Planning a New Workshop - Sloping Shop Floor

[Jeff Erbele]

I am looking for thoughts and suggestions on my future workshop.

We are having a house built with an attached four bay garage. The garage ceiling will be 10'. All walls and ceiling will be dry-walled and insulated. It will have a 200 amp panel. Wiring will be in surface-mounted conduit.

Bays 1 & 2 measure 20' x 20'. They will be dedicated for my DW's car, and storage with pallet racks, yard & garden tools and machines.
Bays 3 & 4 measure 20' wide x 30' deep.
My truck will only fit in Bay 3, but will be in the driveway when I need more shop space such as out-feed or an assembly area. Bay 4 will be the dedicated workshop area. It will not have an overhead front door but has a double walk-in door to the rear yard.

DUST
I am planning on buying a dust control system and a vertical air compressor. I have been reading about dust control here on SMC. The main thing I learned so far is I have a lot more to learn. Frankly I have no clue what I need or should buy for adequate dust control. I don't want to waste money on an inadequate system or paying for excess, wasted capacity. I am having trouble sorting all that has been written; boiling it down to the selection steps or criteria.

NOISE
For noise control, I am thinking about partitioning an area for the DC and air compressor along an exterior wall. Otherwise I really don't want to partition the remaining space as it limits possibilities. On the same note I think some dust is in inevitable. In order to confine it to the 20 x 30 space, I am planning on a commercial grade curtain between bays 2 & 3.

FLOOR
Ideally I would love a wood floor but it will be concrete. I am planning on painting it with an epoxy coating. I will have rubber mats at the work bench and work stations for fatigue reasons.

Now this part bothers me. I was examining the details on the blue print and discovered an architects' note that stated garage floor will have a slope of at least 3" drop over 20'. That equates to 1.5" per 10', or 3.5" in the 30' bays.
I questioned our builder's rep / sales person about it. He said he was pretty sure it was our building code but was going to verify that. He also said the purpose of it was for safety reasons, especially related to gases heavier than air, (carbon monoxide) that they would settle towards the overhead door, having a greater chance of leaving the confined space.

So far it sounds like I may be stuck with the spec. My concern is having to chock anything on wheels, the lawn mower rolling out into the street unless I park it sideways on the hill, drill bits and dowels rolling off machine or work tables and the like. I can foresee all kinds of problems, especially with machines on wheels, every time I move them, having to set up in or out feed roller stands. Maybe I am making a better deal of it than it will be; time will tell. Also I don't know that anybody can help with this, except maybe share how ig of an issue it is, if they have a similar situation, and how they deal with it.

I thought about the possibility of building a level wood floor in the 4th bay, but that comes with another set of problems, the biggest being the transition to Bay 3, a trip hazard, carts or machines falling over the ledge, one bay being level and the adjacent bay having a slope.

Instead of moving machines around frequently, those on wheels, I'll probably have to find a setup that works best most of the time, level machines, their extensions and support rollers and leave them parked there, as much as possible.

Other than the garage floor, things are looking good so far for our dream house.

[Jamie Buxton]

Yeah, garage floors slope. There's the gas issue you mention. There's also the water issue. Water or snow dropping from your vehicle flows toward the door, rather than pooling or flowing away from the door.
Another issue with shop floors is that they're generally not flat. That is, the slope is not the same everywhere. The concrete guys just eyeball it, and hand-tool it.



I've had garage shops for decades. You don't really notice the slope. Machines don't roll away from you. However, it is good to remember the slope when you're building extended projects.

[Yonak Hawkins]

Sounds like it's going to be a great space for a shop. If you're concerned about the floor sloping couldn't you call it a workshop with overhead doors in the plans that you submit to the code department and pour level floors ?

[David Hawxhurst]

i don't have any problems with my stuff on wheels rolling towards the door, my floor is also sloped. for dust collection consider reading bill pentz site about dust collection. my 20 x 20 garage will fit two cars and nothing else, it is tight fit.

[Jeff Erbele]

Yeah, garage floors slope. There's the gas issue you mention. There's also the water issue. Water or snow dropping from your vehicle flows toward the door, rather than pooling or flowing away from the door.
Another issue with shop floors is that they're generally not flat. That is, the slope is not the same everywhere. The concrete guys just eyeball it, and hand-tool it.

I've had garage shops for decades. You don't really notice the slope. Machines don't roll away from you. However, it is good to remember the slope when you're building extended projects.

Extended projects are one of my concerns. Ripping 8 foot material (or any length) takes double that just for the in and out feed. In an ideal shop, machines are set-up once and remain static. I know that isn't going to happen in mine. Ripping a 4 x 8 sheet requires a lot of roller stands being set-up and adjusted.

I am not going to build a 30 foot work bench, but any level bench along the long wall, will have an ever changing work height along its length. I have a padded work mat in the kitchen, about 5/8" -3/4" thick, which is most comfortable to stand and work on, except when I wash dishes. Within minutes I start to get a backache, from bending just a fraction of an inch.

[Michael W. Clark]

You are right, you want the cabs on the wall to be level and square so the drawers and doors work right and it looks good. However, not sure it is a big deal for the machines and outfeed tables. I'm not sure if any of mine are "level", but I have checked them for "flat". Roller stands are rarely set at the same hight as the saw. I found this out the hardway using them for outfeed on the tablesaw.

Since this is your "dream house" can't you designate those last two bays as a shop? You may have to install a partition wall between them and the "garage" to make the inspector happy. However, this may not be a bad idea anyway in terms of keeping dust off of the wife's car, which is (or will be) very important at some point.:)

Mike

[Jeff Erbele]

Sounds like it's going to be a great space for a shop. If you're concerned about the floor sloping couldn't you call it a workshop with overhead doors in the plans that you submit to the code department and pour level floors ?

Thanks for the compliment. I have not had a home workshop for the past 13 years. Even though I owned two homes in sequence during that period, each with two stall garages, circumstances prevented having a workshop. That was killing me. Any projects were done on my truck tailgate or saw horses and in the driveway. Any shop would have been nice. At this point, this will be a dream.

By trade I am a trained and experienced machinist-welder. My career focus was industrial repair, progressing to a technician focused on trouble-shooting, predictive maintenance and failure prevention, culminating in customer service and sales. I was good at all of it, because I found it both challenging and rewarding and loved it.

Because of it, my workshop will include welding shop capabilities. Welding does not fit well with a nice woodworking shop. My solution is to fabricate a welding table with retractable wheels. The welder and related tools and equipment will be on shelves or in drawers under the table. When I feel the need to make sparks I’ll pull the welding table outdoors thru the double doors to the back yard. I am going to pour a slab behind the shop later. The utility area will be screened for the neighbors’ sake, with lattice & vines and bushes & trees.

I learned neighbors tend to be tolerant of trade activities, machine noise, traffic, stacks of materials, etc. If one considers their point of view; what they see and hear. Once they learn the guy next door builds and repairs stuff and especially once one does something for them they like having you as a neighbor. :)

A decent machine shop on top of everything else is not in the plans. I'll limit that to sharpening equipment only; the main machine being my Foley-Belsaw Sharp-All, which dovetails with the woodshop nicely.

To answer your question, it doesn’t matter what I call it. The garage is attached to house. The City and County of Denver view it as such and their codes apply to that. Further, talking to the code & permit department is pointless. We don't submit plans. We deal with the developer only; they engineer and build everything. They approve the plans, then pass them to the city/county for approval and request the permits. They have their own factory which prefabs the trusses, rafters and wall panels. Every thing must go thru them and into their computer system. It spits out blueprints, schedules, work orders and house components. I ask our sales-rep if we can modify the floor slope and he passed it up the design chain. We await the answer.

The prefab factory is incredible. Once everything is approved and scheduled, the house framework is built in automation. No one touches the lumber. Materials go in on conveyors and house components come off the line, finished and bar-coded, in less than 2 hours. The parts get loaded on semi trailers in reverse construction sequence; the first pieces needed onsite are on top of the load. Onsite they have a crane for framing the house, lifting and setting everything in place.

I suspect I am stuck with the sloped floor spec. If I am really lucky, I might get to have the slope reduced slightly.

[Jeff Erbele]

You are right, you want the cabs on the wall to be level and square so the drawers and doors work right and it looks good. However, not sure it is a big deal for the machines and outfeed tables. I'm not sure if any of mine are "level", but I have checked them for "flat". Roller stands are rarely set at the same hight as the saw. I found this out the hardway using them for outfeed on the tablesaw.

Since this is your "dream house" can't you designate those last two bays as a shop? You may have to install a partition wall between them and the "garage" to make the inspector happy. However, this may not be a bad idea anyway in terms of keeping dust off of the wife's car, which is (or will be) very important at some point.:)

Mike
You are correct on the roller stands not being flat. I found the in-feed can be approximately level to the table or maybe a bit higher but not so much that it rolls into the blade on its own. And the out-feed rollers work best if one allows for material sagging when applicable. You don't want the material front edge missing the roller or tipping the stand. Nor does one want to have to stop in the middle of a cut to adjust things. The more I think about it, the less desirable single roller stands are. I think I am going to look into commercial options, longer conveyor racks with multiple rollers. Thanks.

I go back and forth on partitioning the 20x20 from the 20x30 space. For shop dust, noise and climate control (heating or cooling) it makes sense, but limits the flexibility of the total space.

Correct. I promised her a garage parking space. She has a great job and goes to work everyday. I can't blame her for disliking brushing snow off the car windows and scraping frost October thru May. And sawdust on her nice work clothes, simply by opening the car door would not be a good scene. I earn a good living working online, so I don't have to deal with what she does in that regard.

Putting up a partition and designating two bays as a shop may be an option for obtaining a reasonably level floor. Maybe. But at this point, having signed off on design changes:
1. it would cost $250 just for the change request
2. it would delay our start date by a couple of months
3. it would increase the cost significantly. The builder would have to build it. I can't go buy a pile of 2x's, sheetrock and a door and do it myself. That's cause for tears. LOL.
I built two houses, renovated several & remodeled a bunch more, and finished a couple bare basements and a couple of bare stud-wall garages.

Here's the bottom line. I ask the questions, if the slope is mandatory; if it can be reduced or eliminated. If the answer is no I am going to deal with it and refocus.

[Jim Andrew]

I have never had an inspector say anything about the slope of my garage floor on a job. We sloped the floors for the reason that a wet car sheds its water or snow and the water runs out the door. I have built offsets at the door so rain water could not get into the garage, is a pain but nice. Of course, I've been retired since '01.

[Jamie Buxton]

If you're really concerned about it, there are people who have put a horizontal wooden floor in their garage. It usually takes tapered sleepers to deal with the slope, and usually needs shims or other leveling scheme to deal with non-flatness. You'll also want a rotary laser level or the like, to see where level really is. It ain't rocket science. You can find more info by using SMC's Search in this forum.

[glenn bradley]

We all have different challenges with a home shop but maybe some of my experiences will help:

Extended projects are one of my concerns. Ripping 8 foot material (or any length) takes double that just for the in and out feed. In an ideal shop, machines are set-up once and remain static. I know that isn't going to happen in mine. Ripping a 4 x 8 sheet requires a lot of roller stands being set-up and adjusted.
- This is true. If you look at workshops setup for kitchen cabinets and other fixtures made primarily from sheet goods you will notice a marked difference from a shop that makes furniture. If you will be doing a lot of plywood or composite sheet material structures, I would tailor my shop to that function.
- If you make tables and dressers and wall cabinets and sideboards and chairs and will only occasionally make built-ins or other plywood pieces, the temporary roller stands are not that big of a deal. The first thing you do with a big sheet of plywood is make it smaller. Unless you are doing a dozen kitchens, the handling of full sheets may not be as often or as difficult as you think.


I am not going to build a 30 foot work bench, but any level bench along the long wall, will have an ever changing work height along its length. I have a padded work mat in the kitchen, about 5/8" -3/4" thick, which is most comfortable to stand and work on, except when I wash dishes. Within minutes I start to get a backache, from bending just a fraction of an inch.
- As Jamie mentions, the slope is not going to be very precise other than the general drop to the doors. I positioned my bench perpendicular to the slope and therefor required minimal adjustment. I have worked out the positions of my larger mobile tools so that they too end up square to the slope and don't teeter-totter. A pack of shims from the BORG is about a buck for any odd spots in the slab. I keep some setting "over there" in a coffee can; despite sounding sort of crude this works out quite well.
- I too like to have certain tools stay put. I use the concept of anchor-tools; my tablesaw/router table/outfeed is in a fixed position as are my jointer and planer mostly. The jointer and planer can be easily moved 'just a bit' to allow for long or large stock handling. MY larger bandsaw and drill press are also on mobile bases but have not moved in a long, long time. I have three sanders that are also mobile but, mostly move just a bit, now and then to allow clearance while working with them.
- In any shop a mobile work surface or assembly table is a great help and building drawers into one makes one of your storage units do double duty with a set of casters.

[Allen Grenz]

The slope of the slab shouldn't have anything to do with building the house or their pre-fab process... Theybuild the walls square not tapered as they rest on the stem.. The garage slab is then usually poured separately within the stem wall.. I'm not sure why this should even be an issue.. Do you have a Natural gas furnace in the garage or something for the restrictions? Otherwise, you should be able to tell the concrete contractor to put a swimming pool in the garage if you want..lol

[Jeff Erbele]

i don't have any problems with my stuff on wheels rolling towards the door, my floor is also sloped. for dust collection consider reading bill pentz site about dust collection. my 20 x 20 garage will fit two cars and nothing else, it is tight fit.

My truck won't fit in our present 20 x 20 which measure something less. And it the future 20 x 20, I don't know. Maybe if the front bumper touched the wall, I removed the receiver hitch an greased the back bumper, maybe the overhead door stiffeners might slip over it. :D Seriously it is that tight. If it fit at all it would be impractical.

I started reading the Bill Pentz website. My understanding is he has severe health issues due to dust inhalation. He has my very best wishes, but one gets the impression he is on some crusade. I don't mean that in a bad way. I mean one must read an awful lot in order to glean out the take-away, useable information.

I don't need to be converted. I only need to know how to figure out an adequate & economical system, one that works well in a climate controlled, one man, fully equipped, wood shop. Equipped meaning, table, miter and band saws, jointer, planer, shaper, router, various sanders, lathe, and drill press.
Climate Control - I don't know yet if I will heat or air condition the shop. But I would like to have a DC system that allows for either. I am more inclined to heat it in the winter and open the doors in the summer.

Maybe my best bet is to contact him directly, ask for advice and make a reasonable donation to support his overhead.

[David Hawxhurst]

my full size truck is 5' longer than my garage is deep. there is not enough space to get by the first car without having to open the door and walk outside to get around it. live and learn.

bill does have some heatlth issues, but he does have a lot of good info about how to figure out how much you need. i have simialr equipment you have and setup and decided that in my case that the clearvue cyclone was going to be the best set for me at this time. my garage is climate control via a mini split with heat pump option. the weather here is such that not having AC for summer is a killer. i exhaust through filters year round, given your might not need ac for summer time you could vent outside during summer and through filters in the winter. i have very little to no dust in my shop and that is backed up with the dylos meter. being my garage is attacted to the house it was very important to me that the air be clean as prolonged expose can be harmful. at times my shop has cleaner air than the house so i'm will to say that i must be doing something right.

[Harry Hagan]

I don’t think it will be a problem. It’s only 0.15 of an inch per foot. If you were trying to ensure proper drainage out of the area it would be closer to 0.25 of an inch per foot and I’ve never had any problems at that rate of slope.

[Michael W. Clark]

Hi Jeff,
Regarding DC, that's a topic or two within its own. One broad stroke for advice is to pay attention to all components of your system to maximize the performance, i.e. hoods, duct, separator, fan, and filters. All have to work together for the system to work best. Also, given your location, if you are at higher elevations, fan and separator performance may be affected.

[Jim Andrew]

I've set up shop in garages with a 3" slope and was not a problem. If you are going to set up a shop DC system, get at least a 3hp cyclone so you can handle a sander. A 2hp system will handle a Tablesaw and a planer and jointer, but a sander is harder to pick up the dust. If you plan to get a big sander, consider a 5hp.

[Kurt Barker]

At the risk of confusing the issue more, I suggest putting a floor drain in the center of each stall used for parking a vehicle, and having a gentle slope from the perimeter of each stall to their respective drain. When the Denver snow melts, it'll be under the vehicle where you won't have to walk through it to the house and it won't be able to run down to the garage door and freeze it shut or run down your apron. For the portion that'll be a workshop, it can be flat. I built one similarly in a previous home, and regret not doing it in my current home.

[Stew Hagerty]

I'm in approximately half of an over-sized 3-car garage so I have to deal with the sloping issue. All of my stationary equipment (tablesaw, and... ... Nope that's it, tablesaw) has all been leveled. Everything else, including my bench is mobile and therefore goes with the flow.

[phil harold]

At the risk of confusing the issue more, I suggest putting a floor drain in the center of each stall used for parking a vehicle, and having a gentle slope from the perimeter of each stall to their respective drain. When the Denver snow melts, it'll be under the vehicle where you won't have to walk through it to the house and it won't be able to run down to the garage door and freeze it shut or run down your apron. For the portion that'll be a workshop, it can be flat. I built one similarly in a previous home, and regret not doing it in my current home.
check code on this residential garages
some jurisdictions drains are not allowed, period.
others need sand and a gas separators, separate drain fields...

as stated before gas fumes flow to the lowest point thus sloped floors
confine these fumes, as in a drain, is just an explosion waiting to happen

I level my tablesaw and out-feed table because it always become assembly table even so I have work benches..
I deal with more slope than you do so my tablesaw is elevated about 2.5 inches in the front than the rear of the 7' out feed table

I actually like the tablesaw higher than normal (less bending over)

[Jeff Erbele]

Hi Jeff,
Regarding DC, that's a topic or two within its own. One broad stroke for advice is to pay attention to all components of your system to maximize the performance, i.e. hoods, duct, separator, fan, and filters. All have to work together for the system to work best. Also, given your location, if you are at higher elevations, fan and separator performance may be affected.

Regarding DC, that's a whole new field for me. It has been so long since I last had a decent shop, I almost forgot about the chips & dust. The discussions here caused me to think about it and plan for it. I don't want that mess in the shop, much less the house or lungs. Your advice is broad yet helpful - makes sense.

I never thought about the potential ramifications of higher altitudes. Elevation definitely affects baking and one must buy gas appliances rated for it.

I'll have to research if it effects vacuum. It probably does to some degree. The question is, if it significant difference, one must compensate for.

[Jeff Erbele]

I've set up shop in garages with a 3" slope and was not a problem. If you are going to set up a shop DC system, get at least a 3hp cyclone so you can handle a sander. A 2hp system will handle a Tablesaw and a planer and jointer, but a sander is harder to pick up the dust. If you plan to get a big sander, consider a 5hp.

I'm glad to hear the slope isn't as big a problem as I envision it.

I will buy a stationary combo belt-disc sander and/or/maybe a drum sander. Sanders are probably is one of the worst machines for making fine dust.
Right now I have a Shop Smith Mark V with the optional jointer, mortiser, router and a DeWalt Miter Saw.
For those that don't know, the Shop Smith is a five in one, universal machine, table saw, 12' disc sander, turning lathe, drill press and horizontal boring mill. It saves space and money as opposed to buying individual machines and has some unique capabilities (horizontal boring is one of those) but also has limitations and a list of "con's", (changing from machine capability to another gets old fast, even though it is fairly quick and easy). It does well at some things and fails at others. Still I'll probably keep it, but certainly buy most if not all of the stand alone machines, starting with a good table saw, but not until after we move.

[Jeff Erbele]

The slope of the slab shouldn't have anything to do with building the house or their pre-fab process... Theybuild the walls square not tapered as they rest on the stem.. The garage slab is then usually poured separately within the stem wall.. I'm not sure why this should even be an issue.. Do you have a Natural gas furnace in the garage or something for the restrictions? Otherwise, you should be able to tell the concrete contractor to put a swimming pool in the garage if you want..lol

Correct, the construction process has nothing to do with the slope on the garage floor. The footings are level, the concrete walls are plumb as well as level on top, where the square walls will sit. None of that is an issue. The issue is the blue print specifies the sloping floor, which is one step, a stand alone step in the process, anytime after the footings and walls are poured and the forms are stripped.

No I did not order any heating device in the garage, although I probably will install a shop type, hanging natural gas furnace or electric base board later.
Gas is cheap, but we are installing a solar system as soon as we close. I'll figure out which is more economical at that time. We have a solar system now, love it and our solar company.

Even though I want it heated, the developer/general contractor (one and the same) is not one bit shy about quoting high prices for design changes and some upgrades.
Further we are required to pay for all design changes in full up front. That is to insure the developer does not get stuck with some odd-ball thing that would be difficult for them to sell, or have to remodel in order to sell it, should the buyer not be able to close on the house.

Some examples of their prices are $75 per extra duplex outlet, $150 per GFCI outlet, $330 per lo-voltage "hocky puck" accent light (x 10 for the kitchen soffit/upper glass door decorator cupboards - impractical for routine use), $800 for a shower wand, $1,200 for the version mounted on an adjustable height bar, somewhere around $5,000 to install laminate or hardwood flooring on the stairs to the second floor.
The house has three bathrooms, each with 2 sinks per vanity. We don't need, want and very seldom if ever will use both at the same time. It cost about double the price of a sink to not have the second one installed. Because it is a design change, they have to modify the print and order a non-standard counter top, a one-holer.

Our sales-rep told me the sloping floor is a city building code requirement. I searched their code online but have yet to find it. Instead of reading volumes, I am going to call that department and see if they can verify or dispel it, and/or point me to the correct reference.

RE: Otherwise, you should be able to tell the concrete contractor to put a swimming pool in the garage if you want..lol
:) ya I wish I could tell the contractor to do what I want, but it is strictly prohibited in writing, further I am prohibited from making any physical changes to the house until after closing.
I don't need a swimming pool at home. It is an active adult 55+ community. The club house is a block away; it has an indoor pool, an outdoor pool, a whirlpool, exercise room, internet café, lounge area, meeting rooms, plus various activities with a full-time director. It is a HOA - home owners association but free of HOA fees. That overhead including the club house is paid through property taxes; the former non-deductible, the later deductible. That is great! And unique; at least we never heard of it anywhere.

[Art Mann]

My shop is 24 X 28 stand alone but it has 2 bay doors on one end and the floor slopes toward them as the OP describes. There is no problem whatsoever with this configuration so long as the floor is flat. The slope isn't nearly enough to cause equipment on wheels to roll and wood and sheet goods cut just fine on a small slope so long as the infeed and outfeed tables are coplanar. If I were the OP, I would worry more about the floor being flat than that it is level. High and low spots are what causes me problems - not an overall slope. You can have that problem whether the floor is nominally level or not.

[Jim Neeley]

My shop is 3 stalls out of a 4-car garage. Here in Alaska, garages are heated and insulated, with sloped floors and floor drains. No single concrete panel is 4'x8'.

To work around this I built at 4'x8' torsion box using 2 sheets of 1/4" plywood and 1x4's (ripped to 3" to make all sides straight and square) using screwed construction (pocket holes / screws for the 1x4's). To construct it flat required shimming a pair of sawhorses level. Since that time, shims on the corners (where the box meets the horses) provides a flat surface at a convenient height.

I'm planning on a "one-sided" box of heavier ply and 1x4's for a panel-cutting alternative to my table saw. Using pocket screws would permit replacing single boards s they got too cut up.

Just my $0.02.. YMMV.

Jim in Alaska

[Rich Enders]

Jeff,

This is all much ado about nothing. Level your work bench and you will be fine.

[Michael W. Clark]

Regarding DC, that's a whole new field for me.

I never thought about the potential ramifications of higher altitudes..

Tell your chosen supplier your elevation and they should be able to help you. They may steer you to a larger fan, but it won't pull the amps it will at sea level.

Look at the Cincinnati Fan SPB bulletin and you will get an idea of the effects of altitude on fan selection/performance. Most manufacturers have a similar method.
Mike

Edit: Just saw your change order fees, wow!

[terry mccammon]

May I suggest the excellent book by Sandor Nagyszalanczy "Workshop Dust Control" http://www.amazon.com/Woodshop-Dust-Control-Sandor-Nagyszalanczy/dp/1561584991

[Jeff Erbele]

My shop is 24 X 28 stand alone but it has 2 bay doors on one end and the floor slopes toward them as the OP describes. There is no problem whatsoever with this configuration so long as the floor is flat. The slope isn't nearly enough to cause equipment on wheels to roll and wood and sheet goods cut just fine on a small slope so long as the infeed and outfeed tables are coplanar. If I were the OP, I would worry more about the floor being flat than that it is level. High and low spots are what causes me problems - not an overall slope. You can have that problem whether the floor is nominally level or not.

That makes sense. We never got a close look at the interior of the garage until very late in the process, just before signing off on our final design.
Normally they keep them locked from the inside and use them to store samples, office supplies etc. We were in there to look at fireplace rock samples. The one we saw was dressed up with a very nice looking epoxy coated garage floor. It may have visually accentuated the slope and that particular floor may have been greater than most.

Since my OP, I learned that their homes with basements have a steeper sloping driveway and garage floor than those with a crawl space only. We opted for a basement.
Their basements are a full 9 feet deep or better, allowing for the height of an I-Beam in place of bearing walls, should anybody decide to finish it later.

As deep as the footings are, maybe 10-11 feet below grade, they don't dig a very deep hole. Instead they haul in fill. That has an impact on these slopes, in part inside the garage.

Unfortunately all I can do about the floor being flat is express my concerns to the construction foreman at our pre-construction meeting. The rest is up to his supervision and the skill of the cement finishers. The good news is our developer/builder has a high reputation for building quality homes.

[Jeff Erbele]

Tell your chosen supplier your elevation and they should be able to help you. They may steer you to a larger fan, but it won't pull the amps it will at sea level.

Look at the Cincinnati Fan SPB bulletin and you will get an idea of the effects of altitude on fan selection/performance. Most manufacturers have a similar method.
Mike

Edit: Just saw your change order fees, wow!

Thanks, that is a helpful reference. (http://www.cincinnatifan.com/catalogs/SPB-401-internet.pdf)

Fees and upcharges vary greatly. It is not all bad news. Garage insulation is optional but at no additional charge. The 200 amp sub panel for the garage was $200 installed. The total cost on a per sq ft basis is in line with the current market for comparable properties.