the whole edge. Some shops use contact cement, the advantage of contact is that they always have some with them. I think the point of the boil test is that it speeds up the process. For an exterior application you want to know that the product is going to survive multiple cycles of wetting and drying over many years. The boiling water test (which requires several cycles of boiling and drying) is intended to mimic that. It doesn't seem analogous to me either, but it beats waiting ten years to find out if the product works. As far as I know no one makes "exterior" particle board. There is some exterior MDF around, or at least there was. Friends of mine used MDF siding on their house with unfortunate results. Steve Cynie Linton Senior Member Username: cynie_linton Post Number: 6 Registered: 10-2010 Posted on Wednesday, January 18, 2012 - 02:10 pm:    Steve and Ken: This continued conversation has been very helpful. Thanks. I am still thinking about this though so may pop back with more questions. Cynie Steve Taylor Senior Member Username: steveatwi Post Number: 45 Registered: 07-2008 Posted on Friday, January 27, 2012 - 08:34 pm:    Cynie, I had reason today to dip into ANSI 208.1-2009 and to my surprise I found this paragraph; "For products referenced in building code applications requiring enhanced moisture resistance the special suffix "-Exterior Glue" shall be used. For instance "M-3-Exterior Glue" indicates medium density particleboard, Grade 3 from Table B, made with exterior glue to comply with the durability requirements in Subsection 3.3.5." So it would appear that your "Exterior Glue" specification is not unreasonable. On the other hand, as you point out no one seems to know it exists. The Moisture resistance grades are MR-10, MR-30, and MR 50. MR 10 requires that swelling after a soak test not exceed 5.5%. MR 30 requires that the internal bond after an "accelerated aging" (boil) test be at least 50% of the required internal bond for the grade tested. MR 50 requires that both the criteria for MR 10 and MR 30 be met. I believe that the MR 30 and MR 50 grades are included in the standard pending the time that someone may actually manufacture them. I am inclined to use the term "Moisture Resistant Particle Board" rather than "Exterior Glue" because I think the chances of being understood are greater. I would also call for Grade M-2 MR-10, but I wouldn't count on the millwork shop knowing what the MR-10 means. So my moisture resistant particle board item would read; "Moisture Resistant Particle Board: ANSI 208.1 Grade M-2 MR-10." (or M-3 as you prefer.) I would specify moisture resistant PB for counter tops with sinks, and possibly for sink cabinets.