Plywood ceiling fasteners spacing
smokey059
| Posted in General Questions on
I know this is not a typical green building question but I know there is probably someone here who knows
I’m getting ready to install 1/2″ plywood on a ceiling as an air barrier on truss’s 24″ oc. Then some 2x strapping material and finishing with sheetrock. My question is should the plywood be nailed or screwed to the trusses and what is an appropriate fastening pattern along the edge and the field of the plywood. Also if someone knows, do you leave a gap around the wall edges and how much of a gap? Just trying to do it properly. Thanks
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Smokey,
Gap all your sheets 1/8" and the same at the walls. Sheathing is typically sized to accommodate that rather than being a full 8 ft, but some plywood, depending on it's use can be bang on or 1/8" over, so check before buying. You could end up having to do a bit of cutting to accommodate the truss spacing.
The plywood isn't being used structurally, so 12" oc both on the perimeter and in the field will be fine. The type of fastener is also not important. I'd use a nail gun with 2 1/4" ring shanks, mainly because that what I use for all sheathing, so I've got them lying around. You can use screws if you want using 1 1/2" deck screws. It will be a lot slower for no appreciable gain.
Thanks for the info. What about putting adhesive on before nailing ? The plywood will carry the weight of 20 inches of cellulose above or is the adhesive unnecessary ?
Ring shank nails are easier and quicker than screws, even at twice the fastener count/half the fastener spacing. Adhesive would not be necessary.
Thanks for the answers. You guys are a great help