Moving Lateral Bracing
Moving Lateral Bracing
(OP)
I am building a small storage area in my attic (I'll cover the floor in a separate thread). I have what appears to be a Howe truss system. In order to be able to walk into the storage area, I have to remove a lateral brace that spans a set of diagonal chords. The brace is about 5 feet high (so it's in the way for walking), and in the middle of the chord. I want to remove the bracing between three chords (two 24" lengths spanning three chords total), and replace it.
On one side there are two adjacent chords where the chords are to be removed, on the other side I think there may be none (I have to check), as a raised celing puts the next set of chords on another alignment. The bracing extends all the way to a sidewall, where it butts up against a 2x4 vertical, but is not nailed there. The chords are 2x3. The bracing is 1x6. The house is 30 years old, and I have no clue who designed the truss.
Options (and these are the questions):
First, move the lateral brace up about two feet. Do I move it for all the chords in the set, or just the two lengths I want to remove? If I just do it for the two, do I overlap the bracing onto the adjacent chords, and if so, how many? Can I use a 2x4 instead of a 1x6?
Second, replace the lateral bracing with a T or L brace along the length of the chord. If this option is preferred, do I just brace the middle chord (the others will still have bracing on one side), or all three? Do I also use lateral bracing as described in option one? Can I use a 2x4 for the lateral bracing and/or the T brace? How long should the T brace be (90 percent of chord length)?
Yes, I know the best option is to hire a PE to look at this, but this is way too small a job for that.
On one side there are two adjacent chords where the chords are to be removed, on the other side I think there may be none (I have to check), as a raised celing puts the next set of chords on another alignment. The bracing extends all the way to a sidewall, where it butts up against a 2x4 vertical, but is not nailed there. The chords are 2x3. The bracing is 1x6. The house is 30 years old, and I have no clue who designed the truss.
Options (and these are the questions):
First, move the lateral brace up about two feet. Do I move it for all the chords in the set, or just the two lengths I want to remove? If I just do it for the two, do I overlap the bracing onto the adjacent chords, and if so, how many? Can I use a 2x4 instead of a 1x6?
Second, replace the lateral bracing with a T or L brace along the length of the chord. If this option is preferred, do I just brace the middle chord (the others will still have bracing on one side), or all three? Do I also use lateral bracing as described in option one? Can I use a 2x4 for the lateral bracing and/or the T brace? How long should the T brace be (90 percent of chord length)?
Yes, I know the best option is to hire a PE to look at this, but this is way too small a job for that.





RE: Moving Lateral Bracing
A sketch might help...
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Moving Lateral Bracing
I'm talking about moving the "continuous lateral brace" in this sketch
http://www.wwta.ab.ca/1/17.jpg
the brace spans a set of diagonal webs of what appears to be a modified queenpost truss.
http:/
RE: Moving Lateral Bracing
RE: Moving Lateral Bracing
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Moving Lateral Bracing
As it turns out, there are only four trusses of the same shape in this set, and I'd like to move/remove the bracing on two of them that are furthest from the sidewall. The adjacent set of trusses is similar, but the webs are not quite parallel to account for a change in ceiling design. So I can't really tie into the next set of trusses with a continuous lateral brace, unless I angle the brace to connect the webs of the adjacent dissimilar truss set.
What is weird is that the trusses in the set only have lateral braces on one side of the "queenpost" (although the queenpost is not quite vertical, it does have an angle to it). Using the WTCA Figure 1 as an example, the bracing on the right side is missing, the left side bracing is there, and there is another lateral brace on the left side on the web that is parallel to the one that is shown with the bracing. The attached photo shows this (although its not super clear)
There is a diagonal brace across all four of the "queenposts" of the set, attached to the base of the sidewall and extending up to the peak. The brace is a 2x6 (might be 2x8 I didn't measure) and is double nailed to each of the queenposts.
So even though the right side has a virtually identical configuration, there are no lateral braces on that side at all.
I know I should put together a scale drawing of this to help visualize it, and maybe I can do that in the next day or two.
RE: Moving Lateral Bracing
RE: Moving Lateral Bracing
(good grief, now the pdf sketch won't load! I'm getting a "Page not found" error. I'll try again later)
As you can see, the trusses have only two sets of lateral braces on one side (this view faces the nearest sidewall, which is adjacent to this set of trusses). There are no lateral braces on the other side of the queenpost.
The sidewall is NOT a truss, but is comprised of vertical 2x4 with one or two horizontal 2x4 scabbed across them. A stucco wall is attached to the 2x4.
The lateral brace on the longest web extends all the way to a 2x4 of the sidewall, but is not connected to that 2x4.
The diagonal brace on the queenpost goes from the base of the sidewall to the top of the fourth and final truss in this set.
A couple of questions.
First, can bracing be overdone? All the webs are 2x3, and most references state that "T" or "L" braces should be of like timber, but can I use a 2x4?
Second, is there any point to putting a diagonal brace across longest web that currently has the lateral brace (and which I want to modify that brace across the last two trusses). If I use a diagonal, I can angle it so that it is above my head for the last two trusses. I don't think I can use that alone, since I will have removed the lateral brace across two of the truss webs, and their centers will not be braced, so I will probably have to also use T or L braces on those webs.
Third, I have read that you are not supposed to mix lateral braces with T or L braces. Is that accurate? This kind of goes back to question 1, as to whether bracing can be overdone.
Fourth, can I use fasteners other than nails? The 2x3 webs are very dry and brittle, having spent 30 years in an attic where the outside temps exceed 100 each summer, and the dark tile roof has a major southern exposure. I hesitate to use nails for fear of cracking the webs. Several of the webs in other parts of the attic are already severely cracked, and I'm going to have to repair them. When building the floor, I have been using screws and construction adhesive, predrilling the piece to be attached and clamping where possible. I understand that nails have more flexing ability, and screws have more pullout resistance. I'm thinking that the construction adhesive reduces the likelihood of the screws breaking, but that's just a guess. Is the "glue and screw" method acceptable to construct the "T" or "L" braces? How about for additional lateral braces? Repairing the webs?
Fifth, should I consider putting lateral braces on some of the other webs?
RE: Moving Lateral Bracing
2) Yes you can use a diagonal brace on the last two trusses. But unless you recalculate the stress in the web for an offset brace you will need to add a T or L brace to the web.
3) Yes and no, it depends on the situation.
4) You can use wood screws (at least 3" long and .131" root dia.) but you should predrill the holes. Predrilling will also work with nails.
5) Braces are only needed where the truss design or EOR note them as required. You would need to check the truss designs and building plans to see if any of the bracing is missing.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Moving Lateral Bracing
RE: Moving Lateral Bracing
I would try to find the truss company that designed them or a PE to advise you. If several "webs" are already cracked you may have a bigger problem than just removing and shoring up a few webs. You don't know what damage may have occurred due to those cracked webs - teeth pullout in chords and/or webs, excessive deflection weakening of surrounding trusses due to transferred load, etc.....
RE: Moving Lateral Bracing
Moreover, they appear to have been installed like crap. Several of the trusses have bent at an angle at the panel point point splices, yet they framed around them anyway. In addition, these same bent trusses are noticeably leaning over, yet the nearby wall is vertical, so they were installed that way.
One of the webs is sistered with a 2x4 to repair a split, but you can see they tried to "fix" it by nailing the web alone, before they nailed on the sister, since there are nails poking out the opposite side and their heads are below the sister.
I should probably shoot my home inspector, the truss company, and the builder, not necessarily in that order.
How does one go about finding the truss company for a 30-year old house?
RE: Moving Lateral Bracing
My soap box for a moment. Home inspectors are in general, based upon my experience a waste of money. You hire them once every 5 or 10 years max. Their business comes from referals, mostly from agents. They would not want to jeopordize a sale because of some bad trusses.
RE: Moving Lateral Bracing
As for the homeowner, she was dead. We bought it from her heirs. And not likely she knew about it anyway.
But hey, the house has stayed upright for 30 years ...
I may have to resort to hiring a PE to help me sort this out.
On further inspection, 3 of the 4 webs on one side of the "kingpost" (the center upright web) have continuous lateral bracing, but NONE of the webs on the other side have any at all.
RE: Moving Lateral Bracing
Like you mentioned, you'd probably be better off to contact a PE to help you fix all of this.....I know you're like me, when you see a clear problem, you just can't stand by just because it has stood for 30 years, you have to fix it. Many truss companies can estimate the repair by tweaking the software to the conditions you have, like 2x3 #3 lumber....the truss company might have a PE to design the repairs....there will be plenty of overkill on the repair anyway. It doesn't hurt to make a call and ask - and get a price if they review your situation. I know our PE's enjoyed getting out into the field and the complex problems to solve.
Unless you have Mike Holmes, most inspectors don't know much - they took a class or two on home inspections. The more thorough inspectors have had a technical education background. If the inspector was a former builder, forget it, most just want the check.