Options for removing lally column(s)
My wife and I are considering a basement remodel and we are limited in our options because of a few lally columns – one or two of which we would, potentially, like to remove.
I don’t have the blueprints for the basement but I glued together what I could from different plans we have and I think the attached image is pretty clear.
We have two 10″x10″ solid wood beams running the length of the house (top to bottom in the image). Originally, both sat on brick columns but the ones on the right were replaced some years ago with three (3) steel lally columns (placed 8′ apart). The basement ceiling is currently uneven (due to ductwork and plumbing) but is betwen 7 1/2 feet and 9 feet high. The house has four (4) floors, including the basement and is located in New England.
The bottom of the three columns is the one we really want to remove, if possible, but we’d love to remove the middle one as well.
What options, if any, do you recommend?
Replies
You can't just remove lally columns because they are in the way since they support loads from above. As long as you replace the support they provide with some other type support like a structual wall you'll be fine. I'd certainly want an engineer involved in any case since you probably will need a footer as well.
florida,
Thanks for the reply. I was looking for specific suggestions.
I'm making this up based on stuff I don't really understand but read elsewhere on this forum, but something akin to "Based on your span, you probably want a C-Channel on the bottom and some flitch plates along the side with some LVL something and bonded something else..."
What is above that beam? Any walls on or near that beam on the floor above?
The beam (and a corresponding beam above the brick columns parallel and to the left) hold up the house. They rest on the foundation walls at the top and bottom of the picture.
There are wood rafters (?) resting on this beam and the base floor of the first floor rest on those.
There is no question that this beam is load bearing - it, along with it's sister beam, carry the entire load of the house. While I think "astronomical" is an exxageration, the weight on the beam is certainly substantial.
That said, the beam itself is quite large and I have been in buildings with much larger spans and higher ceilings (e.g. any hotel ballroom). It seems to me that it's a matter of materials and bracing (e.g. presumably a sufficiently thick I-Beam wouldn't need any lally columns).
To be clear: I am not asking for a simple "You should do XXX." I'm asking for "You should look into YYY and the people who do that." If YYY is simply "removing lally columns", so be it. I guess I was hoping for a bit more detail
Of course there are always options to clear span any distance. It depends on how badly you need the open space and what your budget is. What you are hearing from multiple sources is that you need an engineer to size the beam for your particular situation as the loads of the building above need to be taken into account. The new point load then needs to be borne on the foundation- all which is too much information for this group.
At the very least you need someone with considerable knowledge of construction techniques to analyze and understand what you have. Someone who can look at it, visualize the structure overhead, and come up with a reasonable plan. This involves not just the structure itself, but the techniques required to replace things without having it fall down as you're doing it.
I will echo everyone concerning the need for an engineer licensed in your state to look at the condition and provide recommendations.
As far as general guidance, for a 16'-18' span supporting 3 floors and possibly some roof, you will almost certainly need a steel beam in lieu of wood. Here are a few things to consider
-Getting an 18' steel beam into place in an existing basement can be difficult to say the least (800 # or so and the beam would have to be in one long section)
-The new beam will likely require new posts @ each end and new foundation elements to carry the higher load
-The existing construction would have to be significantly shored prior to removing the posts. This would need to be carefully thought through by your engineer, or licensed contractor - not a do-it-yourself kind of job.
-Headroom could be a problem if this beam is going to run under the floor joists - I would expect 14"-16" beam depth for planning purposes for the case of removing 1 post. For installation ease, the new beam would probably have to be installed underneath the existing floor joists, allowing them to bear on top of the beam.
Clear spanning the whole basement would likely not be feasible. Hotel lobbies ect. with large open spans generally have steel or structural concrete framing and plan for much more room for structure depth than you will have in your home. A (slightly conservative) rule of thumb for steel framing is to expect a little less than 1" of depth of structure for every 1' of span, so for your 33' span you would have around a 24" to 30" deep beam. This beam would have to be continuous and would weigh around 2500#! Good luck getting that guy in place!
The part about needing an engineer was the best suggestion you're going to get. Nobody on the internet can spec something that important with a full understanding of the loads involved. Assuming you're in a jurisdiction that requires a permit you will have to have an engineer design whatever support you will need.
The point is, columns that large and regularly spaced are likely supporting a substantial load. Even if there was only one floor above, the load could be quite large, and with three floors above it's pretty much astronomical.
Likely the same sort of deal that was made for the right-hand columns could be repeated here, but it requires careful calculation and planning.