Shop Under Garage?

[Kevin Post]

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)
http://www.kerkstra.com/images/residential/l_residential_01.jpg
http://www.kerkstra.com/images/residential/l_residential_02.jpg


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

[Jeff Sudmeier]

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.

[Dave Richards]

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. :D Garage is 32x50.

[Karl Laustrup]

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.

[Michael Cody]

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.

[Kevin Post]

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

[Kevin Post]

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

[Bill Lewis]

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?

[Kevin Post]

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. :eek:

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

[Jonathan Szczepanski]

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.

[Dave Richards]

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.

[Jim O'Dell]

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.

[Kurt Strandberg]

Yes, the garage is bigger than the house. That's the way it should be, right. :D 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

[Ray Bersch]

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

[Jim Andrew]

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

[Ed Weiser]

If I had a choice, I would place as many windows into the space as possible. Even if this means window wells, I believe it would be worth it. My shop is in my basement now and even though square footage is not a problem, the absence of natural light is unpleasant. Do everthing you can to secure natural light. On the subject of air conditioning, assess your needs carefully. Cooling will not likely be a problem--dehumidification will. Don't oversize your unit. In floor heating would be great and could easily work off your home system as a separate zone without transfer of any dirt or dust into the house. Lastly, DO NOT bury your DC ducting in the concrete slab. The reasons are many including potential for water infiltration, encouraging excess cracking of the slab, potential interference with your heating system and, most of all, the total absence of flexibility if you decide in the future to change your shop layout! Hope this helps. I've learned from the mistakes I've made (many.) Good luck. Building a house can be very exciting (and stressful without proper planning.)

[Karl Laustrup]

He also said I can have floor drains in my garage if I want.
-Kevin
Kevin, do this. Have a drain put under each vehicle. Make sure the slope to the drain will encompass front to back and side to side of each vehicle so the runoff will all go to the drain.

[Ray Bersch]

Jim, I think you have some wrong info on pouring this type of foundation. A different mix is used than with a metal or wood formed pour and it is accomplished in one pour. The pours I have witnessed have actually been pumped not poured. Set up time is longer and the cost is likely to be higher.

Termites do not live in the foam forms. In fact, they would not even penetrate the foam. Extermination of termites is best accomplised by treating the ground around the foundation and the nests. Interior treatment is not appropriate unless there is infestation and with a poured foundation, that infestation will be in the wood above ground - with a block foundation, termites can penetrate cracks in the block and move up toward the wood frame - not the case with poured foundations.

I often have problems with subs who have learned to do things one way and will find fault with anything they are not familiar with - so ask around.

[David LaRue]

I have assisted in the construction of a several precast concrete homes in the Detroit area. The whole house was concrete block, with precast floors & wood truss ceilings. We used corefil in the block walls for insulation, and we drywalled the walls, and skimcoated plaster on the ceilings. You could not tell the building was concrete when it was done. The houses hold their heat, and stay cool because once you heat or cool that mass it stays very consistant. I woul not hestitate to make a house this way, and having a shop below the gargare mkes sense to me especially if it is a walkout. :D

[Rob Russell]

The idea of a basement shop with ~ 10' ceilings would be a dream to me. Radiant heat in the floor is definitely the way to go. You will likely need a dehumidifier for the summer - consider a drain for it. Window wells for natural light also provide a source of fresh air if you're spraying finishes. Just make sure the window wells are properly sealed and I'd suggest running drain pipes from the wells down to your curtain drains. Even if you can't do the windows, with lots of light it'd still be a nice shop. If you can, fit a sleeve for an A/C unit in the end wall. That would help keep the shop dry in the summer, too.

If I had the opportunity to build a shop like that, I wouldn't hesitate for a minute. I would also consider enlarging the garage a tad - the extra depth width is handy in the garage for snowblowers, lawn mowers, et al. That fact that the basement under the shop gets bigger is just pure coincidence :rolleyes:.

Rob

[Gary Hoemann]

Kevin, i have been asking myself the same questions when planning a new home. I think everything you want to do is very doable and I also realize that I myself would not spend the money needed to extend hot water, sewer, and other things to a seperate building. I'm in Tennesse so some of it will be different, but with a walk-out basement andd higher ceilings, I think it would have a lot of advantages. One thing I'm still trying to figure out in my mind is how to keep vibration-type noise from migrating upstairs--like d.c. noise. We are a little further out on actual building--good luck.

[Jim Becker]

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.
I would recommend you avoid this, Kevin. It makes it impossible to adapt your shop over time as your needs and tools change and it also makes it difficult to deal with clogs, etc. Overhead, despite the appearance and challenge relative to lighting is generally the best and most efficient way to install dust collection duct. IMHO, of course.

As to the general idea you have, I like it also as long as the ceiling height is where you want it to be. The hydronic heating is also a good idea...separate zone, however, so you can run it lower than the house if you choose.

[Jim Dunn]

Don't, I repeat, DO NOT put drains under cars if they go to a septic system. Any gas or oil spills will end up in those drains and could damage your treatment system.
I believe code here requires drains and a "step" down into the garage so as to avoid gas spills from going under the door, into the house.

[Kevin Post]

Don't, I repeat, DO NOT put drains under cars if they go to a septic system. Any gas or oil spills will end up in those drains and could damage your treatment system.
I believe code here requires drains and a "step" down into the garage so as to avoid gas spills from going under the door, into the house.

I've been thinking about that Jim. The house will have a septic system, just as my current home does so I'm down with the whole bacteria is my friend thing. If the floor drains go to the septic system, I'm not putting them in.

I was told the step-down to the garage from the house is related to carbon monoxide gas rather than gasoline. At minimum, I was told we'll want a lip between the garage into the house to keep CO from seeping in from running vehicles because it's heavier than air. The other thing they do is pitch the floor toward the garage doors rather than the entry to the house.

I never really considered these details until our contractor mentioned them. I'm really cheap when it comes to stuff I think I can do myself. However, he has a lot of great info and I know his experience and efficiency will be worth the cost. I'm a computer guy who dabbles in this construction stuff. I'm glad I have someone else running the show.

[Bart Leetch]

I would have to worry about having a door between the shop & house because of smells like finishing migrating into the living area.

As to putting the DC & air in the floor thats no problem this has been done in commercial shops for years very successfully by pouring a trench down the center of the length of the shop in the floor with a lip on each edge & just out from the wall along the length of the shop & using thick wood or steel plate to cover the trench. This way you can access the system should you have any problems. I see no problem with doing the same with the heating & or AC. I would think that you would need less heating & AC with this ICF system so the ducting may not need to be as large which would make it easier to install in a trench system.

Also with ICF's I would think the time savings would off set other costs incurred for building the shop under ground.

Is there some way that you could build the floor support so it has beam like supports that set on a wall that the top would be say 12" lower than the rest of the walls & put obscure glass between each beam so for say the length of your shop you would have about 25-30 10" x 12" obscure windows letting in light. My Dad did this in our basement between wood beams & it let in a lot of light.

[Kevin Post]

I would recommend you avoid this, Kevin. It makes it impossible to adapt your shop over time as your needs and tools change and it also makes it difficult to deal with clogs, etc. Overhead, despite the appearance and challenge relative to lighting is generally the best and most efficient way to install dust collection duct. IMHO, of course.


Two votes against dust collection under the floor so far...

I agree this limits changing the system later because once it's in, it's literally set in stone. According to my plan, the main run ( 6 inch PVC ) would exist beneath the floor and outlets ( 4 inch ) would come out of the floor at various points to be extended with additional pipe or flex hose. I'm planning one run along a wall and one diagonally to serve the middle of the shop. This is how my garage is set up now and it's served me well with no changes. The only difference is I'd bury the pipe rather than hanging it. The advantage is headroom.

I'm not particularly worried about clogs because the setup I have now has never clogged (not the main part anyway). The only clog I've had has been in the hose coming from the planer. The 6" PVC leading to the DC fed by smaller 4" pipes is the key I think. The only change I may need to make is a bigger motor and fan to generate more CFM because the runs will be longer.

Another reply commented that the pipe would increase the chances for moisture damage and cracks in the floor. I guess I didn't think it would be any different than plastic sewer line that typically runs under the basement floor.

Any more thoughts on this?

-Kevin

[Kevin Post]

Is there some way that you could build the floor support so it has beam like supports that set on a wall that the top would be say 12" lower than the rest of the walls & put obscure glass between each beam so for say the length of your shop you would have about 25-30 10" x 12" obscure windows letting in light. My Dad did this in our basement between wood beams & it let in a lot of light.

That's an excellent idea but I'm afraid I'm limited with what I can do with windows because of the house design.

For those playing our game at home... The front of the house faces south. The 3-car garage is attached to the right side (east) of the house as you face it. The garage doors will not face the street, it is a side entry garage. So the whole east side is out for windows because the driveway and garage doors will be there.

The house will have a brick veneer on the front (south). I think the type of window you're suggesting would interfere with the brick. I am planning to put a window or two in wells on that end, however. That way, I can open the windows and the door at the other end and get cross ventilation when the weather permits.

To the west is the house. No windows there. The entry door into the basement will go through a closed storage area and then through the mechanical room for the house. A total of three doors will separate the living spaces in the house from the shop.

On the north side is our walkout level with an outside entry to the shop. The door will have windows and I'm planning to add another one to the wall. I'm also trying to find a way to install a spray booth on that wall with a vent to the outdoors. Most of the year I could just open the windows to replenish the air that gets sucked out but wintertime is a challenge. I'd freeze... I guess I could postpone finishing until the weather cooperates like I do now.

[Jonathan Szczepanski]

I agree this limits changing the system later because once it's in, it's literally set in stone. According to my plan, the main run ( 6 inch PVC ) would exist beneath the floor and outlets ( 4 inch ) would come out of the floor at various points to be extended with additional pipe or flex hose. I'm planning one run along a wall and one diagonally to serve the middle of the shop. This is how my garage is set up now and it's served me well with no changes. The only difference is I'd bury the pipe rather than hanging it. The advantage is headroom.

I'm not particularly worried about clogs because the setup I have now has never clogged (not the main part anyway). The only clog I've had has been in the hose coming from the planer. The 6" PVC leading to the DC fed by smaller 4" pipes is the key I think. The only change I may need to make is a bigger motor and fan to generate more CFM because the runs will be longer.

Another reply commented that the pipe would increase the chances for moisture damage and cracks in the floor. I guess I didn't think it would be any different than plastic sewer line that typically runs under the basement floor.

Any more thoughts on this?

-Kevin
Kevin -

There is another option for keeping the duct work under the floor. You could build a false floor or crawlspace on top of the the workshop slab. You could then run the duct work, or any other wire or piping under it. If you screwed plywood on top of the floor joists, you would have the abiility to unscrew them and fix any clogs or other problems that would occur. Wood is also easier then concrete to walk on all day.

Just an option to mull over.

[Steven Wilson]

I'm not particularly worried about clogs because the setup I have now has never clogged (not the main part anyway). The only clog I've had has been in the hose coming from the planer. The 6" PVC leading to the DC fed by smaller 4" pipes is the key I think. The only change I may need to make is a bigger motor and fan to generate more CFM because the runs will be longer.


Kevin, if you want a bigger motor and impellor and run longer distances then you'll probably want to rethink having 6" pipe and maybe go with 7" metal. As for 4" drops, they may (sort of) work for very small machines but if you ever upgrade to a sliding table saw, euro combo machine, shaper, etc. then you'll probably want to step up and use 5" or larger drops. Once you've placed the PVC into concrete then you're stuck and any upgrades will involve ripping the floor up. So seriously consider placing your duct work into a channel that you can access and make the channel large enough to handle larger DC pipe and probably electrical conduit. Then you have the flexability to change. BTW running overhead isn't so bad. As for the door to your house (from shop), spend a little money and get a door that seals well. The steel doors used in recording studio's are air tight and are fairly decent at reducing sound transmission.

[Bill Lewis]

Two votes against dust collection under the floor so far...Well here is one vote in the "for" catagory, with explanation.

I did run one duct under the concrete floor of my basement shop (http://www.sawmillcreek.org/showthread.php?t=17408). I just had to do this for the TS at the very least (I ran a power conduit too). I think this is one tool that greatly benefits by this. TS placement is usually out in the middle of the floor, so having an under floor setup is ideal. I hate tripping over cords or stepping over flex duct.

BTW no leaks. My whole basement stays totally dry though, it too is a level walk-out.

I used 4" PVC Electrical conduit because it has very large radius elbows. Of course if I were to do it again, I would use larger diameter, 6" maybe. The conventional thinking at the time was that 4" was adequate. Now I am thinking that I will probably end up with an excalibur and I don't think that the 4" will handle it, but hard to tell at this stage. I have another drop nearby, that would do the trick though.

One caution about running the whole shop DC piping under floor would be that you have design it to maintain velocity as well as cfm. For example, a 12" diameter pipe running the same cfm as a 4" diameter pipe may not have the velocity to move dust and chips. This is one reason why DC ducting gets reduced farther from the unit. If you can come up with a good shop plan and design the system well you should have a really neat setup. You can also do as I did, and combine the two as needed.

[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. :mad:

[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.