Building forms

Patio slabs typically measure 4 inches thick, so construct forms with smooth, straight 2x4s, setting their tops about an inch above lawn level. Wet concrete exerts tremendous pressure, so brace forms well. If you're in doubt about whether your forms are rigid enough, drive a few extra stakes and install added braces.

For proper drainage, slope your patio 1/4 inch per foot away from the house.

If you want to edge your patio with wood, construct permanent forms with redwood, cedar, or pressure-treated lumber. Apply a coat of sealer to further enhance the wood's natural rot resistance, then put masking or duct tape on the top edges to keep cement from staining or scratching the wood. (See pages 122-123.)

I Use stakes, string, and poivdered chalk to 1 mark your patio's outline, as explained on pages 58-59. Be sure to place strings about 3 inches outside the slab's perimeter to allow for forms. To mark curves, wind garden hose between stakes. Strip sod; excavate. Tamp the ground well, then saturate with vegetation killer.

String And Stakes

3 Adjust strings to reflect proper slope. To begin building forms, pound stakes until their tops are at the same level as the planned top level of the forms. Pound stakes every 3 to 4 feet. If you like, pound stakes at any height, attach form boards at proper level then saw stake tops.

2 Install asphalt-impregnated expansion strips wherever the patio will abut a foundation, wall, or other structure. Expansion joints accommodate expansion and contraction caused by temperature changes.

/. Using the stakes as guides, hold form boards f~ at correct level, then nail through stakes inu> boards with doubleheaded nails. Leave strings up during this step, if you prefer, so you can easily double-check the level of the form boards.

2 After pouring the concrete and letting it stiffen a bit, position anchor bolts or post anchors above the footings. Let the concrete cure, then attach posts to anchors. See pages 100-103 for details on sunshade construction.

POURING SUNSHADE FOOTINGS

11f you plan to build 1 an overhead sunshade over your patio, dig holes for footings wherever posts will rest on the patio surface. Several-inch-deep footings are necessary to keep the concrete from cracking under the weight of the sunshade posts.

PATIOS AND DECKS

BUILDING CONCRETE PATIOS

7 Pour the concrete; then, with help from a f riend, strike it off with a straight 2x4 long enough to ride atop forms on two sides. Begin striking as soon as you 've poured the first 3 or 4 feet; this will show whether you're putting in enough material.

I 1 Trowel and finish the patio surface. Two 1 J[ passes with a wood trowel leave a rough, skidproof surface: for a slick finish (not advised for patios), make three passes with a metal trowel. For additional information about finishes, see pages 162-163-

SWhen you 're done pouring and striking the concrete, use bull and darby floats (the darby float is shown) to further smooth the surface and embed aggregate beneath it, Slop floating when water starts to bleed onto the surface of the slab.

7 ^ Once you've achieved the surface texture iZ you want, cover the slab with sheets of polyethylene to hold in moisture. This retards the curing process, allowing the concrete time to bond properly. After a week, remove the plastic and forms, the?i backfill against the patio's edges.

PATIOS AND DECKS

CHOOSING A SPECIAL CONCRETE SURFACE

Building Forms With Sunshade

WEATHERPROOFING PATIOS

Water is the natural enemy of all masonry materials. Moisture finds its way into tiny crevices, then freezes, turning the cracks into open wounds. Water also weakens masonry by dissolving salts and leaching out binders. A good paint or clear sealer will keep out water and maintain the strength of your new patio.

When painting your patio, choose an alkyd masonry paint. Water-thinned latex masonry paints perform well on vertical masonry surfaces, but alkyds stand up better to the normal wear and abrasion a patio is subjected to.

Clear sealants go on fast and protect masonry through the rainiest season. Apply the clear sealer of your choice annually, and your patio will maintain its youth almost indefinitely.

If weather or stains have already taken a toll on a patio at your house, revive it by scrubbing with a 5-percent solution of muriatic acid. Wear gloves and protective clothing, and rinse well. Wait a week or so, then apply paint or a clear sealer.

PATIOS AND DECKS

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