How To Read Roof Truss Plans

So for example a dimension string that reads.

How to read roof truss plans. Truss design drawings have long been a source of confusion for contractors design professionals and building inspectors alike. Live loadany temporary applied load to a floor truss chord. I don t know if it s the result of growing up as an only child but i am a complete sap for any creature with big eyes feathers scales or fins that needs a loving home. L d ratiothe ratio of the truss span l to its depth d both dimensions in inches.

Roof truss span tables alpine engineered products 15 top chord 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 bottom chord 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2 12 24 24 33 27 27 37 31 31 43 33 33 46 2 5 12 29 29 39 33 33 45 37 38 52 39 40 55 3 12 34 34 46 37 39 53 40 44 60 43 46 64 3 5 12 39 39 53 41 44 61 44 50 65 47 52 70. On some roof trusses the 2 top chords extend down over the edges of the bottom chord creating a built in overhang. The first thing to check is what scale the roof is drawn in. Your top chords can protrude beyond the bottom chord anywhere from 1 3 feet 0 30 0 91 m.

4 7 12 would be the dimension 4 7 12 16 or 4 7 3 4. Truss technology in building how to read a truss placement plan a truss placement plan is a layout drawing identifying the assumed location for each truss based on the truss manufacturer s interpretation of the construction design documents. Srr how to read a truss design drawing this four page document presents a generic truss design drawing with color coded explanations for every item of information contained therein. Typically roof live load is snow while floor live loads are furniture human occupancy storage.

The answer is a convention of the truss producing industry. Trusses that are mistakenly installed backwards or upside down cannot support the same amount of load as a correctly installed truss. How to measure residential roof plans. In this drawing a 1 8 scale ruler is being used.

Installation details hanger schedule job information on center spacing and special truss locations are op tional information that may be included on the truss placement plan by the truss manufacturer. The roof below is drawn in 1 8 scale this means that if using a regular tape measure that 1 inch would equal 8 feet. This stands for f eet i nches s ixteenths. Just remember the acronym.

The two lines denotes the direction of the plate. If you think you d prefer an overhang style truss adjust the measurements for your top chords accordingly. The next thing to determine is the roof pitch see how to determine roof pitch the easiest and most accurate method to measuring a roof plan is to square everything off. 12 truss height the height of the truss from the top of the bearing to the top of the top chord trusses with multiple levels of top chord will have multiple truss height dimensions feet inches sixteenths 13 plate size orientation and type plate size in inches.