Attic Truss Bottom Chord Size

O limit attic room bottom chord l d to max 23 for example attic truss with 2x10 bottom chord lumber in the room should not have room wider than 17 9.

Attic truss bottom chord size.

For each truss element is described by both size and stress grade. For traditionally spaced trusses the bottom chord is cut out of 2x4 or 2x6 dimension lumber but can also be cut out of 2x8 2x10 2x12 and even lvl material for roof trusses. The bottom chord typically carries combined tension and bending stresses. The bottom chord therefore carries combined stress of both tension and bending of the truss.

The horizontal beam of the triangle of a bottom chord is used in this simple triangle truss construction. O no bottom chord splice directly over a bearing within a room. A cantilever truss allows for level coverage past the exterior wall such as patios porches entryways and other offsets in the building elevation by moving one or both bearings inward from the end of the bottom chord up to 1 4 of the span. The cap truss is very similar to a gable truss with webs transferring loads vertically into the base truss below it.

A triangle is the simplest form of a truss and the bottom chord is the base piece. Truss capacity is listed by pounds per square foot based on the following load rating criteria. O no top chord splices in haunch of attic room as shown below. About the bottom chord.

For the 50 foot long room you ll need about 24 trusses. Typical triangular trusses parts of a truss panel length peak continuous la teral brace 12 slope pitch tru s pl te top chord heel bottom chord bearing point splice panel point w edg block span out to out of bearings cantilever overhang bottom chord length web double cantilever common trusses their spans king post span up to 16 queen. Factors that determine the size of the bottom chord include on center spacing dead loads. There may be an overhang at the end of a cantilever.

These prices change with the demand for lumber. The bottom chord then extends past the bearing wall. My guess is that the national average for an attic truss that will create the space we just described will cost you about 100 more than a regular common truss. The bottom chord of the cap truss is typically moved up 1 1 2 for 2x4 continuous lateral restraints over the flat top chord of the base truss or the thickness of whatever material may be used 3 4 for plywood osb etc.

Top chord live load snow and other temporary loads top chord dead load roofing materials weight of the truss itself other permanent items attached to the roof bottom chord live load storage or living space and bottom chord dead load. How much extra money do attic trusses cost. 0 25kpa for roof 1 5kpa to attic truss bottom chords low to extra high wind zones nzs 3604 as nzs 1170 references nzs 3603 nzs 3604 as nzs 1170 truss joints the gang nail connector plates are pressed. Bottom chords is at least 3 12 or the bottom chord pitch is no more than half the top chord pitch.