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Dealing with a steep grade

ryanyoung

This may be the wrong place to ask but I had to start somewhere. There's a piece of land in my hometown that's amazingly priced for its size and location, the problem is it's at a very steep grade (almost 45 degrees) angled downward from the street. I've been saving up to build a small house in this area and unfortunately it's so expensive to buy land here that my options are extremely limited.

This parcel is very affordable but I'm going to need to be creative to avoid $50,000 or more in excavation and leveling costs alone. I've always liked the look of the Lautner Chemosphere in California and a similar design seems like a good way of making use of the otherwise prohibitive terrain. I'm thinking of a smaller much smaller home, maybe 800-1100 sf, and am not trying to put the entire structure on a single support column as he did.

I'm having trouble finding information regardig building on pilings, there's lots on building for beach front but very little on using them to accommodate a very steep slope. I'm wondering how terrain affects the cost and possibility of building on pilings. I'm a catastrophe adjuster and have some understanding of construction and design, but not enough to properly appraise the costs or contributing factors. Below are some specific questions:

How deep are pilings typically buried?

What are the warning signs of slope erosion and can it be mitigated?

Is it even possible to build securely when the bedrock (3'-7' below surface) is sandstone?

What are reasonable cost expectations for installing the pilings and subsequent supports?

Are there any other methods of accommodating a steep slope that may be more cost effective?


 
Jun 22, 17 1:57 am
Non Sequitur
All your questions can easily be answered if you hire an architect. You'll also need civil and structural engineers.

As for the cost, foundations are expensive, triple that when it's custom work on a slope with shallow bed rock. Best for you to hire a structural p.eng for a few hours to tout the site and make your offer on the land contingent on having your team of professionals review.
Jun 22, 17 6:14 am
JonathanLivingston

Yeah, There is a reason the land is cheap. Do yourself a favor and inquire about it with your JHA / local planning department. Chances are it is classified as a potential slide zone and possibly prohibited from being built on. So it would be a nonstarter, though you can sometimes get around that with a lawyer and good responsive city engineers. Also very hard to fund if your taking lending to build, because the land has little equity because of the challenging slope. 

Jun 22, 17 1:14 pm
chigurh

could be an un-buildable lot from a planning/zoning perspective....they can kill projects like that will all sorts of sneaky ordinances...do your research. 

Jun 22, 17 1:21 pm
proto

a geotech engineer is also needed for this project in addition to the other professionals listed above

in my area, steep slope residential lots are all that's left of city land that isnt developed. I've seen $100k and up (one recently at $300k) to establish a proper foundation to build on in those locations. Between seismic requirements & proper bearing conditions, the foundation costs really add up quickly.

Jun 22, 17 5:06 pm
ryanyoung

Thanks for all the info, I knew I'd have to hire some specialists before I got serious about this but wanted to get as much research of my own done first.

Based on discussions with the agent I don't think there's any ordinance preventing construction, though I'm not as certain about stability so a geotech will probably be the first step. I'm young and don't have a huge amount of spare capital currently so I need to take this one step at a time to avoid overspending on a lot I may not wind up buying.

Any suggested books that cover similar designs?

Jun 23, 17 12:49 am
senjohnblutarsky

Don't take the word of a person trying to sell you something.  Check with the municipality about the regulations affecting the property. 

Jun 23, 17 7:28 am
Non Sequitur
Ryan, don't try to do this on your own. Books won't come close to the experience of the local professionals that deal with these everyday. Spend a few hundred bones for an hour or two for an arch and p.eng's time and set up a consultation.

It's a decent red flag If the land is cheap and no developer has snapped it up yet.
Jun 23, 17 7:33 am
geezertect

^ If you're young without much money, don't do it.  There's a reason that experienced potential builders have walked away.  There are very few bargains out there.  Some pieces of ground shouldn't be built on even if you can get them for nothing

Jun 23, 17 10:15 am
chigurh

The ordinances usually don't explicitly say you can't build there, they limit driveway grades, or retaining wall counts/heights, building height/area, excavation depths etc, essentially making development impossible, or development that would make any sense financially impossible. On the surface to a laymen it seems like you might be getting an unbelievable deal, but if it sounds too good to be true, it usually is.  Don't ever trust a realtor.  

Jun 23, 17 11:17 am
geezertect

True. Don't listen to the agent. He has a duty to sell the property for his seller, period.

robertchuang

I am building few projects in hillside in LA. I think the most important part of the cost would be hiring an hillside geologist. And they can give you a good indication of a site to build on once they dig into it.



Nov 20, 19 10:37 pm

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