To some of you, this topic might sound a bit random when compared to the other broader topics in my blogs. I select the subject matter based on the number of times I’m asked a particular question. I have not only heard this one over and over, but the fact that so many people are asking if they can add a second story means they don’t understand the process in the first place. You’ll see what I mean in a minute.
So you want to know if you can add a second story to your home, and you are unsure if your foundation or main floor can hold it up. I am here to tell you that the answer is yes, and not in the, “Anything is possible for the right price” kind of way.
I know what you are thinking. “She doesn’t have any idea what my foundation is, so how could she possibly know if it can hold up a second story? Maybe I should ditch this crazy architect and call an engineer.” Right? What I would like to do is educate you on why you will be able to add a second story, because if you understand the process, then you will be able to advance to the next step in your remodel planning instead of spinning in circles around this fruitless question.
I have never come across a house on which I couldn't add a second-story, and I’ve seen all sorts of interesting foundations: There's cast in place concrete, post and pier and concrete block. I've even seen houses sitting on chunks of a log, on tires packed with earth, on a pile of rocks, shall I go on? While I’m not recommending all of these as viable options, let’s break it down and look at what is actually required, because many old homes have a mixture of “creative” construction techniques from a previous owner’s friend of a friend, who knew a guy, who helped with some addition way back when… and we are stuck trying to make this strange concoction function for you and your family. The last thing you want is to spend thousands of dollars on drawings to find out we have to knock the whole foundation down to make it work, right? Stop worrying. That is so not necessary. This simple explanation will make the whole process seem less scary.
The average footing today is 8” thick with rebar (steel rods) embedded it in. Building codes now have large safety factors built into their requirements, making things a lot bigger than is actually necessary to hold up your house. While it would be great to have the beefy 8” thick walls, we can work with what you already have by simply modifying isolated pieces to be the required work horses. Let’s say you want to add a second story to your 1930’s home. Part of your foundation is cast in place concrete (but it is only 6” thick), and one section is concrete block (but you are unsure if it has any grout or rebar in it…. because you don’t have x-ray vision). You can even add a log or two as a stand-in footing just for good measure to make this example really fun. In general, when you add a second story, you have a roof that sits on walls, which sit on lower walls, which sit on the foundation. We transfer loads from top to bottom, right? That’s just basic physics. To be more specific, imagine a beam holding up the weight of a floor above it. Under each end of that beam is a post carrying roughly half of the weight on the beam (my old structure’s professor would be mortified by this simplification but nevertheless…). Those loads isolated in those two posts are called point loads. Architects trace those point loads from the tippy top of the roof all the way down to the foundation, and the structural engineer sizes and details them to make the math work out. The reason we can add a second story to your log-footing home is because wherever those point loads are coming down, we modify the structure in those isolated locations to make the math work out. For example, if a point load is coming down on top of your 6” foundation, the engineer might require that we break open the concrete footing below the wall and pour a new 2’x2’x1’ deep footing in that specific location and voila! Problem solved! If you have a point load coming down on your unreinforced concrete block, the solution might be exactly the same, or something slightly more complicated like temporarily propping up the house and replacing a section of the block with concrete. Even if you had a pile of old shoes as a footing, the same solution would apply there as well. Prop up the house, replace, done. While there are other factors your team will need to contend with (shear forces, up-lift, seismic retrofitting, etc.), trust me when I say that I could bore you to death with other similar examples of how we might deal with any necessary structural modifications for your particular desired outcome. The answer will still be yes, you can add a second story.
Not to throw a wrench in the works, but do you really WANT to go up? Many times it can be more expensive to build up than it is to build out. The reason for this is if you're building out, you can start from scratch with your new level foundation holding up your new plumb walls, etc. The sheetrock is easier to hang, the cabinets sit flush on the walls, the finishes align without 10 million extra hours of finagling details until your fingers bleed…. AND you don’t have to pay for the added space to house a staircase. However, if your lot is small or you’ve already maxed out your lot coverage, if you could take advantage of a view, or if you just want a second story, then great. Go for it. I just had to ask.
If you were allowing yourself to get stuck on the uncertainty of your existing foundation, let me offer some advice. Start with the homework assignment in my Budget blog and download the questionnaire in my Priorities blog. Start dreaming and crunching numbers, and stop worrying about your foundation for now. If you are preparing a party, you don’t get hung up on the entire planning process if you are unsure if you have enough glassware. You begin by determining your headcount, and if in fact you don’t have requisite supplies, you go figure it out. You don’t get stuck in tableware quicksand.
Let me know if you thought this was helpful! Thanks!