# 3.5" lally column vs 6"x6" post



## shadetree (Aug 31, 2011)

Is there any structural advantage to using a 3.5” steel lally column VS a 6”x6” pressure treated post for supporting a girder made up of 3x 2”x12”s? I'm replacing an 83” x 3.5” lally column because it's poorly engineered and was going to build a brick pier, however several people suggested to go with a new steel lally column instead. I am having trouble locating a good steel supplier locally, and if a 6”x6” can support a similar load to a 3.5” lally, I'd prefer the 6”x6”s as they are much more readily available and cheaper.


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## gregzoll (Dec 25, 2006)

One is made out of steel, one is wood. One is smaller, and the other is larger. Wood shrinks over time, steel doesn't.


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## joed (Mar 13, 2005)

wood rots. Steel rusts.


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## Jackofall1 (Dec 5, 2010)

The question that I have to ask, is, what foundation are you intending on putting under the column?

Replacing a column due to poor engineering, could you enlighten us on how it was determined to be poorly engineered.

Mark


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## jomama45 (Nov 13, 2008)

Most 3.5" steel posts I've seen are rated between 15-20,000 pounds load capacity. I highly doubt a 6x6 comes remotely close to this. I know it can be a mis-leading topic here at times, but you DO NOT have to used a custom, built to length column post. A steel post with screw jack at the base is code compliant as well, as long as it meets the min. rating you need.

As stated above, it is critical that the post sits on a legitimate footing, not just the floor.


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## shadetree (Aug 31, 2011)

Jackofall1 said:


> The question that I have to ask, is, what foundation are you intending on putting under the column?
> 
> Replacing a column due to poor engineering, could you enlighten us on how it was determined to be poorly engineered.
> 
> Mark


It's just a crappy home-made column, the cap is far too thin for the load it's carrying and the top is also about a half inch out of alignment from the base. I was planning on leaving the foundation as is, it's about 12" thick and I'm not moving the post that is already there, just replacing it.


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## shadetree (Aug 31, 2011)

jomama45 said:


> Most 3.5" steel posts I've seen are rated between 15-20,000 pounds load capacity. I highly doubt a 6x6 comes remotely close to this. I know it can be a mis-leading topic here at times, but you DO NOT have to used a custom, built to length column post. A steel post with screw jack at the base is code compliant as well, as long as it meets the min. rating you need.
> 
> As stated above, it is critical that the post sits on a legitimate footing, not just the floor.


I'd read on a few manufacturers websites that the adjustable Jack-Posts could be used in permanent installations, but it seemed like the adjusting bit would need to be entombed in cement for it to meet code. Is there another way of securing the adjusting mechanism so that the column remains at a fixed length? What would pouring a proper footing entail? Could a footing be poured on top of the foundation or would I need to cut though the slab? The slab is about 12" thick above grade.


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## jomama45 (Nov 13, 2008)

shadetree said:


> I'd read on a few manufacturers websites that the adjustable Jack-Posts could be used in permanent installations, but it seemed like the adjusting bit would need to be entombed in cement for it to meet code.
> 
> Yes they should be encased to lock them in place. Doing so usually takes alot of load off the screw as well & makes them far more stable.
> 
> Is there another way of securing the adjusting mechanism so that the column remains at a fixed length? What would pouring a proper footing entail? Could a footing be poured on top of the foundation or would I need to cut though the slab? The slab is about 12" thick above grade.


if you're saying the footing is ABOVE or at floor level, then I would suggest using a fixed height post. Here's a manufacturer that may help you out:

http://www.tigerbrandjackpost.com/fixed.htm


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## shadetree (Aug 31, 2011)

jomama45 said:


> if you're saying the footing is ABOVE or at floor level, then I would suggest using a fixed height post. Here's a manufacturer that may help you out:
> 
> http://www.tigerbrandjackpost.com/fixed.htm


I'm honestly not sure there is a footing under the post as it. Right now the post just rests on the flat slab, no bolts or anything. Could an footing be poured on top of the slab to entomb the mechanism for an adjustable post?

I may be going back to just building the column out of cinder blocks :001_unsure:


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## 595287 (Jan 4, 2010)

All supporting members need an adequate footing designed to carry the load exerted on them. The first you should do is determine whether there is a footing. Sometimes when the basement floor is poured the ground where the support columns will rest is dug out to create thicker footing areas within the slab. This is rare. Usually the post footings are poured along with the perimeter footing or shortly thereafter but prior to the basement floor. Then later after the 1st floor is framed, etc., a basement slab is poured over the footing, encasing the base of the post in place.

So first determine whether you have a separate footing for the post and the footing is the proper size and thickness. That the post has supported the girder and presumably the girder, floor, etc. is structurally fine, likely you have a footing and the post was adequate. Just better to check.

As for steel posts vs wood, I like steel because they can be installed to remain adjustable. The issue is that you need a plate that fully supports the entire built up girder (three 2x12's I believe you said). If you used a 6x6 the surface area would fully cover the cross section of your girder.

With steel posts, be sure to get one that is on continuous piece of tubular steel, not the kind comprised of two 4' sections that fit together with pins. These cannot be used as permanent support per code.


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## Clutchcargo (Mar 31, 2007)

What you want to replace it with is a cement filled steel post. This is available at any big box store. Just cut it to length. As all have said make sure there's a footing for whatever you end up with.


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## shadetree (Aug 31, 2011)

Clutchcargo said:


> What you want to replace it with is a cement filled steel post. This is available at any big box store. Just cut it to length. As all have said make sure there's a footing for whatever you end up with.


Not down here, the closest thing to structural steel posts at HD/Lowes/ect are 3" galvanized posts for something like chain link fencing. I guess it's because no one here has basements.


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## gregzoll (Dec 25, 2006)

shadetree, they should have them in the building supplies area, or be able to order it. I have to go out to our Lowe's this weekend, along with the Home Depot next town over, so I will look and see if they have a SKU# on the lolly's at either one. I know that the Home depot stocks them, where the rebar and concrete supplies are. Lally Corp has a 800# on their website, but does not give a list of retailers. Here is what homedepot.com shows for "jack" posts http://www.homedepot.com/Building-M...ID&omni=c_Post-Frame Materials&searchNav=true


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## joed (Mar 13, 2005)

8 foot lally from HD
The Dean Column 8 ft. Lolly Column is 8 ft. in length and cannot be adjusted for security. The post can be used in numerous situations to support up to 14,000 lb.

* 8 ft. length
* Can support up to 14,000 lb.
* 3-1/2 in. width
* Not adjustable
* MFG Brand Name : Lally Column
* MFG Model # : 128330
* MFG Part # : 128330


http://www.homedepot.com/buy/buildi...ts/lally-column-8-ft-lolly-column-129996.html


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## shadetree (Aug 31, 2011)

They don't sell those down here. If I put somewhere else (I tried Boston), it'll have the pickup in store screen like what one would expect. However, all the stores in Austin, it just says "This item is currently not available in your local store." I tried calling 3 different stores around Austin and they said that the SKU & model number number weren't coming up in the system. None of the people I spoke to seemed to know what a lally column was either 



joed said:


> 8 foot lally from HD
> The Dean Column 8 ft. Lolly Column is 8 ft. in length and cannot be adjusted for security. The post can be used in numerous situations to support up to 14,000 lb.
> 
> * 8 ft. length
> ...


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## gregzoll (Dec 25, 2006)

Check with the local builder supplies http://search.yahoo.com/search;_ylt...supplies&fr=att-portal&toggle=1&cop=&ei=UTF-8 They are the ones that are going to have them. I know that it is not the norm to have basements and crawls in Texas, but yes, you should be able to get them.


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## shadetree (Aug 31, 2011)

Lack of success with that hunt is what lead me to originally consider brick or wood. Since wood can't support the load, and I can't find a steel post locally at a reasonable price, looks like I'm stuck building this thing out of brick or cinder-blocks.



gregzoll said:


> Check with the local builder supplies http://search.yahoo.com/search;_ylt...supplies&fr=att-portal&toggle=1&cop=&ei=UTF-8 They are the ones that are going to have them. I know that it is not the norm to have basements and crawls in Texas, but yes, you should be able to get them.


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## gregzoll (Dec 25, 2006)

Structurally, I wouldn't do it out of brick or concrete block. And yes, the columns are expensive. There is a reason why they cost that much, especially for the Lally's. For the cost to build it out of brick or block, for time & materials, it would be cheaper to get the proper steel support column.


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## shadetree (Aug 31, 2011)

gregzoll said:


> Structurally, I wouldn't do it out of brick or concrete block. And yes, the columns are expensive. There is a reason why they cost that much, especially for the Lally's. For the cost to build it out of brick or block, for time & materials, it would be cheaper to get the proper steel support column.


If the columns were priced reasonably ($40-$50) like what I found they are in other states, I'd agree with you. Honestly, if the $40 post joed listed was available at HD, I'd just buy that and call it a day; but the cheapest ones I've found so far would be getting them custom built at a fabrication shop for about $120. It'd be much cheaper to build a cinder block pier and fill it with cement, around $45 or so. 

I'm going to try calling some more steel fabrication shops tomorrow and hope for the best.


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## gregzoll (Dec 25, 2006)

Check the habitat store in your area, or with a shop that does stuff like custom steel work. They may be able to spec out the proper piping with plate for you. Or even check e-Bay. Some local contractors also may have some lally's left over from a job, that may advertise them in a local shopper. Right now I have an offer for a Lally from a friend for my use, but it needs a new plate welded to the screw part.


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## WillK (Aug 29, 2010)

Making the strength calculation in the most conservative manner possible, the load bearing capacity of a 6x6 column:

Using the lowest strength value from the wood species with the lowest strength, pine, the calculation would need to use 960 psi for strength

Calculating 6x6 cross-section with 5.5" x 5.5" you get that a 6x6 post can support 29,040 lbs of load.

Wood shrinks and grows with changes in humidity. Ideally you would want basement humidity controlled, but if there isn't control measures like vapor barriers, drainage and if you have seasonal climate variation, then you might be more prone to seeing the colum shrink and grow.

Ideally you'd want to have whichever column you use anchored top and bottom. 

If you're talking about the existing column being not vertical, you're sure there isn't anything shifted?

Adjustable columns - just want to be sure something is clear. The columns with the screw adjustment are allowable. The ones with the telescoping columns held together with the 2 pins and the screws adjustment, those are only for temporary use and not permanent.


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## shadetree (Aug 31, 2011)

This post would be in my garage, humidity remains about the same year round, but there is a 60-70 degree temperature swing from summer to winter.

The girder has most definitely shifted, however it doesn't appear to have moved any more over the past year. Here are some photos from when I was asking about a brick pier http://www.diychatroom.com/f19/replacing-support-post-115912/#post719498

I think the reason the girder is bent is because the previous own had the column about 2 feet from where it is now, making a 10 foot & 15 foot span and the girder warped over the 15 foot span. 



WillK said:


> Making the strength calculation in the most conservative manner possible, the load bearing capacity of a 6x6 column:
> 
> Using the lowest strength value from the wood species with the lowest strength, pine, the calculation would need to use 960 psi for strength
> 
> ...


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## WillK (Aug 29, 2010)

Looking at that other thread, things don't look right at the beam to the point I'd be considering whether the beam might be in need of rebuilding. I might just be crazy.

A problem of the current structure is that spanning 25 feet with a single mid-span support means that necessarily all 3 boards need to be spliced mid span. Splices should be over the post, and there shouldn't be splices on 2 boards that are next to eachother. I don't know if there are exceptions to that rule, I'm a lay guy and those are the rules I'm trying to stick to in my own project.

At any rate, your diagram from the other drawing seems a little odd, but I believe you might be able to get 20' lumber from a yard if you were configuring as shown so that you could span the 12' and 8' span with a single board, then the rest you'd be able to work with 12' and 14' lengths that are usually available at the big box stores (or get them from the lumber yard at the same time anyway)

More ideal might be to replace it with a steel I beam.

Ultimately, I really think a structural engineer ought to be consulted... For reference, I did that with my project of adding posts and beams in my crawlspace and for $500 I got him to come out, inspect the situation and provide plans. A project like this ought to be done on permit, and plans approved by a structural engineer is likely to be a requirement.

Of course the basics of the project is that you'll want to build a temporary stud wall to support it during the replacement. You have an advantage I don't have, the joists above are properly lapped so you'd be able to support the josits with 1 wall, where my josits are butted so if I was to be doing a simple beam replacement I'd have to support it temporarily on both sides.

Anyway, I know this is going to mean the project will be more costly than you had planned, but I really think you need to consider that those steps are going to be what it takes to get this situation fixed right.


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