Replacing a porch column is actually a very straightforward task (with the right tools). This short article and video show you how to remove your old column. Then, they show you how to cut a new one. Finally, they show how to install the new porch column safely.
Remember, replacing structural components in your home can be very dangerous! Therefore, always consult a professional carpenter or contractor, and a structural engineer, before attempting to tackle the project on your own.
(The following content contains affiliate links.)
POST JACKS make projects like this possible! This +8′ is very similar to what I use:
A large ADJUSTABLE WRENCH makes raising the jacks much, much easier:
12″ MITER SAWS are even better than circular saws for making clean cuts on large posts!
New Porch Column
Galvanized Trim Nails or Exterior-Grade Screws
Porch Column Installation Overview:
The key to making your porch column replacement go smoothly is using a tool known as a “post jack”–or a “jack post.” These adjustable tubular poles are capable of lifting extraordinary amounts of weight. Amazingly, up to 18,000 lbs in some cases!
You use the carefully positioned post jack to temporarily lift the weight of the roof. Then ehe old porch column can be safely pulled out and a new one installed. Again, be careful!
Post jacks come in a variety of sizes. You need one that extends at least the distance from the porch floor to the porch beam.
Step 1: Install Post Jack
Initially, to install the post jack, I needed to ensure that the jack had a clear place to sit.
The porch beam is the structural element that rests on the columns and carries some of the roof weight. The area directly beneath the porch beam must be free of obstructions. Unfortunately, this area often includes railings, which are often directly in the way.
Fortunately, the porch where I replaced columns in this article did not have any railings. (I later installed railings when the new columns were in place.)
Everything is clear below
With the area free of obstructions, I placed a wooden block on the porch floor directly beneath the beam. The block distributed the weight on the post jack. Also, the wooden block helped prevent the jack from scarring the bricks.
Next, I placed one of the steel jack plates on the center of the block. The steel plate gives the metal jack something extremely hard to sit on. You need to use two plates in combination. One at each end of the jack. Use a wood block for the porch beam, too.
You want to position the jack as closely as possible to the column being replaced. Just not so close that you have a hard time handling the jack. Generally, within one foot is probably close enough.
Assemble the jack post
I fit the two jack poles together so that they were at an extended length that brought them within 5 inches of the porch beam. Then, I pinned the two together by passing thick carriage bolts through the aligned holes in the walls of the pole. (The bolts are included with the jacks).
Next, I fit the “screw” into the upper end of the post. I wound it up so that it fit between the beam and the wooden block. I hand-tightened the screw so that it lightly clamped itself into place. (The screw is the only moving part in the post jack). A knob on the top of the screw fits into a circular hole on the steel plate.
Prepare for cranking
At this point, the jack was mostly installed, but was not carrying any real weight. That way, I could plumb the post with a up with a four-foot level. It’s very important that the jack post is plumb.
Importantly, make sure the steel plates can’t shift. Do this by locking them in place with four screw or nails. This prevents the jack from slipping, or “kicking out.”
Step 2: Lift Roof Weight Off Column
With the jack in place, I used a large adjustable wrench to turn the screw. The jaws of the wrench gripped the flat, narrow section on the threadless neck of the screw shaft.
Carefully, I rotated the screw in quarter- or half-turns, but not too quickly. Ideally, we’re only going to lift the roof 1/4″ or less. I was barely taking the load off the porch column. Pro tip: Listen for creaks and pops that let you know that weight is being transferred.
Is there a cap and/or base on the column?
If the column has a decorative cap or collar, pull it down to get a clear view of the top of the column.
Sometimes, the cap will be sitting on the column. If so, it’s acting as a layer between the column and the beam. In that case, you can consider the cap to be the true top of the column itself.
Either way, you want to begin looking for separation between the column and the underside of the beam. Jiggle the column with your hand in between half-turns of the jack screw. As the roof weight is lifted, the top of the column will begin to move easily.
When you can see about an 1/8″ gap between the column and beam, full separation has most likely occurred. You should be able to “walk” the column out by rotating it back and forth.
Is the column fastened to the beam?
If the column was toenailed into place, you need to pull the bottom out first and gently pry the column free. Likewise, if the column was heavily caulked at the top, you may have to cut and chisel some caulk loose.
Either way, you should be able to now fully remove the old column and set it aside. Often, there is nothing more than gravity and roof weight holding the porch columns in place!
Step 3: Measure For the New Column
Stand on a stool or stepladder. Then, drop the tab of your measuring tape onto the surface of the porch where the new column will sit. Carefully extend your tape up past the point where the top of the porch column will be. Find the beam height by sighting the tape where it crosses the bottom edge of the beam.
Currently, the beam is lifted above its normal resting place So the measurement will actually be about 3/16″ longer than what you need.
Subtract about 1/8″ for the final measurement. A difference of 1/16″ won’t matter. It will give the new porch column a little room to get settled.
Step 4: Cut the New Porch Column to Length
In this project I was installing a wood “colonial” style post. These posts have square walls at the top and bottom. There is a turned section in the middle.
A circular saw or miter saw will work to cut wood porch columns. Metal or fiberglass columns may require other cutting techniques.
Before you cut the column to your measured length, stop! You need to consider other factors that may affect the total height.
For one, nearly all wooden porch columns should be installed on a “post base”. This is a metal or plastic foot that keeps the column off of the porch surface. That way, the wood column never comes in contact with standing water.
Subtract the height of the base from your total height measurement.
Also, are going to attach railings that are the standard 36″-42″ inches tall? If so, make sure that you’re leaving enough square section on the lower end of the post. That’s where the railings will attach to the column. You may have to take some material off the top of the post, and the bottom of the post to account for this. I did in this project.
What are you making your cuts with?
When you’ve made these considerations, measure and mark for your cut(s). If you’re using a miter saw to cut the column, just cut the column precisely at this mark.
If you’re using a circular saw, use a speed square. Draw a cut line all the way around the column at the measurement. Set the depth of your saw to cut all the way through the wall of column (pictured below).
Make the cut by using the speed square as a guide for the saw sole plate. Cut each wall in turn, rolling the post after each pass to eventually cut through the full perimeter. (For a better depiction of this process, check out the video at the top of the page.)
Step 5: Caulk the End Grain, Attach the Post Base
Wood columns are prone to soaking up water and rotting at the bottom. Therefore, you always want to seal the end grain before installing the column.
My column actually had printed instructions on it that said “paint before installation”. I like to go a step farther by caulking the end grain with a siliconized caulk.
I smear appropriate exterior-grade siliconized caulk on the bottom end. Then I rub it into the pores of the wood. Also, I spread some up into the cavity of the porch column.
When the caulk is no longer wet, I screw the post base directly onto the underside of the column. (It helps to pre-drill holes for you fasteners.)
Step 6: Install the New Porch Column
Stand the new porch column in place and make sure that it fits the opening the way you expected. Try to get it as near plumb as possible with a level.
This can be tricky. Framers try to line up roof beams directly above the perimeter of a masonry porch like this. However, that can be very hard to do so perfectly. The corner of the porch will often be slightly out of plumb with the beam above it.
When inconsistencies like this occur, I try to find a balance among all of the factors. But I focus on structural value.
I want my column to sit squarely in the corner of the porch, but not overhang the edge of the porch. That would be dangerous. And I always want it to be centered under the beam above for full support. I also want it it be as square as possible to the porch corner, the beam corner, and the house
It takes a lot of tweaking to get these factors right. I often walk around and look at the porch column from multiple angles to be sure it looks right. But most importantly, I make sure it is centered directly beneath the beam and sitting fully on the porch.
Step 7: Remove The Post Jack
Transfer the roof weight onto the new porch column by slowly lowering the post jack.Do this by simply reversing the process you used to install the jack.
Use an adjustable wrench to turn the screw in the opposite direction. While you’re doing this, watch the gap shrink above of the new column. When contact between the beam and column is made, jiggle the column to feel that it is being pinned down.
Watch the column for any signs of stress or movement as the full weight is transferred. When the weight is entirely on the column, the jack will become wobbly. Carefully, pull the screws or nails from the post plates. Remove post jack it and set it aside.
(I like to grab the screw, plate and upper block and carry them down as I gently keep the jack tilted. Just don’t let the jack fall back and hit the house!)
Step 8: Toenail The Porch Column
Gravity should now be pinning the column down so heavily that it doesn’t want to budge. All the same, I drive some galvanized trim nails through the top of the porch column into the beam. That way, it won’t twist.
In this project, newly installed railings also ensured that the column couldn’t “kick out” at the base.
Anchoring the post base
Many post bases come with some sort of mounting anchor. Sometimes, it’s a screw that fastens the base into the porch to keep it from slipping sideways. But, setting these anchors can often damage the masonry at the porch corner.
If the column might slip, consider instead running some high-yield masonry adhesive between the base and the porch. It will provide as much fastening power as the single screw anchor, and won’t damage the masonry.
If you’re installing your porch column on a wooden porch, you can also toenail through the base of the column with a very long screw. Overall, though, porch columns are not prone to moving.
Porch Column Installation Wrap-Up:
If you’re doing a series of porch column replacements (as I did in this project), you go one at a time through them, carrying out this exact same process.
Just remember: always consult a professional carpenter or contractor, and possibly a structural engineer, before tackling the project! Removing structural porch columns, though quite easy, can also be extremely dangerous. Safety is always the top priority in every construction project.
Thanks for reading!
(For a strictly scientific take on column strength, check out this link on mathematician Leonhard Euler’s formula for column load–his work in the mid-18th century made the construction world safer for everybody.)
If you have any questions, or if you have a suggestion for a subject of a future blogpost, please go to our Contact page. Thanks!!