Two level parking attached garage. New construction

[zkdiesel]

Anyone have a twin level garage with parking on both levels?
Anything you would do differently or don’t like about it? Water problems off top level into lower?

Long story short I acquired. 80 acre here in northern Il, in about a year or so gonna break ground on new house. Place is built into of the huge natural hill, current 1900 house is about shot with need foundation replacement at minimum

Either going to move that house to edge of property and sell to a good friend with 2 acres or a bulldozer will end up getting it

New house will be on the huge hillside, be roughly a 2100sq door brick ranch with a walkout basement because of the hillside

How three car garage on top, but then have rear driveway as well and rear lower level entrance for a 3 car garage space below the top level. Figure Park two cars down there and then a bar and have patio off garage down there
Anything somebody didn’t like about this setup? Upper levels cars will be winter driven so the drainage situation will need to be addressed for upper level. Lower level of house/garage will be lucky enough to have no sump pump due to height change, can be gravity drains to farm tile/with waterway as overflow

Do the support Columns ever really a bother? This is just strictly going to be storage area, not a working garage.


Site
Already has approx 18k sq foot in storage buildings currently,
But only about 5K is currently concrete so wanting a nice area to keep the nice vehicles in the house garage

Then new shop goes up, but minds not even wrapped around that yet as my current building is already so perfect with lifts, jib cranes, ventilation, ac, and looks. Luckily Dad is going to be mowing into my 2.5 acre house once I move out.

 

[LXCam]

Come on ZK, you know the rules.




Congrats on the new property. 18ksqft worth of covered storage concreted or not sure brings a **** load of value for seasonal equipment storage I'd think.

As far as your question I have seen structures like this and as long as the lower level doesn't end up in a hole dependent on a pump system to keep it dry there isn't a problem. You'll just need to open your wallet a bit wider for the engineering and construction.

 

[matt_i]

The only downside is the cost to build it. Need large footings to bear the large weight of concrete slab plus the vehicles into walls and column(s). Normally its widespread over the entire slab which is bearing but in this case it will be concentrated.

I would waterproof it like a basement that's expected to be lived in. Full silt-socks and gravel beds. Will be a big excavation.

 

[38Chevy454]

Does the upper level garage have to be over the lower level? Why not just make the lower level as a part of the basement walkout area. So it has living quarters above it instead of the upper level garage. Yes it would take some of the basement sq ft away, but then you can do a std upper level garage floor on top of solid fill. It should end up being less cost as well. You could even make part of the lower level garage roof to be a patio off the main floor, if you wanted to let the garage go out past the outline of the house.

 

[ConCretin]

Upper levels cars will be winter driven so the drainage situation will need to be addressed for upper level

This level will obviously be structural. The most common systems for this application are probably a formed concrete slab, a slab on metal deck or precast plank with a topping slab. Steel (or concrete) beams may or may not required depending on the system and spans.

Each of these systems will utilize imbedded steel of some kind, which will need to be protected from salt. In addition, leaks will be an issue in the lower space. Therefor this slab will need to be waterproof including at cracks and the perimeter. Drainage alone won't be enough.

The best solution is traffic bearing waterproofing, which is commonly used in parking garages but it isn't cheap. Anything less will almost certainly be an issue long term. As others have mentioned, this could be an expensive build.

 

[zkdiesel]

With a smaller house we’d like to stack the garages for the most basement

Excavation of site and hauling in rock will be handled by me and my father in This project
I know the bills will add Up in a hurry in the garage part but will be willing to spend it on that.

 

[DBS5Window]

The biggest issue will be always controlling the humidity in the lower level garage. Too much humidity and a cold upper garage floor will result in condensation below.

 

[reader2580]

My parents have a house with a two level garage with the lower level a walkout basement. Lower level has a single garage door. My dad created an area behind the garage door for all the lawn/garden stuff. The remaining space is a wood shop.

You need to be sure that the basement level is water proofed properly. My father had to tear out all the stud walls in his shop due to water damage. Mold so bad some of the studs looked like they had been in a fire. My father had to have the upper garage floor epoxy sealed to stop melt water from cars from getting down into the shop.

Personally, I would never do this unless you couldn't build a larger garage normally.

 

[Bill Bowman]

Zak:

Having been in your current home workshop, I can't imagine you moving to something else. I'm sure it will be as nice/better than current space, however, I admire your your ambition. Good luck.

 

[LifeLongWNYer]

Look into concrete planks with pretensioned cable reinforcing mbedded in the concrete. There used to be a place near here which fabricated those, they used to give away defective ones, just for fill. I know a guy who took a bunch of "defective ones", which were 30-40' long, and cut off the bad part, then used the remaining part for a house and garage floor. He ran plastic pipe through the cores, and heats his house with solar energy used to heat the water.

Sorry, TMI, but the point is, if you can use short lengths of concrete planks, you might be able to obtain them very economically.



.

 

[75gmck25]

Since that lower level garage is really more like a workshop, do you plan to keep it heated and cooled most of the time?

If you have it insulated, with HVAC running all the time, it will be just an extension of the basement, but will happen to have a garage over it. You still have to worry about the floor load and water drainage from above, but the work space should not have humidity issues (any more than the rest of the basement). You could still zone the HVAC, but would have the option of making it as comfortable as the rest of the basement.

The other option is to build the two story garage area like its a separate utility structure, and not treat it as conditioned space. I'm not sure this would save you on anything except HVAC, since the footings, walls and slab would probably be the same as a single structure.

Another design feature I would consider is how I would get projects (and myself) between the two garage/work areas. For example, you are doing some metal work in the lower workshop, and now that the part is done you want to take up to the garage and try it on your car. How will you get between the two spaces? The simple solution is to take it out the lower level doors, around the house, and then in the upper doors. However, maybe there is a more convenient solution.

Bruce

 

[matt_i]

Instead of investing all of the concrete formwork in creating that lower garage, if you put it into flatwork on the other 18ksqft you might do well also. Along those lines, wiring, security, gutters, other upgrades, etc.

You could always build a 3-4 car garage on the flat if there's enough room on the hill.

 

[Bill Bowman]

"For example, you are doing some metal work in the lower workshop, and now that the part is done you want to take up to the garage and try it on your car. How will you get between the two spaces?"

Trust me on this,.... Zack has enough equipment setting around to get the job done.

 

[kbs2244]

A longtime buddy of mine bought the house built by the general contractor of his subdivision.
Upper class on hilly lots.

From the front the house looked pretty normal but it was on a steep drop off lot.
2 car garage door to the left and a single car door on the right.
The space on the right was double deep (40 feet)

Unless you noticed a driveway along the lot line that went down the side of the garage foundation you wouldn't guess that the upper deep space was over a 20 x 40 lower
garage.
The whole house was on a 12 foot high walkout lower level.

 

[sberry]

Slope to the center of each parking spot so all drains to a drain right smack under the vehicle and pipe it out. Epoxy the floor and even put drain liners to park over. I would heat the bottom workrooms continuous just to the point it keeps the floor above and the parking garage above freezing. 45 degrees, even 50 if its well insulated, daily drivers don't need to be hot but it saves a lot of work if they can thaw, and no ice, start warm most of the time. I park my daily drivers in the shop when its bitter out, I wash them normally and then pull them in. They dry and the next morning there is a huge difference pulling a car out is 50 degrees vs 10. Sundays,,, I got a car full, I park in Sat night and can start out with a somewhat warm car.
I park my plow truck in when its bitter, works so much better than a super cold start up. I got an old rusted out work van with tools in it, I have space in winter and its been inside, so much better above freezing.
If I was building my dream house it would include heated drained floor for the garage. If I was investing in good cars, nice home with big garage would consider coming upo with the 5 large for a hot pressure washer, with outside feed to clean cars. Depreciate so much less, so much cleaner and I make time and take 5 minutes coming home to clean them. It aint free but dirty salty cars are a problem.

 

[joes169]

I'm a concrete and masonry contractor, we've done this very thing probably a dozen times on new homes. We've always relied on pre-cast plank to accomplish it. One of the companies we've worked with is probably within your area, and was always very affordable compared to the much larger pre-cast supplier in this area. They can do all of the engineering for you and give you wet-stamped plans with all of the details you need. I think this was the company:

https://www.msprecast.com/hollowcore/

Couple things to keep in mind with a situation like this:

- Don't think of the upper garage floor as a floor, treat it as a roof, and you can make it work without much issue. We ALWAYS had a qualified roofer come in and run 60 mil rubber over the precast (usually over sloped foam) and up the walls, a few inches minimum above finished concrete floor. The front rubber (at the OH doors) needs to terminate BELOW the hollow cores of the plank to ensure they don't leak.

- Hollow core pre-cast plank have camber to them, usually about 1.5" for 28' long piece in my experiences. Longer spans will have a progressively increasing amount of camber. THe camber doesn't lend well to floor drains, not to mention floor drains in the middle of the rubber material is asking for a lower level leak long-term, and the piping in the lower level is almost always at nuisance height. We almost always pre-sloped with "wedged foam" insulation before the roofer came to lay the rubber down. This way, any water that got through the concrete could naturally drain to the front at the OH doors. Obvioulsy, there's insulating benefits of the foam as well, but it also helped us to keep a uniform upper concrete floor thickness.

When it comes to the foundation portion, it really isn't overly complicated, the walls get treated like any other basement wall when it comes to damp proofing. Just make sure you spend some time with the pre-cast engineers/salesmen to ensure they can convey what they want to the foundation crew.

 

[zkdiesel]

I'm a concrete and masonry contractor, we've done this very thing probably a dozen times on new homes. We've always relied on pre-cast plank to accomplish it. One of the companies we've worked with is probably within your area, and was always very affordable compared to the much larger pre-cast supplier in this area. They can do all of the engineering for you and give you wet-stamped plans with all of the details you need. I think this was the company:

https://www.msprecast.com/hollowcore/

Couple things to keep in mind with a situation like this:

- Don't think of the upper garage floor as a floor, treat it as a roof, and you can make it work without much issue. We ALWAYS had a qualified roofer come in and run 60 mil rubber over the precast (usually over sloped foam) and up the walls, a few inches minimum above finished concrete floor. The front rubber (at the OH doors) needs to terminate BELOW the hollow cores of the plank to ensure they don't leak.

- Hollow core pre-cast plank have camber to them, usually about 1.5" for 28' long piece in my experiences. Longer spans will have a progressively increasing amount of camber. THe camber doesn't lend well to floor drains, not to mention floor drains in the middle of the rubber material is asking for a lower level leak long-term, and the piping in the lower level is almost always at nuisance height. We almost always pre-sloped with "wedged foam" insulation before the roofer came to lay the rubber down. This way, any water that got through the concrete could naturally drain to the front at the OH doors. Obvioulsy, there's insulating benefits of the foam as well, but it also helped us to keep a uniform upper concrete floor thickness.

When it comes to the foundation portion, it really isn't overly complicated, the walls get treated like any other basement wall when it comes to damp proofing. Just make sure you spend some time with the pre-cast engineers/salesmen to ensure they can convey what they want to the foundation crew.

Wonderful info!

 

[MadMechMaster]

5 Car attached parking, plus a new shop? This could be another epic garage build on the Journal.

 

[ConCretin]

We ALWAYS had a qualified roofer come in and run 60 mil rubber over the precast (usually over sloped foam) and up the walls, a few inches minimum above finished concrete floor. The front rubber (at the OH doors) needs to terminate BELOW the hollow cores of the plank to ensure they don't leak.

I like this approach as well and have seen it done successfully. I haven't seen it before but the use of tapered insulation to overcome the camber of the plank and move water toward the OH doors sounds like a great idea.

The other option requires two topping slab placements. The first to level up the planks and hopefully create a little pitch to floor drain locations (the drains have membrane clamps and weep holes) and the second to create a wearing surface and pitch to the drains.

I'm not sure how the cost of the rubber membrane would stack up against traffic bearing waterproofing but either will protect your investment.

 

[readhead]

I have done quite a few raised garage floors as the steel guy. Because of the terrain around here backfilling as much as 16' just doesn't make sense. Usually we would install a beam and decking system but the finish would vary depending on what was underneath. If it was unfinished space, water proofing wasn't an issue.

I have seen a couple of different water proofing systems. The most common is to place a rat slab to provide a sloped flat surface for a layer of rubber then the finished slab is placed. Recently I saw a system where foam was provided to fit in the low convolutions of the decking and the rubber was installed. I was told that this system was much less expensive because less concrete was needed which meant the steel structure could be reduced in weight. Faster also because there was only one trip for the concrete guy.

 

[spudley]

If you're in northern IL., you should be contacting Spancrete in SE WI for an estimate. I have a 24'X34' attached garage fully decked with 8" x 40" X 24' Spancrete panels, capped with 4" of concrete. Not much extra engineering at that time, just a basic footing with 10", 12 course block walls. No posts, beams or leaks after 34 years.
I don't use the lower level for parking as my lot is not sloped, but it's a very useful space. In fact my lot was low so excavating that area saved me the expense of bringing in fill. As noted I run a dehumidifier regularly.