I have recently purchased a flat roof house (1/4″-12 pitch) that has an issue with the garage. The house is about 35 years old, but roof, including sheathing, was redone about 4 years ago. The garage is a two vehicle style, with two lolly columns along the midline to support the roof. One poll is shorter, and supports the large 6″ wide, 12″ tall header that spans the opening and on which the 2×8-12′ joists rest. The other end of these joists are attached to a 5-6″ wide beam made of plywood and 2×8’s that crosses the entire width, and is supported by the second lolly column in its middle and has its ends resting on the side wall framing. The rest of the distance to the back of the garage is 2×8-12′ .
The issue is that the joists running parallel to the length of the garage are straight, but the two beams to which they attach (the header in front and the main beam in the middle) are sagging about 3″-4″ in the middle across the 20 foot width of the garage. This causes the roof the have a sag in it, which messes with the look of the fascia and gutters and siding immediately under this sag. I would leave it alone and just drop down a ceiling to eliminate the look of the sag, but since the flat roof depends on its slope for drainage, and we get a lot of rain here in North Florida, I really need to take out this sag to prevent standing water on the roof, even if it is only for a few hours. The flat roofs don’t do well with that.
The most obvious solution was to have the fix made when the roof was off 4 years ago, but the prior owner didn’t think about it or care or want to pay for this extra framing work, so he just applied new sheathing and roofing over the incorrect framing, and now we are stuck. I was thinking of somehow securing the ends of the beams tot he framing or to the foundation with some metal simpson strong-tie products, then jacking up the middle and opening and inserting two taller lolly columns. My fear is that after 35 years of sag, the beams won’t flex back right, will lift off the framing, and then I am really screwed. My other fear is that they maybe fracture somewhere, bringing the roof down or just causing the joists which are attached to these beams to break free (not sure exactly how the joists are attached to the middle beam, but it looks like just toenailed on and reinforced by corner brackets on each side of the joist). Does anyone have some advice to my jacking idea?
EDIT: Or would it be easier to just support the roof joists at the header and replace the whole thing with two 2×10-8s sistered with 1/2″ ply inbetween, using the center lolly column as the jack studs for each side like you would if you had two 8′ window or door openings next to each other? And for the center beam, support each side of joists, cut out the center beam, make a new one of LVL or just 2×8’s, again using the center lolly column as the jack studs, and then more officially mend the joists to the beam with joist hangers?
Brian
Replies
Brian
If I understand your situation correctly (and maybe this answer is one of your options mentioned?)
Place whatever you wish to jack up the beams on either side of the existing columns (unsure of your header) and take it up a bit, remove the existing column.
Cut the beam in half at that column bearing point.
Continue to jack up the roof and hope none of the roofing is compromised.
Get it where you want it, insert new column under (correctly sized for that now cut beam)-snug it up, bandaid the now 2 pc beam (full plywood plates well secured to both sides, steel, whatever makes sense. Fasten the column to the beam.
Remove the jacks.
Do it in unison to all beams (and/or header).
Calvin
I could cut the existing header and beam and then jack up the two halves and then reattach to the lally column, but after thinking about how I got into this mess, I am fearfull that the parts will continue to sag even though the middle is raised up. The header looks like one continuous sag, and your idea would probably work there (albeit the bottom of each half would have a curve to it, but the middle would be higher at least), but the beam across the middle of the garage is different. The top of the column where the beam sits is 0.5" lower than the ends, but each midpoint of the two halves on either side of this column are sagging about 1.5" down each. I would raise up the middle very little to make this middle level with the top plate of the framing on the ends, but the middle part of each half would still be sagged, looking like a squashed "w". I really think that my idea at the bottom, involving replacing the header and beam entirely and in turn adding in joist hangers to tie the joists in the middle to the middle beam, would make the whole system more sound and take out sags and with an ~10 span each side of the columns, I could make four sandwich beams made of three 2x8-10s and two 1/2" pieces of ply inbetween with lots of nails and construction adhesive that meet at the column, are supported by a thick (1" or so) piece of steel with lags into the 2x8s, and this would not sag ever. The fact that the existing beam/header are only plywood makes continued sagging inevitable. Don't you agree?
Brian
Brian
I understand better now.
There's sag between the column and the outside wall-more than the 1/2" less ht. of the top of the column and either bearing point at the outside walls.
Check the span of the joists and figure the header necessary to stay straight. Steel flitch plate beams/headers do work if sized properly.
I'm curous -- It sounds like there's already a lally in the middle of the sagged beam, it's just that it's not holding the beam up high enough. Why not just jack it up higher? Do it slowly (over several weeks) and it should cause no other problems.
I was curious...
I was curious why they were called lally columns.
Wikipedia says: "The lally column is named after a U. S. inventor, John Lally, who owned a construction company that started production of these columns in the late 19th century. He resided in Waltham, Massachusetts and Boston during the period 1898 through 1907. He was issued four U. S. Patents on composite columns: #61472, #869869, #901453,and #905888. Pat. #869869 was assigned to the U. S. Column Company of Cambridge, MA."
It also says they are filled with concrete to prevent buckling. I'm also curious as to how many are filled with concrete.
Three.
Hmmm, I was thinking maybe 7.
There's a good chance that beam with a curve in it isn't going to straighten out - I'd bet lunch on that.
When replacing beams rather than trying to do something more complicated to save a little work (that normally doesn't work all that well and actually costs time in the end) I simply make a temp wall out of 2x4's with a single plate top and bottom, spaced with a stud under every joist. It supports the weight and is off to the side out of the way so I can work. The individual studs also allow the elevation of the roof to be adjusted as needed. It doesn't take much to hold up a roof and you'll be surprised how easily it will lift up to where it should be. Don't over think it - just get the wall in, cut the beam out, adjust the studs so the roof is flat and slightly high so the new beam can be installed easily, let the roof down onto the new beam, install simpson clips, remove the rest of the temp wall and you're done.
To raise any individual stud the leverage from a 2' pry bar is all that's needed to lift a stud and place a spacer under it. Personally I use torx head deck screws and screw the top plate of the temp wall to the joists and then once the studs are in place put at least one deck screw in to attach the stud to the top plate or when you lift a section a number of studs will fall out. There's no need to put screws in a bottom plate.
edit: You can't put lally's anywhere - they need to sit on a footer. I honestly don't see you saving anything by avoiding just jacking the roof up with a temp wall and replacing the sagged beam with a staight one.