sagging floor joists over tuck under garage

[sun Drop]

I am a homeowner wondering how to fix this problem.

My house is a trilevel / split level built in 1979. Half of house is built on a standard block foundation with a basement --- living areas and kitchen above.

The other half is built on concrete slab. Family room, half bath, entry foyer and 2-car garage are below 3 bedrooms and 2 baths above.

The bedroom floors that sit above the 2 car garage are noticeably sagging. The wood species used for joists (that I could observe from the basement--can't see the ones in the garage ceiling because drywall is covering the joists) is SPF grade 2.

The joists are spaced 16 oc with a span just shy of 20 ft (19' 10 or 11"). The ends of the joists sit on an exterior wall at the front of my house, and an interior stud wall constructed of 2 x 6 24 oc. I checked the AWC span calculator, and the joist size and spacing are just barely enough support for live load 30, dead load 10. We are using one of the bedrooms as an office. Still, I suspect the live load in our daily use is probably closer to 40 psf, and that might be the reason for the sag. According to the caluclator, with live load increased to 40, max span for the joists should be only 17' 10".

I live in PA, and snow load on the roof is an issue in the winter. The roof currently has 2 layers of asphalt shingles.

How can I solve this problem? The garage has one large double sized door and an electric opener. Is there any way to support the floor from below, and still have the functionality of my garage door and opener? Or does the garage ceiling have to be opened up and the joists reinforced somehow? And what about fire safety and insulation in this ceiling, since bedrooms are above?

I really don't know what sort of professional to call to handle this sort of work, and how to make sure I'm getting someone competent. (have had some bad experiences with contractors in the past, even though they came highly recommended)

Also, I would like some idea of what it might cost to do this work, so I can budget for it.

Sun Drop

[Richard A Hetzel]

You don't say what size the joists are, and you don't make clear whether any roof load is carried by the joists. Those are two critical issues, without which no comment is possible.

Where in Pennsylvania are you located? If you're near me (Tobyhanna, Monroe County), maybe I can come and take a look at the house, and then give you a better idea of what to do. No charge for the visit, and an hourly charge if you ask me to design a remedy.

But answer my questions if you can, and maybe further help is possible here.

[sun Drop]

The joists are 2 x 12s, 16 oc. There is a second floor above (bedrooms) and the roof above that. The ceiling joists run perpendicular to the floor joists and support a gable roof with a slight slope (3/12 or 4/12). Actually the house has two roofs -- one over each side of the split level. Plus a small porch roof in the front.

I'm not entirely sure, but I think the celing joists above the bedrooms are 2 x 8s. They are 24" on center. There is attic access, but there is no floor up there, just insulation.

One bedroom is entirely above the garage. A second bedroom is half over the garage, and half of the ground level entry foyer adjacent to the garage. In the third bedroom, there is a section of floor -- about 4 ft x 12.5 ft that sits over the garage. In all these areas, the floor is out of level and sagging toward the middle of the garage ceiling. It's not readily visible to the naked eye, but I can feel the slope in the floor, and even some edges of the subfloor, especially when I walk over the floor without shoes on. All three bedrooms have wall-to-wall carpet, and the subfloor is 3/4" plywood. There are a lot of squeaks in the floor, but I know that's just because the boards were nailed down--not screwed. In fact , downstairs in our living room we recently had hardwood floors installed, but we went around with a screw gun and secured the squeaks with deck screws. Lots of them.

Do you still need more info?

Sun

[Richard A Hetzel]

Those joists, at full design load of 30 PSF live load plus 10 PSF dead load, at a span of 19'-10" on 16" centers will deflect about 3/4 inch. If, as I suspect, some attic load is carried on the joists also, there would be even more deflection. You don't usually get a full design load in practice, so maybe your joists have deflected somewhat less...maybe about 1/2 inch? Or if there is some attic load, maybe back to 3/4 inch. Do you have any way of measuring the deflection? I imagine the garage floor is pitched, so measuring up from the floor might be unreliable. However, 3/4 inch would definitely be noticeable.

How to fix it? Probably the best way would be to remove the garage ceiling, and jack up the joists, using a temporary beam near their mid-span. When they are jacked slightly above level, sister them with full-length 2x12's, installed with the crowns up. Then let down the jacks and remove the temporary beam.

The garage ceiling should be 5/8-inch type X gypsum board, with all joints finished with joint compound and tape.

Cost? Hard to say...it's fairly labor-intensive. I hate to send you back to contractors when you've had bad experiences with them, but they are the best places to get prices. Maybe your bad experiences were because the contractors were not given drawings showing them exactly what was expected of them...that is the best way to get good prices and good results. Ask around about architects in your area, and select a good one, and get the recommendations on paper in full detail. Then you might get better results from a contractor.

[sun Drop]

Richard-

I can't really notice any sag just by looking at the garage ceiling. And you're right, my garage floor is sloped toward the center where there is a drain, so I can't compare measurements from the floor up to the ceiling with any reliability. When I hold a level up on the middle of the ceiling, the bubble is right between the lines. It doesn't budge much even when I move to either side of the middle either.

By the way, I don't know what the ceiling panels are made of. Every wall and ceiling board in the garage is painted white. At one time they were probably taped, but now I can see every joint between every board in the entire garage. The boards are nailed up, and some of the nails heads seem to be brown with rust.

The floors above the garage have a noticeable slope when walking across them. I don't know if everyone would notice it, or I'm just sensitive to it.
Here's a thought: is it possible that the joists are OK but the floor boards are bad/warped? But then why do I only notice it over the garage area? The garage is unheated. Maybe moisture or humidity are a factor.

Should I be concerned that my bedroom will end up in my garage, or is this just a minor annoyance I can learn to live with?

We need to replace the carpets upstairs in the not too distant future. Is there anything we should look for and/or do to make the floors more level from above, rather than below?

Sun

[Richard A Hetzel]

Your bedroom will not end up in the garage.

It's probably more the joists than the floor boards. The joists are at their absolute span limit, so they can be expected to deflect a great deal. I would leave the garage ceiling alone.

If it really annoys you, there are self-leveling cements that can be poured on the floor before the carpet is installed, but maybe once the carpet is in, you won't notice the deflection that much.

Only you can decide whether the annoyance is minor or major.

[sun Drop]

Yeah, that's kind of what I thought. Too bad the builder didn't space the 2 x 12s at 12 oc instead of 16 oc. Then it probably wouldn't be an issue.

Never thought about floor leveler. I'll keep that in mind. But maybe if I get nice cushy carpet padding, I won't notice the irregularities.

I feel better now that I know there's no real danger of collapse :-D

Thanks