Change of plan - openings between townhouses

[Jobsaver]

Think about other rated partition walls though. In other scenarios there will be a rated exit hallway with (rated) doors from adjacent units opening into the hallway. So although the residential code doesn't expressly prohibit or allow a doorway, this concept as a means of compliance with the intent of the code in this unusual situation is permitted by the building code with other residential uses.

This is the very conclusion that led to many of our previous answers. Still, I think Texasbo is correct. There are places that the IRC and IBC just do not interpolate.

One book for one and two-family dwellings. A different book for the balance.

Note that the IPC and IMC have exceptions explicitly spelled out when excepting one and two family dwellings.

 

[texasbo]

Think about other rated partition walls though. In other scenarios there will be a rated exit hallway with (rated) doors from adjacent units opening into the hallway. So although the residential code doesn't expressly prohibit or allow a doorway, this concept as a means of compliance with the intent of the code in this unusual situation is permitted by the building code with other residential uses.

Corridors are protected in one way or another. Furthermore, there is not a single situation in either the IRC or IBC that I'm aware of that allows a door in a wall directly on a property line.

The code can't itemize everything that is prohibited. It says a "1 hour wall assembly", then outlines what you can have in that wall, and that's limited to very specific through-penetrations and membrane penetrations. Would you allow the wall to have 75% windows? Why not, the code doesn't prohibit them? (a question, not a challenge)

In my opinion, if you buy the assumption that openings are permitted, then you have to allow nonrated ones, because nowhere does it say that openings in dwelling unit separation walls have to be rated. Why? Because in my opinion it doesn't allow them.

Again, with all of that said, I would make it work; I'm just talking about the code, as written.

 

[texasbo]

Guys, talk to me about your interpretation of services.

E3501.2 specifically requires only one service for one and two family dwellings.

230.2, 2005 NEC allows only one service per building, and has an exception for multiple occupancy buildings where there is no room to make service equipment available for all occupants.

Beyond that, how can you justify more than one service per building?

Sorry, I don't have access to a later edition NEC right now, maybe it's in a newer one?

 

[texas transplant]

texasbo,

Your question about electrical service goes right back to the heart of the problem, what is this structure and is it one building or two? E3501.2 allows only one service per one and two family dwelling. If this is a duplex, it gets one service, if it is two attached single familys, it get one per side or building.

So is this one or two buildings?

I understand your point that the code says "one hour rated assembly" If openings are not a part of the perscriptive code (IRC), would that mean if you want to have an opening that the opening would have to be as allowed and rated as per the IBC?

I am not sure of the answer in my own head now after following the thread, but those two questions seem to be the ones that need answered. After that all the pieces fall into place in my mind.

 

[Jobsaver]

There is no reason a single family home could not have multiple meters.

Incorrect answer.

Texasbo, one service allowed per the 2008NEC per 230.2. Thanks for the correction. I have been incorrectly taught, and know of two new local homes having mother-in-law quarters having isolated services. Oops!

Edit post: I have now been told by our Electrical Inspector that in both those cases, a single service was established serving two individual meters.

 

[texasbo]

what is this structure and is it one building or two?

In my opinion, it sounds as if it was built as a single structure with a property line running through the middle of it. As others have said, I think there should be a code change that addresses this. In my opinion, it should be the same as townhouses; two exterior walls or a single 2 hour wall.

I understand your point that the code says "one hour rated assembly" If openings are not a part of the perscriptive code (IRC), would that mean if you want to have an opening that the opening would have to be as allowed and rated as per the IBC?

In my opinion, the IRC as written does not permit openings, period. It would take administrative approval of alternate method to put openings in the wall. I would only allow it under very specific circumstances, such as the one posed by the O.P. The code doesn't care who owns it, but it does care if there's a property line, and it does care if it is a dwelling unit separation.

 

[Yankee]

texasbo,Your question about electrical service goes right back to the heart of the problem, what is this structure and is it one building or two? E3501.2 allows only one service per one and two family dwelling. If this is a duplex, it gets one service, if it is two attached single familys, it get one per side or building.

So is this one or two buildings?

I understand your point that the code says "one hour rated assembly" If openings are not a part of the perscriptive code (IRC), would that mean if you want to have an opening that the opening would have to be as allowed and rated as per the IBC?

I am not sure of the answer in my own head now after following the thread, but those two questions seem to be the ones that need answered. After that all the pieces fall into place in my mind.

There is no such thing as "two attached single familys" under the code. I agree that generally a building is only permitted one service, UNLESS it is a townhouse (three or more attached single family dwelling units OR if approved by the BO and each service is labeled "one of two" and "two of two"). So label the services.

This is one building with two dwelling units, it is a duplex.

Yes, the opening can be rated/approved as if this were an IBC building, as any construction in a single family/duplex MAY meet the IBC instead of IRC if desired.

 

[Jobsaver]

This thread rocks! If Jeff had a nickel for everytime I learned something important on this forum . . .

 

[Yankee]

Corridors are protected in one way or another. Furthermore, there is not a single situation in either the IRC or IBC that I'm aware of that allows a door in a wall directly on a property line.The code can't itemize everything that is prohibited. It says a "1 hour wall assembly", then outlines what you can have in that wall, and that's limited to very specific through-penetrations and membrane penetrations. Would you allow the wall to have 75% windows? Why not, the code doesn't prohibit them? (a question, not a challenge)

In my opinion, if you buy the assumption that openings are permitted, then you have to allow nonrated ones, because nowhere does it say that openings in dwelling unit separation walls have to be rated. Why? Because in my opinion it doesn't allow them.

Again, with all of that said, I would make it work; I'm just talking about the code, as written.

Every rated wall in an exit corridor has a door in it . . . the door is rated as well. Windows would be allowed if rated as well. In fact, they are OFTEN installed and allowed in certain doors. Equivalency might also permit an overhead rated fire door that slams down over unrated glazing or openings when the alarm is triggered . . . . it's amazing what one can do if one wants to and has enough money . . .

The code does not care about who owns what, or property lines with respect to anything except protection of building separations and the resulting required protections. If the wall(s) or areas near or on the property line are rated appropriately, that is all the building code cares about.

 

[texasbo]

There is no such thing as "two attached single familys" under the code. I agree that generally a building is only permitted one service, UNLESS it is a townhouse (three or more attached single family dwelling units OR if approved by the BO and each service is labeled "one of two" and "two of two"). So label the services.This is one building with two dwelling units, it is a duplex.

Yes, the opening can be rated/approved as if this were an IBC building, as any construction in a single family/duplex MAY meet the IBC instead of IRC if desired.

Yankee - help me out with a code section on this. All I'm seeing is R101.2 which says the IRC "..shall apply to the construction of...one and two family dwellings"

What section are you referencing that would allow the use of the IBC for an opening at the property line for a two family dwelling?

Also, what code section are you referencing regarding the labeling of the meters to circumvent 230.2?

 

[texasbo]

Every rated wall in an exit corridor has a door in it . . . the door is rated as well. Windows would be allowed if rated as well. In fact, they are OFTEN installed and allowed in certain doors. Equivalency might also permit an overhead rated fire door that slams down over unrated glazing or openings when the alarm is triggered . . . . it's amazing what one can do if one wants to and has enough money . . .The code does not care about who owns what, or property lines with respect to anything except protection of building separations and the resulting required protections. If the wall(s) or areas near or on the property line are rated appropriately, that is all the building code cares about.

That was my point. The code specifically allows rated/protected openings in a corridor. Someone, maybe you, used openings in a corridor as a comparison. Of course it allows openings, because a corridor is protected.

The IRC does not allow openings in a tenant separation wall. Period. When you walk through that door and across that property line, you are not entering a protected space. The IBC doesn't allow doors at a property line either.

 

[Yankee]

Also, what code section are you referencing regarding the labeling of the meters to circumvent 230.2?

Combination of 230.2©(3) and 232.2(E)

(I grant you I have never approved except for under 232.2(D))

 

[brudgers]

Guys, help me out here. For those of you who say the code allows openings in dwelling unit separation, where are you getting that? 317.1 ( 302.3 in '09) requires 1 hr wall assembly. It goes on to talk about through penetrations and membrane penetrations, but nowhere does it allow openings, rated or not.As many of you have said, I'm sure I could and would make it work through deed attachments and/or zoning, but in the code as written, I do not think openings would be permitted.

The IRC does not prohibit such openings explicitly.

Therefore, the provisions of the IBC may be used to address such openings.

In my mind, the opening isn't ideal.

But it is impossible to prevent one from being installed even if you prohibit it during permitting.

Therefore, make the situation reasonably safe.

In fact, one might reasonably argue that the addition of what is essentially a horizontal exit makes both dwellings safer.

 

[texasbo]

Combination of 230.2©(3) and 232.2(E)(I grant you I have never approved except for under 232.2(D))

230.2 ©(3) is under capacities, but like you, under special conditions I wouldn't necessarilly have a problem invoking it. The IRC, however, seems to not want us to do it.

 

[brudgers]

Corridors are protected in one way or another. Furthermore, there is not a single situation in either the IRC or IBC that I'm aware of that allows a door in a wall directly on a property line.

Happens all the time with condominiums.

 

[brudgers]

There is no such thing as "two attached single familys" under the code.

Sure there is. There is just no such thing as a structure consisting of only two townhouses. One could construct two Single Family Dwellings with no setback to the common property line. Each would require its own rated wall.

This is one building with two dwelling units, it is a duplex.

There is no such thing as a duplex in the building code.

Absolutely.

 

[texas transplant]

Yankee,

Under the IRC, a two dwelling building is a duplex (and its one building), but if I want to build my two single family attached homes under the IBC not the IRC, I put a fire wall that meets Section 705 and put in the opening with a fire door that meets section 715. I now have two buildings don't I? Then I get two services and makes two "attached single family" buildings. The opening can be up to 120 sq ft per floor level I think.

I am not really wanting to argue, but logic tells me it is stupid if I can build a single stand alone home and its called a building, or I can build three or more attached single familys and call each one a building, but I can't attach just two and call them buildings. That is the part that doesn't make sense to me.

On this whole question, I tend to agree with whoever said make them install a one hour door on both sides of the wall like adjoining hotel rooms. It might not be the most code correct answer, but my gut tells me it will be better than denying the opening and having them install it after the C of O with no permit.

 

[texasbo]

Happens all the time with condominiums.

At a property line?

 

[texasbo]

The IRC does not prohibit such openings explicitly.Therefore, the provisions of the IBC may be used to address such openings.

In my mind, the opening isn't ideal.

But it is impossible to prevent one from being installed even if you prohibit it during permitting.

Therefore, make the situation reasonably safe.

In fact, one might reasonably argue that the addition of what is essentially a horizontal exit makes both dwellings safer.

I agree with you that it will be installed anyway, and agree that the proper course of action is to make it work.

But just for academic purposes, let's talk code. Something doesn't have to be expressly prohibited to not be allowed. If your contention that the IRC doesn't prohibit it, why bother yourself with IBC? Why not just case the whole thing open and put windows in the rest of it. The IRC specifies how a tenant separation wall is to be built and what kind of penetrations it can have. Openings aren't on the menu.

Nor are they on the menu in the IBC, at property lines, that I'm aware of.

 

[Min&Max]

First I would not spend to much time researching the code book to determine if this was possible. All to often the "Book" says we can't do something that there is no adequate reason to not allow.

1). Build structure as originally planned but provide headers where future openings are desired.

2). Interconnect smoke alarms as previously described

3). Complete structure, do final inspection and issue C.O.

4). Owner applies for permit to provide openings in common wall.

5). Issue permit and also have owner label utility meters/panals as 1 of 2 at lot 3A and 2 of 2 at lot 3B

6). Do final inspection for second permit.

Mother-in-law has separate utilities and can pay as required. Property tax statement will come as two statements to both addresses which HAVE to be owned by one party. Mother-in-law re-imburses son-in-law for her share of property taxes. They can can live basically in the same dwelling but have separate addresses and separate spaces with separate expenses. When mother-in-law leaves for her final resting place the openings can once again be filled in to meet minimum requirements and the mother-in-laws former "space can be marketed as a single family dwelling. All are happy except some _____ retentive bureaucrats.

 

[Yankee]

The reason it is a two family dwelling (sorry for the "duplex" designation) instead of two connected single family dwellings (like suggested) is because the rating between "single family dwellings" (such as TOWNHOMES) is more restrictive than that between the two dwelling units of a two family dwelling.

I agree with brudgers that door opening directly onto or over a property line happens all the time with condos. Walk out the condo door, and you are on another parcel.

Two family dwellings often both have doors that open into a common foyer and then to the exterior door.

I think in the big picture this is approvable. There are a kajillion different scenarios and only one book. You have to get to the intent and get out of the lack of wording.

And we cannot dictate ownership based on the building code in any scenario. Doesn't apply.

 

[texasbo]

This is a good thread.

 

[brudgers]

At a property line?

Yes.

Each condominium unit has property lines in all three dimensions.

 

[brudgers]

The reason it is a two family dwelling (sorry for the "duplex" designation) instead of two connected single family dwellings (like suggested) is because the rating between "single family dwellings" (such as TOWNHOMES) is more restrictive than that between the two dwelling units of a two family dwelling.I agree with brudgers that door opening directly onto or over a property line happens all the time with condos. Walk out the condo door, and you are on another parcel.

Two family dwellings often both have doors that open into a common foyer and then to the exterior door.

I think in the big picture this is approvable. There are a kajillion different scenarios and only one book. You have to get to the intent and get out of the lack of wording.

And we cannot dictate ownership based on the building code in any scenario. Doesn't apply.

Yep.

Imagine a two family dwelling with a single covered front entry from which each unit can be accessed via its own door.