Greetings Jerry,

I believe I remember reading some Trus Joist technical documentation
which indicated no more than one hole should be drilled or lag
screw/bolt driven into any cross sectional area of the top flange.  If
using the Quick Mount Q-Base with two lag screws/bolts, will you be
orienting the Q-Base so that the two lags are in line vertically with
each other or side by side?...  Seems like side by side (straddling
the web) may not be a good approach.  Staggered vertically (straddling
the web) may be alright if the size of the holes and lags are
appropriate for the top flange dimensions and can be installed where
allowed by the rafter/joist manufacturer's specifications.

I hope you are able to accurately identify the rafter/joist
manufacturer and the rafter/joist model so you can reach out to them
for guidance on what are and are not acceptable attachment methods for
their product.

Other thoughts:
If access to the underside of the roof structure allows, installing
appropriate blocking with proper hangers and fasteners would likely be
a more robust way to go.
I have looked into using stainless steel j-bolts to hook the underside
of the rafter members in situations like this as well; the rest of the
install from the top side is just like working with hanger bolts.
If the roof decking/sheathing and its attachment fasteners and
schedule are all known and sufficient, a multi-fastener deck mount
type mounting product may possibly be an appropriate and labor/time
saving option.

Best regards,


Matthew Sirum
P.O. Box 1227
Greenfield, MA 01302-1227  USA
phone: +1.413.773.0611

    ----------  Original Message Below  ----------

[RE-wrenches] TJI rafters
Jerry Caldwell solarcowboy at
Tue Mar 6 15:57:04 PST 2018

Mineral bitumen roll roofing. 2:12 slope.
Everyone who gave input below, thanks for the suggestions.
I've decided to go with the Quick Mount Q-Base product. It allows you
to get 2 lag bolts into the top chord on either side of the OSB web.
Cheers,Jerry Caldwell
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