b'YOUR TOOLKIT FOR BUILDING EXCELLENCEexample: an embedment gap of 1/16 Inch (0.06)of moisture.A short period of high moisture may will result in a 40% reduction (60% Effectiveness) innot cause significant problems, but longer periods the strength of the connection.The manufacturing(or periods that cycle from wet to dry) will increase tolerance (per ANSI/TPI 1) for embedment gap isembedment gaps.Once the trusses are received at 1/32 inch (0.03).See table herein from ANSI/TPI 1. the job site, the responsibility for protection from high moisture shifts to the new owner of the trusses.When embedment gaps are identified long after the delivery of the trusses to the site, it is difficult to identify the cause of the problem. Non-systemicembedmentgapscanbe caused by a variety of issues.Since they are usually few, the focus should be to identify them and get the connection repaired.Figure 4.Table reproduced from ANSI/TPI 1 Owners of existing buildings may notice embedment Embedment gap issues can be: gaps.One possible cause may be high moisture systemic, affecting a large number of connections. conditions (especially if the truss lumber cycles from high to low moisture over time).This can or specific, affecting only a few joints in a non- occur in some special buildings.The owner of a predictable way. building with a high moisture environment may If an embedment gap issue is systemic, the shipmentneed to periodically inspect (or hire an inspector) of trusses should be rejected at (or shortly after) theto look for embedment gap issues.time of delivery.The outer trusses in the shipmentRegardless of the cause, any Metal Plate Connections should be quickly examined for this issue.Missingwith significant embedment gaps should be repaired.this opportunity could cause costly repairs and mayLateral Restraint of Truss Members and Bracing shift the blame (expense) from the truss supplierof the Lateral Restraintsto others.The trusses should be kept dry at the job site andAlthough the track record for MPC Wood Trusses is in the final building.When lumber is exposed togood, some building failures have occurred.Failures high moisture for extended periods, the lumberusually occur when the roof is heavily loaded by expands (mostly in the direction perpendicular tosnow or in high-wind events.Upon investigation the wood grain).This expansion pushes out theof failures, the lack of proper installation of the Metal Connector Plates.Then when the lumberlateral restraint and/or bracing is a common cause. dries, the lumber will shrink, but the wood surfaceThe lateral restraint locations required for the top will not pull the Metal Connector Plates back intoand bottom chords and for the webs (if any) are the wood.This process can cause, or increase, theidentified on the Truss Design Drawing.embedment gap.That is why connections usingDiagonal Bracing of the lateral restraints (if used) Metal Connector Plates should be kept dry.Theis also required and should be verified, but this degree of the problem is dependent on the wetnessbracing is NOT within the scope of the Truss conditions and the time period that MPC WoodDesign Drawing nor is it the responsibility of the trusses are exposed to the weather or other sourcesTruss Design Engineer.Diagonal Bracing locationsFRAME BUILDER - AUG2022 / 15'