Deck inspections 101

One of the most important items of a home inspection is the deck. If the deck needs to be rebuilt, it can be very costly depending on the size, materials and damage if the current deck is not flashed properly.

The focus of this article is the give you insight into some quick observations you can detect on your own without any special tools or training. One should be aware that this list is not exhaustive. What I have chosen to explicate, however, are the critical factors to how I determine that a deck was possibly built without a permit. Hence, I will now commence the enumeration of a few of the most common design flaws. 

First, I want to discuss safety hazards.

Study the photos below and see if you can pick out the problem with these decks. Do you see anything wrong?

Answer: missing balusters. Needed for safety, these should be installed vertically with maximum spacing between of 4 inches. Without these, nothing is to keep small children from crawling through these. The results could be deadly. 

Furthermore, stairs higher than 30 inches that have open risers (depicted above with a yellow arrow) are not safe for children. Risers may be open but should not allow the passage of a 4-inch diameter sphere.

Next, I wish to address the topic of footings.

Footings are needed to properly support the deck structure. They need to be 48 inches deep, 8 inches across minimum. This design prevents frost from lifting the deck and moving it away from the house wall attachment. Improper footings such as cinderblocks, 5 gallon drums filled with cement, and patio blocks will allow the deck to rise and fall with seasonal changes. If you have a porch with windows, it is very common to see cracked windows.

Another common flaw is the split girder design, and the support column running inside the deck band joists. The flaw with both these designs is the fasteners, nails or bolts provide all the strength. The weight of the deck should be resting on top of the support column not fasteners.

Most home inspectors will miss this. In fact, I have seen it signed off by the town building inspector once. Which forced a call from me to the town building inspector to confirm if it is not allowed. It is not.

The installation of Simpson DJ T 14 Z, (see below) brackets is an approved repair in most jurisdictions of New Hampshire. Another approved repair entails using dimensional lumber fastened to the support column extending directly below the girder and all the way to the footing. 

The approved design is seen in the figure above, denoted Figure 1. Notice how the girder stretches the entire length of the deck and the weight is transferred to the support columns below.


Above is the most common guideline that all jurisdictions follow. As pointed out above, none of the previously pictured decks followed these common codes. Therefore, when you come across such a deck, you can assume no permit has been issued.

Why do you need a permit? If you’re a first time home buyer or someone that does not know how to properly build a deck, your town building inspector can be of assistance. Once a permit is issued the town building inspector will inspect each phase of the deck construction to ensure it is up to current codes. Once the deck is complete, the inspector will return and sign off on the deck if it is correct or request the contractor to fix any issues that do not comply.

Some subcontractors who are marginal at their work will try to tell you a permit is not needed. Some will try to convince you that if they build the same size deck a permit is not needed. False! This should be a red flag. The only reason a contractor would suggest this is so that they may perform low quality workmanship. The building inspector watching their work will identify subpar workmanship, alerting you in the process.

In essence, if you hire a contractor to build a deck, I would suggest phase payments, check prior work. Do not make the final payment until the town building inspectors signs off on your deck. This protects you from an inferior product.

Most common town spec sheet for deck guidelines and specifications. Deck Construction Guide lists all aspects of proper deck design.

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Submitted by StephenGaudet