Why bother with the ballpark when you're getting exact point loads and placements back from the truss manufacturer?
By the time we receive the truss drawings the foundations have already been poured, steel columns/beams in the basement are already in place, and rough framing has already begun. Trusses arrive at the job site in a matter of days after approval.
The 2x6 exterior walls are more than enough to support any truss load we will ever encounter. There are only a few questionable areas:
-Over wide window sets we will use a 2-ply or 3-ply LVL. Sometimes this is overkill for the truss loads, but it's cheap.
-Where there is an exterior wall on the second floor with truss loads that does not sit on top of a wall on the floor below we add flush LVLs in the floor system below and pick up those points with a column and steel beam in the basement. Again, it is cheap to over engineer this.
-Areas with a covered porch. These scenarios vary greatly, but we size beams based on the 45 lb. per linear foot number just like the above scenarios.
Some customers make changes that affect the footprint just days before the hole is dug. For us to have the trusses designed ahead of time to be able to calculate the actual loads would delay the start of the project if a change is made, affect the schedules of our subcontractors (approximately 50-60 homes in progress at any given point), and cost us more to have the trusses redesigned than it would to add an extra LVL across a 10' window span.
Our houses range from $250,000 to over $1,000,000. If we spend an extra $500 on a cheaper house or an extra $1500 on a more complicated house to over engineer the headers and beams it is an insignificant cost in terms of the overall project.
