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truss, block, truss, block..........

Isamemon's picture

Just got the newest FHB and it has an artile by Lary Haunn on rolling roof trusses,

Ive noticed in this artile, as well as his books and films, that he installs a rafter or truss, then the block, then the next rafter or truss.

Is this a regional thing, do many of you do it this way ??

we like to roll all the trusses, then go back hang facia boards, then block. This leaves the plate fully open for walking or leaning out to hold up the facia boards

however lke his artile points out , it would stiffen up the trusses  from the start, and we have not done a roof higher then a 8/12 that had a 36'span, maybe in that situation it would help

I would think that if a person was to truss, block, truss, block. after the first one is up, why bother to loose time on marking layout, use the pre-cut blocks to hold you on layout

 not being critical of Haunn, have admired him and had his books since first editions, and learned a lot from him.............just curious

(post #96723, reply #1 of 36)

ise...  larry had a lot of common sense stuff .. but the article was little too basic..

i noticed he built a catwalk down the middle... i think that had a lot to do with his antiquarian crew  ( hah, hah, hah )

i also looked and looked ... couldn't find any mention of stringing and blocking his plates to make sure they were straight..

 i got the part about snapping a line on top of the plate.. but no mention of straightening his wall..

 is this fairly common..  i mean.. doesn't everyone stering and block their wall before they set  floor joists or rafters ?

Mike Smith   Rhode Island : Design / Build / Repair / Restore

Mike Smith   Rhode Island : Design / Build / Repair / Restore

(post #96723, reply #2 of 36)


I nail 5/4 on all the corners of the top plates and run a mason line around the whole perimeter which takes about 3 minutes and then using a 3-4' piece of 5/4 I push the walls in or out until that 5/4 just touches the line and the walls come out just fine. Those days of sighting 40' walls are over plus my bue eyes are getting a little old.......;-)

Joe Carola
Joe Carola

(post #96723, reply #9 of 36)


I have used Larry's method of snapping the top of the wall forever (well I guess I was shown this method in the late 70's, early 80's). As soon as I learned of a way to avoid strings while setting trusses, I've never gone back. You have to make sure the guy marking the trusses is very careful in making the reference line. It can really mess things up if he is not (personal experience speaking here!)

Since it was an article on setting trusses, I assume they felt it wasn't necessary to mention straightening the walls first.

To me, staightening the walls is a step in itself, doesn't matter if you're going up another floor, or setting trusses. Straight, plumb, and level are givens at that point.

BTW- Do you string all your walls? I have always sighted them unless I have one that is particularly long, or if it is giving me fits for some reason.

John Svenson, builder,  remodeler,  NE Ohio

John Svenson, builder,  remodeler,  NE Ohio

(post #96723, reply #17 of 36)

sven... since it is so basic.. i thought it was a weak point in the article


step one: string and block the walls to dead straight.. then brace them so they don't move

one of my guys who moved on to bvigger and better things had lunch with me last week..

 he was framing a house with a new lead man.. stand up the walls, brace them.. then set the 2d floor joists..

 my guy wanted to know why they weren't stringing and blocking.. lead man replied.. "didn't have to.. all of the joists  were cut to exactly the same length"...

 needless to say.... nothing fit from the plate line up

 a guy working by himself might want to "sight " his walls... but it doesn't make a lot of sense to me..

string-block-adjust  & brace.. an SOP tht should be part of the framing bible


Mike Smith   Rhode Island : Design / Build / Repair / Restore

Mike Smith   Rhode Island : Design / Build / Repair / Restore

(post #96723, reply #21 of 36)

Sure don't understand why sighting the walls seems wrong to you. Do you need string to check the crown on joists? do you need string to find the straightest plates?

Course not. You hold them up to your eye, sight them, and even the slightest bow, crook, or twist is apparent.

Of course, as you raise the walls and nail them off, you have to be sure all the corners and intersections are plumb. I always double check them prior to straightening and bracing.

On my jobs, I'm the guy who sights the top plates, while my helper adjusts and braces. Takes less than half the time that stringing does, with no compromise. The walls are always dead nuts on.

If I was working alone I would have to string line. There is no way a guy could sight and adjust at the same time. It requires a partner.

As far as your framer's bible- I guess your's must be catholic, while mine is protestant.


John Svenson, builder,  remodeler,  NE Ohio

John Svenson, builder,  remodeler,  NE Ohio

(post #96723, reply #25 of 36)

you might be one of those whose eyes have not started to go

I use to be able to site a straight line or wall, no longer

however, odd enough, after its built and everything is there, then I can see a straight line, strange I know, I guess its haveing lots of reference points and then I can see the one that is out.

(post #96723, reply #11 of 36)

Larry would never pull out a string to line a wall - everything is by-eye. He says that drawing a line with a speed square across a 2x before making a cut is wasting the customer's $.

He's straight production. Framing tolerance is 1/2" in production. His stuff is better than that I suspect but not by much.

I like Larry a lot - he's a very nice considerate guy. He lived the change from balloon to platform framing. He has a lot of good ideas but disagree with him on a lot of framing techniques.

Talking to him 8 years ago about how we Southern NewEnglanders strap our ceilings with 1x3 and he said "what a waste of perfectly good 1x3" - he'd never consider it.

Hopefully he'll be coming east for Builders Trade in Feb (3rd and 4th). He'll be doing demos of framing. He will raise some feathers for sure.


(post #96723, reply #12 of 36)

"Talking to him 8 years ago about how we Southern NewEnglanders strap our ceilings with 1x3 and he said "what a waste of perfectly good 1x3" - he'd never consider it."

I agree with him on that Mike. Nobody in New Jersey does it. You wont see one new home with Strapping.The only time you see it is on a Remodel or if you fur down a ceiling that's not level some people with fur it down with 5/4x3. I did it when I moved out to Cape Cod back in 1984 and I couldn't believe what they were doing and they couldn't believe that we didn't do it. But we don't do it here and I doubt that we will for a long time. Every time I've mentioned the word strapping no one knows what it means and we never had problems before not strapping.

Joe Carola
Joe Carola

(post #96723, reply #13 of 36)

I've always thought strapping is a holdover from the days when lumber wasn't as uniform as it is today, so they strapped to have the opportunity to flatten a ceiling.  Seemed perfectly reasonable when I learned it.  Can't say I see the need for it today, though.


(post #96723, reply #14 of 36)


When I moved to Cape Cod and told those guys that I never heard of strapping or seen it they really thought that I was crazy. They couldn't believe that we screwed sheetrock to the bottom of the 1-1/2" joists and at the butt joints we only had 3/4" to screw into. I said to them then why don't you strap the walls they're only 1-1/2" wide.

I know they say it's easier for the plumbers and electricians and so on but when I here it's better for nailing it doesn't make sense and then I read that guys will strap I-joists that are 2-1/2" to 3-1/2" wide to me that makes no sense.

Yes 5/4 x 3 gives you more to screw into but you don't need it. The point I'm trying to make is that there's thousands and thousands of houses built and being built without it and we have no problems. It's just another example of doing things a different way. I wont say that strapping is wrong but the people who strap can't say that the people who don't strap is wrong or the quality is poor because it's simply not true.

Joe Carola
Joe Carola

(post #96723, reply #15 of 36)

Back to the blocking, what is the purpose of it?  Is it even necessary? Seems to me that it prevents the insulation from fully covering the top of the wall cap plate.


(post #96723, reply #18 of 36)

They serve a couple purposes that I know of, Matt.  First, they keep birds from flying up between the trusses, or rafter tails - I've always assumed that's why we call them "birds blocks". We build primarilly with open soffits/exposed tails here in the Pacific Northwet, I think as a stylistic nod to the bungalows that were so popular here in the early 20th century, but certainly also as a labor and materials savings choice, too.

The other function birds blocks serve is to keep the truss, or rafter, perpendicular to the top plate, thereby preventing "roll", which is how vertical framing members (rafters, joists, beams, headers) fail - they "roll" to horizontal which of course is weaker.  That's also the function of mid span blocking and bridging.

Yes, insulation is another good question.  We staple cardboard baffles to the bottom of the top chord in every vented birds block bay that extends from the plate line past the height of the insulation.  We then insulate tight against that baffle, allowing air to move freely above the insulation from the plate line to the ridge or roof vents near the ridge.   


(post #96723, reply #20 of 36)

Jim & All:

Thanks for the explanations.  At least I now know why they call them bird blocks, and although we don't do open soffits here in NC we do have to comply with specific requirements to prevent insect intrusion.  Also, I understand the concept of preventing "roll" but we brace our gable end trusses diagonally so I don't see any need for bird blocks.  I live on the edge of hurricane territory, and although we don't have to comply with many high wind codes, I have been exposed to them and know of no requirements for "bird blocks". 

We also use the cardboard insulation baffles, but they are installed ~1" from the underside of the roof sheathing, and are turned down to to intersect with the outside edge of the wall cap plate.  In the event of raised heel trusses, sometimes the wall sheathing is run up higher than normal (using scraps of sheathing) to "keep the birds out", which supplements the cardboard stops.

Not meaning to be rude, but I'll file bird blocks away in the same category as "strapping" and floor system blocking; needed in special situations, but otherwise, just a waste of materials and labor. 

Referencing another thread about "minimalist framing" bird blocks seem like a prime candidate.


Edited 11/27/2004 5:35 pm ET by DIRISHINME


(post #96723, reply #22 of 36)

"Not meaning to be rude, but I'll file bird blocks away in the same category as "strapping" and floor system blocking; needed in special situations, but otherwise, just a waste of materials and labor".

I agree. I can see putting a Bird Block in with an open soffit but to put blocks in-between rafters is a waste of time in my eyes I've never seen it done and for what reason so the rafters don't roll where are they going to roll once the sheathing is on. It's like strapping a waste of time.

Joe Carola
Joe Carola

(post #96723, reply #26 of 36)

maybe its a code thing in our area

we and the inspectors call them bird blocks and also call them freeze blocks,

why freeze , I have no idea

but we have to install them, because local code around here requires not only that they are there but that roof sheeting is nailed to them, even if a closed soffit

I guess when it is the storm of the century, the wind will get between the rafters and lift the roof right off into the neighbors yard  (regardless of all the nailing into the trusses and facia)

killing fido (and the wicked witch)  thus opening up all kind of lawsuits

(post #96723, reply #28 of 36)

frieze, not freeze... makes it self explanatory

(post #96723, reply #29 of 36)

>> why freeze , I have no idea << Freeze (sp?) is just below the intersection of the soffit and the side wall.  The frieze board (I think is actually the way it's spelled) is at the top of the siding and often there is a piece of crown that joins it to the soffit.   In historic architecture, the frieze was often rather ornate.

>> local code around here requires not only that they are there but that roof sheeting is nailed to them <<  That would seem to interfere with ventilation between the soffit areas and the attic.  What area/state/etc do you live in?  What model code do you all use?  Just curious. 


(post #96723, reply #30 of 36)

same here, frieze needs to be nailed to sheeting. opr should I say sheeting nailed to them, vents are either cut into the block or round holes. both have screens

current code books I assume, never bothered to look it up , but its what the inspectors want in two cities

(post #96723, reply #16 of 36)

Strapping is a very very local thing. I'll bet if you returned to the Cape you'd find fewer people doing it now - it's going the way of the dinosaurs. I wrote an article for FHB 5 years ago on the how's & why's of strapping (still "in the bank" and likely to die there).

There are actually a lot of benefits and the costs aren't really that great. (reduced sound transmission, reduced thermal bridging, truss uplift problems eliminated, joist twist and nail pops eliminated, no need to parallel block for parrallel walls, utility running in both directions without drilling, easy remodeling) Then the downsides (firestopping / draftstopping, ungraded lumber in the frame, ceiling electric fixture mounting.....)

Of course with 60% of US homes now using I joist floor framing - almost all of the benefits of strapping evaporate.

When I first discovered that 99.9% of the US did not strap ceilings - It opened my eyes. It was the first time that I discovered that there's more than one way to frame a house.

When you worked on the Cape did you see any benefit to using strapping?


(post #96723, reply #23 of 36)

"When you worked on the Cape did you see any benefit to using strapping?"

Not at all. It was nothing but a pain in the [JOBSITE WORD]. It didn't benefit the framers and I can't see why everyone there thought it was impossible to screw sheetrock to the bottom of a 2x10. So for me it useless.

Joe Carola
Joe Carola

(post #96723, reply #27 of 36)

Am I hearing correctly that the guy who just brought up saving a few studs per house straps his ceilings?  How do you justify the use of all that extra time and material?

The only time I've ever strapped a ceiling is for hanging green rock on 12" centers due to its lesser integrity as compared to the 5/8" type X I have usually put on ceilings.

Language is my second language.

"Doubt is not a pleasant condition, but certainty is absurd."

~ Voltaire

(post #96723, reply #32 of 36)

That's right - I never said that my primary reason for skippin studs was to save lumber. I do it to make more room for insulation primarily.

And strapping ceilings takes no more time than blocking for parallel walls once you develop a system.

(post #96723, reply #34 of 36) not every one blcks and strings.

I can teach a rookie...first day on the job, how to sight a 20' wall without a string. Heres how I do it. I go up and look and notice if it needs to be pushed out a 1/16" or pulled in that amount. I send him up. I make him acknowledge the slight crown. I then instantly straighten it with my brace which I attached while he was getting on the ladder. He acknowledges that it's perfectly straight. I go and check and agree.

From then on, he knows what straight is supposed to look like.

I then double check him on the next five or six. If he's got the eye, then I never check again..if he don't....then he has to be retrained.

I've never had one that didn't pass in two trys.

40' walls? Simple. I start by plumbing the center. Get that perfect, then take a look. A coupla more 1/16" adjustments and the entire 40' wall looks like a l aser. Occasionally, the center has to be tweaked. That is an indication to me that the line was snapped on a windy day and might be 1/8 to 1/4" off. I simply straighten the top by eye and bang out the bottom plumb into the brick space.

I have watched string and blockers team spend four hours on a floor that I will do in ten minutes with a helper.

I don't allow anyone to string and block except under extraordinary circumstances.

One more thing.....usually, when a new guy show up and starts framing...he misunderstands what I mean when I tell him to use ONLY straight top plates. He learns fast when he's up there pulling the junk off. I don't let it use only good stuff on top...or you pull it off. If I have to tell you to pull it off twice...your on you last leg. I won't tell them three times. The third time..they have to go....


Warning! Be cautious when taking any framing advice from me. Although I have a lifetime of framing experience, all of it is considered bottom of the barrel by Gabe. I am not to be counted amongst the worst of the worst. If you want real framing information...don't listen to me..just ask Gabe!


keep looking for customers who want to hire  YOU.. all the rest are looking for commodities.. are you  a commodity ?... if you get sucked into "free estimates" and  "soliciting bids"... then you are a commodity... if your operation is set up to compete as a commodity, then have at it..... but be prepared to keep your margins low and your overhead  high...."

From the best of TauntonU.

(post #96723, reply #36 of 36)

hah.. good 4 u, blue..

 however, we will string and block my job.. and it won't take any longer than your sighting..  and it will stay there until the deck is on or the roof sheathing is on..

your job.. fine..

my job .. i pay for string and block.. i get what i pay for

Mike Smith   Rhode Island : Design / Build / Repair / Restore

Mike Smith   Rhode Island : Design / Build / Repair / Restore

(post #96723, reply #3 of 36)

use the pre-cut blocks to hold you on layout.

Because it never works that way. cant hold them tight enough by the time you get to the end you be twoo inches out. i know, it happen to me.

(post #96723, reply #5 of 36)

I agree , I tried that once . Half way through I was out of whack so I tossed the pre cut blocks went back to reading the tape.

(post #96723, reply #4 of 36)

I guess it could depend on the size of your crew.

When I did trusses, oh. . . . .lot's of years ago, we used an operator, a rigger, a ridge man, 2 wall men, and a floor man.

The floor man's job was to start the first toenail in the blocks and hang them for the truss guys.

The walls were already plumb and aligned and well braced.

Then it was block, truss; block, truss; block truss all the way. Depending on layout, add a temp brace  on each end and a permanent one at the ridge line every 4 or 6 trusses. Check layout every 16'.

First block on the gable end sized to put the first truss on layout from the GE eave sheathing edge. Block the plates and 8' from the eave sheathing edge, block the ridge and bottom chord under it.

The crane never had to wait for the truss crew, always vice versa. Using hammers and nail bags, not air guns.

Come back after they're rolled and finish nailing off all the braces that were only end nailed, add any other permanent braces and the rest of the blocking. In California, we wanted blocking 4' OC and at all sheathing edges.


A Pragmatic Classical Liberal, aka Libertarian.

I'm always right!
Except when I'm not.

(post #96723, reply #6 of 36)

I lay the bird blocks on the plate line to use as spacing since around here all the truss companys cut them at 22 and 7/16 and over a long ways it causes ploblems. I set the 2 end gables and put a string between them to make sure all the ridges plain in perfect and the wall are always braced and straightened before the trusses go on at all.

(post #96723, reply #7 of 36)

Walls are straightened/braced and a pile of 25 1/2in scraps of 5/4 or 2x4 are cut with nails started in each end. They'll be nailed on top each truss [24oc] as they come. One gable set first[farthest from the crane],then a 2x4 nailed on other gable wall cantilevered out the same overhang. No need for crane having to lift over that gable with every truss. If the trusses have 'piggy-backs', they are assembled on ground w/appropriate 2x4s nailed on bottom and lifted in 1 piece by crane.Most of the time anyway. The only 'blocking' we had to do was anytime trusses were over 24oc, like stair openings.


If it were easy....a caveman could do it.

(post #96723, reply #8 of 36)

Around here, 85% of the houses are stick framed, except for the tract builders.  That said, I've never seen the bird blocks used, except once by a guy who didn't pronounce his Rs. 

I agree though with BrownBag.  If you were to do the roll-block-roll-block thing you would get off layout, unless you adjusted the tursses as you went.

In short - we don't need no stinkin blocks!!!!