Page 1 of 3 123 LastLast
Results 1 to 15 of 35

Thread: Shop Under Garage?

  1. #1

    Question Shop Under Garage?

    My wife and I are building a new home this summer. One of the requirements is a dedicated shop rather than having in in the garage or basement of our house.

    I've been talking to the general contractor who has suggested using prestressed concrete planks for the garage floor. This would create a basement under the garage that could be used for my shop. He said he's done it for other people.

    Pro:

    • He says it costs less and requires less maintenance than an accessory building. (no roof, siding, etc.)
    • The county where I live restricts accessory buildings to 750 sq. ft. I will have a 3-car attached garage that is nearly 800 sq. ft. The SWMBO is unlikely to allow me to build a 750 Sq. Ft. shop. My shop is already bigger than the max I could have as a separate structure.
    • I can have heat, electricity and water more easily than I could in a separate structure.
    • I can heat the space with hydronic heat in the concrete floor as I plan to do with the basement in the house simply by adding another zone.
    • Because the shop will be below-grade, it will stay cooler in the summer.

    Concerns:
    • Lighting: There will be few if any windows so natural light will be poor.
    • Ventilation: I don't want the shop connected to the air-handling system from the house to avoid dust, fumes and noise making their way into our home. How do I bring fresh air into the space without freezing in the winter?
    • Noise: The walls, floor and ceiling will be concrete. I'm told that unless the walls are covered with some sort of noise-dampening material, the space is very noisy. (Imagine running a tablesaw in a cave.)
    • Moisture: I'm concerned that moisture will damage my tools. Will I need to purchase and run a dehumidifier?
    • Getting items in and out of this space will not be as convenient as would a traditional garage-type structure. I am not planning to put a garage door on the space. I was thinking about a 6 foot wide opening with double doors.
    • I was concerned about having a low ceiling that would make handling sheet goods a pain. He said they'll just dig the basement deeper.




    Here are some pictures of a house under contruction: (not mine)




    I'd be interested in your thoughts and ideas on this. Do any of you have a shop like this or know of someone who has done this?

    -Kevin
    "He who dies with the most toys is none the less dead."

  2. #2
    Kevin,

    I would not even consider doing this unless the contractor was able to build it with 10 foot walls. About a foot of the walls is used up for the concrete planks and the supporting beams. You are going to want a lot of lights in order to light this space. Also, I would want a door into the rest of the house, if at all possible. Keep this area clear as a second way to escape your shop in case of fire. It would worry me being trapped under my garage with only one way out.

    It is going to be a little echo prone down there, but you can resolve that by putting up stud walls and insulating them around the outsides. With the stud walls in place, I don't think the ceiling would cause as much echo.

    As far as heating the space, I would look into a separate source of heat, whether that be electric, a hot dawg heater, etc. Like you said, you may not need cooling in the summer.

    All in all, I think that it would be a wonderful solution, if you can figure out good access to it. It is something that I will be keeping in mind when I build my house.
    Jeff Sudmeier

    "It's not the quality of the tool being used, it's the skills of the craftsman using the tool that really matter. Unfortunately, I don't have high quality in either"

  3. #3
    Join Date
    Feb 2003
    Location
    Rochester, MN
    Posts
    3,329
    I think if you can do as Jeff suggests and go deep enough, you should have no problems. Keeping the space warm will prevent problems with moisture. The only downside I see to this sort of thing is access and lack of natural light.

    My bride and I had a house designed a few years ago and plan on using the space below the garage for the shop. The lot the house was designed for had problems that made it unsuitable for us so we're looking for another lot.

    We will use insulated concrete forms for the basement and garage and either prestressed concrete beams for the garage floor or maybe some product such as Lite Deck which an aquaintance suggested.

    The ICFs will help with noise and temperature. You might consider them. We did discover one builder who said they aren't good but they'd never used them. We found many other builders who like them and several who have built their own houses with them. One guy even went to the roof on a two story house with ICFs. He said heating costs were incredibly low and you don't hear any road noise. This guy is up by Welch, MN.

    Just for fun, here's a sketch I've been working on from the plans. It isn't complete but would give you an idea. Yes, the garage is bigger than the house. That's the way it should be, right. Garage is 32x50.
    Attached Images Attached Images

  4. #4
    Join Date
    Jun 2004
    Location
    Water Park Capital of the World
    Posts
    2,219
    I agree with what's been said before, make the ceiling 10'.

    My other suggestion would be to make the garage 30-32'W x 28-30' D. Extra shop space and added bonus of extra room in the garage for storage.

    Your concerns are valid, but none are beyond a solution.
    Creeker Visits. They're the best.

  5. #5
    Join Date
    Feb 2003
    Location
    Richland, Michigan
    Posts
    429
    I think this has a lot of merit ... making it deeper to get more ceiling space is a sound suggestion, depending on your lot grade and drainage, even making a bigger garage sounds better. The cost to heat/cool will be significantly less in a basement shop. That is one of it's biggest advantages in a cold climate w/humid summers -- WI or MI same kind of thing. There isn't any better insulation than a few feet of dirt. Lighting is needed in any shop, sure it's a bit more here, but the comfort of the steady temp would make it worth it to me. Now if you can do a walkout that's even better. If not I would put in some kind of 4x4 or 6x6 hatch with a lift to bring stuff up & down with ..

    Another nice thing is not having to go outside to go to the shop ... no carrying things in/out through the weather, etc... a lot of advantages IMNSHO. Of course I always wanted to build an underground house too .. but that is just me.

    One question though -- how do you keep water from leaking down twixt the concrete planks?? Melting snow, etc... has gotta seep down. Even with a poured floor after time this can be a problem. I suspect it's coated some how or maybe some kind of drain system. But I've never seen this type of construction.
    Mike-in-Michigan (Richland that is) <br> "We never lack opportunity, the trouble is many don't recognize an opportunity when they see it, mostly because it usually comes dressed in work clothes...."

  6. #6
    Jeff Sudmeier wrote: As far as heating the space, I would look into a separate source of heat, whether that be electric, a hot dawg heater, etc.
    I'm curious... Why would you choose this method of heating the space rather than heating it the same way the basement of the house is heated? Since I'll already have everything necessary for the basement floor, it seems to me that putting PEX tubing in the shop floor would work best. The shop would just be a separate zone on the existing system.

    -Kevin
    "He who dies with the most toys is none the less dead."

  7. #7
    Thanks for the replies so far:

    The house will have a walkout basement. The plan we have drawn up has a door into the basement of the house as well as the 6-foot opening for a door that goes outside from the shop. They're at opposite ends of the shop. I don't mind access to the house, I just don't want duct work connecting the shop to the house (dust, noise, etc.). The door was always planned.

    The pour height on the plans is 10'-4" now. I think that will give the space I need because the concrete planks are supposed to sit on top of the walls. I was going to hang the ducts for dust collection from the ceiling but then I realized I can put them in the floor before the concrete gets poured.

    We're not planning on using ICFs. I'm not even sure if they would work with concrete panels on top. I'm not an engineer so I just don't know...

    -Kevin
    "He who dies with the most toys is none the less dead."

  8. #8
    Join Date
    Feb 2005
    Location
    Mont. Co. MD
    Posts
    973
    This sounds like the perfect solution. Given you guys probably have a frost depth requirment for footings of about 10' deep up there in WI its nothing to make a useable space below the garage. Just like it is more cost effective to build "up" rather than "out", it seems follow that it will be significantly cheaper to build "down" vs. build "stand-alone".

    Just some thoughts:
    High ceiling yes, minimum of 9' obviously more is better.

    Moisture shouldn't really be a problem if the drain tile and foundation moisture-proofing are done correctly.

    A level walk-out is pretty much a must, like the one in the picture.
    A 5' to 6' doorway is also really a must if you intend to get any equipment and projects in and out. One suggestion I have is to install a functioning French Door, the active door works as your day to day entrance, and the passive door can be opened when needed (jam bolts). Use at least a half glass door to let in some natural light. Oops, I re-read your post, and you mention that. You can however get taller than 6'8" doors which might also be useful. 6'11" is the next size up.

    Stud out and insulate walls and ceiling. Hydronic heat is perfect for the space. How much do you guys use air conditioning in WI? Being so much below ground, you may not need it.

    How waterproof is the garage floor/ceiling? that'd be my main concern. It would certainly have to be sloped adequately for ice/snow melt to drain to garage door.

    Have you had a chance to look at any other similar construction that has been completed, and lived in?

  9. #9
    Quote Originally Posted by Michael Cody
    One question though -- how do you keep water from leaking down twixt the concrete planks?? Melting snow, etc... has gotta seep down. Even with a poured floor after time this can be a problem. I suspect it's coated some how or maybe some kind of drain system. But I've never seen this type of construction.
    I wondered the same thing. I was worried about that salt-laden snow melting and dripping into the shop. I can just imagine not being in the shop for a couple weeks and coming down to find a hole rusted clean through the top of my tablesaw.

    I asked the contractor how it works. He said the planks are grouted together after they are laid in place then a concrete slab is poured on top just like a regular garage floor. He said that alone is enough to keep the water from seeping through. However, I'm probably going to paint the garage floor with some type of epoxy floor paint to keep it pretty. He also said I can have floor drains in my garage if I want. How cool would that be for changing oil and flushing the radiator? (I'm kidding, of course.) They can core-drill the garage floor and install drains with PVC pipe underneath.

    -Kevin
    "He who dies with the most toys is none the less dead."

  10. #10

    Door to House

    Quote Originally Posted by Kevin Post
    The plan we have drawn up has a door into the basement of the house as well as the 6-foot opening for a door that goes outside from the shop. They're at opposite ends of the shop. I don't mind access to the house, I just don't want duct work connecting the shop to the house (dust, noise, etc.). The door was always planned.
    Kevin - If you are worried about dust and fumes getting into the rest of the house, you might want to rethink the doorway to the basement. A friend of mine has a shop next to his finished basement. Even though he doesn't have any duct work in the shop, dust still migrates into the basement with air movement.

    Would stairs from the shop to the garage be a possibility? At least you wouldn't need to go outside to get to the shop. Of course then you would loose some floor space in the shop and garage. I guess it is just another option.

    BTW, radiant floor heating would be sweet! If money were no object, I would put it in my shop.

    Good luck with everything.
    Jonathan P. Szczepanski
    ========================================

  11. #11
    Join Date
    Feb 2003
    Location
    Rochester, MN
    Posts
    3,329
    Kevin, regarding ICFs and concrete above, a friend of mine in South Dakota who does concrete for a living indicated to us that they work together. According to the various makers of the ICF materials, the concrete is actually stronger because the cure time is longer. I think it would be work a look if you can. You won't have to fur and insulate the walls to finish them. All you need to do is put up sheetrock. Electrical is run in routed channels in the foam before putting the rock on the walls so even that is easy enough.

  12. #12
    Join Date
    Dec 2003
    Location
    West of Ft. Worth, TX
    Posts
    5,814
    I would propose the ICF also...just make sure you have a builder that is used to building this way. And you have to use an A/C-Heating person that is used to calculating for this type of structure. A common problem is the A/C is designed for normal building methods, the A/C is oversized for ICF, and it doesn't stay on long enough to dry the moisture out of the air, and mildew builds up. But it is very energy effecient. And QUIET!! I wanted to build a house this way, but before I could find land, the LOML found a house that she fell in love with, and it does work well for us.
    How about using the sky light tubes that will reflect light even with turns in the tube as another way to get light to the shop? It would have to have a couple "pillars" in the garage, maybe one in the front, one in the back, to hide the tubes and protect them, but it would bring in some natural light. Good luck!! The planning is 1/2 the fun! Jim.

  13. #13
    Join Date
    Jul 2004
    Location
    Princeton Minnesota
    Posts
    136
    Quote Originally Posted by Dave Richards

    Yes, the garage is bigger than the house. That's the way it should be, right. Garage is 32x50.
    Excellent thinking,

    I've always told people I want to build a garage/shop with an attached house on the side.

    Kurt

  14. #14
    Join Date
    Feb 2005
    Location
    Bedminster, NJ
    Posts
    289
    Kevin, I have used pre-cast concrete foundations in homes that I have built, they are manufacutered using an insulating board material as a form and then shipped to the site - these basements have proven to be warm and I have noticed that they muffle the sound quite a bit - so, that would lead me to believe you would get the same or better results with IFC's -

    Moisture problems are caused by two factors; high humidity (in the summer) and ground seepage. You can't change the outside humidity, just condition it on the inside, but you can sure as heck solve the seepage problem during construction. Be sure your builder uses plenty of clean stone around the foundation with footing drains to daylight, also put plenty of stone under the slab ( 4" inches is code around here - I suggest six to eight inches) also with drains to daylight - that takes water away and prevents hydrolic pressue from building up under and outside the foundation, then add some extra waterproofing to the exterior wall before backfill - there are several water-proofing products that do a great job. If your lot has a high water table, then take additional precautions - your builder should help. This is very cheap insurance and will pay down the line because seldom is water seepage evident within the first few years after construction unless something is done wrong. These improvements should not be too costly.

    Try adding natural light, use your imagination, - in the photo there is plenty of space on the side of the foundation to add at least one window, but if a retaining wall were built so that more foundation is exposed, another window or two could be added and the retaining wall does not need to be high, just a couple of feet - consider double hung or casement windows rather than typical basement windows. Also, consider using wood framing for parts of the foundation that are above ground, cheaper and less mass to heat and cool (and also shown in the photo.) My current house has almost 1,000 sqft of living space in the basement - but the whole back of the house is above ground and wood framed with plenty of windows. It is all done properly and no one would think it is a "finished baement."

    If noise is a concern, consider a block or concrete wall between the shop and the rest of the basement, then frame it out, insulate and sheetrock it.

    I think you may end up spending more than what a 750 sqft shop would cost, but you will get much more and much better space with a lot less maintenance over the long haul.

    Ray
    Semper Fi

  15. #15
    Can't say I'm crazy about the styrofoam wall systems. You can not pour
    fast like with metal forms, have to wait for the concrete to set up before
    you can pour up higher on the forms, and you can not vibrate the concrete.
    This would allow for pour seams and even small pockets of air. If you have
    ever seen a basement poured, they stack the concrete up 2 or 3" on top
    of the forms, and sometimes have to add concrete after vibrating. The
    termite guys tell me that termites can live in the foam and they can't get
    the chemical to them. So it is hard to kill termites when you have that
    type system. The other thing is the cost. The last basement I considered
    using that system, even if I had done the work myself, the basement would
    have cost more than hiring a basement contractor with aluminum forms. Jim

Similar Threads

  1. Shop Location - What Would You Do?
    By Douglas Robinson in forum General Woodworking and Power Tools
    Replies: 35
    Last Post: 08-20-2007, 4:49 PM
  2. A Garage Shop Underway - Finally!
    By John Scarpa in forum General Woodworking and Power Tools
    Replies: 44
    Last Post: 06-19-2006, 5:44 PM
  3. How would you use a 3 car garage for a shop?
    By Alan Tolchinsky in forum General Woodworking and Power Tools
    Replies: 18
    Last Post: 03-02-2005, 10:59 PM
  4. garage shop heat?
    By dale rex in forum General Woodworking and Power Tools
    Replies: 8
    Last Post: 11-15-2004, 11:30 AM
  5. Cooling A Garage Shop
    By Tom LaRussa in forum General Woodworking and Power Tools
    Replies: 5
    Last Post: 08-14-2004, 4:26 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •