As ambient moisture changes, your OSB or plywood panels will expand and contract. When you butt the panels together tightly, there is no room for expansion and this can cause buckling in the panels. Leaving a 1/8-inch gap between panels allows them to expand and contract without buckling.
OSB should be installed with gaps between sheets. 1/8'' to allow for movement during swings in humidity. Says so right on the sheets. To get sealed, I caulked all the seams and installed an air barrier/vapor retarder.
Provide 1/8” minimum space between panel ends and edges. Use a spacer tool (i.e. 10d box nail) to assure accurate and consistent spacing. Nail 6” o.c. along supported panel ends and edges and 12” oc at intermediate supports. Fasten panels 3/8” from panel edges.
APA recommends a 1/8-inch space between panel edge and end joints. Plywood and oriented strand board (OSB), like all wood products, will expand or shrink slightly with changes in moisture content. If the wood structural panels are tightly butted, there is no room for expansion and buckling can occur.
Properly spacing wood panels by 1/8″ provides a space for the natural expansion of wood panels while they adjust to the environment. If panels are tightly butted together, there is no room for the expansion of wood products and buckling occurs.
we always leave a perimeter gape of 10 mm and push the bards together lightly; some never go tight as the edges are fragile and brake and bind.
Like any wood product, OSB will expand and contract after installation; without a small gap between panel ends, the expansion could cause buckling.
Without sheathing tape, all of those gaps between the exterior OSB panels destroy the integrity and efficiency of the building envelope, in some cases eliminating the envelope all together.
While installing panels too tightly or without any gaps won't allow the material to expand and contract, leaving too much gap can cause excessive movement and noises. To avoid this, you must leave a proper expansion gap of 1/8” to 1/16” between the subfloor panels.
For the curious – 7/16” OSB has a span rating of 24/16 and with supports every 24 inches is good for a roof live load of 40 psf (pounds per square foot) with a 10 psf dead load.
Answer. OSB roof panels should always be installed with the grade stamp facing into the attic and the screened surface (with the nail guide lines) facing up. When the grade stamp is covered by roofing, the building inspector will not be able to confirm that the correct OSB roofing panel was used.
If you look carefully at the sheet of OSB in question, you'll see that most of the fibers are oriented parallel with the length of the sheet, making that the strongest axis in bending.
OSB has excellent moisture tolerance and is much less susceptible to the stress related problems of plywood, such as warping and ply separation. OSB is generally more square and has smaller dimensional tolerances. There are no soft spots such as those that can occur in plywood.
Disadvantages of OSB
Not moisture proof - OSB should be kept dry and does not perform well with prolonged wetting. It can swell, warp and lose strength if left unprotected. Weaker across the width - OSB has less stiffness across the panel compared to plywood. Additional bracing may be needed for some applications.
Use caulk or gaskets for smaller holes. Use tapes and spray foam for larger holes and gaps.
Should Weyerhaeuser OSB Sheathing Be Installed with the Edges Tight Together? No, all OSB sheathing should be spaced approximately 1/8” during installation.
Using OSB as a finished surface? A paint job can help to create a more finished look. It doesn't matter which side of the board you paint, but choose a smooth or rough side that suits your particular application. Spread the panels out for 24-48 hours to let them adjust to the humidity conditions.
APA recommends a 1/8-inch space between panel edge and end joints. Plywood and oriented strand board (OSB), like all wood products, will expand or shrink slightly with changes in moisture content. If the wood structural panels are tightly butted, there is no room for expansion and buckling can occur.
Robertson first pointed out that by design, nails are less brittle than screws, which leads to an increase in shear strength for nails.
The smooth side has a better moisture resistance and will ultimately provide better performance against weather. Facing the board smooth side out will maximize its ability to keep moisture out of the structure.
For OSB, we recommend that you use a solvent-based varnish. You can choose between high-gloss, matt and silky matt versions. Even special varnish for OSB boards is available. It's important to apply it as thinly as possible.
Screws, if driven properly, prevent creaking floors. A screw firmly holds the subfloor in place, which ensures a squeak-less floor for years to come.
Install the sheets horizontally with an 1/8" gap.. The main reason for sheathing a building is shear resistance. That is the resolution of horizontal forces, mainly seismic but wind as well. OSB and plywood will swell with moisture absorption.