Lundy Flooring July 26th, 2017 - 18:44:52
All joists must extend at least 1-1/2" on to a bearing assembly, of either a beam or full height wall, unless metal hangers are installed to provide proper bearing support against other structural components. Beams, which support the floor joists over greater spans, are constructed in the form of laminated joists often referred to as built up beams, or one piece solid load bearing beams, cut from logs or manufactured. Electricians and plumber may often cut or drill into the joist work to install utilities, and this is accepted, so long as they do not remove more material than what is required by codes. This type of floor system is usually the cheapest to install.
Raw sheathing comes in 4`x8` sheets, most often installed as 3/4" thick plywood panels. This type of sheathing is adequate for spanning joist work spaced up to 24" apart. The sheathing is lain with the joints staggered in such a matter, that no two edge joints line up with adjoining sheets. It is very easy to install, requiring the least amount of labour. The sheets are fastened with either 1-1/2" flooring screws, or 2-1/2" nails, spaced about 8" apart. Although not required, it is a good idea to provide backers or supports under the joints, between sheets which run perpendicular to the framed floor assembly.
This shrinking action pulls the floor together, adding strength to the overall system. The advantages of this type of sub-floor are its strength and durability. One important note, homeowners are often disturbed by the small 1/4" wide gaps, generally left between the individual planks after the wood dries out. Although disturbing to see during construction, upon completion, the spaces are not noticeable, and really have no impact on the sub-floor components at all. Strip floors are designed to be interlocking, through lapping or spacing of joints.
Truss floors are simply that. They are constructed from small dimensioned lumber, interconnected in a webwork pattern by the use of metal or wood plates. Occasionally, the trusses will be built on site, utilizing plywood plates to connect the webwork together. Generally they are installed 24" apart, either suspended on bearing walls or beams, or installed with plywood trim or rim joists around the perimeter. Strapping is installed on the bottom side, to prevent turning in place, which is a common ailment for deep truss components.