By Monty Lieber
Q: We have discussed adding a room on the second floor, behind our kitchen, that overlooks the water. We spoke to a couple of contractors, and one of them told us we couldn’t use our existing deck to make the floor of the new room because it had a bump which they called a cantilever, which is too far from the existing roof beams. Is it true that we should start over, instead of saving money with our existing kit?
a. What you’ve heard may or may not be true, but unless someone with the ability and training to calculate the load distribution and confirm it with building codes can verify it, you’ll probably never know if you can save the structure or not. The unwritten rule, compared to the code standard, is that frequent floor joists should not extend more than two feet behind the support beam. If the calculations show that the bending moment, fiber stress and moment of inertia are within a safe range, it may be possible to save the existing structure.
However, it becomes more complicated, because most surfaces have insufficient spreading bases to distribute weight underground, especially because people, incorrectly, assume that sandy soils are very stable. They also have little understanding in general of what freezing conditions can do to the entire structure. In other words, most floors are built on many assumptions, but it’s not a big deal if they move, since cracking and heaving in general are not a noticeable concern.
It doesn’t really matter if the design professional works on a large building or something as simple as a deck, because the ability to cause fatal problems and errors remains the same. Understandably, people want to save money by not hiring an architect or engineer for something that seems so simple, but you might want to consider that most municipalities require plans prepared under the supervision and review of a licensed professional, not second-guessing someone with power tools who builds. Many people learn the hard way, especially when they go to legalize a deck long after it’s been built and in use for years, the way it’s built won’t go through and get a permit without expensive changes.
There are many regulations, statutes, and ordinances relating to each type of structure, from where they can be placed to materials and ways to put them together. It doesn’t take much, just a consultation with an architect or engineer, to know the answer to your question. Building an addition close to the water means making more effort to do things only once, especially with exposure to high winds, force of water, corrosive salty air, salt water, and unstable soil. You may end up with a new chassis, but when you consider your investment and your safety, it’s worth it. Good luck and God bless you!
© 2022 Monte Libre. Readers are encouraged to send questions to [email protected], with “Herald question” in the subject line, or to Herald Homes, 2 Endo Blvd.,
Garden City, NY 11530, Attn: Monte Lieber, architect.