This article series describes critical safe-construction details for decks and porches, including avoiding deck or porch collapse and unsafe deck stairs and railings.
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Even the best-quality fasteners account for only a small portion of the cost of a new deck, and they are well worth that modest investment. When choosing fasteners, pay close attention to their holding capacity and their corrosion resistance.
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Fasteners that are too weak for the job or that corrodes prematurely can weaken an entire deck.
Stainless-steel screws, nails, and bolts cost considerably more than other fasteners, but they are the most resistant to corrosion. You should certainly choose stainless steel if you are building in an especially wet or salty environment. It is also recommended if you are using redwood or cedar.
Hot-dipped (HD) galvanized fasteners are more affordable than stainless steel and are suitable for most decks.
Electroplated fasteners are also galvanized, but their treatment differs from hot dipping, and they do not resist corrosion well. Fasteners that are coated by hot galvanizing (HG) are also inferior to HD galvanized fasteners.
Basic building framing information is found at FRAMING SIZE & Spacing, Age, Types.
Also see Deck Nails, Screws, Hidden Fasteners.
Nails with smooth shanks have the least amount of holding capacity. As the wood shrinks slightly over time, they will loosen and allow lumber joints to separate. Ring-shank or spiral-groove nails, or screws, hold much better. Other nails serve special functions, such as securing joist hangers or light wood trim.
Screws with a yellow zinc coating offer less corrosion resistance. If you will be using a lot of screws, look for those that use a square drive bit. They are easier to drive, and the drive bits last longer than standard Phillips drive bits.
Watch out: do not use non-structural screws. The green arrow in the photo points to a proper nail for use in joist hangers and similar connectors. The orange arrow marks a drywall screw, not rated for construction use, and the red arrow marks an
"outdoor" galvanized screw but one whose box label clearly states not rated for construction use.
We found a deck whose contractor used the red-arrow-marked screws for all of the joist hangers. All of them had to be replaced.
Bolts are heavy duty fasteners intended to carry heavier loads than standard nails and screws. Carriage bolts and lag screws are used to connect ledgers, railing posts, and other critical deck framing members.
Carriage bolts, which require a nut, are usually stronger than lag screws, but cannot be used for very thick connections or if the back side of the fastener is not accessible. Both require pilot holes. Anchor bolts (or J-bolts) are used to secure posts to concrete piers. Use a washer with each type of bolt.
Many people think that the visible heads of fasteners used to secure decking are an ugly presence, especially if they have paid for top-notch decking. In response to that concern, many hidden fasteners are now available. They cost more and take more time to install, but the results can be worth it.
A variety of connectors are made specifically for connecting the various components of a deck; avoid regular, uncoated joist hangers, metal straps, and other connectors, which are not intended for exterior use.
Electroplated connectors are fairly easy to find; hot-dipped galvanized and stainless-steel connectors may be harder to locate, but are worth the effort.
The photo at left shows a proper framing connector screw used in a Simpson Strong-Tie L50Z connector.
Lumber and fasteners are the major materials used in building a deck, but they are not the only ones.
If you will be cutting into the siding of your house to install a ledger, you need to pay close attention to selecting materials that can prevent moisture from causing damage. In most cases, you will need concrete to help anchor the deck to the earth. And to protect the deck from premature aging, you should choose a top-quality finish and apply it regularly.
A variety of methods for securing deck boards to the deck joists are discussed separately at DECK FLOOR INSTALLATION.
Several types of moisture barrier can be used for the area where the house and deck framing connect, although your building code may require a specific product. Metal flashing is available in aluminum, galvanized steel, copper, and stainless steel.
Preformed aluminum and galvanized flashing are inexpensive and easy to install. The style you are most likely to find is formed to slip behind the siding and over the top of the ledger, but better protection is provided by flashing that runs behind the ledger. If you are unable to find preformed metal flashing suited to that type of installation, you can buy a roll of sheet metal and form one yourself. If you use aluminum flashing, and need to nail it, be sure to use aluminum nails; using galvanized steel nails encourages corrosion.
Another option is a flexible, self-adhering membrane. Although these products offer outstanding protection, they require a little more effort to install than metal flashings that can be slid up behind the siding
You will need concrete to form foundation footings and piers, and you may need it to create a landing pad for stairs or a support slab for a hot tub. If you are building a large deck, with many deep holes to fill, it is probably best to have ready-mixed concrete delivered by truck. Check with local suppliers for costs and minimum order requirements. For smaller decks, you can mix your own concrete.
Although dry concrete is a mixture of Portland cement, sand, and gravel, you are usually better off buying bags with the ingredients already combined. Add water as directed on the package.
For creating concrete piers, inexpensive cylindrical tubes are an excellent choice, and they may be required by your building code. The tubes are available in various diameters and can be cut to the necessary length with a handsaw.
The essential ingredients for deck longevity include thoughtful design, careful construction, and routine coatings with a good- quality finish. All wood decks perform better with routine finishing. And even if you are using composite decking and railings, you will need to apply a finish to the deck’s substructure.
Finishes are available in a variety of colors and formulations.
Choose the type of finish you will use when you design the deck. The best time to apply a finish is as soon as possible after the deck is built, so it is a good idea to buy your finish along with other deck materials.
Continue reading at DECK BUILDING & CARPENTRY TOOLS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Or see FRAMING FASTENERS, NAILS, SCREWS - best construction practices.
FRAMING CONNECTORS & JOIST HANGERS - best construction practices.
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