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Thu, Feb. 20

Column: Top 10 defects found in new homes, part II

Last time I wrote about a top 10 list I saw of the most common defects municipality inspectors find in homes being built. It was surprisingly similar to my list of common defects found in home inspections, which includes older homes. There were four items on the new home list that are not visible or relevant to home inspectors, such as the building plans not being on site. There were six items that home inspectors do find frequently: improperly installed or altered anchor bolts, beams/joists, deck framing, stairs, handrails and railings, and the paper on insulation left exposed. You can check the Courier online for my last column and more information on these items.

I have four other items on my list.

Gas appliance vent clearance: The metal vent pipes from any gas appliance - furnace, water heater, fireplace, etc., will get very hot. These vents pipes require at least one inch clearance from any combustible material, and from any insulation. I frequently find these vent pipes close to (or touching) drywall or framing members. Often in the attic the vent pipe had proper clearance, e.g. a 4 inch pipe through a 6 inch hole in the roof sheathing had an inch clearance on all sides. But now the vent pipe is pushed against the roof sheathing, often by roofers when replacing the shingles (in their defense they may be making the vent pipe plumb). In newer homes the vent pipes have sturdy braces on them in the attic so this cannot happen. No insulation should be touching these vent pipes. If there is loose fiberglass or cellulose installed a larger pipe is required around the vent pipe to keep the insulation away.

Combustion air: Gas appliances require combustion air. This is not a new concept. If you’re as old as me you used to call this ‘make-up’ air. If a gas appliance does not have adequate combustion air it will not operate efficiently, which produces carbon monoxide in the exhaust gas. If there is very little combustion air, the gas appliance may “backdraft,” or start pulling air back down the vent pipe (meaning the exhaust gas with carbon monoxide). Combustion air is very important in a small room and/or if there are other devices removing air from the home. Many times I’ve found a gas water heater in a laundry room. I’ve turned on the clothes dryer and exhaust fan and the water heater would backdraft (easily visible with a smoke bottle). Newer homes will have a high- and low-combustion air vent. The combustion air can be from the attic, crawlspace or exterior. Often there are high and low vents in an exterior wall. I have found these vents covered up because previous owners did not understand what they were for.

Another common defect is no damper clamp. When a gas log kit is installed in a fireplace, a clamp is needed on the damper to keep it fully open. If you light a gas log/fire with the damper closed, there is no smoke or odor, just a lot of carbon monoxide entering the home. This is another item that sellers remove because they don’t know why it’s there - they just want to close the damper.

And a missing hi-loop completes my top 10 list. The dishwasher drain line under the kitchen sink should loop up, higher than the bottom of the sink, to avoid a cross connection (e.g. waste water getting into supply water).

Note none of these are expensive to fix, a clamp for a hi-loop or fireplace damper is only a couple dollars.

Randy West owns Professional Building Consultants in Prescott. He is state-certified and has performed more than 7,000 home inspections in the Prescott area. West serves on the Home Inspector Rules and Standards Committee for the Arizona Board of Technical Registration. Contact him at or visit

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