Friends:
Over the years we used all lengths and diameters of lags. We do not use
any of these lags anymore, ever since we discovered the Simpson 1/4"X3" hot
dip galvanized strong drive lags. They require no pilot hole, drive easily
with an impact driver and the inspectors and plan checkers seem to like
hearing the Simpson brand name used on the plans. The 1/4" diameter is
less likely to split a 2 by truss.
Finding the center of a truss is critical and pilot holes are a necessary
evil. We issue each employee a specific color of lumber crayon with
instructions to circle every pilot hole. They then "own" that pilot hole
and are responsible for sealing it. Hopefully, each pilot hole ends up
under a foot anyway.
We use landscape flags to probe pilot holes. The thin wire will prove if
you have hit a truss. If you miss the truss, bend a slight angle on the
wire and rotate it until the end strikes the side of the truss. Extract
the wire and hold it in the same orientation as when you touched the side
of the truss and it will tell you accurately where the edge is. If someone
needs to crawl the attic to put in blocking, wind the flag tightly around
the wire and insert it in the pilot hole. It will unfurl and mark the spot
so it can easily be seen even in the dustiest attic.
William Miller
Does anyone out there want to buy a bucket of various size lags?
WM
At 12:28 PM 4/27/2010, you wrote:
Hi Drake and all,
We have had both engineers and inspectors question the use of a 3/8" 4"
lag in a 2x4 top chord and I think rightfully so. When we have a chance
to spec new construction we have the architect replace the 2x4 top chord
with a 2x6.
And when we have to go into 2x4's we either shorten our lag to a 5/16"
3.5" or even 3" (if we can get away with it on the uplift calcs) so we
stay in the top half of the wood fibers on the truss. We have also
sistered or blocked 2x4s when there was concern.
But like Bruce said - I cannot imagine there ever being a problem with a
2x6 with a 4 " lag (only 3.5" of which goes into the wood) unless you were
using 1/2" lags!
The real issue is in installation. Installing a lag so that it glances
the side and splits the rafter or hitting a knot and not backing off could
cause problems. So we are really careful in installation to make sure we
are right on the center of the truss - we drill tiny probes everytime -
that's where the real issue is - once engineering is happy of course.
Hope that helps!
Jeff Clearwater
Village Power Design
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