joistsstructural
I have a two story house and some of the joists between the floors are sagging about an inch or two. When I walk around upstairs I can feel the level difference and downstairs you can slightly see the lines of one or two joists in the ceiling. These joists happen to be the ones our bed is on so I'm guessing that is the cause. There aren't any cracks or gaps anywhere. I'm not sure how concerned I should be, and if it's normal or needs to be fixed.
oh, the house is around 30 years old.
Q. Hard lines are the walls on the first floor underneath, joists on the first floor landing run left to right so does that mean the central wall running front to back is 'load bearing'?
If your house is in the UK (which I'm guessing it is), then without a doubt the central wall running from front to back is load-bearing.
Q. Initially I thought of putting 8x2s front to back, supporting them on internal walls where possible. Problem is that the angle of the eaves would not allow me to rest the ends on anything substantial so could I just bolt them to the rafters as long as they were supported by the walls downstairs too?
Refer to this question here on SE, and read all the answers and comments found within.
Running parallel to the existing ceiling joists is the easiest and preferred way to go.
Removing the binders "locally" to allow the new floor joists to pass is "normally" considered acceptable (then connecting/pinning them back to the new joists passing through), though you would want to check such a detail with your local Building Authority before doing so.
Otherwise if you go the other way (perpendicular), you end up going above the existing ceiling joists, which causes a major re-work of the existing wall plate area that sits on the exterior wall and the roof area above.
Q. Then I got thinking that I'd need to go left to right .. a) because the load bearing walls go down the centre of the house and b) because if I don't the ceiling binder will be in the way. Same problem however with regards to getting the joists to sit on the external walls and I'm guessing I'm not allowed to bolt a plate to the chimney wall and hang things off that.
Whatever you do, do not connect anything to the chimney wall. Doing so is an absolute no, no in the UK (if I have your location correct).
Again, refer to this question here on SE, and read all the answers and comments found within.
Of course another option is to remove the existing ceilings (lath and plaster), binders, etc. Leave the existing ceiling joists and install new appropriately sized floor/ceiling joists parallel to the existing, then fix a new plasterboard ceiling to the new joists. Granted, such an option adds considerable mess to the job, and a reasonable cost increase.
Since you can get to the floor from underneath, you can shore up the flooring by adding new joists between the existing ones. This will not be a FUN process, but the process is simple enough, just labor intensive.
First, add cross braces between each joist at each end, of the same dimensions as your existing joists. You'll want them to be snug fitting between each joist, and well supported with joist hangers.
Now, between each brace, halfway between each existing joist, hang new joists to fit between the cross braces you added. Before you permanently hang the joists, prop them up from beneath with 2x4 temporary posts to force the tops up to be level with the tops of the existing joists (pushing the flooring above back into shape), then secure them permanently in place with joist hangers.
Add blocking between the old and new joists as well, to ensure the new joists don't warp/twist.
See the pic attached to help clarify what I mean
Best Answer
A properly sized floor joist should never deflect. Is your bed a water bed?. Joists are supposed to be sized to handle a minimum of 60 to 80 pounds per square foot, which is actually a lot, since loads are distributed across the entire span. If you are seeing ridges, cracks, or movement under load, you have a problem. I have seen joists wain, crack or even fracture at a fault in the wood grain. If this situation has gotten worse, or happened suddenly, I would seek a pro to take a look. Don't want to scare you, but this is not normal and warrants further investigation. This is not a job for an amateur.