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Main Line, pa
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Lexington, KY
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 Joist sistering question
[#2] Posted: 06/01/2010 - 5:48:30 PM |  |  |
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I wouldn't complain about those repairs, especially since they're bolted. If the sistered joists were only nailed together, I'd tell someone that bolts or lag screws should be installed, but from what little I can see in your photos, the repairs are okay.
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Linden, MI
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Joist sistering question
[#3] Posted: 06/01/2010 - 5:59:07 PM | | |
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Something does not look right to me. In the first picture, the original joist it crushed about two inches. The band joist also must be seriously damaged. How could they sister in a new joist of the same size without jacking everything up?
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Mark Mustola
ValueCheck Home Inspections
Linden, MI
www.ValueCheckInspections.com
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Louisville, KY
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Newberg, OR
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Joist sistering question
[#6] Posted: 06/01/2010 - 8:36:17 PM | | |
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They should have cut out the affected materials during the "repair"
I'd write up that repair as unconventional, and recommend they find out if any permits were pulled for splicing the joists.
Blazenut- those are plain old splices, not a sister. Splices are not covered by the building code and are supposed to be designed.
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Brandon
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Newberg, OR
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Joist sistering question
[#8] Posted: 06/01/2010 - 11:22:28 PM | | |
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Bill,
I've always called it a splice, and have never been questioned. I'm not doubting you, but do you have something from an authoritative source showing the distinction between a scab and splice? As you say, I've always thought that a scab was the board that tied a splice together.
Either way, it's not covered in the building code, and technically would have to be a designed repair in my opinion. Would I pull permits or hire a design professional for my own place-- no way.
How do you determine when it becomes necessary for a full length sister, placement and number of fasteners, necessary overlap, etc.?
In regards to permits. If the AHJ's laughed me out of their office, I'd kindly request that they change the permit requirements.
For years I struggled with trying to figure out what to write when inspecting this type of repair work. I finally decided that trying to determine whether the repair is adequate is beyond the scope of my inspection. I now say what I see, let them know that it must be a designed repair, should have been permitted, etc.-- it gets me off the hook. I still thoroughly check out the work and often give an opinion as to how well it was done, but tell them I'm not fully qualified for this type of inspection.
Most of the structural "repairs" I see look like a 5th grader designed and implemented the work herself.
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Brandon
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Kenmore, WA
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Joist sistering question
[#9] Posted: 06/02/2010 - 12:06:30 AM | | |
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Hi,
Here's the problem; the new wood is scabbed onto rotten wood. What friggin' sense does that make?
Here's a quick lesson about rot.
Rot has 3 stages; incipient, intermediate, advanced.
In the incipient stage, the wood looks pretty good and feels pretty good when you probe it or smack it with a hammer; however, rot spore is already in the wood and is moving through the cells like a virus through a bloodstream. I saw something somewhere once - can't remember where - that said that when only 10% of a board is infested with incipient rot it loses 50% of its strength. 50%!!!
In the intermediate stage, the wood starts to look a little "off" - maybe it has a waviness to the surface because the cells inside the wood have begun to shrink from the rot and it Maybe it's soft to the touch and you can dent it just by squeezing hard.
In the advanced state - what you see there in that photo - the wood is seriously damaged by rot and it's strength is a fraction of what it was when it was in the incipient stage - which was already weak.
So, only the end is rotten, right? Wrong; by the time the advanced rot shows up incipient rot has already advanced far far ahead of the leading edge of the advanced rot. It that's a 10 or 12ft. joist, it's probably got incipient rot all the way to the far end and then the middle 40 to 50% is in the intermediate state and the last 10 to 20% has advanced rot. In other words - it's crap and you can't rely on crap to hold bolts.
Termites, annobiidae, lictids, mordoc are all attracted to soft, rotting wood - that's just lunch.
Bolting good wood to the side of that piece of wood was an idiotic thing to do. They should have put a new full-length joist in next to the original, cut out the original, fixed the sill, tapped the new joist into position and then secured it in place.
Never accept sistering where rot is concerned. If you have something with mechanical damage and no rot, sistering will work; however, when there's rot you're just putting a Scooby Doo Bandaid on a severed artery. Don't do it and don't accept it.
ONE TEAM - ONE FIGHT!!!
Mike
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Lafayette, Louisiana
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Louisville, KY
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Newberg, OR
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Rochester, New York
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Newberg, OR
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Joist sistering question
[#16] Posted: 06/02/2010 - 8:41:19 PM | | |
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| Quote: Originally posted by Brandon Whitmore
Bill,
I've always called it a splice, and have never been questioned. I'm not doubting you, but do you have something from an authoritative source showing the distinction between a scab and splice? Sure. The word has appeared on quite a number of engineer's reports and design repairs, specifically identifying a board added to reinforce a damaged joist or rafter, that does not extend the full length of the member. More often then not, the documents specify the scab is to extend 4' past the damage, split, hole, etc. The term has also been used by structural engineers speaking at conferences, again using it to refer to reinforcement of a damaged or altered structural member.
I've seen the term used the same in many, many publications from respected authors and organizations. I have well over a thousand books, papers and journals published over the past 200 years describing building practices, restorations and repairs. Here's just the first few off the shelf:
Wood-frame House Construction, The Carpenter's Manual, Structural Use of Wood, Successful Restoration, Preserving and Maintaining the Older Home, The Old-House Doctor, Preservation for the Property Owner and Renovation a Complete Guide, all describing the term scab, or "scabbing-on" as a structural repair method of using a short board or even plywood alongside "diseased" or otherwise damaged structural member.
Quite a few of my posts here in the past show that I advocate using correct and accepted terms for building methods and components. I'm quite sure that I've been using the term "scab" correctly, although when I looked it up in the Handbook of Building Terms and Definitions, the only entry for scab was: "An insulting term applied to one who is taking the place of a man on strike".
Quote: For years I struggled with trying to figure out what to write when inspecting this type of repair work. I finally decided that trying to determine whether the repair is adequate is beyond the scope of my inspection. I now say what I see, let them know that it must be a designed repair, should have been permitted, etc.-- it gets me off the hook. If you're not comfortable, or are not familiar, with what is to some others a common repair, that's probably best. Having seen termite, fire and other damage repairs to joists and rafters on almost every inspection for 25 years, I get to see what works and what hasn't. That, combined with research and working with design professionals for several decades, gives me the confidence to give clients some really useful advice in most cases. I really try to limit statements intended only to get me off the hook.
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| Bill Kibbel, Historic & Commercial Building Inspections - Old House Resources |
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Newberg, OR
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Joist sistering question
[#17] Posted: 06/02/2010 - 9:21:41 PM | | |
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Bill,
Thanks for the explanation. The reason I requested info. from you is that I couldn't find a great definition of a slab vs. a splice on- line.
Quote: If you're not comfortable, or are not familiar, with what is to some others a common repair, that's probably best.
I'm definitely familiar with the repair. I probably don't see it nearly as often as you, since post and beam construction is the norm. I only see joist construction on the main floor in about a third of my inspections (random guess).
It isn't that I'm not comfortable looking at the repair to decide if it looks OK (usually crap work), it's just that I'm not a paid design professional. I'll voice my opinion of the repair, and leave it to my client to decide if they want to look into it further. Often times, I find minimal overlap, a minimal number of fasteners-- usually nails, and "scissoring" of the joists at the overlap. Basically, it is often really easy to say that it's been poorly repaired.
Quote: I really try to limit statements intended only to get me off the hook.
Poor choice of words on my part.
It comes down to the fact that someone following me on an inspection may make an issue of it, whether or not it looks ok. They could indicate the fact that it should have been designed and permitted, and would be technically correct. I don't want a client calling me up complaining that I didn't let them know.
Thanks Bill.
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Brandon
Portland Home Inspector |
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Pearland, Texas
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Joist sistering question
[#18] Posted: 07/14/2010 - 9:15:28 PM | | |
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I see a lot of sister bracing, I agree it should be adequate length to allow support, placed over good timbers and bolted in place.
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Robert Welch
ATEX Inspects
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