LSU Lap Nailed Truss

[Ohio_Bill]

I ran across this truss plan awhile back and decided to give it a try .  We have built 35 of them and they are very easy  and simple to construct . I build them on 3 of the bibbyman  sawhorses  one placed at one end ,  one in the middle  and the other end gets one . The boards lap over each other as the drawing shows and you just nail them together . 

  

 

[wetdog]

They look good. How did you get them up?

[Al_Smith]

They look fine .Now do you prefer this method over glued and nailed plywood gussets ?

[1woodguy]

 Thanks for this!
I have never made any overlap type trusses,
always made the usual types .
The overlapping type will be a lot easier
And quicker when I am working by self.

P.S Just last night we were discussing a double carport I needed to make
And wall up later.
have some 14ft posts ,thinking will make it tall enough for anything I could possibly have on on pickup or trailer and still drive in side

[Ohio_Bill]

Al, Yes I do prefer this method for barns and outbuilding. It is much faster and simpler.  It all nails together and then you trim with a chain saw. Two of us can turn one out every 12 min and we are senior citizens.  The plans call for 2 by 4,s   I used 2 by 6,s .   

 

They look good. How did you get them up?

[wetdog]

O, Wish I had one of those.

[firecord]

Had to be good if it has LSU in the title!

[Ohio_Bill]

Firecord , I wondered how long it would take for someone to  say something about LSU .  Its got to make you feel good  that someone  Called Ohio Bill  uses  LSU  Truss's . 8)

[Al_Smith]

Well they look plenty strong enough .I do like the pictures too showing those southern Ohio hills .People crossing  the state in the north think Ohio is flat as Kansas they just haven't seen the whole state  ;)

[Jemclimber]

Thanks for sharing this. I'm planning to put up a sawmill roof this spring, and this may be the truss I use.

[bandmiller2]

Mayby I'am A fussy old phart but they look kinda jackleg lapped over like that,I think I'd use flush with plywood gussets. How critical is the placement of the cross braces. ??  Frank C.

[NMFP]

When I was in school, we made some of these and tested them with static loads and shock loads.  They were a different size and design but the problem was that you could not get the same strength as a traditional truss.  The reason being that with a conventional truss, you are transfering the weight and load through pieces and applying even pressure on subsequent lower part of the truss.  The issue with these is you are solely relying on mechanical fasteners for holding power.  The experience we had was that the fasteners, over time, will work loose from loading and unloading of static and shock weights.

The thing that really helped and I graduated before I saw any major results was the use of screws instead of nails.  They would not pull apart like nails would.

Either way you build, I would use either method as they both have application!

[beenthere]

The thing that really helped and I graduated before I saw any major results was the use of screws instead of nails.

Interesting, because one of the negatives I saw in this design would be the use of screws (have very little shear strength) rather than nails. Maybe bolts at those laps between crossed over pieces would be best, as those joints are all about shear for their strength. So finding out more about the LSU plan and design might be a good idea.
And in the end, there may be way more strength in the truss than is needed for the loads that are going to be realized.

[redbeard]

One method that I have used is use a wide crown roofing stapler and stitch both sides of joints.flipping the truss can be flimsy its nice having extra hands but once other side is stitched they are very strong. This method really works well on smaller trusses sheds ect.

 

[beenthere]

That stitch will at least keep the jointed pieces in alignment which is good for compression strength.

But being at the end grain that way, there is very little to no strength in tension. But it will hold until a gusset is nailed on or some sheathing is nailed on to add tension strength. Truss manufacturers will use the steel gusset plates which overlap out 6-12 inches from the joint for strength. And even they will not take any degree of racking (normally not a problem once the building is up).

[Don_Papenburg]

The old trusses used to have a pipe inserted between the laps and a bolt through that .  The pipe was installed in a hole like you would cut with a holesaw.  It would be less than half the thickness of the wood truss member.   That made for a good tension compression joint compensation.

[beenthere]

Don
I remember those and they were great for a lap joint. But sure don't see them used much anymore... believe they were called "split ring connectors".
Like

http://fabrication.clevelandsteel.com/viewitems/shear-plates-split-rings-spike-grids/teco-split-rings-timber-rings-

also

split ring connectors

[scrout]

I made the exact style but I used four 2x6, two each for the top vs. one.  Worked well.  I spanned 20 ft.

[Al_Smith]

Now I'm not so sure about that shear strength on screws  .Maybe a drywall screw it's true but those deck screws with torx heads have some strength now .

I've always built trusses using plywood gussets and glue with ring shank nails .I think the longest has been 36 feet .

[Ohio_Bill]

Al, my nephew just built a large shop   52 by 40   and put the whole thing together with high tech screws with an impact driver.  I think he used 250 dollars worth of screws but nails are not cheep either.

[Don_Papenburg]

That's the animal I was thinking , Beenthere.   I forgot about it being split .  I think that the labor involved plus the fact that you have to do some math or proper measuring to make it work would be the reason for them falling out of favor.

[mikeb1079]

interesting truss design...i was thinking the same thing about load transfer when i saw the overlapping 2x's.  if one used screws i'd be careful to use a structural screw with a decent shear rating, as the the whole roof is basically supported by those fasteners (as has been mentioned). 

[bandmiller2]

Glued and screwed, I'd use liquid nails between joints pulled tight with deck screws and if your nervous come by with your nail gun and hit it again. Ever try to pull something apart that has been liquid nailed.?? If theirs reliable drawings for trusses that are flat on top (parallel top and bottom) they would be perfect to span log loading areas. Frank C.

[barbender]

Frank, I think the reason liquid nails and the like are not structural rated is they will creep under a load. Your right, I was building a partition wall in our basement. I glued it down with liquid nails, well I ended up having to move it. When I pulled up the sill plate concrete came with it That stuff sticks!

[backwoods sawyer]

I milled for a guy that had three big dairy barns that the trusses were build using this pattern, difference was all the boards were 2x12 gave a lot more area to nail screw and glue. better to have over kill then to under engineer it.