Underground home garage?

[malibuquest]

So, what does everyone think of this. I am considering building an undergroudn garage in my backyard. We don't want to ruin the view with a 3 car garage so thought we might build something completley below grade. Access via a sloped concrete ramp. Any suggestions as to size? Need to be able to turn cars around inside to drive up and out.

 

[hetkind]

Very, very expensive...make SURE you get your drainage correct, and turning cars around inside would be a plus. What part of the country are you planning on building in and have you come up with a budget? What does your general contractor think of this?

We have a semi-buried two level three car garage planned, on the edge of a steep ravine...


Howard

 

[KEH]

Like Howard said, very expensive. Don't think they work in a wet climate. We average 46 inches of rain in Sc and I have seen an underground home abandoned and the fill dug out from around it. If you are in a dry area get local advice.

KEH

 

[Okie Pete]

A guy i know lives in a house that was built in the late 40's . It sits in a part of town that the street is about 12 ' below the house. When the house was built a underground garage was built in front of the house. The garage floor is level with the street. The house sits in one of the higher parts of town. There is a small stream of water that trickles out of the floor and out the door most of the year.
You may want to place drain tile around the out side walls to drain off any water issues .
Check with your local contractors if there are any ground water problems.

 

[SPDMETL]

I like the idea. In a local wealthy area is a guy who has a double tennis court on a steep hill with garage doors under it. I'd love to see what kind of deep-pockets Hot Rods are in there...

 

[JCQuick]

can't do that her in fla you'll hit water

 

[6768rogues]

Anything can be done if you have enough money. Not worth the substantial extra cost to me, but if you have the money, why not?

 

[rickycobra]

Firstly you going to need to check out the soil before you go any further.

 

[malibuquest]

Thanks for all the comments. Clay sub-soil below top soil. I believe it would be just like building a basement, except that this basement will have a concrete roof with grass growing on it. All of this stuff is conventional here in Ontario, Canada. Waterproofing is very important, but do-able. Exterior weeping tile around the footings and good drainage is also important I know. Big questions in my mind are size of garage to allow a few cars to park and get in and out, i.e. turn around. Also, how steep of a grade can I make the concrete ramp to get in and out? This could easily be heated with radiant heating to keep ice off.

 

[malibuquest]

A guy i know lives in a house that was built in the late 40's . It sits in a part of town that the street is about 12 ' below the house. When the house was built a underground garage was built in front of the house. The garage floor is level with the street. The house sits in one of the higher parts of town. There is a small stream of water that trickles out of the floor and out the door most of the year.
You may want to place drain tile around the out side walls to drain off any water issues .
Check with your local contractors if there are any ground water problems.

I think we have come a long way in terms of waterproofing over the past 70 years, thanks for the comment though.

 

[malibuquest]

Anything can be done if you have enough money. Not worth the substantial extra cost to me, but if you have the money, why not?

Cheaper than buying the neighbouring house and tearing it down to build new garage. Also cheaper than buying property eleswhere and building new. Would much rather be able to walk into the backyard to work on cars etc too!

 

[RTrac1]

10% slope on the driveway.

do you plan on grading the lawn around the driveway ramp? or building a retaining wall.
if grading... 1 on 3 side slopes at a minimum.

 

[socapots]

You say Clay sub soil.. is that a dirt clay mixture?? Does water drain through it well??Water does not drain through strait clay.. if that is the case you will need to have a sump system connected to weeping tiles. A drain in the floor connected to the sump pit would be a must as well. Some areas will not allow any kind of drain in a garage to begin with. so make sure your area will approve your design before you do anything else.
as far as the approach goes.. it can be as steep as you want i guess. just remember you will see ice and snow from time to time. Getting in and out could become an issue.
But like i mentioned above.. make sure the area you are living in will allow you to build underground, and have proper drainage.

 

[socapots]

got me curious about it now. lol. I did a google search like i assume you did.
Lots of info out there.

 

[malibuquest]

Help me out here, if you can. HOw long does the sloped driveway need to be to get down to 7' of depth?

 

[malibuquest]

Good point. Interior drainage, ice and water from cars etc. would be a necesity for sure. I wonder what the building department will say. They can be difficult and would probably have a meltdown when I bring them plans for this!

 

[370z]

it will be like the bat-cave! i like it

 

[RTrac1]

Help me out here, if you can. HOw long does the sloped driveway need to be to get down to 7' of depth?

at a 10% slope... every 1' of depth needs 10' of ramp

so... 70'

 

[bluesman2a]

It has a very high cool-factor (yes, bat-cave-ish), but there are LOTS of practical hurdles you will need to overcome with money.

1) If it's below grade, anything you drain will HAVE to be pumped back up/out to keep it out of the work space (i.e. weeping tile/floor drains, toilet, sink, etc.).

2) If/when those pumps fail. you WILL be the proud owner of an underground wading pool. Have a back-up.

3) Your entrance ramp is basically just a big ice/snow/water catchment system. That will ALL roll down-hill. Make sure you have a slit-drain all the way accross the door(s) to keep the water from rolling in.

4) Rust. You WILL have it. No matter how good or hi-tech your waterproofing is, it's an underground room, things will sweat. Tools (and cars) will RUST. You will fight a constant battle with this. Above ground garages have this issue too, but you will have it worser. You will need to keep a dehumidifier running constantly, especially when you add in wet vehicles tracking in road-salt/ash/gunk.

5) You have real winters there. Your cars will have real ice/snow/road-gunk. Put in floor drains. Yes, you'll have to pump that out too. Oh BTW, that road-gunk is gonna be REALLY hard on your pumps (see #2).

Yeah, I'm a real glass half-full kinda guy, what can I say, I've spent stupid amounts of money on my garage and I didn't have to solve ANY of those problems. Listen to the people here, there's HUNDREDS of THOUSANDS of dollars and hours of experience. Each hurdle will be unique and it will cost you time and money to solve and chances are you will run into MANY people who have no clue how to deal with your structure/issues cause it's not "normal".

Now on a positive note: if you DO decide to change your mind, there are MANY examples of how you can camoflage your garage to blend-in/dissappear into the backdrop and/or look handsome. I remember one member who had to deal with a home-owner's restriction and he built his shop so that it LOOKED like a neighboring home when viewed from the street. Landscaping goes a long way too.

For better feedback, a couple pics and a drawing of your lot situation might help and get better solutions/suggestions.

 

[cheap bastard]

I had a 20s bungalow with a garage in the basement. The top of the foundation was two feet above grade at that side of the house. The ramp was 28 feet with a depth of 6 feet. (8 feet floor to joists) Beside the fact only 20s and early 30s cars could traverse the drive, the idea has merit. The only real issues were drifting snow and heavy rains. The drains consisted of two floor drains into a 6 inch pipe that flowed into the city sewers. I'm sure there was some build up in the system that slowed the flow, but the system would allow for some puddling in the area. The drifts often completely buried the drive making for some big snow moving projects. I could only move snow one direction as there was a deck along the side of the drive I kept clear. The other issue can be liability. The entire length of the ramp is a fall hazard. If your yard is fully fenced as mine was, nobody should be at risk, but your local ordinances or insurance may require a rail. That will, of course, make snow removal more difficult.
A dehumidifier will be needed all year to keep rust, mold and odor in control. You may want to buy stock in WD40 as you will need to treat tools with every use. Tool boxes can trap damp air, there may be a need to address that as well. Moisture is always an issue. It is nice having a cool place to work in the hottest weather, though. Since there is still a need for humidity control, you may as well run an air conditioner.

 

[socapots]

Good point. Interior drainage, ice and water from cars etc. would be a necesity for sure. I wonder what the building department will say. They can be difficult and would probably have a meltdown when I bring them plans for this!

There are ways to over come all that sludge,
It will probably end up being a big *** pit that all the water can drain into. That will be where it is also pumped out of...
Id guess it would be located across the garage close to the door.. or maybe even right at the door. Big Steel grate across it. That way anything coming in under the door (and there will be alot) and anything melting or getting into the garage area will drain to the same spot (your garage floor will slope to the drain). You will probably have to have that Pit sucked out by a pumper truck from time to time.
saw somewere on the net a guy actualy heated the slope that came in. This allowed light snow and ice to melt off and drain into the pit..

something else to find out about before you get spending real money is how far down is the water table.. last thing you want is to start digging to find out you have a giant pool the next morning.. For example. Right now where i am (just outside of Winnipeg), my sump pumps in the house are still running.. my basement is only 4.5 or 5 feet in the ground.. so alot of water around.
just go over everything alot, and talk to the right government agencies about what will be required to do the job.

eithe way when you get underway post some pics. I'd be interestd to see the build.

 

[38Chevy454]

Not the same thing, but on an old house I had in KY the lot sloped down from the street. The driveway wrapped around the back of the house and had a 2-car garage door. So the basement was the same level as the garage. The nice thing was that instead of a divider wall, it was completely open, I had 2600 sq ft of temp controlled basement garage. I could fit up to 7-8 cars down there, but they had to go inside in-line and on either side of the central beam and supports down the middle. No turning around once in there, and you had to clear out the normal daily driver spots and anything in front of a car to get it out. I always thought it would have been nice to have another garage door.

 

[sneezer41]

How about 'arf buried. landscape a bump not so high as to block your view, but enough to help with the sloped drive and water issues

 

[idoine in toronto]

I live in Toronto, ON and have a partial underground garage. It's about 5' below grade with our house above. It's essentially part of the basement with a down sloping driveway, and is waterproofed similar to the rest of the basement.

The lowest point of the driveway has a trough drain in front of the garage door and is linked to the storm drain to handle runoff from the driveway. It's a two car garage and we back straight out similar a typical garage.

Check with your building and planning dept. to see if what you want is permitted and what the restrictions are. This type if garage is no longer allowed where I live.

 

[dahur]

A few years ago I was pretty serious about having an underground home built. Davis Caves in Illinois only does this type of construction, however I believe most of the time they build on grade, then cover it over on the sides and top, (bermed) so essentially it is underground. For technical questions, I'm sure Marty Davis could answer any you might have.
http://www.daviscaves.com/index.shtml

 

[thrifty bill]

Cheaper than buying the neighbouring house and tearing it down to build new garage. Also cheaper than buying property eleswhere and building new. Would much rather be able to walk into the backyard to work on cars etc too!

I guess it just depends on where you live. We close tomorrow on a house two doors down, mainly to get its garage (24x26, detached) and its large flat lot (actually it includes two lots) with room to build a workshop. It is a duplex, so it has good income potential, and real estate around here has taken a major hit, so it wasn't very expensive. Our current lot is on the side of a hill, fully wooded with large 75 year old trees (Maple, Norwegian Spruce, Oak, Dogwood, etc.). Building on our current lot was not going to work. We live right downtown in this community, and finding something suitable so close took a while. We are in the mountains of NC, and there are not many flat lots. Right now, no one is looking to buy anything real estate wise, so this one sat on the market for many months (and became more affordable).

Our current house does not have a garage.

I guess this is an advantage of living in an area with relatively affordable real estate.

This is a really weird way to get a garage and workshop, time will tell if it was a very smart move....

This is our current house. Every tree in the background is on our lot. 1934 river rock bungalow. Just rebuilt the front steps, so they look a lot better:

 

[malibuquest]

Thanks for all the input, lots of good warnings and suggestions.
Yes, there is a lot of water in the ground around here, our new basement addition has sump with a back up and it runs all year round. ICF foundation makes it dry and warm and not damp at all. That, along with radiant in floor heating make it the most comfortable part of the house. I figure we would do the same with the underground garage. So, good pumps with backups, heated floors to keep temp up and moisture down, modern waterproofing systems on the outside of ICF formed walls and heat in driveway (sloped part anyway) to melt snow. Still seems fairly straight forward to me. I do like the idea of buying two houses down, or something similar, but we don't have the same real estate problem here in CAnada. The economy here is on a tear and I would be looking at $400,000- and up to buy near me. Underground would be cheaper by more than half of that.
Keep the good ideas coming and thanks!

 

[socapots]

again.
keep us posted man.
I'd love to see pics of how it gets built.

 

[gquayle]

at a 10% slope... every 1' of depth needs 10' of ramp

so... 70'

Using trigonometry, a 10 degree slope would take 40 feet to obtain a 7 foot drop. A drop of 1 foot for every 10 feet of ramp is only a 6 degree slope.

 

[Herb]

What about some type of elevator to move vehicles from floor to floor? It would take up a lot less floor space and maybe a great deal of the price would be comparable to building a concrete ramp.

 

[hetkind]

Using trigonometry, a 10 degree slope would take 40 feet to obtain a 7 foot drop. A drop of 1 foot for every 10 feet of ramp is only a 6 degree slope.

10% grade is NOT 10 degree, it is one foot in height for every 10 foot run...so 100% grade is 45 degrees.

Howard

 

[SARG]

The concept is a little like putting the septic tank on the roof to save lawn space for future trenching ........ just plain silly.

 

[SuperSocket]

You can always get a sub-terrain lift rather than doing a long drive approach. This will also be totally un-conspicuous too.

 

[danfromsyr]

Cornell University here in Upstate New York had a similiar scenario
they built thier bookstore udner the grassy quad, with only a section of greenhouse skylights on the surface. and the entrance cut into the slight hill side.
really I don't see it much differant than a good deep basement for wall water infiltration
and a stone deck roof (except with grass) for the ceiling infiltrations.

 

[malibuquest]

Thanks for the photo! That is what I figure too. Not as far out as it sounds, just thinking outside the box a little bit. In our heritage neighbourhood and with our heritage home, tact is very important.

 

[malibuquest]

You can always get a sub-terrain lift rather than doing a long drive approach. This will also be totally un-conspicuous too.

Yes, I thought of the lift idea and it is still on the drawing board. Thought it would be too expensive as some places are asking $50,000 for lifts! Also, not sure how the building department would treat this, could be one more big headache! Figured the ramp would be simpler, cheaper and virtually no future maintainence.

 

[malibuquest]

A few years ago I was pretty serious about having an underground home built. Davis Caves in Illinois only does this type of construction, however I believe most of the time they build on grade, then cover it over on the sides and top, (bermed) so essentially it is underground. For technical questions, I'm sure Marty Davis could answer any you might have.
http://www.daviscaves.com/index.shtml

Thanks for this. HAd a look and they obviously do this sort of thing all the time. Again, not rocket science, just standard building practice done the right way!

 

[venom50svt]

I love the idea.. I thought about it before. I use to deliver to a company that made large concrete castings. The castings were for floors that were used in motels and buildings..
My thought was to build a "cellar" or foundation and use these concrete flat sections for the ceiling... Rubber liner to waterproof and "Dow" board to insulate. Have the side walls made with poured concrete not block so it would not have the weeping problem.
The outside walls would be coated in tar and a rubber membrane installed. The same could be used for the floor...
The weak spots would be any joints, but with the evolvement in plastics i'm sure there is a product on the market that could be buried for a hundred years without breaking down.
For access to the "bat cave" there is a lift that is advertised as --now you see it--now you don't... Alift that allows you to lower a car and then park one on top in a single garage.. Just use that lift to lower a car or what ever to the lower level..
Another plus is that it could be used as a bomb shelter... Hmmmm " Omega Man.........................

 

[RbrtAWhyt]

We don't want to ruin the view with a 3 car garage...

A nice, well built 3 car garage is a hell of a nice view in it's own right...

 

[malibuquest]

A nice, well built 3 car garage is a hell of a nice view in it's own right...

Not when the yard is only 50' wide and the garage in question blocks the view of the swimming pool!