It used to be a requirement that the garage be lower than the rest of the house in order to insure that gasoline vapors did not enter the dwelling. Apparently that rule has been removed in some jurisdictions in order to facilitate movement for the elderly and handicapped. Instead, code now simply requires that the floor be gently sloped toward the garage doors. Apparently, the code authors feel that the slope provides an adequate safety margin.

Personally, I think I would feel uncomfortable without the step down. I also like the idea of being able to hose the garage out without flooding the house with water.

We are planning a step down in our new house.

Ditto frog_hopper, I thought it was code. Is it too late to change the plans now? I'd do at least an 8" drop for the reasons stated. I'm sure it's not the end of the world if it stays at the same level as the rest of the house but I'd be more comfortable with a drop if it were possible.

The drop should be a multiple of a comfortable stair height. We currently have a 5 1/2 inch drop into our rec room, which was originally the garage. It's not too bad, but it would feel better if it were 7 or 7 1/2 inches.

I agree with all of you. I'm going to ask if there is something we can do, but it might be too late. :(

In my experience, placing a first floor slab at a level above the surrounding grade so that water is encouraged to not move upward and also preventing the exterior siding from being too close to the ground usually puts the first floor a step above the garage unless there is a steep apron at the entrance to the garage.

Our garage is the same grade as the back level of our 3-level house. Of course, that level is 6 inches above grade there, with a slope-apron away from the garage entrance. Sure makes it a lot less hassle to carry/dolly-move large things outside/inside.

No big deal for us, and pretty common down here for new construction, whether tract or custom.

Our old house was like this and it was great, especially if you had someone who was on crutches or used a walker or wheelchair and needed to get into your house. We tried to do it with our new house, but it didn't work out--I miss it.

My husband is a FABULOUS communicator... NOT! I just clarified this with him and he said we WOULD have about 4" or so floor level difference.

I guess in his mind it wasn't much of a step, but to me at least it's something.

:)

AFAIK, 4 inches is the code minimum where it is still required.

No step here - house built in 1993. Love it. Not even 4 inches. There is probably a 1.5 inch door transition. I think there is about a 1 inch difference in height between hardwood and concrete - must have been 1/4 inch before we put the wood in (was vinyl).

Safety - hogwash. Vapors - you have to be kidding. I hose out the garage all the time - with a pressure washer - and hardwoods just beyond the door. Do I spray directy on the door transition - no. Otherwise - A NONISSUE.

Of course the garage floor is sloped - now that is definitely code around here. But one of the things that I really liked about this house was the lack of steps getting into it. The front porch is just a single step up and the lot is sloped so back yard is high. House is brick so the siding part is a nonissue.

Nicely summed up, mightyanvil.

Many communities still require all residences to conform to NFPA 101 - Life Safety Code which is sometimes enforced by a state Fire Marshall. I don't have the latest edition but since most communities that use it reference the '97 edition, it is likely that it still requires a 4" curb between a garage and a house.

Unless you find out what codes are in effect in your community and confirm your interpretations with the local building official you should not be making life safety related design decisions about a house. I know designing your own house has become a national sport but there are rules.

Building codes still require that the ignition source of a water heater in a garage be elevated above 18" unless the unit is equipped with a Flammable Vapor Ignition Resistant System.

Apparently the code authors and the manufacturers of water heaters still take the possibility of gasoline vapor accumulation in a garage seriously.

If your garage floor is close to level with your first floor you should consider adding a weather protected/sealed threshold if it doesn't already have one.

Darn - I lost my post.

Gasoline vapors do not cause a reportable number of house fires because modern cars do not leak vapors. Have you ever smelled gas from a modern car in a garage. The systems built are quite good at preventing any leakage. Just as good if not better than natural gas plumbing in a modern house.

Yes - you can have an all electric house because of the tiny amount of fires caused by natural gas or propane leaks. Yes - you can build a ranch so that everyone can escape in the event of a housefire. But please know that gasoline vapors are not listed as a cause of housefires (smoking, electrical, heating, arson, candles, etc.). Gas vapors from a gas can are much more likely (probably 1000x) but that still is not on the US fire administration's radar.

This is a non-issue. But build your all electric ranch in a neighborhood that you can walk to everything since automobile accidents kill 10x more (really almost 15x) people than housefires. Also - don't smoke (#1 cause of house fires). Arson is number 2.

6 months in NC burn unit - 2 years burn research - don't think I think about fires.....

Must not be code in my state as I have seen a number of homes with no step up from garage. In fact they do it on purpose calling it a "barrier free" entrance for those who may be handicaped.

Statistics should not be used to lower the fire safety of a building.

A gasoline leak or spill in a garage is always a possibility no matter how careful you are and because the invisible vapor burns rather than the liquid, the ignition source can be some distance from the spill. Keeping ignition sources above a certain height and preventing the vapor from entering the house or passing into a basement are perfectly reasonable precautions.

I'm another with a 'level' floor between the garage and house... my neighbors' houses are the same way, and I don't think anyone gives it a second thought.
I never heard about the vapors, and I wonder if my neighbors have.

That said ---
If the vapor thing IS an issue, wouldn't the fact that the garage floor slopes to the garage doors alleviate the vapor issue? The garage doors aren't air tight....

Well, the house slab got poured today and the garage slab will be poured tomorrow. Looks like there will be about 1.5 - 2 inches level difference. The garage IS supposed to slope, we'll see how it goes. :-)

I guess if I stop posting (after the house is built), you can assume I've been killed by all those gasoline vapors.... and not having a step wasn't safe. :) heeeheee

mightyanvil - we will have to agree to disagree. I understand your point but not looking at statistics means you spend (waste?) time and energy preventing injury where it really doesn't exist. There are dangers in the world and I believe we should minimize those but you first need to realize what they are in a quantifiable way.

I was just talking to someone yesterday and they pointed out that it is more dangerous (to your children) to have a pool in the house versus a gun. It is true (from what I can tell) but to adults a gun is far more dangerous b/c of suicide. Kids do use guns for suicide also but at much lower rates than adults.

so cars>>>>pools>guns>>>>>>>>>>>>>gas vapors. But I do admit - 4 inches is nothing...

The relative risk of different home hazards is irrelevant to a home designer. A hazard is a hazard. The possibility of an occurrence is enough to justify reasonable avoidance measures. People should attempt to protect their children from pools and guns. The most dangerous hazard in a house is a lighted cigarette. Next is an unattended stove top. It's only the less frequently occurring hazards that you can do anything about.

People have little fear of gasoline because they don't understand its unusually hazardous nature. Therefore, you can be sure they will always find a way to produce gasoline vapor in their garage and that it will travel. It is logical and reasonable to remove ignition sources from the garage (or below a certain level) and to prevent vapor from traveling into the house.

The 4" curb was required in the old CABO, BOCA and UBC codes but removed in the 2000 IRC. Massachusetts took the trouble to amended the IRC to put it back in and so did many other states. A garage slab level with a house floor has been illegal here for over 30 years.

The slope of the garage floor does nothing to alleviate the potential for vapor build up and if the requirement were for the drainage of spilled gasoline it would not be allowed to slope to a drain.

The reasoning of the new code is that garage to house doors are adequately sealed against vapor due to the energy code requirement for weatherstripping and that makes sense on paper. Unfortunately, not all builders and building inspectors understand this and certainly homeowners don't feel obligated to maintain it.

The building codes in the US are under constant attack from very powerful organizations that represents large homebuilders. It has become difficult to keep any protection in the code that raises the cost of a home. But a national consensus code like the IRC doesn't prohibit a designer from using their own judgment or a state from amending it.

According to Ameriburn.org, a 5 year study (1993-98) found 6000 house fires and 500 deaths directly attributable to gasoline vapors. Grant that those are not large numbers, nonetheless, those were all *avoidable*. Spending even a few thousand dollars on a properly lowered garage floor is nothing compared to the cost and pain of enduring burns or worse from a fire caused by gasoline vapors.

If gasoline vapor were visible, no one would even keep a lawnmower or a gas can in their garage much less a water heater or even think of repairing a vehicle there.

"Grant that those are not large numbers, nonetheless, those were all *avoidable*. "

Not being argumentative, but how do you know that? How do you know that they were ALL avoidable?

Did the site state that all the fires and all the deaths were due to even flooring?

(I dislike statistics that are incomplete or misconstrued....)

"Cars are built so well they don't leak anymore," or words to that effect.

People work on cars in their garages. Examples: Modern cars have their fuel pumps in their tanks. When the pump fails, dropping the fuel tank is frequently the only way to replace it. Often, fuel must be drained from the tank before it can be lowered.

Fuel filters require replacement. Try replacing a fuel filter without spilling gasoline. People make mistakes, especially amateurs doing something for the first time. There are plenty of mistakes that can be made that will spill gasoline when servicng vehicles.

People usually store their gasoline powered lawnmower in the garage, along with trimmers, edgers, and chainsaws, etc. People usually store a can of gas in their garage. There are lots of things that can go wrong with any of these devices, and a lot of them aren't made well.

"Houses don't blow up due to gasoline fires these days," or words to that effect. Why remove the very safety requirements that may be preventing the fires in the first place?

Luann ~ neither the site nor I indicated that flooring was or was not responsible. The figures were for fires/deathes attributed to the presence of gasoline vapors. The fact that gasoline vapors are heavier than air is a well-known scientific fact; and if there is gasoline in the vicinity, there *will* be vapors. The fact that many years ago, safety experts concluded that a 4" drop of the garage floor below the adjoining living area floor would be a sufficient safety precaution was also not addressed.

"Avoidable" in the context means that there were ways to avoid the possibility of the situation --- i.e., if gasoline-powered equipment is never permitted inside the dwelling, then it is unlikely that there will be a fire caused or contributed to, by gasoline vapors. However, where there is gasoline, there will also be vapors (possibly slight from modern cars, but sure from mowers and storage cans); and there are procedures and methods for decreasing the likelihood of an explosive fire. Anytime well-known and documented preventive methods are ignored, the person/situation ignoring the situation is *not* avoiding the danger/s posed. They may not be courting the danger, but they certainly are not doing anything to avoid it, either.

My feeling then and now is that spending a few $K to ensure that gasoline's heavy vapors will be less likely to disperse into living quarters is a reasonable precaution when posed against the horror and pain of burns. YMMV

I have no idea what the codes say, but I know a lot about garages, spending a lot of my leisure time in ours. I work on old cars, old tractors, and old outboard motors. I'm sure I've unleashed plenty of gasoline vapors, in addition to other noxious and/or flammable chemicals. I personally would not have my garage level with the house. I don't even like having the garage attached to the house, but in some areas, it is a code requirement (???) I know that a Tampa FL neighborhood had to get a special variance to build detached garages in a new neighborhood.

Low fast spreading gasoline vapors in a garage are inevitable. Ignition sources in a home are plentiful. The point is to keep them apart.

The curb is just one small precaution and assumes that there are more ignition sources or basement stairs beyond the door. The statistics are useless because they don't include enough curbless designs and most of the severe residential garage fires are caused by gas/electric water heaters or cigarettes igniting gasoline vapors from storage cans or vehicle repair. There's no point in trying to keep vapor from getting to ignition sources in the house if there are such good ones in the garage.

I posted earlier that our old house had a garage on the same level as the house and we liked it. We lived there for 20 years. It seems to me that we had to have a special door/frame/threshold that sealed the door so vapors would not get into the house. Gasoline vapors have a strong odor and not once in the 20 years did I smell them in our old house. We live in Wisconsin so had snow blower, lawn mower and roto tiller in the garage as well as cars. We don't fill gasoline tanks in the garage because we didn't want a spill in the garage. The same with changing fuel filters--I'm almost positive that my DH does that outside as well as changing the oil on our cars. The only time I ever smell gasoline vapors in our garage is if someone leaves the little pressure release value open on the gas can. It is obvious when that has happened the second that you walk into the garage, but the smell from that never made it into our house. If I used my garage in such a way that there would be gasoline spills on a regular basis, I might be concerned about floor level, but if I used it like we do, I wouldn't. It seems to me that if a garage that is attached to a house blows up, that the house will go too regardless of the floor levels.

"According to Ameriburn.org, a 5 year study (1993-98) found 6000 house fires and 500 deaths directly attributable to gasoline vapors "

I could not find this reference anywhere. The USFA lists top 10 causes of fires (with the bottome one being 0.2%) and none of those include gasoline vapors. Gasoline is surely a contributor in arson, car fires and others.

Ah - found it. Statistics - lies, damn lies - you all know how it goes.

That number is for gasoline related burns. Not vapors. That may include arson. It certainly includes using gasoline as a way of helping trash to burn - which is a huge cause of fires/burns. It would certainly include smoking while changing a fuel filter. Gasoline is incredibly dangerous - there is no doubt in that.

Changing fuel filters in a garage is incredibly irresponsible. Storing gasoline in a garage is similarly risky. (hello - starting a car is a great ignition source.) If you smell gasoline in a garage - then you are doing something incredibly dangerous. Doesn't matter all that much that it isn't getting into your house.

Yes statistics matter. There are always risks and compromises. You are chasing a non-issue. Please - if you want to be obsessed with safety - find where the real issues are and don't create false hazards. Time or Newsweek had a great article/special issue about the irrational fears we have nowadays. Fear of things that almost never happen and then neglecting things that do. Talking on a cell phone in a speeding car - now there is an issue.

Our masonry contractor included a 1" drop extending to just inside the garage door closing line from the slab perimeter. In other words, the garage doors close an extra inch beyond the garage floor proper. He furnished the names of several other clients that he did that for and contacting them, they were very pleased how it prevented rain migrating under the garage door seal into the garage. Looks a little peculiar when the door is open but not noticeable at all when closed. Can't be more than an inch though, or the garage door may not be high enough at the top!

Wow.... thank you all for your feedback. Now I'm a nervous wreck. We were out of town this weekend and came back to find the garage slab to be completely flush with the house slab. That was a shocker. The way the dirt had been cleared underneath there was room for at least 2-3". Totally clueless as to why they would pour it at the same level as the house. And not that it matters at all to them, but it obviously cost us more money in concrete as well (almost $6,000 for both slabs).

My husband says he's not worried, but after reading all these posts, I sure am worried...

The plans for your house should have specified the level of the garage slab.

One review set that we have in our possesion with no drop specifies 'GARAGE SLAB 1/2" BFF OF HOUSE.' That tells the builder that the garage slab should be 1/2" below the finished floor height of the house. The 1/2" accomodates the tiles specified for the mudroom floor.

What did your plans specify?

All you need is a good door with a fire rating. I posted earlier that our old house had a garage the same levelas the house and that I thought we had to get a special door. I asked DH if he recalled and said it was just a fire rated door. If you get a fire rated door, you get the whole door system with the threshold, etc. so that it fits well. As I said earlier, I never smelled vapors in our house. And as others have pointed out, you should avoid doing things that allow vapors to build up in your garage. Jeld-wen and other manufacturers have fire rated doors. I posted the therma tru link below just because it had more information about the frame thant the jeld wen web site--click on the split jamb frame link. Good luck.

Here is a link that might be useful: fire rated door

The IRC already requires this door to be solid core wood, solid or honeycomb core steel, or a 20-min. fire-rated door (without a rated frame)

What you need to prevent vapor movement is weatherstripping especially at the threshold. That will be as good as a curb if you maintain it.

This thread is quite humourous. If I were to go by the majority of the replies on here I would assume that smoking a cigarette at a gas pump is 100% ok and would never result in the unseen vapors igniting due to my cigarette. I have never seen any reports or statistics pertaining to this, so I can only assume that the warnings are false and I am completely right