Expert: Ted Barnhill (Principal, Design45 LLC) - 1/4/2008

Question
QUESTION: Hi Ted!  First, Happy New Year and I hope you start sending us a bit warmer weather than you've been sending us the last couple of days!  I live about 15 miles east of Columbus, Ohio.  I have a 30 year old 2 story custom built home that I had built during the blizzard year of 1977.  I do have the building plans available if you need to see some page from it, I can send you a jpeg of any part of it.

   I have been working with Jim Carlin, another expert on the "allexperts" web page, regarding tiling of my floors (about 900 square foot of tile).   In preparing for the job, I have learned that my floor is not level, and unfortunately is also not flat.   I've fixed the area in my foyer (about 210 sq. ft.) where I removed an original tile floor over a 2" mud base by installing a sleeper floor to bring it up to the same level as the entrance onto my dinette floor.
   However, the floor that comprises the kitchen, dinette, dining room and laundry room all slant to the middle of the floor from all outside edges.  I investigated what the issue is by looking in the crawl space under this area.   What I found was that a 23' long steel I-beam (5 3/8" wide x 8 1/8" high x 1/4" thick) resting on the poured crawl-space walls is bowed downward from its endpoints to its middle.   It is bowed by about 1 5/16" !   The 2 x 10 floor joists 16" on-center run perpendicular to the steel I- beam.  One end of the joists sits on the poured concrete basement or crawl-space wall and the other end on the steel I-Beam.  The steel I-Beam cuts across the middle of the kitchen floor and under one wall of my dinning room. One joist span from the middle of the kitchen toward the outer kitchen wall is a 10' run, and the other run toward the foyer area from the middle of the kitchen across the dinette is 14'.   Both runs are cross-braced with 1" x 4" boards at the midpoint of their runs.   There is a load-bearing wall between the laundry room/dinning room and the kitchen / dinette; and that wall runs perpendicular to the steel I-Beam 10' from the one end of the steel I-Beam.   This load-bearing wall is supported underneath by 2 sistered 2 x 10's that are about 3 5/8" apart solid braced every 16" with a 2x10 piece of lumber.  So, there are a total of (4) 2 x 10's that support the load bearing wall in the floor joists.  (I have a picture of this area I could send to you that would do a better job of showing what I am talking about if you email me at pested@aol.com).
   MY QUESTION IS:  BEFORE I lay the tile on this floor, what do I have to do to either level the floor by some means (like using self-leveling compound), or to raise the floor to make it level or flat?   There is NO support for the steel I-Beam other than the 2 end-points that rest on the poured concrete walls.   I checked my house drawings and discovered that there was SUPPOSED to be a support pier installed midway across the I-Beam span, but it was never put in.   I suspect that is why I now have the deflection I have.
   Is it wise to try to raise the floor supported by the I-Beam and install additional supports, or just install the supports under the I-Beam with everything slanted the way it is, then use self-leveling compound to level / flatten the floor prior to installing ceramic tile (13" square tile layed on the diagonal)?
   I read on the http://www.hammerzone.com/ website about how to raise a floor.  It is involved, but doable by me I believe; even though it would be scary and I would worry about cracking plaster, windows, granite counter-tops, water pipes, etc...   Also, I doubt it is possible to raise the floor by jacking up the steel I-beam; rather, I would jack it up using a long 4 x 6 timber placed on the bottom of the floor joists along side the steel I-beam.   Then, once I got it up to level, I would shim between the floor joists and the I-Beam.
   As additional information, I went into the crawl space today and with the aid of my laser level, I took measurements that show the deflection of the steel I-Beam.  THe measurements of deflection were as follows every 2' a measurement was taken (NOTE: I measured distance upward from the middle which was the lowest point in the span):
(0' Left End) 1 3/8"  (@ 2') 1"  (@ 4') 3/8"  (6') 3/16"  (8') 1/16"  (10') 0"  (12') 3/16" (this is where the load-bearing wall is located at 12')  (14') 3/8"  (16') 5/8"  (18') 1"  (20') 1 7/16"  (21' Right End) 1 9/16"
   Is it really possible that the weight of the floors have made this I-beam deflect by about 1 1/2" over the 30 years that the house has been built?  Or, is it possible that the steel I-beam wasn't straight when it was put in?   It is a 2-story house with conventional shingle roof, 2 x 4 stud walls with drywall applied.   Except for the foyer, all of the floors have been carpeted over 3/4" T&G Plywood up until now.  Only heavy item added to the house were granite counter-tops in the kitchen about 6 years ago.  The cabinets are against the outside walls supported by the poured concrete crawl-space walls; except the island (34" x 66") that sits in the middle of the kitchen directly over the I-Beam.
   Hopefully you can help me with what I need to do to assure that I can flatten my floors and make my subfloor stable enough to tile over while averting any future problems.

THANKS!

Jerry Raack
Pataskala, Ohio
pested@aol.com

ANSWER: Jerry,

Happy New Year to you.  We're warming up fast right now -  looks like we will get a respite from the deep freeze this weekend.

Sorry to hear about your overloaded beam.  1 1/2" deflection is a big sag, and you are right to want to correct it before laying tile.  There is no doubt that the omitted pier is the culprit here.  Your beam is sized to span 12' or so, and not transfer any major point loads (such as your bearing wall that lands about midspan on your 23' beam).  It is very undersized and has deflected over its life.  

Also, the point loads on your crawlspace walls where the beam ends bear are probably more than twice as great as they were designed for.  Do you notice any cracking of the walls or settling of the foundation in those locations?

I assume that your second floor joists bear on the loadbearing wall that you described, meaning that the upstairs floors are also about 1 1/2" out of level over 10' or so (at the center of the house).  If you have clear span roof trusses you probably have noticed cracks in the drywall at the ceiling/wall joint over time.

I agree that jacking up the beam is unlikely to straighten it out.  It has deformed under the severe load, and probably continues to deform more and more over time.  I recommend at a minimum that you install the center footing and pier as originally designed, so that the problem does not get any worse.

If you are not troubled by the uneven floors upstairs, you could go with floor leveler, though you will need a lot of it!  You'll have to reinstall any base trim, and possibly cut or rehang doors, etc.  Properly leveling the floors by raising the joists would also probably require, as you mention, additional finish work, but the result would be a home with all rooms more or less level.  From your description I don't see a reason to fear window or plumbing problems, but by all means have a local contractor experienced with floor raising take a look at it if you are uncertain.  You may want to remove and later reinstall your granite counters if they are likely to move much.

Given the extent of your problem, it is probably well worth finding a local structural engineer to look at your beam and footer sizing, and visually inspect the beam for signs of failure.  The hourly rate for such a consultant is, in my experience, always worth it.

Good luck, and feel free to follow up with additional questions. -Ted




---------- FOLLOW-UP ----------

QUESTION: Ted,
 Thanks for the quick answer.   Unfortunately it was what I expected: that I have a real problem to solve before I move on.  I have 2 followup questions if I may.
1. If I go to put in a support pillar under the middle of the span, what should the dimensions of the bad under that support be?  I'll get to work on that if I can get an idea how big a pad to mix and pour in the crawl space.   Working there is no fun due to the low overhead (just 26" of space between the bottom of the I-Beam and the top of the 4" of gravel under it).
2. Should I get a short Lally Column to hold it up, or build up a column made of cement blocks to hold it up?
3. I assume I should get a bottle jack and try to raise the steel beam a bit to put in my column so I get a really tight fit initially to stop any further movement of the I-Beam?
4. You wrote " I don't see a reason to fear window or plumbing problems" if I raise the floor.  My biggest fear is developing a leak in the copper plumbing.  There is an upstairs bathroom directly over this steel I-beam.  If I raise the floor an inch or more, why would I not run into problems with cracking joints of the copper tubing?   Is it because the entire copper tubing setup raises the same amount as the walls and hence "stays in place" relative to everything else that is moving?
4. Last, how would I go about finding a good structural engineer here in Columbus, Ohio area to give me some advice? I looked in our huge yellow-pages directory under the heading of "Engineers - Professional Guide" and they have lots of types listed.  Do I need a Structural Engineer, a Civil Engineer or an Architect?  And, among these areas, how do you find someone I know I could trust?  Is there a rating system of some sort?
Thanks,
Jerry

Answer
Jerry,

Finding a good structural engineer will require calling through the phone book, or asking any contractors you may know for references.  You want a Structural Engineer with professional registration (their name will be followed by P.E.).  Some firms and individual engineers routinely work hourly with homeowners, while others take on only commercial projects or work on residential projects on a  of construction cost or flat fee basis.

If your existing plans don't show adequate structural information for the pad and column, I recommend that you have your local engineer size these elements.  Your pad may be in the ballpark of 30" or 36" square (12" thick), and a lally column should be fine, but have your engineer do proper structural design.

You may want to have an experienced contractor weigh in on your plumbing issues.  Normally, as a structure like yours is moved or leveled (slowly!) there wouldn't be any point where pipes would shear, as the change in geometry is very slight in any location.  However, this may not be the case if your roof is clearspan or you have other special conditions.

Good luck, and again, feel free to follow up if you'd like.  -Ted