A home inspection should catch most of the glaring issues in a home, but there are some deal breakers that are hard to pinpoint. In fact, some major headaches don't reveal themselves during the inspection because they are outside of the standard inspection scope. To get the most out of your inspection, it's important to note a few things that may be overlooked.
1. Damaged or blocked sewer lines
Some issues don't show up immediately and a partially blocked or damaged sewer line is one of those things. Inspectors will run water through the fixtures and try to determine the age & type of drain pipes used but won't always catch damaged pipes. In fact, sewer-pipe scoping may be the only way to identify issues and that service isn't included with a standard inspection.
2. Failing HVAC & cracked heat exchanger
These two issues are less common in the PNW, but still good to note in case the house you are purchasing has the equipment. HVAC equipment can be fine one day and stop working the next day. Especially under stress, equipment can fail without warning. A similar issue would be a cracked heat exchanger. Again, it's not part of the standard inspection to examine it, but some can develop cracks. You can always hire an HVAC contractor to inspect these elements, but that is a hefty cost and takes a few days to complete.
3. Electrical issues
When it comes to electrical issues, an inspector can identify a receptacle that is faulty, but can't always determine the problem's source. It will require a professional electrician to find the disconnect in the system.
4. Structural problems
An inspector will be able to determine what is normal or not normal when it comes to a sagging roof or slanted floors, but they won't know how much it would cost to repair or the extent of the damage. Also, depending on the time of year, the roof or foundation may be covered in snow and a standard inspection would not be able to see all the potential problems.
Again, depending on the time of year, leaks may not be there one day and surprise you the next. Also, in the case of a vacant home, if the plumbing systems isn't being used on a daily basis, any leaks may have dried up and not show themselves for a few days after the water is on. The best thing you can do is check drains in cabinets before and during your move. Sometimes, drains will get bumped by belonging during a move and this could cause them to start leaking.
To spare yourself some of these common headaches, take the time to find a certified inspector who is very familiar with the area you are purchasing in. They are the experts and will be able to know where failures are likely to occur.