Q: Last spring, mice made it into the ventilation system of our house. We believe we have sealed their entrance points and they are now...

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Q: Last spring, mice made it into the ventilation system of our house.

We believe we have sealed their entrance points and they are now gone. However, the air coming out of the vents in two particular rooms sometimes smells bad (we think from mouse urine).

Is there a safe way to eliminate odors in the ventilation system without ripping out the hardwood floor that was installed just before the mouse invasion?

Since we may be dealing with mouse feces, what types of services would be considered safe without making things worse for our house’s air quality?

A: No need to rip out the hardwood floor. First, check to see that the vent pipes in the two smelly rooms are actually sealed closely to the floor and that they are not disconnected elsewhere (like in a smelly crawlspace).

I would not be surprised to see the vents partly disconnected from the floor.

If you are convinced the smell is coming from the heating system, you will need to have it cleaned and sanitized.

Air-duct-cleaning contractors have many methods for cleaning the system. One may use back-flowing pressurized air, a powerful vacuum, an agitator brush, partial duct disassembly or all four, depending on the specifics of the system. Products can be sprayed into the system to sanitize it and reduce odors.

Ask a friend or relative for a reference, or find a contractor through the National Air Duct Cleaners Association (www.nadca.com).

Q: I have a home that was built in the early ’80s. In shopping for earthquake insurance, they asked me if the home is bolted to the foundation. In one area, where the top of the foundation is visible in the garage, I see the bottom 2×4. It has no bolts.

This visible 2×4 rests on top of another solid piece of wood maybe 1/16th inch above the concrete in some areas, which seems rather odd. This lower piece of wood is a blue-greenish color, and may be part of the foundation form that should have been removed. What am I looking at?

A: You are seeing a poured-flush sill plate. The green piece of wood you are seeing is the sill plate and is poured directly into the foundation. The bolts were drilled into this sill plate and the foundation poured around them. This actually results in a stronger connection to the foundation than bolts alone. So yes, you are “bolted to the foundation.”

You might ask, if this method is stronger, than why isn’t it done more often? Several reasons: The framers can adjust the dimensions of the home more easily if they are in control of the sill plate. Small adjustments of 1/4-inch in each direction are routine. This method costs more in lumber and spilled concrete, and results in more mistakes. The foundation workers must work around the 2×4 at the top of the wall, making the job of getting concrete into the form, settled and finished much more difficult.

Darrell Hay is a local home inspector and manages several rental properties. Send home maintenance questions to dhay@seattletimes.com. Sorry, no personal replies. More columns at www.seattletimes.com/columnists.