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Installing a lally column or support post

QuestionI live in a very old house; the basement has square brick lally columns with old steel lally columns placed right beside the brick columns. The brick is disintegrating, and I would like to eliminate the brick columns altogether and replace both the brick and steel lally with just one new steel lally. What type of steel lally would you recommend? Also, what should my concerns be (if any) about how to shore up the area we are going to be working in? I plan on finishing it and use it for laundry, etc. I don't want the house to cave in while we do this.

AnswerWhile this appears to be a complicated project, it's really quite simple but it does require many steps in order to complete it. Before doing anything, check to see if the beam is split on the brick support or the steel support. My guess is it's on the brick, and the steel support was added later on when the brick was not stable enough to hold the beam in place. Locate the split because that's where you will need support. What if the beam isn't split? The support is usually placed in that location because the beam cannot span any additional length. Now that I've said that, go visit your building department and get a building permit. The new steel post needs to be properly sized and may require engineering. The engineer may also detail the footing requirements.

Look at the beam to see if it's sagging; if so, this would be a perfect time to jack it back into place using a hydraulic jack and a 4x4. Put the jack as close as you can in this area while leaving yourself enough room to work. Then build two temporary walls to support the beam. You can use 2x4's for the walls. Build them to fit—put a bottom plate on the concrete floor and nail a top plate to the header. Then cut your studs to fit and place them 16" on center; toenail in place. Position these walls under the beam so there is one on each side of the brick column as close as you can but, again, leaving some room to work.

The idea here is to support the beam so you can remove both the steel pole support and the brick column. After they have been removed, locate the seam. Hang a plumb bob at the seam and center it on the beam. Now lower the plumb bob until it reaches the concrete floor. Have someone mark the floor for you. Draw a circle on the floor that will accommodate a 12" diameter tubular fiber form or the size specified by the engineer. Now rent a rotary hammer and break up the concrete in this area. Undermine the concrete by removing the dirt using a garden spade. This will allow you to use a 5 lb. hand sledgehammer to break the concrete. It's OK if you break the concrete larger than the tubular fiber form. Now remove the dirt to a depth of at least 28" or the specified requirement from the engineer. Fit the tube and drop it into place so the top of the tube is just below the concrete slab. Purchase enough premix concrete to fill this tube; the side of the premix bag will feature a chart that will tell you how much concrete to use for your size of tube.

Mix the concrete in the basement in a wheelbarrow, and use a shovel to pour it into the tube. Let it dry for about a week. Now measure the distance between the top of the tube and the underside of the beam. Take this measurement, and a measurement of the width of the beam, to a steel fabricator so they can make the post for you. Make sure they add a base plate at the top and bottom of the post and that the plates are predrilled with 3/8" holes in all four corners.

Place the finished post on top of the new concrete footing and underneath the beam and level it vertically from two sides (you may have to use steel shims). Once you are happy with its position, mark the holes at the top and the bottom of the plates. Remove the post and pre-drill the beam so you can use at least 2" lag screws. On the bottom use a rotary hammer to put in lead lag shields in the four holes that you drill. Finally you can put the post in place and install the lags at the top and bottom. Do not tighten until you have all the lags in place.

When things are secure, go ahead and remove the two temporary walls. Then go back and put concrete into the hole around the post in the floor. Flush the new concrete to the existing floor concrete.

Pole-Wrap Now you can finish the floor and the header. The post can be wrapped with Pole-Wrap, which eliminates the need for a box around the post. You might have to build a decorative piece to cover the base plate at the top before installing Pole-Wrap, and after installation you can paint or stain Pole-Wrap to match the room.

Classic Column

Another product designed to conceal a lally column is Classic Column's Tuscan-style ABS caps and bases. Hollow PVC pipe is split lengthwise to encircle the structural support post and then is dressed up with a decorative cap and base.

Copyright © 2002 & 2005 LAF/C.R.S., Inc. All rights reserved.
Question answered by Leon A. Frechette.

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