electricland

roughly speaking, one of the main supports for your floor has lost its structural integrity. It broked. ;)

So to prevent the floor from collapsing while they replace said joint, they have used a floor jack (one right now, another to follow - jacks are devices which can be pumped up to a given height and a flat part on the top will hold up the floor - just like a car jack, except not ;) on one side of the joist (floor support thingy!) to hold up the floor. The second jack will be placed on the other side of the joist. Then they will extract (likely cut out) the cracked floor joist and replace it with an unbroked one so that your floor, you know, doesn't collapse ;)

I sense that in this place, "scabbed" is being used in its union sense of "standing in for" the floor joist ;)

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lest it is unclear from the above, a "joist" is a structural element, often made of wood that holds things up, and is essential for structural integrity ;).

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So far as I know about 6-8 of the floor joists in your house have been scabbed. Which is to say they have been doubled up (not to disagree with the very learned and well spoken Westerner above, but instead of removing said boards I think they plan to add to them) thus I think they are likely going to leave the existing wood in place and just attach the new wood to it in order to beef up its structural strength.

One of the main problem that I have seen with said joists is that they have pulled away slightly from the headers to which they were attached due to about 100 years of the house settling. Here is a web site that explains what they are up to: http://www.hammerzone.com/archives/framecarp/supplement/floor/joist1/sister.htm

They called it sistering but more or less the same thing.

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ah, duh. Of course - add to don't take away from. I should know better... DUH!

I've helped DO this... I REALLY should know better....

(we have more or less permanently scabbed corners of our house where it settled a little too much...)

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OK. I'll probably repeat information from the link bryghtboy provided; apologies if that is so.

A joist is part of your flooring system; you are probably aware of this. Nowadays a structural joist is usually 2x10; 2x8, 2x6, or even 2x4 if it's not a living space on top. There are also different kinds of engineered joists, which don't matter here. Joists are typically 16" or 24" on center (you may have the joy of converting to the international standard of measurement).

Older houses often had 2x8 or 2x6 joists; I've found 2x8, 2x6, and 2x4 in mine, anywhere from 16" to 30" apart. Makes for alot of bounce.

I suspect their "scabbed" is my "sistered", adding a second joist alongside the first to provide additional support. The new joist doesn't have to be as long as the first, though it should be at least half the length. If it is as long, it can be a bear to get in, since it's usually longer than the room and you're working in a confined space.

The reference to a jack is a little confusing. A stud is the full-height wall "support", usually a 2x4; 2x6 for exterior walls. A jack is like a stud, but instead of going full-height, supports a window or door header, or is otherwise cut short. Cripples are the extra short studs beneath or above a window or door.

At a guess, they may have cut -something- to push the cracked joist up (we usually cut the temporary about a 1/2" longer/higher than the final height, and wedge it in there), sistered or scabbed the first joist, and are now using the temp. ("jack") to repair a second, less serious cracked joist.

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You had it exactly right and well stated, just added an extra step one that would make perfect sense... just would be a lot of effort to implement and most contractors and handymen I have met are all about K.I.S.S. and did I mention the lazy? :)

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I sometimes take self-deprecating to artistic levels ;).

and most contractors and handymen I have met are all about K.I.S.S. and did I mention the lazy? :)
clearly, you've never worked with my Dad ;). (CEO by day, hard-assed foreman by night! ;)

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D'oh. I just thought of another possibility.

Nowadays, joists sit on top of plates, the flat 2x4/2x6 on top of the studs.

In the past, sometimes they would notch the floor joists, so although the joist was a 2x8, for example, only 1/2 of that would actually rest on the plate. This is now considered Bad Framing, as only the part sitting on the plate is structural; so in the example above, you really have 2x4 joists. Not so cool. These joists usually crack horizontally (split) in the notch; it could be repaired by lifting with a temporary support and nailing on a plywood or metal gusset.

But that's probably not what they're doing.

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There are two problems with cutting out an existing floor joist. 1 - they're nailed to the flooring above, so you need to either sawz-all all the nails off or pull them from above, which requires access to the subfloor. (Also, subflooring is usually glued to joists nowadays, and that stuff is serious hassle.) 2 - as noted in the linked article, a floor joist is -usually- room width + 8-12 inches. Usually the only way to get a full length floor joist into an existing structure is to cut a hole into the joist bay from outside (which means cutting into at least the rim joist, if not the sheathing and siding) and slide the new one in.

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I'm intrigued by the header reference. Are her floor joists hung from headers, or is this another vocabulary thing?

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Incidently, I found a joist in my dining room ceiling that was originally a 2x8, but had been cut down to a 2x4 for about 3' of its length, near the center of the span, and then scabbed (the right word, in this case) with a regular 4' 1x8-ish board just so they could hang the lathe (and thus plaster) off of it.

I think we double sistered it; my washer and dryer sit on top of it now.

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I find a lot of the vocabulary just confusing because people use 5 terms to mean the same silly piece of wood. Though in this case I wasn't exactly sure what to call the boards that the floor joists are attached to... so I guessed at header. Basically I meant the 2x8 that they tie into at the end, here have a little diagram of what I meant.

_________ < thingie I meant by header
| | | |
| | | | < Joists
| | | |
---------- < Other end of the structure.

As for the jack refernce, if they are doing the same thing as last time when I was there, then they mean an actual jack to life up the joists back to the proper placement before sistering them. I also saw that you were saying that most joists are 2x8 or 2x6... I do believe the ones in ELL's house are 2x10 because we scabbed/sistered some modern 2x6's on them and covered about half of them as I recall, could only be 2x8 but an original 2x8 not a 1 3/4' by 7 3/4' or whatever it is.

As a side note all of the original building material in the house is actually the dimensions suggested by the measurements, so a 2x4 is 2 inches by 4 inches ... none of that silly 1 3/4' stuff... which means restudding the walls is a little harder at times.

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Just realized I said an actual jack by way of elucidating on the term jack... which really isn't helpful at all. Sorry *embarassed face*

What I think they mean is a mechanical jack of some variety to push the wood back into place before they attempt to make its placement more permenant and sturdy through adding more lumber.

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No, I knew what you meant. Probably a hydraulic jack.

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If the measurements are actual (ie, really 2" x 10"), we usually say "2x10 true". A 2x6 is 5-1/2", so it'd cover about half, as you said. What size is "standard" depends on when the house was built, how nice it was, etc. Mine is a cheap, 1870's-ish house, I suspect recycled from another building. 2x10 true suggests to me a slightly higher class house, possibly 1880 - 1920.

I'm still intrigued by the "header".

Most houses today are built one story at a time. The walls consist of a bottom plate, studs, and a top plate. The joists sit on top of the top plate, and a rim joist goes around the exterior, as so (side view):
[] <---2nd floor wall
- <---bottom plate
===joist====| <--rim joist
- <--- top plate
[] <--1st floor wall

The load (weight) of the joists rests on the plate. The rim joist doesn't really carry any weight, it just keeps the joists vertical and provides support around the outside of the house. I'm -guessing- this is what you're seeing.

Older houses were often balloon framed; the studs went to from the foundation up 12', 16', 20', or more, and supported the roof directly. Second floor joists in this case were usually nailed onto the sides of the studs; the weight is then borne by the nails securing the joist to the stud; obviously an inferior method. I thought maybe they had nailed a plate to the face of the studs, and then fastened the joists onto that -- that'd be something new to me (at least as a overall framing technique; it's often done at stairwells and other floor openings).

Usual balloon frame (side view):
[]
===joist=[]
[]
[]

Variant balloon frame w/ plate attachment (side view):
[]
==joist==|[]
[]

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OK, LJ took away all my spaces. The RIGHT side of all the diagrams should line up, not the left.

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I'm trying to imagine how they initially constructed the building... because there have been at least 2 fairly major renovations since then. I suspect that they built it one floor at time though, because the interrior walls on all three floors don't have any bottom plate and rarely have any top plates.

Structurally the double brick around the outside is doing a lot of the supporting, along with the other building it is attached to. I do remember seeing the floor joists for the second floor running directly into the brick of the party wall... which I thought was kind of odd but what is more sturdy than brick I guess. I think the rim joist in your diagram would be nailed directly into the exterior brick wall because I don't recall seeing anything else supporting it really.

Most of the joists that we worked on perviously were attached to the staircases, they looked much like your first diagram only minus the connection to the wall instead they were slapped directly onto the staircase... then somebody later on moved the basement staircase... which I think is part of what caused some of the structural problems. They also added 2 bay windows on the exterior of the house opposite the staircases.

Hope that is somewhat more clear, getting way out of my depth here as far as structural architecture description goes. I might just not be remembering the wall that was supporting the joists but pretty sure there was a significant lack of them in some cases :)

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I love old houses. They're like puzzles.

Then again, I hate puzzles. But I'd still love to see the house.

Hrm. When did EL post all those pics of the inside?

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I did know about the joist bit, but not the rest -- thanks!

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Ah. That makes sense. I'm now wondering which floor they did it for.

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Ooh. Yeah. That sounds bad. I forgot to ask to see the joist in question yesterday (too preoccupied with the HRV unit). But I'm pretty sure that's not what they're doing either.

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I saw no jacks yesterday, so will have to inquire. I think they meant a temporary number to hold up part of the ceiling while they do something else, but I could be wrong.

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