# floor for garage



## Rick18071 (Jun 6, 2011)

A owner that wants to build a 1,100 sq. ft. unattached garage does not want to put a floor in.  It looks like 2009 IRC R309.1 requires a floor with no exceptions. Is there anyway that he could build this without a concrete floor?


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## rshuey (Jun 6, 2011)

I'm pretty sure it just has to be an approved noncombustible material. 2A, concrete, either one.


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## fatboy (Jun 6, 2011)

There is no definition for a "garage" in the IRC (all I have at home is the 06). The 06 merely states that the floor must be non-cumbustible material, and if for the storage of automobiles, be sloped to facilitate drainage. Move on, call it an ag building, shop, storage, whatever. IMHO, R309 is aimed at attached garages, detached......well I think you have some wiggle room.


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## rshuey (Jun 6, 2011)

Limestone sand can be compacted to 92 plus percent compaction as well.


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## mark handler (Jun 6, 2011)

> SECTION R309 GARAGES AND CARPORTS R309.1 Floor surface. Garage floor surfaces shall be of approved noncombustible material.
> 
> The area of floor used for parking of automobiles or other vehicles shall be sloped to facilitate the movement of liquids to a drain or toward the main vehicle entry doorway.


You can approve any noncombustible material that can slope to drain. I would not approve an a material that will absorb and retain fuel or oil, like dirt or gravel.


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## rshuey (Jun 6, 2011)

Concrete can absorb those as well, if concrete did not absorb liquids, it would never be able to be stained.


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## mark handler (Jun 6, 2011)

rshuey said:
			
		

> Concrete can absorb those as well, if concrete did not absorb liquids, it would never be able to be stained.


You are right, Concrete 98% sheding vs gravel 98% absorption


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## beach (Jun 6, 2011)

What Mark Handler said (It might stain, but I wouldn't call it absorbant in the sense that it would retain enough fuel to be a problem.....)


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## FredK (Jun 6, 2011)

fatboy said:
			
		

> There is no definition for a "garage" in the IRC (all I have at home is the 06). The 06 merely states that the floor must be non-cumbustible material, and if for the storage of automobiles, be sloped to facilitate drainage. Move on, call it an ag building, shop, storage, whatever. IMHO, R309 is aimed at attached garages, detached......well I think you have some wiggle room.


I like this approach and since it's detached I'd approve it.


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## fatboy (Jun 6, 2011)

It's amazing all those 100 year old barns that are still standing out there, not sure how they survived with those dirt floors with the John Deere's parked on them.

I have bigger battles than a detached accessory structures floor. If it were my submission, the structure would now be a garden shed.

Again, JMHO.


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## rshuey (Jun 6, 2011)

I agree with fatboy.

In PA, if it's under 1000 sf it is exempt from a permit. (unless the local AHJ amends the Act). Where I live, I can build a 999 sf accessory structure and no permit is needed.

I love it.


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## rktect 1 (Jun 6, 2011)

Would not work around here.  I base this solely on the fact I am not allowed to issue a permit for a gravel driveway.  I make the jump from there to garage floors.

Also, just because a resident decides not to get a permit for a gravel driveway, does not entitle them to keep their gravel driveway.

Is what it is.


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## steveray (Jun 6, 2011)

CT has an amendment for detached, more than 10' separation distance.....it's all good...


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## Frank (Jun 6, 2011)

Dirt is typically noncombustible and the 2009 IRC does not mention a requirement to be nonabsorbant material.


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## Papio Bldg Dept (Jun 6, 2011)

These are all 2006 codes, but this is how we start our reviews for accessory structures:

R105.2 Work Exempt from permit.

Building:

1. One-story detached accessory structures used as tool and storage sheds, playhouse and similar uses, provided floor area does not exceed 120 sf.

R309.3 Floor surface.  Garage floor surfaces shall be of approved non-combustible material.

R403.1.4.1 Frost Protection. Exceptions: 1. Protection of freestanding accessory structures with an area of 600 square feet or less of light-framed constructtion with an eave height of 10ft or less.

R403.1.6 Foundation anchorage.  When braced wall panels are supported directly on continuous foundations, the wall wood sill plate...shall be anchored to the foundation in accordance with this section.

R501.2 Requirements. Floor construction shall be capable of accomodating all loads according to Section R301 and of transmitting the resulting loasds to the supporting structural elements.

In your case, a permit would be required.  Frost protection of footings/foundations would be required.  Anchorage to footing/foundation system.  Dirt floors are not addressed precisely by the code, simply the requirement to accomodate loading and provide drainage.  In this case, I would recommend some type of compaction, and a crushed rock or gravel surface to allow for drainage.

In our jurisdiction, all accessory structures over 120sf require, would at a minimum, require a monolithic slab, with a 12"x12" thickened edge.  Over 720sf (local amendment increase from 600sf) would require frost protection, continuous footing/foundation.  Accessory structures intended for the storage of motor vehicles would be required to provide a hard surface such as concrete or pavers leading to the structure, but would not apply to the interior.  If it is in fact an AG building, intended for AG use, then we would have no problem allowing him to build a something similar to an engineered pole building with pier footings and a dirt floor.


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## mark handler (Jun 6, 2011)

fatboy said:
			
		

> It's amazing all those 100 year old barns that are still standing out there, not sure how they survived with those dirt floors with the John Deere's parked on them.I have bigger battles than a detached accessory structures floor. If it were my submission, the structure would now be a garden shed.
> 
> Again, JMHO.


 It's amazing


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## steveray (Jun 6, 2011)

Mark.....That top one has plywooded windows...that is being burnt by the FD.....they do go up good though....you should see a 200 yr old tobacco barn go!  Nothing but air and fuel!


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## fatboy (Jun 6, 2011)

wow, I'm sure that was tough, do I need to do a google search to find pics of structure fires WITH concrete floors? Just saying, let's keep it in perspective.

BTW, both those pics look to show fires on the second level..........hmmmm


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## mark handler (Jun 6, 2011)

fatboy said:
			
		

> BTW, both those pics look to show fires on the second level..........hmmmm


Is this veiw better?


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## Papio Bldg Dept (Jun 6, 2011)

fatboy said:
			
		

> wow, I'm sure that was tough, do I need to do a google search to find pics of structure fires WITH concrete floors? Just saying, let's keep it in perspective. BTW, both those pics look to show fires on the second level..........hmmmm


While I understand what you are saying here, and don't want to see this post flamed with pics of burning buildings, a key, albeit an OT point from the original post, about fire separation distances being considered, especially when discussing storage sheds and garages.  If there is no permit required, or the AHJ is too busy to be bothered with accessory structures, then who considers fire separation distances for lot lines and adjacent structures.  R309.2 clearly addresses fire separation of detached garages within 3' of other structures.  IMO


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## Frank (Jun 6, 2011)

From my experience wood, concrete or dirt floor makes no significant difference in a barn or shed fire.


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## fatboy (Jun 6, 2011)

And I'm not going to get drawn in........to each his own. Here, me, I'd allow it, period. All I was saying. Cover my a$$, I'll redline it that vehicle storage is not permitted, like I said bigger issues than this out there.


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## Yankee (Jun 6, 2011)

Papio Bldg Dept said:
			
		

> If there is no permit required, or the AHJ is too busy to be bothered with accessory structures, then who considers fire separation distances for lot lines and adjacent structures. R309.2 clearly addresses fire separation of detached garages within 3' of other structures. IMO


The applicant is still required to build to the juristictional code, with or without an application


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## Papio Bldg Dept (Jun 6, 2011)

Yankee said:
			
		

> The applicant is still required to build to the juristictional code, with or without an application


So then why dismiss the original question...what does the IRC say about floors in accessory structures?  Is it okay to be dirt?  Does it need to be compacted?  Does it need to slope and drain?  These are the valid questions that are being dismissed because no permit is required by AHJ in the name of bigger fish to fry.


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## Rick18071 (Jun 6, 2011)

If the floor is dirt or gravel how do you keep it from changing the slope to the drain or door? My 3rd party company was sued by a home owner once because of no slope, so now we have to get a bucket of water to test the slope in garages.


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## Papio Bldg Dept (Jun 6, 2011)

Rick18071 said:
			
		

> If the floor is dirt or gravel how do you keep it from changing the slope to the drain or door? My 3rd party company was sued by a home owner once because of no slope, so now we have to get a bucket of water to test the slope in garages.


Comparing the 2006 & 2009 codes, I see little change.  R309.1 tells you the floor material needs to be 'approved' and the 2009 code went so far as to italicize the word.  R501.1 & R501.2 says that for 'all buildings' Chapter 5 shall control the design and construction of floors, and such construction shall accomodate all loads according to R301.  Chapter 5 covers wood, metal, and concrete floors.  Dirt and gravel floors are not covered.  If you didn't modify R105 to exempt structures under a 1,000sf, then I would suggest getting an engineered design for a floor that meets the requirements of the scoping provisions.   IMO, it needs to be concrete or treated wood with drainage system.


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## beach (Jun 6, 2011)

*Websters:*

*1ga·rage*

_noun_

\gə-ˈräzh, -ˈräj; _Canada also_ -ˈrazh, -ˈraj; _British usually_ ˈga-(ˌ)räzh, -(ˌ)räj, -rij\

*Definition of **GARAGE*

1

*:* a shelter or repair shop for automotive vehicles

The OP said "Garage".... IF he was in Calif. (I don't know where he is from), the code specifically states: 406.2.6 *Floor Surface* "Parking surfaces shall be of concrete or similar noncombustible and nonabsorbant material."

So, I guess the answer is, it depends on which state and which code you are using...... and which fish you feel like frying.....


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## Rick18071 (Jun 6, 2011)

This garage is over 1,000 sq. ft.


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## beach (Jun 6, 2011)

> This garage is over 1,000 sq. ft.


See 406.1.2 of the CFC (Area Increase)


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## Daddy-0- (Jun 9, 2011)

I agree with fatboy and frank's interpretations on this one.

BTW...those barn fires look like they started in the loft. I will bet that they were from spontaneous combustion of green/uncured hay and had nothing to do with vehicles or dirt floors. Hay fires are NASTY.


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## DRP (Jun 9, 2011)

I live on a dirt road, over half the roads in the county are dirt. The state used to oil them in the summer to keep the dust down, never saw one burn. Not that this was a smart thing to do from a water quality standpoint but a little perspective. There is a roof over a garage. We are learning as we go but it is interesting to watch the pendulum swing.


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## Yankee (Jun 10, 2011)

Papio Bldg Dept said:
			
		

> So then why dismiss the original question...what does the IRC say about floors in accessory structures? Is it okay to be dirt? Does it need to be compacted? Does it need to slope and drain? These are the valid questions that are being dismissed because no permit is required by AHJ in the name of bigger fish to fry.


IMHO the required slope is for floor material which is considered impervious, the reason being to protect the wall construction from becoming wet. I understand we are talking IRC, but I believe the IBC allows Post Frame Buildings without concrete or wood floors.


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## fatboy (Jun 10, 2011)

"I understand we are talking IRC, but I believe the IBC allows Post Frame Buildings without concrete or wood floors.

Goes back to my earlier comment that I feel the "garage" section of the IRC is directed at attached structures.


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## Yankee (Jun 10, 2011)

Rick18071 said:
			
		

> If the floor is dirt or gravel how do you keep it from changing the slope to the drain or door? My 3rd party company was sued by a home owner once because of no slope, so now we have to get a bucket of water to test the slope in garages.


A gravel floor can be compacted and sloped upon competion of the project. Just like the rest of the building maintenence, what happens after the CO is not a building department issue.


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