I’m having 40′ trusses placed on my framing and I’m a little confused on how to erect them. I have had several opinions and I need a little clarification about it. One thought is to ‘X’ brace 3 together in the center as a starting point and then erect a truss from one side out to the outer wall (gable). Sounds good to me but how do you place the ridge blocking between each truss as it goes into place (2′ centers)? Do you ‘toe-nail’ a block to the ‘in-place’ truss; place the new truss against the block; face nail through the new truss into the block – then repeat it for the next truss? As I see that sequence, it’s toe-nail a block, position a truss, face nail into the block, toe-nail into the just placed truss, place a truss, etc to the end. Do the ‘gang-nail’ plates on the trusses subtract (1/8″ each side) from the truss spacing? Sorry to sound like a ‘newbie’ but I am and once up there with those trusses, I want to know what I’m doing (I hope). I plan to have metal angle plates along the top plates to position the trusses as they are swung into place as a starter point. When they are all up there, I’ll go back and ‘X’ brace every other group of 3 for strength, along the center web and the two outside webs to prevent ‘racking’. There will be interior ‘catwalks’ on both the top and bottom chords. At the ends of the trusses, they will be tied to the plates with metal ‘hurricane’ plates. Does this sound OK to the experts? I’ve had really good thoughts about this project so far and need to understand this little last problem. Thanks. J-J
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I'll post a link or 2 Monday morning that may help you out a bit. Don't have the links handy at the moment....
Maybe you'll get some useful sugggestions overnight, though.
What is the white man's greatest contribution to the world? Blondes. [Adam Rifkin]
no kidding we jsut did 40 foot clear span trusses last week. they are monsters. 6/12
ther might be easier ways or bette rways but this is what we did
of course out top plates were laid out, we had our walls braced very well, more then usual. and had long 2x6s sticking way up at the gable ends, attached to outside sheeting and studs
we had a temprary cat walk the height of the walls ( 10') running down the middle, we had our trusses delivered so that the gables wer on top and when the truck got ther ewe had them set on the deck and two gus quickly sheeted them leaving openings for the sling
two other got on the walls and directed the trusses. We only hd a 60 foot span (60x40) so we split the trusses into three piles and had them set up, wiht hthere peaks resitng on the catwalk and about 4 rafters in form each end. By then . the gables wer ready to go. we had them lifted in place and nailed them off to the plates and the temporary bracing
the rest was like rolling any trusses. the 4 of us had them rolled in by the endo of the day.
next time however when the gables are on the ground will cut the lookouts too
the truss delivery guy said that if we wnted them sheeted we shoudl have ordered them that way
it was kind of spooky and we braced them well, they were kind of wiggly ad I am real glad we sheeted the gables first.
somehere in FHB there is an article about some guys that sheet, put in blocks, enclose soffits and attach barge rafters before the gables go up
untill last friday, I didnt think it was so special.
next opnes Im gonnna try that way unless other posters here say not to
lastly , trusses are neat things, the homeonwers filmed the project and wer impressed at the endo fo the day , how much had been done
well its sunday, 11 hours from now we will be sheeting that roof.
again , there might be better ways, but it workd for us
Edited 6/13/2004 7:02 pm ET by hammertime
JJ,
How big is your crew? Can you hire some day laborer grunts?
Do you have your truss drawings yet? What permenant braces are required? Put them in as you go along with the temporary braces.
The truss next to the GE may not be 2'OC from the GE. It should be 4' minus what ever sheathing overhang (1/8" tp 1/2") is specced from the gable eave.
What is the support OC required if you lay them flat? How tall are they?
Will you have a crane there until their all set?
The blocking you got right. One guy on the ground/floor presetting the toenail nails into the blocks and hanging them from the bottom chord of the previous truss while you are walking the next one down to place. What is your block spacing? 4'OC or 8' OC or at each webbing? How many blocks per truss. The truss manufacturer can tell you the thickness at the gang nails, it's been too long for me to remember that detail and someone else was the cutter anyway. Precut your blocks but remember those specials at the GE.
One crew setting blocks and trusses and one crew walking them down is 3 times faster than one crew doing it all.
If you use a crane to lift them one at a time, one man on the ground rigging is enough.
If we can know what you have to do and how many men you have to do it with, we can give you a better plan.
In any case I prefer to start at a well , and I mean really well, braced GE and work to the other GE installing the permenant bracing as we go.
http://www.tpinst.org/Color%20HIB%2091%20Sheet_v3.pdf
http://www.tpinst.org/my_pubs_hib.html
SamT
Edited 6/13/2004 8:34 pm ET by SamT
The link Sam T posted to the PDF file is the one I was going to post this morning. There's a lot of info there about how to brace trusses. Takes a while to pick through, but you should be able to find your answers.
If this is your first set of trusses, I'd suggest using a crane to set 'em. For one thing, I think it's the easiest way to set trusses.
And if the crane guy sets a lot of trusses (particularly if the truss company provides the crane) the operator will be able to give you a lot of suggestions about how to proceed. The operator will also stop you if you're doing something unsafe.
I've posted several times here about truss erection bracing. The trusses can fall over if they aren't braced well. This can cause a lot of grief - Injuries and a lot of lost money. Don't take the bracing issue lightly.
Save a horse; Ride a cowboy [Bigs & Rich]
Hey Boss,
DIRISHINME raised an interesting question re ridge vents.
What are your thoughts about ridge blocking where ridge vents are planned?
SamT
I can't see any reason to have ridge blocking when you're using trusses. What purpose would it serve?
Seems to me like it would be a heck of a waste of labor and materials.A constant dripping on a rainy day and a cranky woman are much alike! [Proverbs 27]
Many, many, moons ago, with someone else in charge I installed a few sets of trusses.
We always blocked at every intersection of webbing and top chord. Are any blocks along the top chord needed?
I believe that some blocking aids in keeping things on layout and kinda holds the truss in place till bracing is applied, but you da man, so I axing yu.
Samt
I've never heard of anyone installing blocking at the ridge and at each web intersection. Can't imagine why anyone would do that.
There's no reason to have any braces or blocks on the top chord once the plywood is on. The plywood is all that's needed to keep the top chords in line.
I never liked blocking for keeping ANYTHING on layout. If the blocks are a hair long or short, you get a cumulative error as you work your way across the building. But that's just personal preference.A sensible man watches for problems ahead and prepares to meet them. The simpleton never looks, and suffers the consequences. [Proverbs 27:12]
I whole heartily agree.
For trusses that big, pay a few extra bucks for a small crane truck or in many cases there's a crane on the truss truck. Scaffolding down the middle is not a bad safety idea either, if they would domino they can't roll all the way over.
Several years ago I had 20 48'ers that we had erected set and were finish bracing. Unknown to me the carpentry contractor decided to set the plywood bunks on the roof for sheeting, using the crane. I was in the trailer with the owner at the time. On the 3rd lift they tried to set a bunk on the opposite side of the erected trusses, which because of the angle made it a blind lift. The bunk was still swinging back and forth when they set it on the trusses, dominoed the lot.
Fortunately, the mason's had left their scaffold up, that prevented the trusses from flipping completely under. One broken ankle, 2 carpenters in need of a change of shorts. I think if the trusses would have flipped, everyone of them could have been killed.
Even with experienced people, the carpentry contractor and myself, critically stupid mistakes can be made. And the boss should not quit supervising a dangerous or critical job until the job is actually completed. Hire a crane.
Never serious, but always right.
Edited 6/14/2004 1:30 pm ET by Russ
Crane service from truss plants varies a lot from one place to the next. In some markets, you wouldn't DREAM of sending trusses out without a crane. In other markets, the truss companies NEVER provide cranes.
Personally I'd rather see more bracing on the trusses rather than scaffolding under the center. Keep 'em from falling in the first place.Sex takes up the least amount of time and causes the most amount of trouble.
I believe the scaffolding down the center is to aid those of us who do not have wings on our feet ;-)
The temp bracing is independent of the scaffolding, and there can never be too much.
Re keeping the trusses on layout, that's why you put layouts on your temp bracing before installing it. Then as you sheet the roof, one carp holds a tape measure perpendicular to the top chords just above a sheet to be installed and moves the members on layout as another person pops the nails. Block are unnecessary and just introduce error. For example, if each block is just 1/32 long, guess where you are at on the 24th truss!! Matt
Ridge blocking? I wouldn't put that in unless it was specified on the truss design sheets. It is rather effective at reducing the effectiveness of ridge vents. To get the 24" O.C spacing, lay out some 8' 1x4s and a bunch of 16' 1x4s with your 24" spacing, and nail them to the top chords as you go. Probably at least 3 on each of the 2 roof planes. It's a bit of a PIA as you must slip each successive truss under the temp bracing. Plan for extra crane time. Assuming a simple rectangular house, (yea right!) set your gable ends or outer 2 full height trusses, and brace these trusses plum and strong. Run a string line between the tail of each truss along the length of the house. Then set the intermediate trusses aligning them on the string. If you feel you need to use blocking, nail it in such a config so as not to block air flow. Also they make these metal brackets that serve the same purpose. Here is 1 type: http://www.strongtie.com/products/connectors/TSF_PT.html Based on the size of your roof, it may be worth the expense, but I'd still use the 1x4s.
Good luck,
You are right to want to know what you're doing before you get up there with the trusses. Those thing can kill you (and one will make no sound when it falls--I know from experience when a gable end truss wasn't secured well and the wind blew it over on me). We used a fork lift to lift the trusses but pulled them into place using muscle. We'd get all the trusses lying down on the wall and point of one resting between the bottom chord and point of the previous one. I recommend using the strong tie system where you flip metal ties down as you go to space the trusses--the ties are designed to pinch the top chord of each truss. Otherwise premark 2x4's 16' long or so and nail them to the top chord as you go (one each side of the ridge on big trusses). They will have to be removed after you sheath the lower part of the roof. (Strong ties can stay, or be reused.) The truss manufacturer should supply you with a bracing diagram--in our part of the country you are required to brace according to this diagram.
Put up the gable ends first--we nailed an upright brace or two securely to the outside walls at the gable ends and leaned the truss against it (only if the truss was not pre-sheathed--if it's been sheathed the sheathing extends below the bottom chord and prevents leaning the truss--you have to stand it up on the top plate of the gable end wall right away and nail it temporarily (duplex nails) to the braces). Then run a taught stringline between gables near the ridge and make the top chord of each truss touch it when the truss is placed on the layout lines previously drawn on the walls' top plates. That helps get the rafter tails (ends of the top chords) hanging out the same distance from the walls. Once the gable end trusses are up and secured to the braces, you can lean several trusses against them, again nailing them temporarily. Then drag them one at a time to layout.
Those are the main things I remember--but for God's sake, be careful! I can't stress enough how dangerous this can be. We usually ran a scaffold (we called it a "pic") under the trusses--a place to stand as well as a better way to support the trusses before they were flipped up and dragged into position. Like several of the other guys said, if a truss falls then, it will hit the scaffold and be less likely to kill some poor slob below. We generally tried to get some of the plywood sheathing on the roof before quitting for the day to help prevent racking if a wind blew up. (We generally waited until the sheathing was on before cross bracing, but if it looked like a storm could come up, we tried to do both before leaving for the day.)
Good luck. I always hated setting trusses--almost as much as putting on shingles on a hot, humid day. But it was somewhat harder to get hurt doing shingling! I would try to get someone on site who is familiar with setting trusses to assist you. It's not that hard, but fairly dangerous. Hope this helps.
JJ
I have worked on about 35 projects now where we had a a 45 foot span.
On all of them we erected the trusses on the ground in banks of 6 on a ribbon plate, braced them, ( you could even part sheath them I guess ) then lifted them onto the plate with a crane. The crane had a spreader bar with hooks hanging off to hook under the top chord.
Whilst one is being craned into position the next bank is being erected.
Mike Guertin wrote an article in FHB some years back using a similar method. You may wish to do a check and find out witch article it was.
It is very fast and very safe compared to the alternative.
regards
Mark
http://www.quittintime.com
I have done somethine like Mark suggests. A 24'x28' garage with 10' stud walls and a 4' concrete foundation paired with a 2 man crew dictated that we be creative.
The two side walls were framed, sheathed and left on the slab. Then end walls (front wall with door and back) were framed, sheathed and supported by the mudsills and temp blocking. Now we had a plane approximately 5' off the ground to set trusses on. A 2x4 plate was laid out, the trusses were erected, sheathed, papered at about 5' above grade. A crane lifted the roof structure off the walls and placed it on a flat area of ground. The walls were tilted up and braced, and the roof lifted up and on.
Worked like a charm.
Jon Blakemore