Shop Under Garage?

[Nathan Genke]

Kevin,

You describe the shop that I currently have. I did use ICF's, 6'0 double doors, two windows, access into the house, radiant heat, sink with hot and cold water, and 200 amp panel just for the shop. I put up the ICF's myself, so the cost ended up being about the same as a standard poured wall, minus my time (Oh and you can vibrate some ICF's and pour as fast as the pump truck pumps). The garage does have floor drains but they are hooked up to the sewer. The down side is the drain pipes hang below in the shop. The shop walls ended up a little over 9'6". A dehumidifier keeps the humidity at 50% easily all summer and the temp. doesn't go over 74 degrees. In the WI winter the radiant floor heat and ICF walls create one of the most comfortable spots in the house (second only to in front of the fireplace).

Regarding water drainage through the floor isn't a problem. I used spancrete panels, then a rubber membrane (required by spancrete, but sometime left out by contractors because of the extra cost), then a minimum of 2" of concrete is poured over the rubber. In my case, 5" was poured around the perimeter sloped to 2" in the center at the drains. The spancrete is crowned in the center, so the edges need to be thicker to start and then thicker yet to get drainage to the center. Not a problem if you don't have drains.

I would highly recommend putting in 2 under slap dust collection runs down the centerline, 1/3 of the way in from each end, or one right in the middle. The table saw is the prime target, and you always know the table saw is going to be close to the middle of your shop. I didn't because I ran out of time, but I'm regretting it big time now. (If I didn't have radiant heat, I would seriously consider cutting up the floor and installing them now.) The dust ports don't have to be in the "perfect" place for future layouts. You can get them close and adjust layouts accordingly. I think it is better than having to put drops right in the middle of the shop. Even if you decide not to use them you put a cap on them and there is no issue. If they were to plug the runs wouln't be that long that you couldn't rather easily snake them clean. I would still keep runs along the walls above the floors for machines along the edges of the shop. Of course I have a 3hp cylcone, so a couple of extra elbows and longer runs doesn't really matter too much to me.

A couple of other thoughts that maybe aren't obvious. There are 4 steps down from my basement floor to my shop. As you mention your garage floor is lower than your house floor, this transfers to the floors in you basement as well. If you have a 9 foot basement and don't make the shop lower than your basement, your shop will probably only have 7'8" ceiling height assuming two steps from your garage to the house. So plan on some steps and leave room.

I wish my shop was a little bigger (dont we all). We have a 3 stall 25 x 34' garage, which means the shop is 24x33'. To make a little more room I put the tools in the shop portion and claimed a third of the basement under the house for lumber and general storage. With the shop under the garage and basically encased in concrete, virtually no noise makes it into the house. The shop itself really isn't noisy either because the insulation on the ICF's don't really let sound bounce off the walls. It's comparable or even quiter than my previous basement shop

The picture shows the spancrete being put in place. The view is from the house looking through the shop under the spancrete. The double doors are at the end with windows on each side.

Let me know if I can answer any specific questions.

Nathan

[Nathan Genke]

Well maybe the information wasn't very timely, but hopefully someone else will benefit from it....

[Kevin Post]

This brought back a lot of memories. How time changes everything!

My house is well under way. I opted against using pre-stressed concrete and placing the shop under the garage. Instead, I have a 4-car garage 26x44 attached to the house. Ceilings are about 11 feet high. I have floor drains...

So much has happened since this thread was last active. Here's the abbreviated version:

• House construction started May 4.
• There have been numerous delays because general contractor forgot to order roof trusses (this was in June). The house was open to the elements for over 3 weeks.
• Subs not showing up because general contractor was not paying them.
• Contractor is pulling subs from my home to work on other homes that are also behind schedule.

This builder was voted the "2005 Builder of the Year" by the local builder's association. My house is still not complete as of this writing. We had beautiful weather this summer and my house should have been done in Sept. (it's just under 2500 s.f.) I fired him about 3 weeks ago for non-performance and poor workmanship. I took over the project myself. I'm trimming now and hope to be done around Thanksgiving.

The latest issues I've discovered after I firing him:

• I had to re-build the basement stairs because they wouldn't meet code. Someone didn't know how to calcuclate and cut stair stringers. The rise on the bottom step was just 6.25 inches. The rise on the top step was over 10 inches.
• I discovered while hanging cabinets that the ceiling in the kitchen is not level. From one corner to the other (about 12 feet) the ceiling slopes just over an inch.
• The floor in one of the bathrooms is so bad that the ceramic tile wouldn't stay in place when it was set in the mud.

I'm mad as hell right now.

[Rick Christopherson]

New Edit: That's what I get for not reading the entire thread. I had no Idea this thread was a year and a half old when I wrote this.

There are a lot of postings here and I stopped reading about halfway through them all.

Part of my 1800 sqft workshop is under the garage using pre-stressed flooring. The area under the garage is my primary machining area.

Because most of my basement is below ground with poured concrete walls such as yours, the temperature remains fairly constant at 60 degrees year round, although it does warm up if I leave the back doors open in the summer.

Even though it has not yet been completed, your spancrete will have a topcoat of concrete applied over the planks. I had the foresight to install a floor drain in my garage before the topping was poured. Even if your contractor tells you that you can’t do this, do your homework, because you may find that with the proper conditions you can, and spancrete is one of the first necessary conditions. I would also recommend getting some type of strap or threaded stud between the planks before the topcoat is poured. This will give you mounting points for firring out the ceiling with wood strips. This is something I hadn’t planned ahead for, but wish that I had.

Also, a couple of years after the house was finished I began to notice that road salt was dripping off my truck and penetrating the 2” topcoat, even though there were no cracks in the garage floor. (I think current code might call for a thicker topcoat today for this very reason.) It was flowing between the spancrete planks in a single area, but this was right over my tablesaw. I corrected this a couple of years ago by epoxying the garage floor, which is great. My recommendation is that you epoxy the floor within the first year for a better finish. If you do it soon enough after the pour, you don’t even need to prep the floor.

[Randy Gillard]

My old boss did this in his house and loves it. Less likely for tool theft as compared to a large outbuilding. I would be concerned with the lighting. Buy full spectrum lights and your done. He said it cost him about $8000 for a 20x24 foot shop. Not bad.