DIY Network

Building a Deck

How to Remove a Concrete Porch

The first step in adding a redwood deck to an older house is to break up the existing concrete porch, followed by setting the new support posts.

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  • Time

    Several Weekends

  • Price Range

    $2,500 - $5,000

  • Difficulty

    Moderate to Hard


Step 1: Prepare the Site

Based on the deck's dimensions, begin by preparing the site. In our example, an existing rail fence is removed with a sledgehammer, while a jackhammer reduces the concrete slab to rubble. Note: Because the complete deck will eventually cover up this area, it's only necessary to break up the concrete and extract the bigger pieces.

clear the site to prepare for the new deck

Step 2: Lay Out the Dimensions

Next is the process of laying out the dimensions of the new deck with stakes and string. After identifying the spots for the support posts, make sure the layout is true using a framing square.

stake out dimensions for deck and check for square

Step 3: Dig Holes for Deck Support Posts

With the layout done, the next step is using a two-man power auger to bore holes in the soil for the deck's support posts (Image 1). Make sure to dig to a depth past the frost line for the region. Then refine the sides and bottom of each hole using a posthole digger (Image 2).

Step 4: Mix Concrete and Place Posts

Add water to a dry concrete mix in a wheelbarrow, churning it with a mason's hoe. Once the proper consistency has been established, place the support posts — which are long 4 x 4's.

place support post in hole and pour in concrete

Step 5: Finish the Concrete

With the concrete poured to the top of each hole, agitate the posts to release any trapped air. Then make sure each post is plumb using a level (Image 1). The thickness of the concrete holds the post in place. With the posts set in place, next trowel the top of the concrete sloping away from the support post for proper drainage (Image 2). Allow the concrete to dry overnight.

Step 6: Check Post Alignment

To ensure the front-facing support posts are in alignment, tie a string line across them. In our example, the middle post is set back about an inch and will eventually require a wood spacer to correct the problem.

use a string line to detect any alignment problems