Cutting engineered floor trusses

Michael, 24" used to be common around here, but sometime after the 70’s I suppose everyone started using 16", except for rafters.

Engineered floor trusses are not common in this area, but this is a newer home built by a large GC, who is well known for top quality in this area.

I was thinking the 24" oc was causing the “wavy” and uneven floors above.

I have made the decision to let these types of inspections go from now on, regardless of how hungry I am. It takes just as much, if not more time than a complete Home Inspection, but I only charge about 1/2.

Sticking to Home Inspections only unless I get ambitious and get a PE license! :cool:

Rehabbing 2005 build now with my son-in-law.

Yep, 24" o.c. floor trusses.

Interesting Michael, Our flooring is T&G as well. I was only 9 in 79’ but I inspect them all the time. Around here most are built on 16" centers but 19.2 is becoming common due to the money factor. If I saw 24" centers I would likely call it up for lack of support as it is very uncommon. May have to do some reading on it now. Didn’t get into the carpentry racket until 1986 myself.:wink:

How deep is the floor truss you typically see?

14" and 16" mostly. Ive installed anywhere from 12" all the way up to 32" myself. Mostly on commercial applications though.

One thing I keep forgetting to add is was there 2x6 or 2x4 installed on the vertical members of the joists? Should be installed tight to the underside of the top chord and be continious through all of the webs. We call them truss ties.
That is a very common mistake I see here a lot. Either that or the tin basher cuts them out.

Most I see in residential are 16 - 20 and yes the 2x6 stiffens them up so they all move together instead of individually.

All day everyday 24 inch o.c. and top cord bearing is the predominate method in my area. Length of span is directly proportional to depth of the truss.
Most common design is 40psf live load and 55psf total load and L360 while the better builders will use L480 for design deflection allowance.Meaning a fully spanned 4 x 2 orientated floor truss at 22 inched deep could span 25-9 inches. At L360 it would be designed to deflect up too 7/8 inches along the total span at L480 deflection would be designed to an allowance of just less than 5/8 inch.
Too make a short story long anytime I come across a fully spanned floor truss that has deflected a inch or more I call it out as not likely meeting design intent. Having grown up in your great State I think it likely most construction you will see will be L360

Thanks, Mark…I thought I was smart till now :oops:. I read it 3 or 4 times, and I still get lost on the L360, L480, and “deflect allowance”. That’s why I recommended a structural engineer:p

Sorry about that. Did not explain very well. For roof and floor construction take the total span convert to inches and then divide by 360 in most cases (or 480) and that will give you the designed deflection in tenths of an inch then convert to a fraction. By the way I’m coming too visit my folks this summer and am curious if the bridge construction will be complete so that I know how long I will have to drive to get a Hussens pizza?

The bridge will be completed in Jan 2014.

I live straight up the hill from Husson’s!!!