Replace Rotted Front Porch Columns — Roof Shored, New Columns Set
The round or square column holding up the porch roof has gone soft at the base, split up the side, or the porch roof above it has started to sag.
JMB Builders will replace rotted front porch columns across the Twin Cities metro. We shore the porch roof beam on temporary posts, take out the old column, check the beam and the slab or footing under it, and set a new load-bearing column in fiberglass, PVC-wrapped or wood, anchored at the top and bottom and held off the concrete so it does not rot again. Priced per unit, quoted from photos within one business day.
- Priced per column
- Roof shored before the old column comes out
- New load-bearing column, anchored top and bottom
- Licensed MN contractor BC809005
This page is for columns that are the structure. Many older porches and newer builder homes use hollow round or square wood columns that carry the porch roof on their own, with no post inside. When the base rots, there is nothing to splice and nothing to wrap: the column has to come out and a new one has to go in. If your column is a box built around a sound treated post, a column wrap is the simpler job.
A column holding up a roof cannot just be pulled. The beam above it gets shored on temporary posts set on solid footing on either side, snugged up until the load is off the column. Then the old column comes out, and we look at what it was sitting on. A cracked slab, a heaved step or a rotted beam end above gets dealt with before the new column goes in.
The new column is rated to carry the load: fiberglass, a structural PVC-wrapped column, or a solid wood column. It sits on a base that keeps its end off the concrete so water drains away instead of wicking up, and it is fastened at the top and bottom so it cannot kick out. Caps and bases are sealed. Painting is quoted as a separate line, or leave it primed and paint it yourself.
When the porch roof has already sagged or the beam is rotted, that repair comes first and gets quoted with the columns.
What you supply
- Photos of each column top to bottom, a close-up of the base, and the porch roof beam above
- The column height from porch floor to the underside of the beam
- Your style choice: round or square, smooth or fluted, tapered or straight
- Your paint color if the columns get painted — painting is a separate line
What JMB supplies
- Temporary shoring posts and bracing to carry the roof during the swap
- Removal and haul-away of the rotted columns
- Check of the beam above and the slab, step or footing below
- New load-bearing columns cut to height, with bases that keep the column off the concrete
- Top and bottom anchors so the column cannot move
- Caps and bases sealed, nail holes filled, primed or factory finish
- Finished photos in your job folder
How it is priced: per unit
Quoted in writing from your photos within one business day. What moves the number:
- Column material: fiberglass, structural PVC-wrapped or solid wood
- Round vs. square, height, and tapered or fluted styles
- Rot in the beam above or the porch floor below
- Cracked slab or heaved step under the column
- How many columns in the same visit
- Railing attached to the column that has to come off and go back
Send photos of each column, a close-up of the worst base, and the beam above it. A tape measure across the column top and bottom helps us match the size.
How long it takes
Columns are often ordered to size, so the wait is the order. Once here: two columns in a day, including shoring, removal and setting.
How your project works
- 1
Send photos, get a written quote
Send three photos of the space and a sentence about what you want. You get a clear, itemized quote within one business day. We only come out to measure first when the job needs a tape measure — no pressure, no games.
- 2
Pick materials, or bring your own
We help you choose profiles and materials that fit the house and the budget, or match your existing millwork exactly — or you buy the door or trim yourself and we install it. Everything is confirmed before the crew is scheduled.
- 3
Clean, precise installation
The crew shows up on time, protects floors and furniture, and installs with tight joints and consistent reveals. Photos of the finished work go in your job folder.
- 4
Walkthrough and invoice
We walk the finished work with you. If anything is not right, we fix it before we call the job done. Then one invoice, paid by check or direct deposit — no card fees, no payment links.
Situations and options
Fiberglass column
Load-bearing, will not rot, round or square, smooth or fluted. Comes primed, gets cut to height and set on a vented base.
Structural PVC-wrapped column
A load-bearing core with a PVC sleeve, square profile. No rot at the base, and paint is optional.
Solid wood column
A treated or cedar column for a period porch. Sealed on the end grain, set on a standoff base and painted, since wood still needs upkeep.
Replace Rotted Front Porch Columns — Roof Shored, New Columns Set: questions, answered
Can a porch column be replaced without the roof coming down?
Yes, with temporary shoring. The beam above is supported on temporary posts on either side of the column, taking the load off it. The old column comes out, the new one goes in and is fastened, and only then is the shoring removed.
Should I wrap my rotted porch column or replace it?
It depends on what is inside it. A box built around a sound treated post can be wrapped after the post base is repaired. A hollow column that carries the roof on its own, with rot at the base or splits up the side, has to be replaced with a new load-bearing column.
What are the best replacement porch columns for Minnesota?
Fiberglass and structural PVC-wrapped columns hold up well because they do not rot at the base, where freeze-thaw and standing water ruin wood columns. Wood columns still work on a period porch when the end grain is sealed and the base is held off the concrete.
Why do porch columns rot at the bottom?
The base sits on concrete that holds water, and the end grain of a wood column wicks it up. Each freeze opens the wood more. A base that keeps the column end off the concrete and lets water drain is the fix.
My porch roof sags. Is that the columns?
Sometimes. A column that rotted and shortened lets the beam drop. A sag between columns is usually the beam itself. Either way, it gets shored and looked at, and the beam repair is quoted along with the columns.
How long does it take to replace porch columns?
Once the columns are here, about two columns a day, including shoring, removal and setting. Beam or slab repairs add time and are scheduled with the columns.
Recent JMB work, from our job log
59 installs recorded across 30 Twin Cities communities since Dec 2025. Window and door installs for homeowners and for the builders and dealers we sub for. Counts come straight from our job log; no customer names.
Get a written quote for this job
Three photos and a sentence is enough. You hear back within one business day. Or text the photos to 763-204-2099.
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Read morePage reviewed September 26, 2026 · JMB Builders LLC, MN license BC809005 · All exterior trim pages
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