How to Replace a Rotting Porch

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Repair vs. Replace

I remember when I was called to a home to repair a porch.  As soon as I saw this porch leaning to the right, it was obvious that non-pressure treated wood was used.  I broke the news to the homeowner that we would need to completely re-build her porch from scratch.

Replace a Rotting Porch

What many people do not grasp is that it sometimes costs to repair something that is too far gone, than to tear it out and do it over.  It’s tough to place a percentage on when to do this, but my rule of thumb is if more than 50-60% of a structure is rotted it usually makes sense to tear it down.

There are quite a few steps to replacing a rotting porch and each is important.  I will provide a summary of each to serve as a reference when a homeowner calls you to replace a rotting porch.

How to Replace a Rotting Porch

Building new porch steps

Replace a Rotting Porch

This step is not a difficult home repair and even a do-it-yourself home owner can do this with just a little bit of carpentry knowledge.

For this specific project shown above, the wrought iron railings were permanently set into the concrete pad so we needed to work around them.  We comopletely removed the porch and disposed of it.  We were delighted to find that the rot had not found its way back into the house sheathing and structural rim joist, otherwise you will find yourself working on a completely different type of project.

Flash the house

Replace a Rotting Porch

To prevent the main house from rotting, you need to install flashing at the house and porch connection.  We always install two layers of flashing; a redundant rubber flashing layer and a PVC, copper or aluminum preformed to fit the ledger board flashing.

The picture above shows the Vycor rubber membrane installed on the side wall of the house wall prior to installing a new 2×12 pressure treated ledge board.  We ran this flashing down below the level of the 2×12 to make sure water drains past the house framing and onto the ground.

Click here to continue reading the following steps for replacing a rotting porch:

  • Installing the ledge board,
  • Cutting the stringers,
  • Apply the trim before the decking,
  • Preparing the porch decking,
  • Installing the porch decking,
  • Preparation for painting
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Robert Robillard is the editor of the blog, A Concord Carpenter, Assistant Editor of Tool Box Buzz and principal of a carpentry and renovation business located in Concord, Massachusetts. Rob hosts the Concord Carpenter... Read more

6 comments on “How to Replace a Rotting Porch

  1. Kevin

    Grace, that’s the way to go Rob. A belt and two pair of suspenders approach with a secondary flashing over the ledger,(taped in, I hope) and a Kleer apron board under the door.

    Excellent attention to detail Rob.


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