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Or Can They?

By Bob Mulloy


LEDGER -Is the ledger joist anchored to the house and is it flashed? The ledger joist is usually the first piece of stock fastened to the house. But simply face nailing the ledger board in place is not enough to both anchor and support the deck. The ledger board must first be flashed or held off by cleats to prevent moisture damage to the underlying siding, and then it must be secured to the house frame with anchor bolts. Time and again, I find both the anchor bolts and the flashing missing on decks built by so called professionals and inspected and passed by local officials. It seems that every summer there is a news story about a raised deck that has collapsed causing multiple personal injuries - tragedies that could have been prevented. As a home inspector, safety concerns should be paramount in your mind, so look under the deck when possible and check for lag bolts as a means of secure attachment.


FLOOR FRAME -Is the floor frame undersized, over-spanned, or over spaced? You may not be doing a code compliance inspection, but quite often a deck frame cries foul. The specifications used by the average do-it-yourselfer never cease to amaze me. I am sure that you have walked out onto a deck and observed springy floor frame issues, but did you look under the deck to see why? And did you alert your client that there might be a deficiency in this area? Many times a center beam is totally missing or cantilevering is excessive. 2 x 6 floor joists may span a distance of 14-16 feet with 24 inch spacing producing a floor frame that behaves like an elastic band when you do a little "bounce test". A bounce test is something I routinely use to sense deck frame problems. I simply walk on the deck, stop at several strategic places, rise up on my toes and drop my weight on my heels. No one else needs to know what I am doing, but if I feel excessive movement then I investigate more closely.

FLOOR JOISTS - Floor joists need a minimum of 1 1/2" of end bearing  to safely transmit live and dead loads through the beam and downward through the posts and footings to stable earth at one end, and into the house frame at the other. End bearing is achieved by wood-on-wood support or by the use of mechanical attachment with metal joist hangers.  Resting floor joists on a beam is a good example of wood-on-wood end bearing is preferable as there is no reliance on mechanical fastener failure.

The use of metal joist hangers, properly secured with a suitable joist hanger nail secured in every hole, is the next best option for end bearing as the stirrup within the hanger provides a shelf to support the joist.  Overall, the objective is to transfer point-loads in a stable configuration that will also resist pull-out and lateral movement.

LATERAL BRACING - Does the deck have a means of lateral bracing? Raised or elevated wood decks make me nervous! Countless times I have walked across a deck and have found that it wants to follow my path by shifting from side to side. So, another simple test I use is a "lateral shift test". I stand on the deck along the center of the outside guardrail. Facing it, I grasp the guardrail, spread my feet and try to shake the deck frame laterally. Sometimes, a raised deck frame will respond with frightening lateral movement. Imagine a group of people walking across the deck and the deck frame moving laterally and collapsing! Every year there is a story in the news about just such a tragic occurrence and people are unnecessarily injured.

In my opinion, the decking boards alone do not provide adequate lateral bracing. I like to look under the deck and see angular braces at the posts, or a piece of strapping nailed diagonally under the floor joists. If I find that a deck frame exhibits excessive lateral movement, then I alert my client.


HANDRAILS & GUARDRAILS - Do the handrails & guardrails pass your scrutiny? Putting codes aside, lets use a little common sense approach to handrails and guardrails. I start at the deck stairs and a few simple questions. Is a handrail present or missing? Is a handrail needed? If a handrail is missing, why not recommend that one be installed for safety? I grasp the handrail and apply lateral pressure. If it moves, I investigate further and document my observations. Of course the height of the handrail, size of the openings and projection are important, but following my common sense approach, I next check the handrail for those prevalent splinters and nail pops.

Moving up to the deck surface, I walk over to each guardrail and give it the old "movement test". If the guardrail is loose, not high enough or has splinters, then a WARNING is highlighted in my report. Likewise, if the spacing between balusters is excessive, I document the facts and make appropriate safety suggestions.

STAIRS - Are the stairs safe? Going back to the deck stairs, I look first at ground level. In my opinion, a deck staircase that falls onto a concrete stoop at grade level is a far superior installation than ending the stringers directly on the soil. Decay is preventable if ground contact is eliminated and treated lumber is used. I find that many deck staircases are not level as either the stoop or the soil under the stringers has eroded or settled. Using that common sense approach again, uniform tread & riser dimensions are something that is a foreign language to the do-it-yourselfer, so of course I inspect accordingly. Open risers may be allowed, but I like to suggest that closed risers provide greater protection against tripping. Other typical defects such as, loose treads, decayed treads, decayed stringers, nail pops, poor attachment, etc.; are all documented when warranted.

While on the subject of stairs, the step down from the interior floor to the outside deck should not be ignored as often the elevation may be far beyond maximum riser dimensions. One thing I frown on is a deck that is built at the same elevation as the interior floor. In my experience, building a deck and interior floor at the same elevation is undesirable as an egress door can easily be blocked by snow & ice, and moisture can easily infiltrate under the door threshold creating a new water supply for the home. Not much can be done after matching deck and floor frame elevations are completed, but I educate my client that it is important to clear the snow away from the door, maintain all caulking and monitor the area for moisture problems.


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Bob Mulloy is President of Allsafe Home Inspection Service, Inc. in East Bridgewater, Massachusetts, and a national presenter on the topic of deck failures. He is a licensed Massachusetts home inspector, a member of the American Society of Home Inspectors (ASHI), and Chairman of the Education Committee for the local ASHI NE Chapter. Bob is also a Massachusetts Board approved continuing education provider for home inspectors. He can be reached at 508-378-7170, by email at rmulloy@verizon.net, or via his website at:


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