The mood of your deck party can be severely altered with a harsh gravitational experience, all because of deck attachment issues. What good are fasteners that don’t resist local weather conditions? Or nails too small or untreated to prevent rust and corrosion? Or materials that bend more than expected? This neglect during deck setup can eventually cause abrupt deck separation, if not corrected.
Your Family’s Safety Depends on Proper Deck Development
Only use the right fasteners. Look for this. To resist corrosion, all fasteners used in deck construction must be hot-dipped zinc-coated galvanized steel, stainless steel, silicon bronze, or copper. Joist hangers and anchoring straps are subject to the same requirements as fasteners. IRC table R602.3 (1),
Corrosion resistance in your deck’s hardware is not just safer, its a code requirement. It’s even more important when in contact with ACQ treated lumber.
Here are some examples of some of the codes to follow:
- Non-freestanding decks must have positive anchoring to the primary structure. This means no toenailing or using nails to make this connection. ( RC Section R502.2.2)
- Builders must use lag screws, or bolts and washers when attaching the deck ledger to the primary structure.
- 4x4s or 6x6s beams cannot be used as girders (Figure 3). All structural beams and girders must be constructed with multiple 2x4s to 2x12s, with the depth and the number of layers of the members determined by the span and spacing.
- Solid lumber such as a 4×4 or a 4×6 can no longer be used as a beam. Most beams must be built up from layers of 2-by material. Figure 4. ( IRC (Section and Table R502.5 (1) )
Good Deck Builders Must Know What to Expect
If using Composite decking materials, your deck builder should check with the individual manufacturer’s specifications. Why? Many have been tested and approved for installation on joists spaced 12 inches on center, not 16 inches or 24 inches.
Over the past ten years, the quality of some building material has declined. You have to know how to adjust. For example, deck joists often cantilever beyond the outer girder. The old-school rule of thumb was that as much as one-third of the length of the joists could cantilever beyond the beam. But about 10 years ago, the building codes reduced the allowable spans for most softwood lumber because of declining material quality, and now cantilevers shouldn’t extend more than 24 inches beyond the beam, unless by specific engineered design.
Decks Need Enough Support and Anchoring
Decks need strong anchoring against uplift and braced laterally. It not only prevents racking, but it prevents the deck from becoming a projectile in high winds or an earthquake. This applies whether the deck is attached to the existing structure or freestanding.
Deck need good footings or piers and their posts not only support normal loads, but also to help provide the needed uplift resistance. Concrete footings, at or below the locality’s frost line, can be as basic as a pad in the bottom to support the column, with stone back filled around it, or a solid-concrete pile with an anchor bolt installed on top to hold the column in place (Figure 5).
Figure 5. Frost footings do more than support the deck’s downward load, they also anchor it against wind uplift. The footing and the deck need a positive connection.
Decks usually need guardrails and handrails to prevent problematic social scenes or bodily injury. Some owners don’t want a guardrail to affect the view from their deck. They want something not too tall and often ask for benches or planters to act as guards. But IRC Section R312 requires a guardrail for porches, balconies, or other raised floor areas where the floor surface is more than 30 inches above the adjoining grade. Required guardrails must stand at least 36 inches high. The guards’ infill rails or balusters should have gaps no more than 4 inches apart.
But what about benches?
A bench can be installed against a guard, but if the deck is more than 30 inches above grade, a flat bench cannot be the guard (Figure 7).
Figure 7. Railings need be no higher behind a bench than anywhere else, but a bench alone cannot serve as a guardrail.
But what about screening?
Porches and decks enclosed with insect screening, if 30 inches or more above grade, must also have guards. Handrails are not guardrails, although the terms are often thought of at the same time. Per section R311.5.6, a handrail is required when there are four or more risers in the stair run. When the stair is more than 30 inches above grade or above the floor below, a guard is also required. A compliant handrail is either circular with a minimum 1 1/4-inch and maximum 2-inch diameter or 1 1/2 inches square.
Though foundational neglect can lead to rapid deterioration, early detection can allow your deck find a safe remedy.
If you suspect your deck might be experiencing a potential dis-attachment disorder, please allow our deck specialists to diagnose your deck health and prescribe a thorough treatment today. Don’t risk someone you care about being injured.