Building on a sloped lot

[Dogbert]

Building on a sloped lot is possible, but how much more does it cost? I have a lot on Lake Travis that I'd like to build a lake house on, but it has a significant slope and I doubt a septic system is possible. What are the options?

 

[jimmyjazz]

Two years ago, the last bid I received before I scrapped my house plans pushed an initial estimate of $485K to $550K on a large (5,000 sf) house. Most of that excess was due to the slope of the lot.

 

[NCAAFBALLROX]

I have a contractor that I've been doing some jobs with out here & he's originally from Illinois... the land of basements.

He said that you could do a full on slab OR a basemented slab & the basement option is going to cost less. I don't have any kinds of ratios or percentages, but he said it's more than noticeable.

This gives you both more space to store all your consumer junk (gotta keep us out of a recession! Buy more Chinese junk!) as well as an escape location in case of a tornado. Then there's the resale benefits...

If anyone wants contact info, send me a PM or reply here.

 

[Dogbert]

Hell, a basement would be great. I have no problems with that at all.

 

[HornTillDeath]

There are several houses out here in the lake travis area that have a basement/understory storage area because of the slope.

Spetic however could be a bigger issue. Contact Marc Pate over at Pate Construction and he can come out and tell you if septic is going to be a problem. They do lots of work out here on slopes.

 

[jimmyjazz]

For what it's worth, the numbers I quoted above included a walkout half basement. The front half of the house would have been 2 stories, and the back half would have been 3 stories. Obviously, the lot sloped steeply down from the front to the back.

 

[Uninformed]

What am I missing? A gravity flow septic system is easier on a sloped lot. Is the issue that the water from the septic will flow into the lake too fast?

 

[Thunderhoof]

Well, there might be a couple of issues with the septic.

For one, I don't know if this is true up there but here in this part of the Edwards recharge zone you have to have 3-4 feet of soil to install a traditional septic system. Also, with that type of system the drainfield itself is essentially level. Yes, the pipes running to the field may be sloped and in fact need to be, but if level ground and soil are at a premium, then you'd have to consider other options.

The other option that most people around me have gone to are aerobic systems. These are the systems that have sprinkler heads which drain the tank when it reaches a certain level. Of course, the water has been treated some and no longer smells like sewage when this occurs. These systems take up far less room, but you still need to dig a good sized hole to put the tank in underground.

 

[Thunderhoof]

Oh, and the soil requirement is a code or permit-type issue. I'm not really sure on the specifics. I do know that there were a lot of septic companies out there running scams on this stuff 8-10 years ago. Traditional systems are pretty cheap to install, where aerobic systems are not. Aerobic systems also require regular maintenance.

I know people who have built on sloped lots. There are lots of options, depending on the grade. I really like split-level homes. I know one guy who actually had his lot milled down (not all of it, but a good sized area where the house was going to be located) before he built. It looks hideous at first, but then the house covers up the scar and topsoil and landscaping covered the rest.

A carpenter friend of mine who just looked at this thread told me that building on sloped lots will always be expensive because it's not a building job that just anyone can do. It takes a custom design, for one. Also, it frequently takes a builder who knows "why" certain things should be built a certain way, not just "how".

If the grade isn't too steep, milling the lot + either a split level design or one including a basement would seem to be pretty good options.

 

[Not that Bob]

Spend much time thinking about how run off will flow, how to route it, and how to maintain the drainage system once designed and built. Don't ask me how I know this.

 

[Uninformed]

We are on a sloped lot and there is a depth requirement for septic, but I don't think its 3 ft. It is less than that (Maybe 18 inches if I remember right although I probably don't). Too deep and it doesn't drain properly and too shallow and you can have health problems. Each pipe is at a different height because of the slope away from the house, but they are all exactly 18 inches below the ground. Other requirements include footage of pipe based on the number of bathrooms in the home, soil condition, and setbacks from pools and neighbors. Here the requirement is 20ft between pool and septic and 15 ft. from properly lines. If there is too much rock, it can keep the system from draining properly and instead of dissipating into the soil, the water can follow underground streams and such.

 

[Dogbert]

Thanks. Some excellent advice.

I went to the Pate Construction Web site and saw some pictures of a lot not much different than mine. So perhaps septic is possible. Unfortunately, my lot is almost waterfront and is less that 100 feet from a cove on the lake.

 

[NBMisha]

Regarding the basements, in our last neighborhood in norcal, every house was a "cliff dweller", on very steep hillsides. The standard approach was to cut a basement foundation into the slope, and build on that. Except, in all these houses the basement was fully finshed out, and had windows etc , outdoor egress, iow made part of the main house concept. And these were big houses, too.

Definitely go with that concept and get the most out of it.

 

[kevwun]

Don't get drunk and roll in to the lake. You might want to put up a barrier to prevent this from happening.

 

[Xminus6]

In reply to:

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[jimmyjazz]

It was a pretty basic house. Stained concrete on the 1/2 basement and the upper half slab, economical hardwoods elsewhere, 10 foot ceiling on the main floor, 9 foot elsewhere, KitchenAid appliances, basic granite in kitchen, shingle roof, stone exterior, vinyl windows, some crown moulding, little window casing, etc. It would have been "nice" but hardly high end.

 

[NCAAFBALLROX]

Re: Septic.

2.43 PSI for every foot of elevation.

 

[Scooter]

I would spend more time thinking about what your going to do with runoff than worrying about a septic field.

 

[Uninformed]

One thing that could end up being a big concern is the amt. and porosity of rock that you may hit. I've built a pool into hard limestone (not in Texas) and it sucked.

 

[Dogbert]

Runoff? What kind of runoff? From the roof? From the septic?

If you can't do septic what options do you have then?

 

[Scooter]

Hey Dogbert. My current home is on a slope. The builder and previous owners did not account for rain/snow runoff coming down the slope toward the house, not to mention overflowing gutters -- they even had one downspout that just dumped out in front of the house with nowhere to go but under the stemwall. Proper drainage is crucial for any home built on a slope. My parents had a home in a gated area off of Far West. It had a downspout that frequently overflowed causing water to go under the house. $28,000.00 later, they fixed a problem that could have been handled with a $50 gutter repair.

Just sayin, unmanaged runoff can do major damage, especially for a home on a sloped lot.