other than holding up the floor? Can I pull up my floor and remove the floor joists without weakening the structure of the walls or roof or what-have-you?
More detail: it’s a single-family residence, with standard 2x4 framing on 18" centers. It has a continuous concrete perimeter foundation under the outside walls, and footings/piers holding up the main beam. I’d like to do some work under the floors, but the crawlspace is SO tight (6" to 18" high) that it would be MUCH easier to remove the floor structure to get an open work area.
How many are you planning on taking out? And you’re going to put them back when the work is done? I’d think that sistering the joists on either side of the opening would be a good idea.
As a bath remodeler, we do this all of the time. Not the entire floor but often the entire bathroom floor. Of course I offer this without being able to see your exact situation.
Joists are holding up interior partition walls, among other things. They’re also an important part of the frame of the house, increasing its overall stiffness and resistance to lateral forces.
OK, these don’t hold up any partition walls; I’ve checked.
That’s the part I was concerned about.
As Don’t fight the hypothetical pointed out, nobody can check out the structure, so this is a theoretical question. In response to Great Dave’s question, I was intending to remove ALL the joists from a single room. If structural issues allowed, I was considering the possibility of leaving them out permanently.
In essence, on the ground, using tamped earth, insulation, crusher run, poly vapor barrier to get things to the desired height. (I’ve got some documents around here somewhere that show the proper way to do that.) Consider it something like a glorified packed earth floor.
You must first ensure that you have load bearing under the joists that run into the room. That may require an additional foundation and pony wall. Given the tight space, I don’t think you’ll be ahead with a beam. You may have to add joists under the wall or walls that run parallel to the existing joiststo support those walls. After that jou may buck off the offending joists allowing for one more “joist” to face the bucked joists.
Joists can function as tension ties and removal requires structural alternate.An example would be collar ties replaced by structural ridge.
If floor loads are the only strain on your joists then you could be safe to go ahead but they could be part of a designed load spreading diaphragm where removal weakens a larger area.
Hard to say sight unseen or without more detail.
Let me be the first to urge you to hire a structural engineer to look over your plans before making such a large alteration to your housing structure. I happen to be a structural engineer although I have very little experience with houses (I mostly do bridges) and I’d probably hire an expert myself. This type of modification could potentially be very dangerous. Also (again I have little experience with residential structures) but wouldn’t an alteration of that magnitude require a permit?
What is it you’re doing down there, anyway? If you’re just burying a body, you can safely remove the flooring and the subfloor, and maybe with that gone, you’ll have enough room to do what you need to do. Sure, the joists will be in the way a little bit, but it might still be preferable to hacking out a shallow grave with a trowel while you’re lying in the crawlspace. And even if you have to remove a piece of one joist temporarily, your house is not going to fall down. Just support the free ends of the joist you cut, and when you’re finished, replace the piece, fastening it to the cut ends with steel mending plates.
I’d second this. We were planning on building a house, and the engineer who designed it said that we couldn’t remove more than X number of joists without compromising the structure. (In essence, they prevented the walls from exploding outward due to the downward force of the roof.)
My plans were goofy, but not nefarious. Anyway, it looks like Plan A is ruled out, as there is a chance the joists play a role other than just holding up the floors. That’s why I was asking.
Plan B will involve just pulling the floor and a couple of joists; all to be replaced. I’ve done that before in other houses.
As to what I’m hoping to do: I want to address some problems under the house. The well line and expansion tank and controls are under the house (under the room in question) and are difficult to get at to work on. In addition, there’s no insulation under the house; the floors get cold in the winter and the expansion tank et al are subject to freezing in bad weather. I’ve put on insulation and heating tape, but I’d like to move it all into conditioned space. I’d like to contour and tamp and get a vapor barrier down on the crawlspace floor, which is just dirt right now, and a home to various insects, snakes and occasional skunks. I want to repair/replace/seal the air ducts that are under the house. If I could have done it by removing the whole joist/flooring setup and redoing that from the ground, that would have been my preference, but I can just as well do it keeping the existing floors.
Oh, and thanks everyone! That’s why I was asking before I did anything that might be stupid.
When you go to put the floor back together, you might want to consider framing in a trapdoor so you don’t have to disassemble the whole room the next time the plumbing needs attention.
I’ve never come across tension in the floor joists as a structural design concern. i would expect that the proper considerations for vertical load bearing, which are simple enough will address that concern
Why is a litttle alarm ringing in my head?
In addition to the potentional of earth-wood contact from adding tamped earth to a crawl space, leaving the cut ends of the joists flopping in the breeze is especially ill-advised if it turns out that they really were serving as ties (tension load), have rigid pipe running through or below them (as the cut ends sag, the pipes (try to) stretch…)
Make the holes as small as possible, sister on new joists (nail guns are wonderful toys), and re-create the original structure as closely as possible.
Unless you are a structual engineer qualified to re-engineer the structure on the fly, in which case, go wild.
Your posting here suggests you aren’t, and since nobody here can tell you what those sticks are/aren’t doing there, please make the smallest possible changes.
you’ll probably sleep better, too…
Oviously this is not such a case, but ever here of balloon framing? IIRC, the floor joists were exactly that - ties.
In any case, leaving cut joists flopping… <shudder>
