Thinking of buying a 1970s house?

One of the most fundamental threats to your pocketbook as a new home owner is the condition of the foundation. However, most people do not know that the biggest threat a foundation faces is from plumbing leaking under it. The sewer line is in constant use and many homes built in the 1970s have cast iron sewers. These cast iron sewers have a working life of around 30 years (project executed at KIMAB, Europe’s leading corrosion and metal research institute) which means most of the homes built during this period or earlier have leaking sewer lines!

When moisture escapes from a sewer line under a home it has a particularly dramatic effect on homes built on North Texas soils. It causes the foundation to rise, or heave, to give it its technical name. This movement can be dramatic and causes many problems with the structure. Clearly, if you are buying a house it is important that you have the sewer checked. If you think the average home inspector is going to do this for you, you are wrong! A home inspector simply runs water down the drain to see if it drains slowly. A symptom of a leaking sewer is not a slow drain. After all, if it is leaking, the water has some where to go!

This glaring omission in the inspection process has been corrected by Yellow Hat Inspections, which has a special methodology for determining if the sewer condition is affecting the foundation. It consists of three stages: 1. measure the level of the foundation, 2. examine the sewer pipe under the house with a fiber optic camera and 3. analysis of the collected data.

The following graph shows the measurements of a small 1100 square foot home. You can see that the foundation has heaved in three distinct points. These measurements indicate that the foundation has lifted up over 2.5”! The foundation plot indicates to the inspector the types of issues that the structure might have. You would think this would be a routine task that all home inspectors would do but it’s not. Most simply look at the foundation! You can look at a foundation - you don’t need an inspector to do that for you, do you? 

The graph shows that the foundation has leaks under the house at all major sewer connections. This is to be expected as the connection points of a sewer line are the weakest points and most likely to leak. As the water enters the soil under the house the ground expands with tremendous force pushing the foundation and the house standing on it up!

The next stage is to inspect the sewer system. Videoing a sewer line is not the most glamorous job I have ever had but it is a very worth while service for my home buyers. Take a look at the picture below. Notice how corroded the iron pipe is and it will not come as any surprise to learn that the rise in the foundation was due to the leaking sewer.

Most people reading this will not be surprised to find out that iron sewers under homes leak after 30 years of use; which begs the question why does the home inspector look at it for you? At Yellow Hat we always recommend that you have a video scan of the sewer line under the home you are about to buy.

Call Yellow Hat on 972 832 3460

Find out more about us; Google yellow hat inspections or look us up on Angie's List and see our Super Service Award for 2012