Q. We’re looking to buy our first home, and the one we like most has a strange thing we’ve never seen before. There are tree trunks in the basement that hold up the support beam. Is this OK? They aren’t even or straight, like a wood or steel post, and even have some knots in them. Should we be concerned, even though we’ve already made an offer?
A. You’re not necessarily barking up the wrong tree to make an offer on a house like this, but it does show the age of the home. When people say, “They don’t build houses like they used to,” I usually think, thank goodness.
What you’re seeing was common through the 1920s, when locust trees, known for their resistance to decay and insects, were used as support columns. These trees have been used for structural support for many centuries. Their most well known use was for supporting the city of Venice when the swamp-dwelling inhabitants, who lived on small islands, stabilized and built the city. Using locust posts, they could conduct their marine merchant trade while protecting themselves from the regularly invading Goths, preparing for attacks by seeing them from the north from 20 miles away, long before an attack could take place.
The Venetians rammed locust posts deep into the seabed and supported those beautiful Renaissance structures on them. In the James Bond film “Casino Royale,” there is an intense fight scene that takes place in a building under extensive renovation. At the end of the scene, the building, which actually was having the locust posts retrofitted, like most of Venice, collapses into the watery depths. From an architect’s perspective, knowing about the structural changes underway, this was very interesting as well as dramatic.
If the locust posts aren’t split and cracked but are smooth and semi-straight, they should be fine to continue to do their job. If you see signs of weakness or are suspicious, contact a licensed architect or engineer who has experience with these conditions for a closer look. If you decide that the columns need changing, then the job requires building temporary walls in the basement on either side of the main beam to support the whole structure of the home before the columns are removed. Correctly calculated concrete foundations, called footings, will need to be installed by digging up the concrete floor where forms are set and the footings are placed.
Whether steel or wood columns are installed, the anchors for them need to be properly placed and attached. The columns, when installed, should be connected, at the top and the bottom, to the footing and to the beam. This isn’t a small job, and requires an experienced company that protects the area from dust before cutting the concrete, orders the right strength of cement for placement in the formwork and knows what connectors to install top and bottom. Good luck!
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