Help with Foundation type and home location - NY

[Sassy]

Neat idea how they've used brick & you can park your car underneath but I totally do not like the style of the house - reminds me too much of mobile homes but hey, that's what I see the new designers using - all the modern apts, city houses, buildings...  even Bill Clinton's library looks like a big mobile home - as far as I'm concerned, not very imaginative.

But what do I know, I'm just a cave dweller  

[John Raabe]

That will be an expensive house with lots of steel beams, moment frames, and custom engineering. Not a candidate for an owner-builder project (with the possible exception of Glenn!)

[glenn kangiser]

I could do it with scrap I have collected, but likely I might forget to ask for approval.....

[Squirl]

By the looks of the picture the floor free spans 25-30 ft. That is impossible to do with standard dimensional lumber. That would have to be all steel or engineered trusses.  Those widows look like they would cost more than some of the cabins here.  Whoever builds this has a lot deeper pockets than me.

[Net_Eng]

How about this one?

The idea here is to have a raised pier to use as storage, open garage/parking and possible a kitchen. This is how houses are in South America.

The problem is, with snow and high winds, I am not sure if this will be permitted or practical.

http://www.houseplans.com/841-square-feet-2-bedroom-1-bathroom-Beach-home-plans-0-garage-(31448)

[MountainDon]

Anything can be done with an engineer.

Whether or not it could be owner built is another matter. That one is better. From the front at least you can see how the load from a ridge beam can go straight down to the main floor level. Looks like the load can then be transferred down to center columns and footings. But there's that engineer guy with his hand out again. Nothing against engineers, they earn what they do and know stuff the average owner builder has no clue about.


If you read through the IRC anything you see there can be done with no engineer in many places. Some places have governed themselves to the point an engineer is needed for approval of any building plans. But unless you live in one of those places if the IRC shows a method you can do it yourself. If it is not in the IRC you can't do it on your own, without an engineers approval; things like houses on stilts and so on.

[Net_Eng]

Why do I need an engineer?

The code officer said that if its less than 1500 Sf and cost less than 20k, I do not need an engineer.

[Sassy]

I like that house    don't have any useful advice tho 

[Squirl]

It may cost more than 20K. (looks like it)  Also, I don't know about your exact location, but the exact wording on the building permit for mine is "I want to obtain a permit for a Residential Home Under 1,500 Square Feet.  What do I need to apply for my permit?**Detailed structural plans, lumber size and spacing, labeling of all rooms.""** Code Official reserves the right to require engineered stamped plans for all projects."  This is the catchall legal compliance so that people can't go and try and build an extremely complicated, experimental, or anything they aren't readily familiar with.  Most jurisdictions have this.  The last design might comport to NY ICC guidelines.  The height of those piers does not look it, but nothing stops you from spending $640 to find out.  Also the 5 ft of unsupported deck off the front doesn't look it either.  The chimney design looks like it might not be standard too.  It has vaulted ceilings for each side, which would require a truss or ridge beam.  Either of these would require a engineer stamp of them individually or the plan as a whole.  It depends on your inspector.  If it they do flag it, you could probably get a quote from a local engineer how much it would be for them to certify the plans.  The picture of two Ferrari's and a BMW roadster under the house looks like they are targeting a market that wouldn't care about hiring an engineer and builder

From their own website.
In some regions, there is a second step you will need to take to insure your house plans are in compliance with local codes. Some areas of North America have very strict engineering requirements. Examples of this would be, but not limited to, earthquake-prone areas of California and the Pacific Coast, hurricane risk areas of the Florida, Gulf & Carolina Coasts. New York, New Jersey, Nevada, and parts of Illinois require review by a local professional as well. If you are building in these areas, it is most likely you will need to hire a state licensed structural engineer to analyze the design and provide additional drawings and calculations required by your building department. If you aren't sure, building departments typically have a handout they will give you listing all of the items they require to submit for and obtain a building permit.

Additionally, stock plans do not have a professional stamp attached. If your building department requires one, they will only accept a stamp from a professional licensed in the state where you plan to build. In this case, you will need to take your house plans to a local engineer or architect for review and stamping. In addition, plans which are used to construct homes in Nevada are required to be drawn by a licensed Nevada architect. All house plans from Houseplans.com are designed to conform to the local codes when and where the original house was constructed.

[Squirl]

Just did a quick look through of that website they have 1000 plans under 1000 sq. ft.  Like this one.

http://www.houseplans.com/213-square-feet-1-bedroom-1-bathroom-Cottage-house-plans-0-garage-(36350))

Look familiar?  They look a little like the little house plans.  And what a steal only $2500.  

[MountainDon]

Why do I need an engineer?

The code officer said that if its less than 1500 Sf and cost less than 20k, I do not need an engineer.

My thoughts are thus: Tall stilty things are not the usual run of the mill projects. As soon as it is up off the ground a ways, in my opinion, it is a whole new ball game and one most of us have played in. The elevated platform like that needs to be sturdy thing to deal with potential wind forces. Your ability might be superior to some others, I have no idea. I've seen a number of scary home builds that were close to the ground, only a few feet off the ground, to make me think that professional engineering advice could be very valuable in building something like an entire house elevated some 8 to 9 feet in the air.

Maybe it's just me and that is just my opinion.

The under 1500 sq ft and under $20K.... just how complete does it have to be for that $20K? And what gets included in that?  I think our cabin came in complete with appliances but no furniture at $46 a sq ft. It was 470 sq ft, around $21-22K

[Kramer]

When you're building something that isn't exactly 'tried and true', I see 3 distinct possible scenarios.

1.  You hire an engineer.  He tells you how to build it so it will last.  This costs money.

2.  You don't hire the engineer, but go overkill on the materials (look at an early railway trestle for example).  It will last.  But it costs a lot of money.

3.  You don't hire an engineer, and underestimate the forces involved in critical locations.  It won't last.  It costs you money in the end because it falls over.

Code may not require an engineer's stamp, but they're acting on assumptions that you're going to build something that is tried and true.

[Net_Eng]

What do you guys think about a 30' x 30' and raised 3' from the ground with concrete piers?

What are some of the materials (lumber, Joists and metal roofing) limitations I could run into?

I am working on a sketch and will share later

[MountainDon]

Three foot piers, of any material, will need to be extremely well braced if three feet high and each sitting on its own footing pad. At that height I would not want to depend on most soils to prevent lateral or rotating movements. The way to think/look at this is to ask, what will hold each pier in the proper place and vertical if the earth turns to mush?

If a continuous perimeter footing was poured with provision for rebar tieing the footing and piers together than the concrete piers might work well. That is done in the raised floor method. A search should turn up a topic or link or two on the forum.

[Net_Eng]

What will be a recommended height using concrete piers? My greatest fear is serviceability and protection from the ground.

Whatever I do, it had to be 4' down to pass the frost barrier. If I have to do a footing, I better do a crawlspace. If I have to do a crawlspace, I will be better off with a split level basement. The problem with footing/crawlspace/basement is money/money/money but if that is best for me.... well I have no other choice.

[MountainDon]

I'm not an engineer and I tend to be conservative.  I can't recall ever seeing a recommended ratio of above and below ground for piers. That may be cause there are simply too many variables.

I doubt it matters what the pier is made from as far as any ability to resist lateral slipping or tilting (rotating about some point below the surface). Concrete may have a longer life than wood in some places but that's about it. My opinion.

I built our 16x30 cabin on ten 6x6 PT piers. The footings are 44 to 46 inches deep. The piers only protrude 12 inches above ground. That is a ratio I am comfortable with, but I have no scientific data to back up the decision. The soil is sandy, gravely with good drainage. I also have plans to add some PT lumber and plywood panel bracing across the piers at the east and west ends as well as between some of the piers on the north and south sides. Why? There are no signs of any issues; the concerns are sprouting from my mind and more reading that I've done. Or I must be becoming more conservative as I age.

At this point I'm not certain what I would do if building something larger. For one thing at the same location I'd have more slope to deal with if making it wider and do not feel comfortable with more pier sticking out above ground.

[Net_Eng]

So, I think we have different understanding of "footings". I interpret it as a continuous wall 4' down, the same size of the building... like a crawl space. If I understand your reply, it doesn't matter if its continuous or not.

Here is what my plans were:
1. A series of 4' hole in the ground using sonotubes and their extended bottom.
2. These sonotubes will be 7 feet tall, 8" wide with a 4 rebar extending the full length
3. At the top center of the pier/footing, I will have a bolt which is tied to the rebar and extend about 3" which will secure the sub-floor to the pier/footings.

[MountainDon]

At the top center of the pier/footing, I will have a bolt which is tied to the rebar and extend about 3" which will secure the sub-floor to the pier/footings.

But what keeps the pier from tilting if some combination or wind, water and some other natural forces combine to push on the walls of the house. The bolt(s) connecting the pier top to the beam does not offer much in the way of resisting rotational forces.

A footing as used with the average pier and beam builder is a square or round concrete pad (poured in place or precast) placed down at/below frost level. Sixteen to twenty inch square or diameter, depending on soil.  A pier or post placed on top of one of those has little to no inherent stability. They depend in large on the soil preventing lateral or rotational movement. When see that someone is wanting to build on piers I automatically think of one pier, one footing pad. If that is not what you meant, I stand corrected and apologize.

A continuous footing or steel reinforced poured concrete goes all around the perimeter, with bent rebar securing around the corner. Additional rebar can be placed with legs protruding upwards, ready to receive a poured concrete column or a pier built from concrete blocks, filled with concrete and rebar. This makes for a more stable foundation using piers than the above with each pier independent of the other.

It does matter if it is continuous or not, continuous is better. Sometimes, something like I built can get away with what I did. I know more now than I did when I started out. Like I said I plan on some additions in the form of what amount to braced panels. I feel, and again point out I am not an engineer, but I feel that any piers much taller than mine require better bracing than what is commonly seen.

A couple suggestions from Don_P  http://countryplans.com/smf/index.php?topic=9264.msg119918#msg119918

or this one  http://countryplans.com/smf/index.php?topic=6189.msg85537#msg85537

One could probably get away without the brick curtain wall but panels at least at the corners would add lateral movement resistance.

[MountainDon]

That is what I mean by a rotating force. The pier will not likely hinge on the very bottom end, but would move, rotate, around some point below ground, unless there is something serious built in to resist that movement, if/when the ground becomes too set, big winds blow, maybe the ground shakes a little.... If all the bottom ends of the piers were locked into a full concrete perimeter footing it becomes much more difficult for rotating or tilting to occur.

As pictured that is lengthwise down the long side of the building. The same thing could happen across the width, maybe even more so as that side of the building is longer. In the case of a square building it's even steven.

This is the sort of thing I'd like to hear a licensed PE comment on.

[Net_Eng]

Would something like this work?
http://www.sonotube.com/products/sonotubeconcreteforms/tubebase.aspx

[MountainDon]

Those probably better than a plain tube on a normal poured/cast footing. .... but read installation tip number 8....

Sonotube form and TubeBase footing form combined cannot exceed/extend 24" or more above grade/ground.

Reading further they warn about proper bracing if taller than 24".... to exceed/extend 24" above ground/grade when pouring concrete, the Sonotube form MUST be braced to prevent movement of Sonotube form while the concrete is curing. (Conventional methods: Strapping or 2X materials w/stakes; wooden collar; frame with side braces)

So much depends on the soil. That is why the IRC does not include things like these as prescriptive solutions.

What costs more, an engineer to look and advise, a set of tubes and feet, a poured perimeter with tied in piers/columns, fixing something that didn't work out?     Sorry I don't know the answer for certain. The tube bases would be better than something else I'm sure. But again, I'm not a PE.

[Net_Eng]

So I am guessing you are recommending something like this http://www.cabinstartup.com/index.php?p=196&album=1&gallery=1

Here is a cost analysis he did for the different foundation types. http://www.cabinstartup.com/wp-content/uploads/2010/01/Cost-Estimate-Basement-vs-Crawl-Space-vs-Concrete-Slab.pdf

I am thinking that the the pier type foundation may not work for me even if I drop it to 24", what do you guys think.

PS. Do not hesitate to correct me if I am wrong. I rather have your appropriate comments rather than paying for it later.
MountainDon, I really appreciate your comments and knowledge. Thank you very much.

[MountainDon]

You got it! 

[Squirl]

2ft is a pretty decent height for a crawl space.  If you want more height what I have seen many other do around here is they use PT posts to get little taller.  It is easy to add wood bracing to the wooden post to the foundation.  You are not in a heavy seismic activity area or a heavy wind area that I know of.  If you are not building a tall building, this should greatly decrease the lateral force on the piers.  The larger the footing and the more the posts, the less susceptible to rotating force.  As I said in the beginning of the thread all options have drawbacks. While post and pier is the least expensive foundation design, it is the most susceptible to shifting.  Good soil, drainage, and depth can be more important than the actual type though.  Without those three things any foundation can fail.

[Net_Eng]

What do you guys think about this Dug's foundation? Could he have gotten away without the ties?