Excerpt from my regular column in the Santa Barbara News-Press.
Question: My wife and I want to have a doggy door put into the wall of our house so that our dog can come and go from the house to the back yard as he pleases. Can a doggy door be put into any wall and will cutting a hole in the wall weaken the house and damage it in any way?
Your Handyman: Yes a doggy door can be installed in most any exterior wall on your home and if installed correctly will not harm your home, but the job will go quicker and easier if some time is spent in selecting the location. What you want to avoid if possible is selecting a location for the pet door where utilities like a water or gas pipe or an electrical cable are present. If the location you are considering has a garden hose valve nearby on the outside of the wall, or there are electrical outlets nearby on the inside of the wall, then the likelihood of a pipe or cable being in the way of your pet door is greater.
Once you have the location for the pet door selected, the first step is to trace the outline of the hole needed for the door opening onto the inside drywall or plaster using the paper template that comes with the door. You will need either an electronic stud finder or the old fashioned magnetic stud finder that I prefer, to determine the location of the wall studs which usually are about 15” apart, and the door will need to be centered in the space between two wall studs. Take care to position the opening relative to the height of your pet so that the finished door is easily accessible for the dog or cat. Carefully drill a 3/8” to 1/2’’ diameter hole in a bottom inside corner of the traced opening taking care not to insert the drill bit any farther than necessary inside the wall so as to not damage a pipe or cable. Use a drywall or jab saw to carefully cut along the line, once again being very careful to not penetrate any farther than necessary inside the wall. A jab saw is much easier to control than a power saw and will be less likely to cause damage to unseen utilities. After a small section of wall is removed, place your hand inside the wall to confirm that there are no pipes or cables in the way.
Once the interior wall is opened up, the next step is to take a long drill bit of a smaller diameter to carefully drill through the exterior wall from the inside corners of the opening, making a hole in the exterior siding that lines up with the corners of the inside opening. Take care to make sure that your drill bit is level so that the corner holes in the exterior siding line up both horizontally and vertically with the inside corners. If your exterior siding is stucco or smooth plaster, then your drill bit will need to be a masonry bit in order to drill through the cement based siding.
With the corners of the exterior opening marked by the 4 drill holes, you can now sketch the opening size on the siding and if it is a wood siding, you can prepare to cut the opening by drilling a larger starter hole for a reciprocating power saw like a sawzall or a jig saw. If your siding is stucco or plaster, you can make the cut using either an angle grinder or a circular saw outfitted with a masonry blade.
The pet door will have an inside piece and an outside piece that overlap in the middle of the wall, and once your opening is complete the door itself is pretty simple to install using the screws provided by the manufacture. Be sure to use an exterior grade caulking to seal the outside edges of the door to keep out moisture and insects and your door is ready for pet traffic!
If it turns out that an electrical cable does pass through the opening then you will need to install a new electrical box on each side of the door and loop a new section of cable over the dog door opening inside the wall. These two new electrical boxes can either be installed with electrical outlets or with a solid cover plate but the wire connections for the loop going over the dog door must be in an accessible box per electrical codes. It is unsafe and a code violation to have any wire connections hidden inside a wall without access. If you do not have experience and knowledge on how to safely and correctly do this electrical work, then you need an electrician.
If a water or gas pipe is discovered in the opening, then the pipe will need to be also looped over the opening which may not be an easy thing to do without substantially enlarging the drywall opening, and in the case of a threaded steel pipe, it would probably be best to select a different location for the door.
One last very important concern for a pet door is to not unintentionally provide access for the local wildlife to enter your home. Several years back my neighbor woke up in the middle of the night to find a family of skunks in his kitchen happily eating the cat food after hopping through the pet door. My neighbor quietly went back to bed, the skunk family politely left when the cat food ran out, and the cat door was permanently sealed up first thing in the morning.
Skunks, raccoons and opossums are common throughout the Santa Barbara area and you may want to consider a pet door with an electronic feature that allows the door to open only when the pet approaches while wearing a small sensor device on the collar. This feature will add to the price of the door but will keep out unwanted late night visitors and is probably money well spent.
Owner, YourHandyman & Construction
CA License #935259