Nitpick: SIPs may be used in modular construction, but I’d consider them to be more of a material type than a method, like modular or prefab. I have a friend who uses them for his custom homebuilding “hobby”. Materials costs can be higher for SIP walls than for stick framed walls, but my friend likes them because he finds them easier to build with and they’re really energy efficient.
I’ve been watching Bob Vila’s Home Again recent series of episodes on modular pre-fab homes.
With the builder he’s highlighting, it’s basicaly an assembly line of walls and roofs which are then assembled together on site instead of building from scatch on site. All the basics are the same when put together. It’s just the middle part of the work itself itself that’s different.
Opened my predjudiced eyes, let me tell ya. Seems like a very good way to go.
I agree. You always need to be thinking about resale value. If you can stretch and spend $100k on a house that will be worth $120k, you’re much better off than if you had spent $90k on a house that will be worth $80k.
This really isn’t all that true if we are talking about a stick framed house. Standard structural stud walls have enough excess strength built in them to handle an upper story. (BTW, the brick on the outside of most houses is not structural) 3 stories might be a stretch but the bottom story of 2 story houses are pretty much exactly the same as those found in a single story house. The studs aren’t any larger and they aren’t closer together. You don’t have to add columns provided you have load bearing walls below the load.
The most you have to worry about is wind load. You need more bracing.
It is true that you have floor joists when you add a second story, but… duh. You got to walk on something. You might also need beams. Again. No kidding. But that’s all a part of the structure for the second story. You also have beams below the first floor - grade beams. Except those are made of concrete and are integral to the slab. A floor made of joists along with the structure to spread the load to where it needs to go (beams) is a WHOLE lot cheaper than a structural slab, which you are practically cutting in half.
This is true.
This is probably not true.
This is not true.
Nah. While it’s true that you have to do it, it really isn’t all that difficult.
Wider than what? You either have floor joists because you have a second story or you don’t have any at all. Unless your first floor is raised, which is possible, but it doesn’t need to be any stronger. The load of the second floor doesn’t go through the first floor’s joists.
Again, wider than what? It’s true that you’ll need more lumber but you make your foundation cheaper.
This is true. But in all I am thinking that the 92% that desdinova quoted is probably mostly accurate. It’s cheaper to build up than out, unless you go very high, which requires steel. Steel’s expensive.
Also true.
I would recommend that the OP get a loan. The expense of housing is precisely why we have mortgages.
I really, really, really hope it is at least partially grounded in reality… Marshall & Swift is the construction cost manual the entire real estate appraisal industry is based on. If there are any other cost manuals out there, I’ve never heard of them.
If that book isn’t at least reasonably accurate, we’ve been appraising buildings wrong for a very long time (at least, more so :p)
I think he was saying that floor joists in a two-story house need to be wider lumber, e.g. 2x12’s vs 2x10’s.
I don’t think it has been mentioned in this post, but ranch-style homes are less practical if your lot is on a hill. The larger footprint means that more earth moving is needed.
Would a ranch on a slab be cheapest? I don’t want a basement, and I think having two stories robs you of some floor area (a staircase costs you 50-80 sq. feet of area). I also like an open floor pan…kitchen, living room, dining room in all one space-this means fewer interior walls. Also, if I opt for fixed windows, do I save money?
I really like modern houses, so a somewhat stark appearence is OK with me (I absolutely LOATH Victorians)! 
Yes, a slab foundation will be the cheapest, depending on where you live (so tell us your region, man!) The perimeter of your foundation has to extend below the deepest point where the earth may freeze (the frostline.) This is only a few inches deep in the Southern US, so a slab is a cheap way to build. The frostline can be several feet deep up north; I assume it’s cheaper to lay floor joists on a perimeter foundation there.
Regarding layout, I can’t repeat enough that a box (rectangular exterior) with a simple gable roof will save you money. The roof requires less planning and is easy to build and roof.
An open floorplan should save money; there are fewer walls, less wiring and fewer doors. Also, you can probably make more efficient use of the floorspace. A central load-bearing wall running the length of the house may make the ceiling and roofing costs cheaper, since the trusses or attic joists only have to span half the house’s width. You would need to use headers to support things in the open areas. Then again, the wall may not be necessary; trusses can be made to span the 30 feet or so that I assume we’re talking about.
Beyond floorplan and framing, try to have all your plumbing fixtures share the same wall; the bath should back up to the kitchen. Also have those rooms on the side closest to your water and sewage (or your well and septic.)
I think that flooring, electrical fixtures and kitchen and bath fixtures are places where you can really save money. Stick to the cheaper product lines at the supply houses, but get a tub that won’t crack. If you have an electrician friend, they might be able to help you reduce the number and length of runs in your houseplan (for example, you will need an outlet every six feet along a wall, so a fourteen foot length of wall will require an extra outlet over a twelve foot length.)
Now, where should you spend money? I’ve always heard that one should put any extra money into the bottom and top of a house; the top protects, and it’s hard to fix the bottom. Were this house mine, I would put extra money into the foundation (in a slab foundation, I’d pay for better subsoil, deeper beam footings, another sack of cement per yard of concrete and/or more rebar, in that order.) I really hate how cheaply most slabs are made. On top, I would make the roof overhangs wider, to keep sun off the walls in the summer and keep rain away from the walls and the foundation. I’ve also found metal roofs (Galvalume, specifically) to be both affordable and long-lasting, but they’re not for everyone. You also want (at least in the South) to have a good ventilation system in your attic (probably a ridge vent) to reduce the amount of heat sitting on the other side of your insulation.
All said though, the cheapest housing bet would be in a subdivision built by a budget homebuilder (i.e., Kaughman and Broad Homes) or in a Jim Walters home if you already owned the land. That said though, I’d much rather build a home like the one I described above, just to make sure that it was done right.
How much does a basement cost, as a share of the ground floor?
How much does an attic cost? (Or is it thrown in for free, as it were?)
[slight hijack] What about a fourth floor? I understand that there are a couple of leaps in cost when you build up. At some point steel is required (at what floor?) and elevators must be installed (when?).
Also, after you have a steel structure and an elevator, what is the cost of an additional floor, as a fraction of the cost of the preceding floor (or whatever you want to choose as your base)?
Are there major commercial/residential cost differentials? [/hijack]
Important disclaimer: I’m a commercial appraiser, and rarely do anything involving single-family homes.
I’ll have to get back to you tomorrow when I’m in my office on this one…
If it’s completely unfinished, it’s thrown in with the roof, assuming we’re talking about a home with a pitched roof.
M&S doesn’t say anything about fourth floors on single-family homes to my recollection. For, say, a highrise apartment complex I’m pretty sure each floor is calculated to cost a fixed percentage of the first floor up to some point, at which we’re talking about a pretty non-standard property and the usual calculator approaches are meaningless.
I’d imagine there would be no problem building up to a four story wood frame house, but above that you’d want steel or concrete. Of course, that ignores the fact that most single-family zoning districts won’t let you build a four (or even three) story home.
Barring any objections from the local fire marshall or code enforcement officer, elevators are not required so long as it’s your home and not a public building. Even for public places it’s a little tricky… the Americans with Disabilities act is not a building code, and doesn’t say much of anything specific about what buildings need to be compliant. I’m no expert in the ADA, so I really don’t know. I can tell you two story garden apartment complexes certainly don’t need elevators, though.
Have to look that one up tomorrow too… off the top of my head, here’s a useful guideline: anything weird is gonna cost a lot of money. If we’re looking for maximum floor area for minimum cost, weird stuff like steel and elevators out of the question for “normally sized” homes, say, at least less than 10,000 square feet (yes, I’m setting the bar for normal pretty high here). But if we’re talking about giant multi-family affairs, high-rises are probably more efficient, particularly in areas where land is particularly expensive. Out here in the midwest, that isn’t a problem. What’s more, most renters appear to prefer garden (two-story, walk-up) apartments, so builders find those more efficient for their purposes in this part of the world.
There don’t have to be, everything is negotiable of course. I find that, typically, a new multi-family development will cost more per square foot of living area than your typical new home. Of course, multi-family developments typically have office space, swimming pools, etc. They’re also usually sitting on pricier land (typically it’s only the crummier land that gets relegated to single-family residential use). This is by no means always the case, though. I may also be heavily influenced by the fact that much of my consulting and appraising is involved in the Federal Low Income Housing Tax Credit program, and their tax credits are a function of their construction costs (within reason).
I can also tell you that, at least around here, “commercial grade” is frequently a synonym for “cheaper” as far as finishes are concerned. Commercial grade carpeting and sinks, for example, usually refer to very thin carpet and plain jane white toilets.
In the end, there’s no real difference between the cost of installing one thing in a residential home and the same thing in a commercial building. It’s the fact that the materials and designs are fundamentally different that causes the disparity. A prefab metal warehouse costs far less than a home of the same size, and a full-service restaurant will cost far more.
Sorry desdinova, I completely mis-understood your point. What I asumed you were saying was that the top floor wasnt as expensive to construct as the bottom, for the reasons I pointed out. Ergo if you were to construct a single story building the same size as the first floor of our hypothetical two story, it would be around 92% of the cost as well.
I have to concede that the world of real estate apraisal is a mystery to me. Too many non-relevant factors for me to consider. All I know is a two by four costs me the exact same amount no matter where I put it, but seems to increase exponentially in value the closer to the ocean it is nailed up.
No disrespect intended prisoner, but in my 20+ years in the construction industry I have gotten many blueprints from “recent architecual school grads” that had me and the boys laughing our asses off in the trenches. I trust you don’t routinely spec 9’ ply sheathing or 22’ I beams in your drawings.
Naw I kid, you know as well as I that drawings frequently go back because it is impractical to build them as planned. Just a reality of the biz.
I will answer some of your questions though, but if this gets into a long, blue vs white collar shit slinging match lets open our own thread so we don’t lose the OP’s original direrction.
*This really isn’t all that true if we are talking about a stick framed house. Standard structural stud walls have enough excess strength built in them to handle an upper story
If this were true all you would have to do to convert to two floor would be to rip of the roof and frame another story on top. I know damn well it aint done like that.
I’ll give ya that standard stick framing is used on a ground floor but it is built with the second floor in mind. This includes widers headers, load bearing interior walls etc. not to mention wiring races, ducting runs and the the whole host of crap not needed in a single floor.
*Nah. While it’s true that you have to do it, it really isn’t all that difficult.
For an architech no, but he will incur more cost paying for the more complex drawings. Of course he could just install a single, central wet wall and situate the kitchen and baths around that. Piece of cake, even for the owner/builder type.
*Unless you plan to build on million dollar an acre real estate.
This is not true
Are you seriously suggesting it would not cost less to buy a half acre at 500K and build a two story than it would to shell out a mil for the land for the same sq footage single story house? Dude, lumber is expensive but not as much as prime land.
*Wider than what?
Wider than the joists on a single story joisted floor. As I said, you can install pillers in the ground and use much narrower joisting in a single than you can on a second where you have a greater span. Hell, in the old days we used 2x6x8’s with 5/8ths subflooring for the “plantation style” houses. Damn them things were noisy to walk on.
I won’t even go into earthquake codes as it’s been far too long since I built anywhere that had them. I’ll just state that two story homes I worked on in the SF Bay area had substantially more to them than the single floor types.
Oh I forgot to add, a couple of reasons for up cheaper than out.
Land cost of course and dont forget the labor/ equipment cost of grading a larger footprint for the structure. You are right, the larger the lot the larger in general the crew working it tends to be. This CAN add a substantial cost. I completly forgot to factor in what a dozer crew would run in my advice. On resale the larger lot would also command a higher price.
I was mostly adressing materials cost and the greater need for skilled labor to build up. Of course large single floor places sell for more than same sized two stories packed together in a cul de sac. Welcome to reality EvilG.
I really do believe he would do better cost wise if he were building on cheap or already owned land if he left off the second floor. Especially if he plans to do most of the work himself. None of us have even considered his location and how much it would cost to connect to utilities. If hes in the sticks it may well be a huge consideration.
Cornflakes tosses out some very good advice for the would be owner/builder I take it he is a builder or an experienced handy. His advice on how to prioritise spending is top notch.
Um, is the staircase included in “Gross Living Area”?
If it isn’t, you have to take into account the fact that a one floor unit will have no floorspace taken up by the staircase. That might offset the .92 ratio somewhat (although I would guess that a staircase would take up less than, um, 4% of the footprint).
Big Picture, as I understand it:
It’s generally cheaper to build up. OTOH, there’s an abrupt cost-shift when you add an elevator or change the structure of the home to steel.
Q: Does this cost shift generally occur between the third and 4th floor? If so, how much extra does the 4th floor cost, as a percentage of the base floor, once the elevator and new construction method is taken into account?