What size of joist would i need for a room size of 4.828m x 5.500m?
Answers:
12" joist for a 12" span? Good God.
5.5M is getting pretty big for a board. An engineered joist might be better if you're going to have a room on top.
It depends on how close together they are and how you fasten them together. A real tight connection between joists can help them support each other. 2x12s would make a fairly stiff floor at 17' and 16" apart.
The traditional calculation is one inch per foot; a twelve-foot span would require a twelve-inch joist. Modern materiels may have reduced this ratio, but better to make it too strong than too weak.
Depands on whether you have any dwarf walls i.e. small walls under the floor which break the span of the joist , the more dwarf walls you have the smaller cross section of joist you will need.Also need to know which way your joists are spanning are they spanning 4.828 or 5.500m , also remember to add at least 150mm end rest for your joists.
Hope this helps.
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