Title: Metal Plate Connected Wood Trusses

Introduction: This three part policy addresses minimum plan, fabrication and installation requirements for metal plate connected wood trusses.

Reference Code Sections: UBC 2303.4 Metal-plate-connected Wood Trusses, and UBC 2311.6 Metal Plate Connectors

In addition to any other code requirements, the following shall be included with all trusses submitted for approval. These are minimum standards and are not intended to be all-inclusive. Truss fabricator’s layout sheets must match the roof and floor framing plans.

a. Location, identification and spacing of all trusses.

b. Each truss with a separate designation referenced to the truss drawings for different shapes, spans or loading conditions.

c. All load bearing points.

d. Any concentrated and suspended loads (e.g., AC units, beams, columns, ladder framing, fire sprinkler mains, etc.)

e. Any bottom bearing conditions other than standard (e.g., hangers used for truss bearing, dropped ceilings supported by trusses, etc.)

f. Permanent lateral or stability bracing in addition to that shown on the truss calculations.

g. Any specific attachment details such as holdowns for uplift, hip truss attachments at girders, etc.

h Location and loading requirements of drag trusses, including proper specification of straps, correlation of strap and chord member widths, etc.

i. Correlation with general building design requirements (load paths).

a. The plan preparer (or architect or engineer as applicable) shall certify that s/he has reviewed the truss manufacturer’s submittal for consistency with the building design.

a. Wet signature of the truss engineer on the layout sheet if the truss designations are not computer generated.

b. Wet signature of the truss engineer on a specific truss calculation if there are hand- written notes or requirements on the sheet.

c. Name of project and truss fabricator.

d. Identification of all trusses reference to layout sheet.

e. Exact span, shape and web configuration, including gable end trusses over 6’ high.

f. Truss spacing and load duration factor.

g. Size and gauge of metal plates at each joint.

h. Lumber specifications including species, grade and sizes for chords and webs.

i. All design loads for top and bottom chords (dead and live, uniform and concentrated), including loads imposed by other trusses on girder trusses.

j. Minimum required bearing of truss; specify wood plates or hangers.

k. Truss Plate Institute (TPI) bracing requirements attached to the submittal.

a. All truss fabricators must submit current copies of ICBO certification as an approved fabricator, or inspection reports done by an independent inspection agency within the previous six months.

– Are all trusses shown and identified on plans?

– Are there proper footings or supports at all bearing points?

– Does the layout match the roof framing plan, exterior elevations, and any non-typical spacing?

– Has the plan preparer (or architect or engineer as applicable) provided certification of truss span and load criteria?

– Are the applicable uniform and concentrated loads shown?

– Do hangers, anchors, fasteners, etc., meet design loads?

– Are uplift connections, if any, shown?

– Does duration load factor meet code?

– Are negative reactions shown requiring resistance to uplift?

– Does metal plate design meet the applicable ICBO evaluation report?

– Are structural gable end trusses designed for outrigger notching?

– Does the design load meet code criteria, manufacturers data, and as follows:

a. Roof Trusses:

Top chord live load:

4:12 or less 20 psf

4:12 or more 16 psf

Snow loads ( )

Top chord dead load:

Membrane, shake, shingle or

comp shingle 7 psf

Tar and gravel 10 psf

Concrete or clay tile 14 psf

Concentrated loads ( )

Bottom chord dead load:

5/8" sheetrock 5 psf

Plaster 10 psf

Concentrated loads ( )

Suspended ceiling 4 psf

Ducts and misc 2.5 -5 psf

Bottom chord live load:

Nonconcurrent 10 psf

General:

Special loads per UBC T 16-B

b. Floor Trusses:

Top chord live load:

Residential 40 psf

Non-residential 50 psf

Balconies (residential) 60 psf

Exit corridors 100 psf

Storage (light) 125 psf

Top chord dead load:

Residential and office 10 psf (concrete topping will be heavier)

Bottom chord dead load:

5/8" sheetrock 5 psf

Plaster 10 psf

Suspended ceiling 4 psf

Ducts and misc 2.5 -5 psf

General:

Special loads per UBC T 16-B

– Are calculations provided for load bearing beams, girders, columns and footings supporting trusses?

– Are roofing, floor and ceiling materials identified in calculations and on drawings sufficient to verify loading?

– Does truss manufacturer have an approved and current inspection report or ICBO evaluation on file?

– Is TPI bracing literature attached to the submittal, or bracing shown on drawings in compliance with TPI requirements?

– If trusses are preservative treated, are strength factors reduced accordingly?

– If trusses are not designed for green lumber, is a dry lumber verification method established?

– Are approved truss drawings and layout on the job site?

– Does the configuration match the drawing?

– Are parallel chord trusses installed right-side up?

– Are cantilevered trusses installed right-side up?

– Do girder trusses have the same number of plies as shown on the drawing?

– Are girder trusses connected together with the same type nail and spacing as required?

– Are trusses installed over studs if studs are 24" o.c., or if the truss reaction exceeds 2000 lbs?

– Do trusses have the proper bearing width as shown on the drawings?

– Are any trusses cut or notched?

– Does the truss spacing match the drawing?

– Are bottom chords stamped with truss manufacturer, live and dead loads, and spacing criteria?

– Are web connections tight or within the 1/8" allowable average if gapped (NOTE: limit 2 per truss @ 1/8")?

– Is roofing material the same as shown on the drawings?

– Are bottom chords braced with a rigid ceiling or at a maximum of 10 ft on center?

– Are drag trusses and/or shear collectors located per engineered layout, with proper connections?

– Do grade marks match drawings for all chords and webs?

– Do sizes of lumber match drawings?

– Do plate sizes match drawings?

– Does plate manufacturer match that used on the drawings?

– Are plates the correct gauge?

– Are plates in the correct location? Are they installed in position to the geometry of the joint so that they are no more than 1/8" out of perpendicular to the joint or no more than 1/4" out of parallel?

– Are plates installed tight (NOTE: REJECT a 1/16" gap)?

– Are plates installed over knots, teeth flattened or dominoed?

– Is lateral bracing installed as shown on drawings?

– Is additional permanent bracing installed as shown on the framing plan?

– Is gable end bracing installed?

– Are any special anchors, holdowns, hangers and etc. installed as shown on the drawings?

– Do plates or members show signs of being mishandled, including crushing or cracks?

– Do trusses show signs of excessive exposure and deterioration due to weather exposure?

– Have trusses been preservative treated? If so, be certain that designs were adjusted accordingly.

-End-

This policy is intended as a reference only, and shall not be construed as a regulatory document. The building official shall have the total authority for its application.