If your front-porch slab has settled, chances are the contractor used the wrong fill dirt around the foundation of the house. Although this problem doesn't have a quick and easy solution, the steps involved aren't complex. Materials:
sledgehammer
120-lb. jackhammer with bull-point bit
commercial air compressor
concrete saw (an alternative to the jackhammer and air compressor)
power tamp
steel reinforcing rods
wire mesh for concrete support
measuring tape
2" x 4" or 2" x 6" lumber (depending on how thick you want the porch)
2" x 4" x 2' wooden stakes
hammer
16-penny nails
level
gravel
garden rake
concrete (have it delivered by a concrete truck)
wheelbarrow
concrete float
dust mask
leather work gloves
steel-toed boots
safety glasses
hearing protection
- First you'll need to remove the posts supporting the roof over the porch. Put in temporary supports to hold up the roof while you're working.
- Break up the old porch using a 120-pound compressed-air jackhammer and a bull-point bit (figure A). You can rent a jackhammer and air compressor from most equipment-rental stores. If you're uncomfortable using a jackhammer, break up the porch with a concrete saw. Start at the outer edge of the porch and work inward, toward the house. Work back and forth evenly, taking care to avoid damaging the foundation of the house.
- After breaking the porch into small pieces, break the base portion into even smaller pieces (figure B) to use as fill.
- Compact the gravel with a power tamp (figure C): a well-compacted base will prevent the settling problem you had with the original porch. A gas-powered tamp may be rented from most equipment-rental centers. Work in short, even sweeps until the base is solid. Wear steel-toed boots when using a power tamp.
- Lay steel reinforcing rods over the gravel base. If the reinforcing rods from the original porch are intact, reuse them. Otherwise, buy new rods.
- Drive stakes where the corners of the new porch will be (figure D). If the soil is loose, brace the stakes with offset stakes.
- Create a form (figure E), a mold for shaping the concrete. Attach 2" by 4" or 2" by 6" lumber (depending on how thick you want the porch to be) to your stakes.
- Place supporting stakes every 3' along the form.
- Use a level to make sure the form is plumb. The form should slope away from the house, falling 1/8" for every foot of width.
- Make sure all the joints are tight and that the form is sturdy enough to hold the concrete.
- Pour gravel into the form, and spread it over the entire area. Smooth it with a garden rake. You may want to tamp the gravel if the ground is soft.
- Lay wire mesh over the area, covering all the gravel. You may want to elevate the mesh by placing it on top of some rocks. Make sure the mesh is at least 2" below the top of the form.
- When the wire mesh is in place, pour concrete into the form. You could mix the concrete yourself, but for large jobs, it's best to get it from a concrete truck (figure F). Most concrete trucks have a chute to pour concrete directly where it's needed. If the chute isn't long enough, you may need to transport the concrete from the truck to the porch with a wheelbarrow.
- Pour enough concrete to fill the form completely. Use a garden rake to smooth it as you go and eliminate bubbles.
- When the concrete is in place, smooth it with a concrete float or a smooth trowel (figure G). It's important to get the surface smooth as quickly as possible.
- Allow the concrete to harden for about half an hour (the amount of time may vary depending on the brand). Then texture the surface with a broom, and run a concrete edger around the form.
- Cover the concrete with plastic, and keep it damp as it cures (this is especially important on hot days). This will help the concrete cure to the hardest possible finish.
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