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Old 02-17-2005, 03:12 PM   #6
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Join Date: Dec 2004
Location: Ottawa, ON
Posts: 34

My joists are made by Alljoist, model AJS 20, 9 1/2" high by 2 1/2" wide flange.

There is a section in the manula for Maximum Floor Spans, allowable stress design - 100% load duration 'glued and nailed subfloor'. Under that heading is a table indicated Live/Dead Load (psf), the largest section is 40/30, at 16"o.c the maximum span for L/360 is 16'11". This is the same value found under the 'improved performance' section for L/480 as well.

So, in addition to everything I posted above, my subfloor is glued and nailed, then I screwed it to the joists each 6". The underlay was screwed down every 4".

I suppose that I could always jerry rig a black spray paint can on top of a ladder about a 1/2" away from my ceiling, then jump on the floor above it. If I have black paint everywhere I will know that my floor deflected 1/2". You don't need an engineering degree for that!
RobC is offline   Reply With Quote