I’m starting a job shortly where I’ll be replacing a pair of failed 2×10 garage door headers. Both headers sag about 1 3/4″ over a 9′ span. Had the whole thing engineered and will be installing triple 9 1/2″ LVLS.
My question… how much, per day, is it safe to jack the floors up? I was thinking somewhere around 5/8″ per day over three days. Is this too fast? Above the garage is two bedrooms. Oak flooring to be installed as soon as I’m finished. One double mullion window (sticky but functioning) resides in the wall above the garage door openings. Already warned the HO (verbally and in the contract) that cracking of the plaster above may occur.
Thanks for your help in advance,
Brian
Replies
Just bumping this back up....could really use a little advice regarding time frame :)
Did A similar repair a couple of years ago and we jacked up 2" in a couple of hours. There were a couple of minor hairline cracks that a coat of paint fixed up. Personally I would rather expect a few cracks and get the job done than waste a couple of days and still maybe get cracks.My experience tells me that plaster isn't very flexible. But if minor damage is a major headache I'de try half an inch a day, but still tell the client to expect cracks. Anyways good luck . cheers
.........Rik.........
If you don't want the plaster to crack, I'd say 1/8" per day sounds more reasonable.
But as someone else alread pointed out, there's some value in just getting it done and getting out of there.
Bumpersticker: I brake for…wait…AAAH!…NO BRAKES!!!!!
I did this about 10 years ago, only it wasn't a tuck-under, so I didn't have to be too careful about how rapidly I did the lift. (Ours was also sagging over an inch, but in the 16 foot span, with two 2x14 headers. I used 4-5 cheap adjustable lolly columns to do the jacking.)
But from what I've read/seen elsewhere, doing it over 2-3 days (turning the screws 2-3 times a day) would probably be reasonable. Be sure to unlatch the windows and open them slightly (a half inch or so) to minimize stress on them.
Think about how you're going to pluck out and replace the beam. I had the luxury of doing this while residing and was able to do it from the outside, the only "pain" being that I had to tear off some stapled-on brownboard sheathing first. Also, a Sawzall was required to cut the nails, of course.
If you try to replace from the inside you're going to have your jacks in the way. Doable, but a pain. Also, keep in mind that the door must be closed throughout this operation, and cables may be in the way. Removing one of the doors (or just the top couple of panels) may be helpful to allow you easy access.
In my case, I let it down on the new LVLs, measured the sag, then jacked it up and shimmed up the middle that much, resulting in a perfectly straight opening. That may be more than you want to do, but probably adding a 1/4" or so shim in the middle would be reasonable.
Just completed the job that this thread was in reference to. Found a few things I thought some of you might find interesting. First of all I did jack it up over a few days. I jacked it up about 5/16" every twelve hours for three days. This really wasn't a hassle cuz it's right around the corner from my own house. Once I got set up, I just swung by on the way to work, jacked a little and reset the screw jacks, and then went back after dinnertime and did it again. We still managed to get a few decent size cracks around the headers of each double mullion and a couple of minor cracks at blueboard seams in the bedrooms upstairs.
Figured out why 2x10 headers failed easy enough though! The 2x10's were just set flush to the outside of the frame, inside and out. No 1/2" ply in between, and no nails "sistering" the two together. Same thing in both openings. Just two 2x10's acting independently of one another grinning at the street. Also found zero building paper under all the Masonite siding. No flashing over the garage door trim. No footings under the jacks holding up the garage headers. No anchor bolts on the stem walls connecting the concrete to the framing. No PT sills or sill seal in garage.
These are very nice split-ranches in Natick, MA. They go for about $400,000 and are only about 10 yrs old. Some butcher made a killing whipping up this development. Now I'll get to make a killing fixing it all. What a waste of money for unsuspecting homeowners though huh?
On a high note, the HO was thrilled with our work and wants us to give him a price on stripping the Masonite, installing Hardi-Plank and housewrap, and replacing all his windows. Neighbor wants a new deck. Man, I love the spring!
The things I've found that help are to start by raking out any existing cracks in the plaster, and pulling the baseboard above where you're going to jack, and raking out the plaster to maybe 1/2" above the top of the sole plate. This minimizes the transfer of stress to the plaster.
-- J.S.