Structural Engineering advice

That_Guy

I've recently turned 30 and started formulating my new 10 year plan. I set some very realistic goals when I was 20 and accomplished pretty much all of them. Part of this new plan is to build my dream house. I've begun initial planning and wanted to bounce some ideas off some folks here. I am hoping some of you have practical experience with structural engineering. I haven't even made any drawings yet since I don't know the feasibility of some of these ideas.

I want to build a poured concrete home. I've read a lot of bloggers who have built their own from rebar, wooden forms and a few truckloads of the gray stuff. I don't want to go with a traditional foundation however. Having grown up on the coast, I saw a lot of homes are built on stilts (don't know the technical term) for safety during flooding. I also know that in earthquake prone areas foundations can be fastened directly to the bedrock. My idea is to create a hybrid of the 2 where in steel pylons are driven into bedrock with the foundation being directly poured into and around anchors at the top of the pylons. Ideally the foundation would be at or below ground level so it doesn't look different from a normal home. I realize this might be going WAY WAY overboard but I basically want to build a bunker that will survive the worst of climate (or political) change over the next century for myself and any descendants I might have. I want something that an archaeologist could possibly dig up in a thousand years to see how someone in the 21st century might have lived.

From what I know of structural concrete construction, it's not a terribly difficult process. I've sent a lot of time watching the pros do it around town, on youtube and on tv. It seems to me like I could do much of the work, only calling in the pros to drive the pilings, pour the structure and do the trade stuff like plumbing and electrical. I know a bunch of tradesmen so I feel like that wouldn't be much of a challenge either. Ideally I would integrate much of it in the structure itself, around the rebar further easing installation.

Is this a crazy idea?

bowen

Seems pretty crazy, the foundation would survive but the house might not.

What location are you looking at? They tend to underpin where there's a lot of seismic activity I thought?

schuss

You'll need a crew to do it properly, as you'll want to be pouring much larger sections at once utilizing full mixer trucks, as economies of scale make that a more efficient way to do it. You'll also want an architect available to sign off on drawings and ensure some level of code compliance, as the last thing you want to do is build it and be denied an occupancy permit.

That_Guy

schuss wrote: »

You'll need a crew to do it properly, as you'll want to be pouring much larger sections at once utilizing full mixer trucks, as economies of scale make that a more efficient way to do it. You'll also want an architect available to sign off on drawings and ensure some level of code compliance, as the last thing you want to do is build it and be denied an occupancy permit.

Naturally I would get a real architect to look at any plans I might draw up. and sign off. My plan is go in several phases. Phase 1 will be driving the foundation. Phase 2 will be me constructing the forms, roughing in the plumbing and placing conduit channel. Phase 3 would be the big pour.

bowen

make sure you leave as much rough-ins as you could ever possibly need too

Liquid Hellz

Its not a crazy idea but it is expensive. There are two basic types of pilings http://www.understandconstruction.com/pile-foundations.html

Once these are done you can basically build whatever you want on top of it, from a highway overpass to a skyscraper. If your doing it yourself or managing the project and other people yourself plan on it taking 2-3x longer than anyone tells you so your not disappointed when you cant move in as quickly as you had hoped. Have fun with it, maybe create a photolog or blog because it sounds interesting!

tinwhiskers

I'm confused, by what you mean by wanting the house to look like a 'normal' house. Normal is a really useless word to use here.

In the upper midwest a full basement-block or poured- is normal and the top of that is usually 1 to 3 feet above the ground level.
Further south, or on the coasts you get poured slabs, where the houses just rest on a flat table on concrete, there is no basement. This is really common in like Kansas for example, which is a really poor idea because of the tornados, but...
And in flood prone area's you get housed built up on stilts-which you also won't see in cold areas because all the air flowing underneath the house would fucking kill you're ability to keep it warm in winter.


Also depending where you are bedrock can be very very deep. For example here's a map of WI. For large areas of the state bedrock is >50ft from the surface.


What 'makes sense' in building stuff is almost entirely based on the location. So where are you planning on building your survivalist bunker?

J/K, everyone knows it's gonna be in Montana.

Enc

This kind of custom, client driven spec homes are something several of my family members do for a living. Generally this is only for a very high end clientele. I'd expect this to be in the very highest range in your area. For Florida, where the average new home is in the 300k range, something like this I would expect to probably run in the 800k to about 1.6 million range depending on how much square-footage you are looking at. Adjust that accordingly for the average in your area (which will likely be waaaaay higher out west on the coast not only due to housing costs but also earthquake mitigation).

It certainly isn't crazy, if you can afford it. In Orlando alone I know of at least 15 builders in this sort of classification and I am hardly well versed in them. Plenty of crews are out there that keep a strong portfolio, have in house accredited architects and designers, and simply work to make your dream homes reality. It's totally a thing and a popular one right now (as vanity home projects are a major place the 5% is still investing in the economy).

The Pick Two: Time, Cost, and Quality is definitely true in this field.

That_Guy

Right now I am living in the mountains of Western North Carolina but have not decided if I will settle here. ARCGIS confirmed my suspicions (given how much of is visible on the surface) that the bedrock is pretty shallow around here. When I said "normal house" I meant I didn't want it to look like it was up on stilts like a beach house, mostly due to concerns about heating and cooling costs. I haven't decided how much if any of the structure would be below ground level. Most of the homes around here have basements.

Thanks for providing the correct terminology here. An End Bearing Pile Foundation is what I am looking at. I fully expect the materials cost to be far in excess of traditional building. I feel like I can eek out a good savings in the end though DIY and tradesmen I am friends with.

I plan to install far more conduit and piping than I possibly think I would need. I've done enough low voltage wiring jobs at work to know that far too few places were built with the intention of expanding later.

This plan is 5-10 years from completion. I am in no hurry and will be taking my time with this.

Edit: I will take cost and quality over time any day of the week. Through my job I know architects, plumbers, electricians, structural engineers, GCs, and full on commercial construction companies. I am sure I could throw together a crew with over a century of experience between them for a couple weekends.

Enc

If you are building in west NC you will have plenty of builders to choose from if you go that route. The Luxury cabin market (which isn't just cabins), is a booming field right now and from Boone to Ashville there are a ton of spec home companies. Over the last five years a lot of the best folk we used to work with from construction to cabinetry have relocated there due to the boom.

Basar

I am not 100% certain but a friend of ours, an architect, has built a house for herself exactly as you have described if I understand it correctly. This is her house: http://elvankaradeniz.com/Proje/assos-kayalar-koyu1/

Turkey is almost %100 concrete housing. I can ask her about the right way to go about it when you have some drawings, etc.

That_Guy

Basar wrote: »

I am not 100% certain but a friend of ours, an architect, has built a house for herself exactly as you have described if I understand it correctly. This is her house: http://elvankaradeniz.com/Proje/assos-kayalar-koyu1/

Turkey is almost %100 concrete housing. I can ask her about the right way to go about it when you have some drawings, etc.

That is a really fucking cool home. I want to do something kind of like that, just not so lush and elaborate. I am happy with squares. I feel like i can build square concrete forms. I don't think those awesome arches are in my budget range.

zepherin

So I was a concrete superintendent back in a former life, and concrete buildings are interesting, they are more expensive than stick frame houses but it's doable. Now are you are not going to be able to do this by yourself. I don't know how able bodied you are but it generally takes 5 or 6 laborers and a finisher to handle truckloads of concrete.

You may want to consider doing the house with precast concrete. Essentially the site prep happens and they have the shell made off site and assemble it on site.

How much are you thinking of doing by yourself?

Now if we can narrow down the climate I'll show you some great add-mixes that'll make that concrete outlive you.

That_Guy

I have no intention of doing the pouring and finishing myself. I don't have the skills to handle that much concrete, nor do I have the machinery like one of those 10 foot long vibraters. I feel like I could handle the rebar, conduit, piping and forms. I recently spent an afternoon watching a construction crew bang together a concrete mold at a job site downtown. It doesn't look difficult to do if you plan it out correctly. Hell, something like this looks simple enough to assemble in an afternoon with a plier/wirecutter combo.

I do IT for a living. I can take apart and put back together laptops and other electronics with ease. I have an understanding of loads and forces I have even done low voltage wiring on new construction. If I can do that, I feel like I can follow an assembly diagram. It's not going to be easy, but I feel like enough of this is doable by a non-professional to offset some of the costs associated with construction. I think I am capable of tying together pre-cut/bent rebar with steel wire. I think I can glue and assemble pre-cut and marked conduit/plumbing pipes. I feel like I can bang together some simple wooden forms from pre-cut scrap wood. I'll bring in experts for check over my work and do things I can't.

We get all 4 seasons around here. It can stay below freezing for a week or more at a time in the winter and we sometimes see a foot or more of snow at a time. Summers tend to hover in the high 80s to 90s. Everywhere I look the climate is getting more and more extreme so I only expect this to get worse. I'm not expecting opus caementicium but I do want something that would outlive me.

bowen

I am happy I can live vicariously through you, I want lots of pictures man

Foomy

I would look into insulated concrete forms, I've seen a few houses built from them and it sounds like it's what you want.

You just put it together like giant lego styrofoam blocks linked together with plastic ties and some rebar, then the concrete gets poured into it.

This way you get the advantage of all your walls being very well insulated, and then you can put whatever outside finish you want on it to make it look "normal"


edit:
heres an example build of one using them:

https://youtu.be/5LrlSR-Qm8o

if you didn't care about the extra time it looks pretty feasible to do all the form setting yourself and then just bring in a crew for the pours.

zepherin

Ok so you don't save much money doing the form and rebar yourself, I wouldn't recommend it. Yes you can plan and set it yourself. You don't have the tools to really get a good compact on the earth, so if they mobilize to set the site up, demobilize for you to set the forms, mobilize again to pour the concrete, it's not ideal.

For concrete you can use a high performance mix.
http://www.cement.org/for-concrete-books-learning/concrete-technology/concrete-design-production/ultra-high-performance-concrete

It's usually used for commercial applications. It has superplasticizer in it, and when it is ready to pour you have about an hour to get it into place before it becomes very hard to work with.

If you are using an architect consider going precast. Same material, architect handles layout and rough ins, but you don't need to worry about the forms and a lot of the worry.

http://precast.org/2012/12/dream-home/

schuss

I'll also ping my father, as he's done a bunch of commercial concrete buildings (and even won an award from the concrete council or whatever at some point)

Fiendishrabbit

I want something that an archaeologist could possibly dig up in a thousand years to see how someone in the 21st century might have lived

Then don't use concrete. At least not the modern type of concrete. Modern concrete has a projected lifetime of 100-150 years. Even after 60 years it will lose a lot of integrity and lose its resistance to wear and erosion.

Note. Roman concrete lasts for millenia, but getting your hands on the proper type of volcanic sand...

zepherin

Fiendishrabbit wrote: »

I want something that an archaeologist could possibly dig up in a thousand years to see how someone in the 21st century might have lived

Then don't use concrete. At least not the modern type of concrete. Modern concrete has a projected lifetime of 100-150 years. Even after 60 years it will lose a lot of integrity and lose its resistance to wear and erosion.

Note. Roman concrete lasts for millenia, but getting your hands on the proper type of volcanic sand...

He can use fly ash it has similar properties, and with superplasticizer it is better than what the Romans used. There is a world of difference between commercial materials and the stuff you buy at Home Depot. If you want to get real fancy you can seal it, but standard concrete is going to run ~600 bucks a truck load. It's ok has a ~6" slump and is what most people encounter for residential. 3000-4000 psi compression strength.

High performance concrete runs ~1100 bucks a truck load has a 1"-2" slump and a 9000-11000 psi compression strength. It's great, but it is expensive so most of the time it is not in the spec.

spool32

How was the @Sir Landshark signal not lit for this thread!

get in here and drop some knowledge dude

honovere

I'm probably biased, but I would advise getting an architect. The cost for one averages 5-15 % of the building cost and you'll get a house that is up to code.

There are architects, mostly young small firms, that specialise in building homes on a budget while still looking good.

Sir Landshark

I'm pretty tired today so maybe I'm just not reading clearly, but can you clearly state your design goals? You want the house to last 100 years? 200 years? You want the house to survive some sort of Noah's Ark type flood event? End bearing piles on bedrock aren't going to do shit for uplift, fyi, unless you socket them in (in which case might as well go crazy and drill shafts into the bedrock since you're doing R/C anyways).

I saw some mention of seismic resistance too? Above and beyond what would be typically required by code (IIRC design seismic forces are roughly set to the 500 year event)? So like, what, a 2500 year event? 10000 year event?

I'd recommend coming up with a clear list of design criteria and then hiring a design team (arch + structural + MEP) to draw up some plans.

Enc

As a note, the best seismic resistance is to have your house be a zeppelin.

EclecticGroove

That_Guy wrote: »

From what I know of structural concrete construction, it's not a terribly difficult process. I've sent a lot of time watching the pros do it around town, on youtube and on tv. It seems to me like I could do much of the work, only calling in the pros to drive the pilings, pour the structure and do the trade stuff like plumbing and electrical. I know a bunch of tradesmen so I feel like that wouldn't be much of a challenge either. Ideally I would integrate much of it in the structure itself, around the rebar further easing installation.

If you plan to do this, do NOT just sink in the power lines and such. You need to be able to get access to this stuff without cutting/breaking into concrete. Pipes break, wires need to be replaced/upgraded over time. You'd saving yourself a ton of headaches down the line if you allow easy access to this stuff.