It’s probably one of the single most requests that I get from homeowners looking to add on. They need a couple bedrooms but don’t want to take up what little backyard is left. It’s understandable with nearly all of San Diego homes built prior to the 1970s. Nearly all of them with bedrooms smaller than 10’x10’. Everyone needs more space. However, after meeting with a couple reputable contractors you may quickly learn that not only is it more costly to build up than to build on the ground level…it’s way, way more to build up than to build on the ground level.
Depending on who you ask, you’ll probably receive ball-park quotes of around 75% to 100% more (and up), just to add that second story. Well, that’s absurd you might say. You’re only adding 400 sq. ft. How could it possibly cost nearly $200K? To be honest, most people don’t really stop to ask why at this point. They just say, okay, never mind, and then forget the whole thing. But for those who are curious, here are some general factors that will drive up the cost in getting that two-story:
1) The age of the home. And you may think, oh, the older the home, the more it’s going to cost. And to an extent, you could be correct, but not necessarily. The factor I’m referring to is actually the way the roof of the existing house is currently framed. If your home was built in the 60s and earlier, there’s a likely chance that your home was built with conventional ceiling joists, roof rafters, ridge beams, etc. Versus newer homes that are/were built using pre-engineered trusses. The advantage for the older home is that there’s a likely chance that the second story floor can be framed without having to take out the existing ceiling. At least not entirely. In many cases, you can just remove the existing roof and build the new floor over the top of the old ceiling. This isn’t the case with homes built with trusses though, where both the support for the roof and the existing ceiling are all one big, pre-engineered mess that would all need to be taken out and thrown in the dumpster prior to any second floor being built. All this means of course is that it’s generally more costly to build over the house when the house is built with trusses versus when the house what built using conventional framing. But again, that’s not always the case, and in either case, you’re still removing a lot of the existing ceiling and a good portion of the roof. Neither would need to be done when simply adding that 400 sq. ft. on the ground floor.
2) Upgrading existing footings. To the extent that you were correct in thinking that the older the home the more expensive to add the second story, this is the factor I was also referring to. As a designer, it’s common practice when I’m designing a second story over the existing house that I’ll try to line up at least a few of the second floor walls with walls below. If those walls are on the exterior, there are existing footings that will need to be upgraded to meeting second floor building standards. This means digging down and undermining much of the existing footings so new, thicker, deeper footings can be doweled in and poured. In the case of a single story, you would just need to dowel in the new slab to the existing footing and pour the new slab and footings.
3) Adding new footings for new support walls. Depending on the design of the second story will depend greatly on where the existing footings will need to be upgraded to meet building standards for second stories. However, unless you’re going to be following exclusively the footprint of your existing first floor (resting the second floor walls only on the exterior walls) you’ll undoubtedly have some interior walls that will need to be converted to support walls. This means if your home is on a slab, the flooring on that first floor room will need to be removed in the area where the new footing will go. Then the existing concrete will need to be cut/jack-hammered and removed, and new, deeper footings will need to be poured. Then, you the homeowner can decide how best to patch the floor. In most cases, rather than live with a flooring patch that simply won’t match, the entire flooring in that roof/area will be redone, adding costs to the project.
4) Upgrading interior walls to new support walls. Following along the same path, once you have a new footing under an interior wall, that wall will also need to be upgraded. First, all of the drywall will need to be removed. Then, in the bottom sill plate there will need to be new retrofit anchor bolts drilled and epoxied into the new footing. And this is all done by a “Special Inspection.” This is an inspection that is done by an outside inspector (not the Building Inspector). There’s a good chance that the wall will have additional hardware as well if the engineer who stamped the plans called for it. And likely, the wall will be upgraded to be a new shear. This means after the electrician rewires the wall with new switches and outlets, new shear panels (OSB plywood) will be hung, prior to any new drywall, texturing and painting.
5) Engineering Costs. The cost of hiring an engineer is likely something that you can avoid when building just a single story. However, a plan for a second story must be engineered prior to submitting for a building permit.
6) Second stories take up more space. You think, oh, you only wanted to just add around 400 sq. ft. But in truth, you’re adding stairs in addition to the 400 sq. ft. And at the second floor level, there must be some account for some bit of hallway space. Plus, even if you weren’t considering adding a bathroom on the first floor, you can’t honestly add a new second floor without at least adding a bathroom. So the 400 sq. ft. is more likely 500 to 600 sq. ft. The simple matter is that if you’re going to spend the money and the time and the hassle to invest in a second story for your home, you want it to look nice. And just from experience as a designer, it’s difficult to make 300 to 400 sq. ft. look nice over the existing house. I’m sure you’ve seen them driving around your neighborhood. Those ugly, box-over the house, in the backyard additions. The simple fact is, with only a few hundred feet over the house, it’s just not going to tie into your existing house well. So, either come to terms with the fact that you’re going to have a second floor that doesn’t tie in well, or plan on adding a couple hundred additional square feet to make it more appealing.
7) Building plans cost more. In addition to the engineering fees, just by pure nature of the beast, building plans for second story additions cost significantly more. With single story additions, typically the new roof ties into the existing roof with a simple fill. You can have a permitted set of plans that are only 3 or 4 pages. With a second story though, it’s at least double that. There’s a demo plan that wouldn’t likely be on the single story plan, there’s now first and second story plans vs just a simple single story plan. There’s both floor framing and roof framing plans. There’s details on top of details showing how the existing first floor roof and ceiling will remain supported and how it will tie into the new second floor. Etc., etc.
8) Plan check, permit fees, school fees. Also by nature, because of the complexity of second story plans, plan check fees and permit fees will both be significantly more. And because of the size of the new second story project likely being over 500 sq. ft. there’s a mandatory one-time school fee tax to your local school district. In San Diego, it’s around $3.20 per square foot.
9) Making the exterior blend. This is where you get into the “optional costs” (assuming you didn’t count the additional square footage to make it tie in better and the additional bathroom on the second floor as “optional costs”). Further assuming…let’s assume your home has stucco on the exterior walls. Chances are that color coat is old enough that there’s just no way your new stucco is going to match with the old. So you have say, 1200 sq. ft. of existing home that has old stucco and you have 500 to 600 sq. ft. of new home with new stucco, plus any of the existing walls that were upgraded on the first floor for shearing purposes. Point being, is the only way to make that not look like a noticeable patch job on the first floor is to refinish the entire home with new stucco color coat.
10) Living expenses. When building a second story over the house, almost never does the homeowner remain in the home. It’s too invasive. You have the second floor over the existing home, which means much of the existing first floor will need to be remodeled as well. Between first floor walls and footings being added, flooring and drywall being removed, wires hanging all over the place, it’s just very tough for people to live in those conditions. For most homeowners, that means renting a place for the next 6 to 12 months in many cases. Again, additional expenses that you wouldn’t have when only building a single story.
In most cases when I’m discussing the possibility of designing a second story, it generally ends a few different ways. Either they don’t do it, they build on the first floor, or they build it to the max. In almost no cases have I worked with homeowners who settled for less when venturing into this type of project. If you’re going to think about investing in your home on this level (physically, mentally, financially, etc.) then you can’t settle (in my opinion). In some cases, a half a loaf can be better than none. But building a second story is not one of those cases. It has to be done in a way that will make you and your family happy. Because if you settle, then you can very well look to your finished home with feelings of regret. Like, hmm, maybe we should have added a couple hundred more feet and made it tie in better. Or, maybe we should have got the whole house re-color coated so the stucco will match.
