Why I don't like OSB:
OSB swell is generally greater than in plywood due to the release of compaction stress in OSB created during the pressing of wood chips into an OSB panel. Plywood that has swollen will return to its nominal thickness as the wood dries. OSB will remain swollen to some degree after it dries because the panel will still have the higher "compaction ratio" that was present as of the date of manufacture.
The comparison below, undertook by the APA, lists the thickness swell (in percent) using a water soak test.
Plywood Average swell= 6% to 8% depending on thickness
OSB Average swell= 10% to 15% depending on thickness
Over a period of time, when subjected to high humidity or a series of dramatic wetting events, OSB is more prone to panel swell than plywood especially at the edges. Panel swell is most noticeable along the edges where it is critical for flooring and roof sheathing to match-up as not to show through the flooring or roofing materials.
Research done by the USDA Forest Products Laboratory (Research Paper FLP-RP-574) shows that over an extended period of time, under low constant loads and temperature, and in high-humid conditions, OSB will sag or "creep" more than plywood.
50% RH Fractional creep values
1.4mm Plywood
1.7mm OSB
85% RH Fractional creep values
1.9mm Plywood
5.2mm OSB
Cyclic RH 50%-85% creep values
2.0mm Plywood
4.6mm OSB
Long-term, plywood sags less than OSB in humid conditions. In humid areas with vented attics and crawl spaces, using plywood for roof and floor sheathing can reduce risk of sagging roofs and floors.
APA Technical Note N375B states that plywood panel bending stiffness is 10% greater than OSB at equal joist spacing. Panel bending stiffness is the capacity to resist deflection.
Density of plywood is 34-36 pounds per cubic foot compared to OSB at 38-42 pounds per cubic foot.
One 23/32" 4'x 8' plywood piece would weigh approximately 67 lbs.
One 23/32" 4'x 8' OSB piece would weigh approximately 78 lbs.
Plywood is approximately 15% to 19% lighter than OSB. While the additional weight of OSB does not mean increased strength, it just means that it is heavier to handle on the job. In addition, OSB's higher weight means higher thermal conductivity (thus slightly less R value) than plywood
T-test....ordered the Cab because Spirit was a sponsor! I like to support sponsors. When I sent in the order, they never even acknowledged receipt of the order. I had to ask for acknowledgement! No communications on their part. I had to inquire about status when nearly 2 months had gone by. Never received an invoice for the $1500 deposit...have you purchased a body from them? Never inquired if I wanted any changes.
" I also know Spirit does tell all when they build a product for a customer and will back it up with a money back return" LOL
I guess I am way more particular about my cars than other must be and always have been since I built my first street rod in 1968.
Since I am the bad guy, you can delete me completely including the other build thread. You don't need me and I don't need you!
Good bye!
They were both on T-bucket style frames, both 96" wheelbase, both Chevy powered. Both had coil sprung rear and torsion bar front suspensions. I stretched the blue body 2" in the "C" area to improve legroom and reshaped the doors to strengthen the door opening. Both bodies were fab'd out of 3/8" plywood and 2 x 2's and laminated with fiberglass. They were fun to drive and attracted a lot of attention wherever I went.
