I am remodeling a mid 80’s prefabricated house. I am wanting to hang drywall on the ceiling. I have found that the roof trusses are only built out of 1 3/16 tall by 1 1/2 wide lumber. They are 16 in on center, and 14 ft long. Will that hold 1/2 in drywall? Or should I sister in some 2×4’s for added support.
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What was on the ceiling before you started the remodel? have you removed the previous material?
The strength of a truss is from all the members, not only the bottom. The number, size, and spacing of other members of the truss all contribute to the strength. What is the design of the truss?
If the truss is strong enough for the load of the drywall, in addition to structure and roof loads, you should be OK. Drywall screws for half inch drywall only have to be 1.25 inches, so will not even penetrate an inch into the bottom member of the truss.
Thanks for the reply
The previous ceiling was this cardboard material that came with the house, fairly light weight stuff. I have removed the material.
After a quick google search I would call the truss a monopitch truss? It’s only half of the house, since the house was split down the middle for trucking.
The details matter. in addition to the size of each member of the truss, the grade is taken into account, as is the specific fasteners used at joints.
how far apart are the intermediate vertical members of the truss? (is it a single, unsupported 14 foot long board, or does the truss support it in one, two, or more places along the 14 feet?
Along the 14 foot truss, you will hang 18.6 square feet of drywall. [16/12 * 14] at 1.35 Pounds per square foot, that is 25 pounds (plus some nails and paint) over the 14 foot length.
You can get an idea on how much the drywall will make the bottom of the truss sag by hanging some weight, and measuring the distance to the floor before and after. You could also lay a level or straightedge across three of the rafters and measure the middle one with and without added weight. Three gallons of water should weigh about the same as the half inch drywall. ( I would put water in a bucket and use a rope to hang it, but only an inch above the floor)
If the truss has one or two intermediate supports of the bottom chord, the weight each section has to support per span will be reduced.