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EngRMP
Joined: 05 Mar 2008
Posts: 40
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 Posted: Wed Mar 05, 2008 6:49 am Post subject: House on very steep land |
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Hi folks,
I have bought a 1 acre lot on very steep land in St Croix. In about 10 years I hope to build a retirement home. I would like to use these 10 years wisely and do whatever planning and prep work that I can. So, I'm exploring various sources of knowledge and information.
I'm hoping that folks have some ideas for me to consider. Here are my initial thoughts:
- the lot is very steep, and I want the house as high as possible for the best view of the ocean. By steep I mean that it drops 100 ft over about 200ft of travel. I think I need to raise the eventual lot by 10-20 ft in order to get any view of the ocean (and capture breezes). Can I use these 10 years to gradually raise a lot and secure the soil with vegetation or other structure?
- the house has to survive hurricanes.
- drinking water has to come from rainfall (there are no natural water sources on the island)
- sewage has to be handled locally (septic tank, field, etc)
- buying things on the island is probably expensive. I wonder if I should consider a kit home that I transport to the island?
- the good news is that I don't have to worry about freeze/thaw cycles (unless we enter a global warming ice age). Temperature change is probably only 20 degrees from winter-summer.
So, there are lots of "interesting" challenges... and opportunities.
Is this a good challenge for a university to take on as an educational project? Are there useful sub-forums in this forum that I should peruse? If so, which... any obvious ones, that a dummy electrical engineer like me might overlook? Does anyone know of engineering firms that specialize in building techniques for steep land? How about construction techniques and materials for hurricane zones?
Thanks, in advance,
rmp
PS, I have KML topo lines to view on Google Earth. |
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csintexas
Joined: 06 Feb 2006
Posts: 1303
Location: USA
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| Posted: Wed Mar 05, 2008 7:39 am Post subject: |
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I don't think you could build stable ground on that kind of slope without building some very expensive retaining walls. You will need a professional engineer. No one will be interested in this as a class project. Without any other info I would guess you will probably be best putting the house on peers.
I would imagine you will be able to find engineers and architects in that part of the world that have experience designing that type of structure.
A lot of stuff will have to be shipped regardless so using a kit would primarily save labor although using SIP's may enable a lighter structure. I wonder how much concrete costs there. It sounds very very expensive but you probably could tell that already from the cost of other similar houses in the area.
That's a good idea about using the time to start planning. My dad spent a few years around that area living on a sail boat. Sounds like fun.
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Chris Stewart
Modern Texas Home Project |
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Madimel
Joined: 06 Feb 2008
Posts: 110
Location: Scottsdale, Arizona
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| Posted: Wed Mar 05, 2008 8:05 am Post subject: |
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| On a lot that steep and limited budget you have to be careful on your wish list of things that you may want. One of the major items that you left out is the size of the home that you are thinking about. Obviously, the smaller the footprint, the easier it will be. Since it is a retirement home, it sounds like that you will have to contend with stairs, either on the site or in the home or both, either of which is not an ideal condition. Leveling the lot to make it a uniform level is just unsightly. With lots such as these, you almost have to design around the vehicle since the drive and the garage with positive drainage will take up a tremendous amount of space. |
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mx2
Joined: 18 Jan 2006
Posts: 1820
Location: Miami, Florida
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| Posted: Wed Mar 05, 2008 1:34 pm Post subject: |
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I'm designing a house now in Haiti on the side of a mountain and the issues are pretty much the same. A very expensice item, regardless of what you build the house out of, is the retaining wall. However the first step is doing cut-and-fill with a retaining wall to level out a pad, rather than just building a retaining wall and filling it. Basically its filling-in in front of what your digging out.
But there are some tricks...one, rather than just filling in up to the retaining wall, many opt to build this as a cistern and collect rainwater, and on drought occasions, buy a truckload of water. Then you sit your house on top of this reservoir.
As for the house and making it hurricane resistant, it really comes down to quality. If quality control is not easily available (like in Haiti) then build out of concrete, preferably block because labor may generally your cheapest item...check with your local builders. When in Rome...
But it could be built out of wood, if built well. That would require an experienced Architect. But for one, I suggest a hip roof, low profile (one-story) and design it to be shuttered nice and tight. Batten down the hatches matey!!
Sewage is a septic tank and for environmental reasons, please make sure it's not near the water nor poorly built.
You may want to consider solar energy, battery and generator for those days you can't take it...Nature that is. I would build a little bunker for those items a few yards away at least.
Another quick design solution to alleviate retaining wall costs is to step your house...the upper portion overlooks down to a lower portion, perhaps enclosed as a double height space, etc...but then again, your asking for wind pressure issues....
When in doubt, do as all islanders do and...keep it simple. When a hurricane does come, leave and come back to re-build!
mx2.5
_________________
*Art of Architecture: The conscious use of skill and creative imagination in the production of an aesthetic building.
*Science of Architecture: The calculated use of technical skill and knowledge in the construction of a functional building. |
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mx2
Joined: 18 Jan 2006
Posts: 1820
Location: Miami, Florida
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| Posted: Wed Mar 05, 2008 1:35 pm Post subject: |
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p.s. don't forget one of the most important issues...site drainage. Rain water sheds down the face of the mountain and can rip away at your foundation.
mx2.5
_________________
*Art of Architecture: The conscious use of skill and creative imagination in the production of an aesthetic building.
*Science of Architecture: The calculated use of technical skill and knowledge in the construction of a functional building. |
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EngRMP
Joined: 05 Mar 2008
Posts: 40
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| Posted: Wed Mar 05, 2008 2:13 pm Post subject: |
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Hi MX2,
Thanks much for the replies. All excellent points:
- yes, I only want a small home (the minimum allowed is 1500sqft). I figure my kids can build a bigger home on the lower portion of the lot later... or tear down what I build and start over.
- I am very concerned about soil erosion. That's why I thought that maybe I could gradually raise the site over 10 years. If I raised it by 2 ft/year, I thought I might be able to gets plants established on the new slope that would help to stabilize the soil.
- I'm not a building engineer, but I thought I might be able to build up concrete posts over the 10 years also. If these were 2 ft in diameter and 8 ft apart, and I added 2 ft of height each year and buried them in fill, then I'd end up with 20 ft concrete posts embedded in stable soil. I'm sure it's not that easy, but since I have 10 years, it seems like I should be able to take advantage of that time period to prepare the land.
- yes, I'll be 62 in 10 years, and I already complain about stairs. So, I'd like to keep EVERYTHING on one level if possible. I like your notion of building around the driveway... that's maybe a good way to approach the problem.
- I like to landscape, so I'm already planning a meandering path that takes it's time to navigate the 100 ft of slope. At various switch-backs I'll open little planting/sitting areas that have different views of the Sun and island. And, I might be able to coax and collect the rain water into a pond along the way and keep fish (at least a few fish to eat the mosquitos that will try to make the pond home).
So, I see lots of opportunities. But, I'm sure that I need some serious engineering help. And, I'm very open to experimentation with architecture, materials, energy saving, low impact, etc. I contacted a few universities to see if they were interested in a study project for their students (to prepare the land). I think the liability issues scare them. So, if anyone has any advice on where to look for ideas on how to help my self and others, I'd greatly appreciate it. |
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mx2
Joined: 18 Jan 2006
Posts: 1820
Location: Miami, Florida
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| Posted: Wed Mar 05, 2008 2:54 pm Post subject: |
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10 years is a long time, even for the islands... 
And then you'd only have the foundation ready. I think it would be best to contact a local builder and have them give you a price (and method) for doing the complex things. Have them prep for you a road and a pad (flat area with foundation ready to build upon) for you upon which you can slowly build the actual house over 10 years instead...that's a lot more fun!
In terms of University projects, they would love this kinda thing, at least for the earlier Design Studios. Just ask them to design the house and let them have at it! The engineering will have to be looked at more carefully regardless. Good luck and enjoy!
mx2.5
_________________
*Art of Architecture: The conscious use of skill and creative imagination in the production of an aesthetic building.
*Science of Architecture: The calculated use of technical skill and knowledge in the construction of a functional building. |
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birgco
Joined: 01 May 2007
Posts: 254
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| Posted: Wed Mar 05, 2008 4:54 pm Post subject: |
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I would scrap the idea of trying stabilize that steep a slope with super expensive retaining walls. All you need is a torrential rain/hurricane event and your house could end up in the ocean at the bottom of a mudslide. There is rock (volcanic or otherwise) under that hill and that is where I would spend my money. Pin some heavy duty steel or wood columns to the rock and leave the underside of the house open so hurricane force winds and rain will pass through. Also, by keeping the depth of the house (front to back) to a minimum, you will lessen the drop down the hill and the length/height of the vertical foundation columns.
It is also a good idea to check out other houses on island that are built on similar sites.
Find the oldest one and that's your site design.  |
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Madimel
Joined: 06 Feb 2008
Posts: 110
Location: Scottsdale, Arizona
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| Posted: Wed Mar 05, 2008 5:08 pm Post subject: |
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I agree with seeking the advice of a local builder. Building a home or preparing a home site over a course of ten years could yield disasterous results should a hurricane or a tropical storm hit your site. I also want to know how you intend to excavate or bring fill on the site. How do you plan to compact the material? If you do this incrementally, your rental fee of the equipment that you will need will add up beyond the original scope of work should you decide to do it at the same time.
I think it is a good idea to invite a group of students to use your site as a case study, but don't expect too much. Architectural schools tend to be very theoretical and won't spend much time on budget, buildability or your lifestyle (program). |
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EngRMP
Joined: 05 Mar 2008
Posts: 40
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| Posted: Wed Mar 05, 2008 5:26 pm Post subject: |
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Hi Birgco,
Thanks for the ideas:
- yes, I don't like the idea of retaining walls either... too much potential water to hold back. However, I was thinking of building up (over time) concrete posts to serve as "stilts" for the house. I would also bring the land up with the posts, but just use vegetation to hold the soil. If I took 10 years to build up 15-20 ft, then I was hoping that I could keep the land stabilized and not need retaining walls. The soil would hold the posts in place.
- Although I like your idea of tieing into rock. Since I have to dig into the side of the hill to form a pad anyway, I'll probably expose rock that I could tie into.
- Very good idea to keep the house narrow to keep from dealing with a lot of the slope. I guess I could live in a trailer home genre. Actually the other attractive feature of this approach is that all rooms would have views of the ocean.
- Excellent idea to look at the oldest homes. I know that St Thomas has MANY homes on slopes. They seem to just build on wooden stilts. I don't know... as an engineer, that just makes me nervous. But, it probably has the least impact on the land, and thus leaves the land as stable as before the house. Oh, I see, I think you're saying to use this approach, but tie the back of the house to the rock (via steel or wood), and support the front of the house with steel posts that are as long as needed to reach rock.
- I have to have a sistern to catch water anyway, so I think most people build that under the living quarters, which is a way to build up (use the sistern as part of the base of the house). |
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EngRMP
Joined: 05 Mar 2008
Posts: 40
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| Posted: Wed Mar 05, 2008 5:36 pm Post subject: |
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Hi Madimel,
Thanks for the thoughts:
- Hmmm, intuitively it seems that preparing the site over a longer period of time could lead to more stable conditions (very slight, incremental changes; more time to look for and react to instability). I must be missing something.
- it seems that more than one person likes the idea of involving students, so I think I'll pursue that (maybe I'll post an invite in this forum). I like the idea of making this opportunity available to students. Yes, I work with many researchers myself, so I realize that they might get more out of it than I will; but, who knows, over 10 years, I'm sure that they'll come up with many ideas that I'd never come up with. |
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teamjdc
Joined: 25 Oct 2007
Posts: 145
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| Posted: Thu Mar 06, 2008 1:00 pm Post subject: |
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A) Any specific design suggestions you get here are purely speculative and potentially dangerous and expensive.
B) Do not spend time or money "improving" the site without professional guidance.
C) Doing anything without a geotechnical investigation and a structural engineer is a huge mistake.
D) Doing anything without investigating local laws, codes and which palms to be greased is a mistake.
E) I'm guessing you got the land for what you thought was a bargain price. The landscape is littered with cheap, unbuildable lots. Many of them can be found on eBay. |
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csintexas
Joined: 06 Feb 2006
Posts: 1303
Location: USA
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| Posted: Thu Mar 06, 2008 2:04 pm Post subject: |
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Yes you may be able to find someone interested in the house design portion of this project (I was referring to the engineering and practical issues involved) I wouldn't seriously expect to get anything but some ideas out of that though.
Building up 20 feet of fill on a flat site is problematic enough much less trying to build it up on a steep site. Sure over time dirt will naturally compact and plant material will stabilize it to a degree but I wouldn't bet a house and my life on it.
I think you need to find an engineer that is local.
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Chris Stewart
Modern Texas Home Project |
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EngRMP
Joined: 05 Mar 2008
Posts: 40
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| Posted: Thu Mar 06, 2008 3:58 pm Post subject: |
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Teamjdc, csintexas,
Thanks for the replies and experienced opinions:
- yes, I’m abandoning the building up concept (unless I hear otherwise from an engineer that knows the local geology).
- I’m thinking steel I-beams. Vertical members out in the front of the house, and horizontal members under the house. I’m guessing that would minimize the impact on the land. And, if I keep the house to around 20 ft deep, then that minimizes the slope that I have to deal with (thanks birgco).
- right now, with 10 years to plan, I’m very much in the conceptual stage. Play with some ideas and contemplate pros and cons (safety, cost, aesthetics, aging lifestyle, etc).
- teamjdc: I did not pick up the property for a bargain (with my budget). There is a huge variation in lot prices. I understood that you either paid upfront to get a level lot that was buildable; or, pay to prepare a cheaper lot when you’re ready to build. I only had the budget for the steep lot. But, my thinking was that if I had 10 years to think about it, that I might be able to come up with some optimized and acceptable (budget vs requirements) solutions. And if not, it’s probably still a nice investment. It is a beautiful location with views of the north and south shores of the island (only if I can keep the house high on the lot), is 300 ft up and captures eastern breezes (again, only if I can keep the house high). It’s wonderfully situated out of traffic, but close to town.
- I’m just an electrical engineer, but I see so much variation in architecture (from log cabins to sky scrapers), and so many different solutions for (basically) the same problem (dome houses to log cabins to town homes to ramblers) that I get the sense that there are probably 1000 ideas that I would never think of on my own (shapes, sizes, materials, construction techniques, etc). The more ideas I can garner, the better I can discuss ideas with engineers and architects.
- Intuitively I think that building homes in the mountains of Colorado, or the cliffs of Malibu, or the hills of San Francisco must face the same issues. Are the local engineers really the only/best sources of info?
- I’m also willing to think out of the box a bit. Can I partner with learning institutions so that they get experience and I get ideas? Can I partner with other baby boomers that might want to time-share the retirement dwelling? Are there new building or architecture companies that might be looking for an opportunity to show off their skills (whether it saves me money or not)? I’m also interested in working with young and disadvantaged from universities and companies. It’s a way for me to use this opportunity to perhaps give back a bit. |
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teamjdc
Joined: 25 Oct 2007
Posts: 145
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| Posted: Thu Mar 06, 2008 4:47 pm Post subject: |
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Perhaps posting some photos might help.
At this poijt you're talking about going 300' up a steep slope. Steep is subjective so I have no clue what it means.
I've passed on my warnings and they will not change. I cannot imagine a scenario where you can bypass geotech and civil/structural engineering.
I'm afraid the skyhook store is sold out and they don't expect another shipment in out lifetimes.
I also wonder how you intend to access the building site to build and live.
I hope it works out for you, but I've heard too many sad stories and I must say, yours is starting out as an extreme example. |
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