Thread: two hour fire in crawlspace

My brother-in-law is rehabbing an older home in Philadelphia. He's adding a room with a crawlspace, for laundry I think. The rest of the home has a basement. He was told by city code officials that the crawl must have two hour fire protection, so he has to install two layers of 5/8 type X gypsum. Anyone else have such a requirement in other parts of the country?

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Not in my area of Arkansas, but then code here doesn't require fire seperation of the garage and living space either, go figure....

John A,

No two Hour fire rating but one a jointing county and one town mandated Fire Sprinklers.

I have not read the ordnances, visited county AHJ and they were not consulted and had not seen what was passed.

John is the home a shared townhouse? Where exactly is the 2 hr. fire
separation ? Is it between walls or under floor joists? In SC Fire separ-
ation is needed between shared walls, crawl spaces or attics that run
through adjoining buildings. Single family is between house & Garage.

Gregg

It's a row home, at the end of the row. The added room is not shared or adjoining any other unit. The 5/8 gypsum is going on the bottom of the floor joists.

I don't like the sound of the sheetrock on the btm of the joists in a crawlspace, tends to act as a vapor trap. I am sure they must know what they are doing though

Originally Posted by John Arnold

It's a row home, at the end of the row.

That's why.

There is likely less than 5 feet to the property line, right?

The fire rating is determined on the distance from the property line, and the floor is being treated like a wall (which means the wall should also be two hours for the same reason). I'm going with the '2 hours' based on what they said, not looking it up to see if '1 hour' would suffice, just commenting that the wall and floor should be the same the fire rating based on distance to the property line.

If he constructed a block foundation wall around the addition, he would likely not need to have any fire rating to the floor system. If it is that small (for a laundry room), I would recommend doing that is this will eliminate long term problems related to the gypsum board being under the floor and exposed to the weather, plus, any penetration through the floor would need to be treated as a fire rated penetration and would require expensive fire stopping. He would have to do the math to see which is less $ and which is less trouble - the two might not be the same, in which case he would need to select the choice which best suits his needs and capabilities.

If he is adding a room it won't be a crawl space anymore!

To me this is a good idea for fire protection, especially if it is a laundry room.






Rolland Pruner

Originally Posted by Rolland Pruner

If he is adding a room it won't be a crawl space anymore!

I'm confused. (Seems to happen frequently.)

If you add a room to an existing building using a raised floor system (not slab on grade) and it is not over a basement, does it not have a crawlspace under it?

Confused me, too.
New room. New crawlspace under new room.

Jerry's thougth is possible;

John, were there any windows in the room?

If no windows, then yes, fire rated due to property line; windows may throw out that possibility.

Darren

Originally Posted by Darren Miller

If no windows, then yes, fire rated due to property line; windows may throw out that possibility.

Unless the windows are not supposed to be there ... ... someone in plan review or the inspector may have - dare I say - "missed" that?

Jerry,

Thinking about it again, somethings wrong. If fire rating is needed, then the foundation wall must also be fire-rated (it's supporting the fire-rated wall).

Darren

Originally Posted by Darren Miller

Thinking about it again, somethings wrong. If fire rating is needed, then the foundation wall must also be fire-rated (it's supporting the fire-rated wall).

No, the intent is to keep the fire inside for two hours. You don't want a fire in that unit to burn down neighboring units.

There are several reasons for having fire rated walls, ceilings and floors within a structure.

Then there is fire rating based on distance to the property line to protect other structures - I believe that is the intent they are going for.

An example would be townhomes. There are not fire rated ceilings or floors (assuming slab on grade) in the town home, only fire retardant treated roof sheathing for 4' out from the fire rated partition separating the townhomes or a 30" high parapet extending up through the roof.

The intent is not to save the townhome which is one fire, the intent is to save the adjacent townhomes from that fire by delaying its movement for 1 or 2 hours, enough time to allow everyone to get out and the fire department to bring the fire under control and save the other units.

This happened recently in Sanford between here and Orlando a few months ago when a plane crashed into some townhomes. the fuselage hit one and the engines and wings took out the adjacent ones to each side.

The center townhome was destroyed in the fire, the two adjacent townhomes suffered considerable fire damage from the engines and fuel. the other townhomes to the side of those two were relatively undamaged - except for water damage due to firefighting needs. When the fire was out, there was a vacant area between two fire partitions and the two adjacent townhomes were burned out to the second floor. The other townhomes survived.

Just like it was supposed to do - the fire stopped at the fire rated partitions.

Not that it matters, but we will disagree.

You can't have a fire rated structure 'suspended'; if a foundation wall is involved, that supporting wall must be rated at least as much as the walls or ceilings it's supporting.

Let's say there is a crawlspace and a gas line or electric service runs through it. A fire starts is the crawl and burns the wood frame 'foundation' wall.

Darren

Originally Posted by Darren Miller

Let's say there is a crawlspace and a gas line or electric service runs through it. A fire starts is the crawl and burns the wood frame 'foundation' wall.

When is the last time you found a "wood frame" "foundation"? Not going to happen.

However, you have a point in that there could be a fire in the crawlspace and there is now no fire rated wall separating the fire "under" that structure from other structures.

However, the way you are stating it is in regards to supporting the structure above - that's not the point, the point is to contain the fire to one structure. In that case, yeah, there would be no fire rated separation to the property line.

However, as soon as you threw in that "gas" line, you now need to meet:

- G2415.11 (404.11) Piping underground beneath buildings.

Piping installed underground beneath buildings is prohibited except where the piping is encased in a conduit of wrought iron, plastic pipe, or steel pipe designed to withstand the superimposed loads. Such conduit shall extend into an occupiable portion of the building and, at the point where the conduit terminates in the building, the space between the conduit and the gas piping shall be sealed to prevent the possible entrance of any gas leakage. If the end sealing is capable of withstanding the full pressure of the gas pipe, the conduit shall be designed for the same pressure as the pipe. Such conduit shall extend not less than 4 inches (102 mm) outside the building, shall be vented above grade to the outdoors, and shall be installed so as prevent the entrance of water and insects. The conduit shall be protected from corrosion in accordance with Section G2415.8.