Poorly constructed roofs. One thing I see a lot is in the areas of the roof valleys there can be traps that will cause dirt and leaves to accumulate then when a storm comes the water will back up and eventually find its way through into the house. Another is poor drainage around the property, the house should not be the lowest point in the area. You don’t want water runoff to go toward your foundation.
If you are buying an existing home, look for any improvements the seller may have done to the home over the years. Contact your local building standards department and see if any building permits were issued for the work. If not, you may want to have a professional look over the work before placing an offer.
Be sure to understand what improvements require building permits before jumping to conclusions. This will vary from market to market.
One of the main things to look for is a good foundation. If you see vertical and horizontal cracks that create a pyramid or Christmas tree shape on the wall or especially in corners, they come from loose ground before the footer was poured. You will want to have that looked at by a professional.
Many of us have experienced backed up drain lines in a home, it can show up in the showers, sinks, tubs and toilets. Home inspectors do not scope the waste lines during the home purchase inspection process. The common running of water and flushing the toilet during an inspection is not an accurate test for the demands on the waste system when living in the home. Not all that uncommon is a new homebuyer to find that once they have moved in drain lines begin backing up.
There are three common causes which can cost in the tens of thousands of dollars to address. If the waste line trenches were not properly compacted and backfilled during construction the waste lines can have low sections under the house slab or breaks at the “tap” where the house line connects to the City sewer, both which prevent proper flow and lead to backups. Improperly glued connections which leak invite tree roots which can break or heave the lines having the same effect. And homes built prior to the mid sixties often have steel or clay lines which corrode and collapse.
For a couple hundred dollars a plumbing locating or inspection company will run cameras through all the drain pipes and give you a copy of the footage. Knowing your drain pipes are in good working order and will not create a nightmare situation on the first holiday gathering is worth the extra cost during the due diligence phase of the home buying process.