The column looks fine. No rot at the bottom, no rust, no split, nothing you could point at and call broken. Yet there's an open joint where the top of it meets the beam, or the porch roofline has developed a sag that shows up every time you pull into the driveway.
Two things are worth knowing before anything else. A porch column almost never fails on its own, and the part of the porch that moved is the part you cannot see.
A porch column sinks because the small footing under it was poured beside the house rather than on the house's own footing. When water takes that ground away, the footing drops, the column rides down with it, and the gap at the ceiling or the dip in the roofline is the last part of the drop to show.
Your porch stands on a second set of footings the house never got
Your house sits on a continuous footing, dug to bearing soil, tied together, inspected. Your porch columns usually do not.
A porch column carries its share of the roof down through whatever is under it, and what's under it is generally a small pad poured at the same stage of construction as the steps and the front walk. The owner puts a porch like that in the same family as an entryway, for the same reason: "more similar to a porch without the wing walls, or the steps without the compaction, because they're built on the same thing the steps are."
A wing wall is the short masonry wall that carries a landing back to the house. Anything standing on one of those is standing on the house. A column set on its own pad in the yard is standing on ground, and ground is negotiable.
Two kinds of porch, and only one of them has columns to worry about
Metro Atlanta has both. One is a continuous concrete pour in front of the house, an entry slab with steps and a walk hanging off it. The other is the one this post is about, described by the owner as the setup where "you may have a wood porch with individual brick or stone or block columns holding up that porch."
The difference matters because of how each one fails. A poured entry sinks as a unit and shows it at the seams. A columned porch fails one support at a time, and a single column dropping half an inch will bend a roofline across twenty feet.
The smallest footing on the property
A house footing spreads a lot of weight across a lot of surface, below the depth where the weather works. A porch column footing is a fraction of that size, poured shallow, and frequently set into dirt that was pushed back around the foundation wall rather than dug into undisturbed ground.
Nothing about that is unusual and nothing about it is a defect. Porches got built this way for a century. What it means for you is that the ground under one column can give up without the house ever noticing.
Why is the gap at the top when the trouble is at the bottom?
Because the roof above your column is held up in more than one place, and the house is one of them.
A porch roof runs from a ledger on the house out to a beam carried by the columns. When one footing drops, that column drops with it, but the beam has other support and the roof has real stiffness, so the whole assembly does not follow all the way down. The load transfers to the columns that didn't move. What opens up, eight feet above the actual problem, is daylight.
The order runs from the bottom up. The footing goes first. The column riding on it goes next. The brick or stone around it cracks, the beam above it loses bearing, and the roofline is the last thing to show anything at all. Homeowners call the office describing the top of that sequence, in phrases like "columns are now separating from the framing" and "porch column and beam and stone cracking."
A gap where the column meets the beam
Wood and steel columns usually show it this way. The top pulls free and you get a shadow line, then a visible joint, then daylight. People describe it as the column "not touching" anymore, which is exactly right. Once a column stops touching, it has stopped carrying anything, and its share of the roof is riding on its neighbours.
A crack or an opening at the base
Brick and stone columns are bonded at the top and land on their own footing at the bottom, so masonry tends to fail low instead. A stair-step crack near the base, a horizontal joint that has opened, or a gap between the column base and the porch floor all say the same thing the daylight at the top says.
A roofline that has gone wavy
The easiest symptom to read is the one you see from the street. Porch rooflines are built straight. Sight along the fascia from one end, or stand at the kerb and look at it against the roof behind it. A dip over one column points at that column, and a long gentle sag across the middle usually means two of them have gone down together.
Water, slope and fill, not the soil everyone blames
You will read on nearly every foundation site in Georgia that our red clay swells in the rain and shrinks in a drought, and that the seesaw is what shoves footings around. The USDA soil survey does not support that here. NRCS maps most of metro Atlanta as Cecil, Appling and Pacolet, and SSURGO rates all three low for shrink-swell, with linear extensibility around 1.5 to 1.8 percent. Dense soil, not restless soil.
What actually takes the ground out from under a porch column is plainer than that and easier to do something about. A downspout discharging at the corner of the porch. A grade that falls back toward the house and holds water against the footings. A front walk and a driveway that shed into the same narrow strip of dirt. Fill that was pushed back against the foundation wall and packed at the top and nowhere else.
Any of those will hollow out the dirt under a small pad without leaving a mark on the lawn above it. All four have fixes. A soil type does not.
Did the column fail, or did the ground under it?
Everything downstream depends on this one answer, and it's the answer a homeowner can usually get to before anybody arrives.
A column that has failed is a column that lost material. Wood in ground contact rots from the bottom and goes punky when you press a screwdriver into it. Steel in standing water rusts through at the base plate. Masonry loses its bed joint and crumbles. In every one of those, the ground may be perfectly sound and the column is the thing that has to be dealt with.
A column that has settled lost nothing at all. Sound wood, solid brick, intact steel, just two inches lower than it used to be and pulling a roofline down with it. The owner is blunt about which of those two he is called for, and about the difference between repairing a column and replacing one: "when I think of replacing porch columns, that's the columns that hold the porch up. We don't... we've never done that. We just jack them up."
Which answer you have decides whether this is a structural lift or carpentry. The porch column repair page sorts the symptoms and covers what the repair takes once the fork is settled.
How far a porch column drops before anybody notices
Less than people expect, and that's the useful part.
A quarter-inch of drop at one column is invisible at the column and obvious at the roofline, because a porch roof is a long straight edge and your eye is very good at long straight edges. By the time there's a finger-width gap at the top of a column, that footing has typically gone down an inch or more.
None of that is an emergency and nobody should be telling you it is. A porch that has settled an inch has been settling for years and will not do anything dramatic this week. What it will do is keep going, because the water that hollowed out the ground under that footing is still arriving on the same schedule.
A column, a few piers, and a porch back where it started
What this looks like when it's finished, in a customer's own words:
"Great experience using Anglin's. Very authentic people, generational local family business. They were very honest and clear about the work. Communicated well and showed up promptly on the day promised. Crew did a great job installing a few piers to raise a column on our porch and our front steps. Highly recommend using them for foundation and chimney restoration projects."
Patrick Steed, 5 stars
A few piers, one column, and the steps alongside it. The owner's description of what a correct lift restores is one short sentence: "The roofline all comes up together."
What you can read from under your own porch roof
Five checks, none of them costing anything, all of them making the visit shorter:
- Sight down the porch fascia from one end, then from the other end. Note where the low point is and which column it sits over.
- Look at the top of every column where it meets the beam. Daylight, a shadow line or a joint that has opened says that column has stopped carrying its share.
- Look at the base of every column for a stair-step crack, an open bed joint, or soil pulled away from the pad.
- Hold a level against two or three columns. A column that has gone out of plumb has usually tipped as its footing tilted, which is different from one that dropped straight down.
- Walk out during the next hard rain and watch where the downspouts, the walk and the driveway are actually sending water.
If the low column and the wet corner are the same corner, you have most of the diagnosis already.
Frequently asked questions about sinking porch columns
Are my porch columns load-bearing, or just decorative?
Most exterior porch columns carry real load, because a porch roof has to land somewhere and the columns are where it lands. A genuinely decorative column is usually a hollow wrap around a post, or a slim feature at an opening that has a header doing the work above it. The quick tell is what happened when this one moved: a column that dropped and took a roofline down with it was holding the roof up, and a column that dropped while the roof above stayed dead straight was not.
What does a gap between the top of my porch column and the ceiling mean?
A gap at the top means the bottom went down. The roof is held at the house and at the other columns, so it resists following a single footing all the way, and the separation opens at the weakest point in that path, which is the joint at the top of the column. The size of the gap is a rough measure of how far that footing has dropped, and the column is no longer carrying anything while the gap is there.
Should I worry if only one porch column has dropped?
One is the normal number. Each column stands on its own small footing, and those footings sit in different dirt, take water at different rates and were poured with whatever care the day allowed, so they fail one at a time rather than together. What matters more than the count is whether the low one is under the wettest part of the porch, because that tells you the cause is still active.
Does a sinking porch column mean my foundation is moving too?
Usually not. A porch column footing is small, shallow and often set in fill, so it can lose its ground while a house footing dug to bearing soil beside it stays exactly where it was. The check worth doing is indoors on the same side of the house: diagonal cracks at door and window corners, a door that stopped latching, or a floor running downhill move the question off the porch and under the house, and signs of foundation problems covers what else to look at.
How do I tell a settled column from a rotted or rusted one?
Look at the material at the bottom twelve inches, because that's where a column dies. Press a screwdriver into a wood column near the base and see whether it goes in; check a steel column at the plate for scaling and flaking; look at a brick or stone column for mortar you can rake out with a fingernail. Sound material at the base with a gap at the top is a ground problem, and soft material at the base is a column problem, and the two get fixed in completely different ways.
Will a porch column keep sinking if I leave it alone?
Generally yes, because nothing about the cause has changed. Water is still arriving at the same corner on the same schedule, and the hollow under a footing tends to grow rather than heal. Movement is rarely steady, though, so a column can sit still through a dry year and then drop again after a wet spring, which is why a date written on today's measurement is worth more than the measurement itself.
Have somebody read the roofline with you
Somebody can stand under your porch, sight the roofline, look at the top and the base of every column and tell you whether a column failed or the dirt under it left. That answer decides everything that follows, and the visit costs nothing.
Anglin's has been putting metro Atlanta porches back where they belong since 1930.
If the steps beside the porch have gone down too, why are my front steps sinking covers that half of the entry.
Call 770-422-2924 for a free look.