How to Deck a Patio or Slab

Patios made of concrete have 2 drawbacks. Many of these concrete slabs eventually develop cracks and look broken. After the cracks are patched the repairs are easily visible resulting in the slab looking even worse than before. The alternatives are regular patching sessions or breaking up the concrete and hauling it away. However, another alternative solution would be to cover the concrete patio with wood decking using sleepers that are supports which replace conventional joists.

There are advantages to creating this type of deck. In the first place it's not necessary to remove the concrete slab which is hard work and can add to the expense of a project. Concrete is extremely heavy and removal costs are generally based upon weight. Secondly, the slab can easily serve as the foundation for the new deck. It will not matter if the surface is cracked or pitted because it will not be seen once the new wood surface is in place.

Finally, the decking boards are more flexible than the concrete. This makes them more comfortable to walk on and provides a measure of resilience that can easily absorb some seasonal heaving associated with concrete. With concrete splitting can occur with even the slightest movement. Once a crack opens water is free to enter, freeze and expand in winter. This makes the split even wider which of course allows more water in and the deterioration continues in an ever increasing cycle.

The basic idea of decking a patio or slab is to install wooden nailers on the concrete followed by a finished deck surface fastened to the nailers. Pressure treated wood is the best material choice for the sleepers or nailers. A special nail gun can be rented from a tool rental outlet or a home improvement store to drive a hardened nail through the wood and into the concrete. Exercise care and caution in the use of this tool and wear the proper safety gear while following the tool manual instructions closely.

Once the deck design has been planned lay the 2x4 boards out on the concrete slab on 16 inch centers. Include the perimeter boards. It is wise to lay out the sleepers perpendicularly to the house wall which will allow water to drain away from the home. Use harned nails (sometimes called cut nails) or masonry nails to fasten the sleepers to the concrete. Standard common nails should not be used because they will bend rather penetrate the concrete.

Attach the nailers making sure that the spacing of the boards is consistent. With 2x4 sleepers rather than 1x4s it is much easier to level out irregularities in the slab. Thinner boards will bend up over the rises while dipping a bit into the low spots. The 2x4 boards will bridge most of the gaps easily. If there are larger depressions in the slab nail the sleepers at the high spots and insert pressure treated shims in order to keep the 2x4s levels as they ride over the low spots.

The next step is to install the surface decking. Since the decking boards do not sit directly on the concrete slab air has the opportunity to circulate around the wood. This means that pressure treated wood does not have to be used as decking material. Other alternative material choices such as redwood, cedar, composite or vinyl decking can be installed. If pressure treated wood is selected it's a simple matter of coating the wood with a semitransparent stain and sealer to eliminate the green tinge.

In installing the decking boards either galvanized nails or treated deck screws can be used. Screws are by far the better choice offering greater holding power. Use a screw length that will reach through the decking board and most of the way into the sleeper but not into the concrete. Trim the end edges of the decking and add a facing board to hide the end board cuts. Apply at least a finish coat of sealer once the wood is dry. A stain and sealer application is another finish alternative that will work to protect this new outdoor living space.

The choice to deck a patio or slab is a practical one that involves less work and expense than removing the patio altogether. In the end a low level deck built over the old concrete slab will provide an outdoor space that will last for years and require a minimum amount of maintenance.

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Comments

Sun, 15 Mar 2009 at 8:07 PM, by Larry
Good article with simple and straight forward approach to common problem of cracking back porch slab.

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