Two-family projections

[Sifu]

I don't do a lot of two-family projects so maybe I am missing something. IRC 302.1 prohibits projections of any type within 2' of a property line. Further refinement of the code occurs for townhomes and two-family dwelling units. The code section for two family units contains no refinement or exceptions for projections so my assumption is not allowed. So a building with a wall up to the property line, with a projection that actually extends across the property line.. How does this work?

 

[steveray]

If there is a property line between the units, it is not a 2 family dwelling....

 

[mtlogcabin]

The IRC does not require a property line between townhomes like some of the legacy codes did. Our zoning does require a property line between townhomes. It is a problem that we currently ignore since fires do not care about property lines we just require the projection to be rated

 

[cda]

Looks like the neighbor could legally take a sawsall to it?!!!

 

[Sifu]

If there is a property line between the units, it is not a 2 family dwelling....

Yes there is a lot line, but I haven't considered that it wouldn't be a two-family building. I don't see a definition for two-family dwelling that specifies this. I see what you are saying, just not a definition, such as the one for town-homes. If they are just single family homes the projection question is still relevant though.

BTW, I have been confused by their fire separation design uses 2-hr shaft wall where they abut, and a 1-hr wall where they do not. Maybe the idea that they are two single family units tight to each other helps clarify that. But then the projections would definitely be enforced from the single family perspective.

IF I get what you saying, we have two single family homes side by side, each with it's own 1-hr wall because there is a lot line between them. But, if no lot line, the same two families could live there but only have a common 1-hr wall separation. Does the property line offer a greater risk?

So now I have two questions: Is it a two-family dwelling? Are the projections allowed? (pretty sure that is put to bed either way)

 

[cda]

There is horizontal separation, of the projection?

 

[tmurray]

We reached out to our code authority (authors of the code) on something like this and they indicated that a fire separation would be required to separate the two attic spaces. Luckily, officials can use their discretion. Just make sure everything is documented.

 

[Joe.B]

Would the lot line problem come down to the issue of a potential sale of one lot? Theoretically the new owner could do anything (within law/code) they want to their building, including knocking it down, yeah? The other building would need to be constructed in such a way that it would still be standing and fire safe right? As for projections over a property line I'd have to agree that the neighbor could legally cut anything that projects over unless there was some kind of easement, at least here in CA. We get calls all the time about how to handle a neighbors tree. We have to disappoint them by saying "no, you can't force your neighbor to do anything to his tree." But the consolation prize is "yes, you can cut anything that projects over the property line."

 

[steveray]

If you are on the "same lot" you are under the theoretical "same control or access" and safer....

 

[Sifu]

Looks like the neighbor could legally take a sawsall to it?!!!

This is a major national builder, they are doing this everywhere and have been for years. For some reason it caught my eye and I can't figure out how they are permitted to have these projections across the property line. I have a call in to try to talk with the designer about the strategy but confidence isn't high that they will respond. It looks like they are constructing these as two separate single family dwellings against each other, but either way, I don't see the projections being allowed. As far as who owns the projections.........someone else can fight that battle.

 

[cda]

This is a major national builder, they are doing this everywhere and have been for years. For some reason it caught my eye and I can't figure out how they are permitted to have these projections across the property line. I have a call in to try to talk with the designer about the strategy but confidence isn't high that they will respond. It looks like they are constructing these as two separate single family dwellings against each other, but either way, I don't see the projections being allowed. As far as who owns the projections.........someone else can fight that battle.

Do they have a common attic,,
Like a duplex?? But divided?

And also back to the projection is horizontally separated

 

[TheCommish]

just because it has been done that way does not make it correct, or because I have approved it in the past requires me to have to repeat the same mistake again.

It is up to the applicant to show how the proposed project meets the code and answer your questions. I would like to issue the permit to Mr. designer, help me understand the design, and answer these questions. No answer to satisfy the inspector, no permit issued. Take you time and think about the issue from all the angles, building and zoning if applicable

 

[Sifu]

From a zoning perspective in my AHJ it is possible to either have a property line or not so zoning isn't the driver here, but maybe they do it this way as a matter of consistency since they work everywhere. I'll wait a few days to see if I hear back from the design team.. My original question was if there was something special about an IRC two-family dwelling provision that would clarify why they have these projections...but now I realize they are not using the two-family provisions anyway so I think the question is no longer relevant.

What I think is happening here is they desperately want the overhangs for aesthetic purposes, so they have included them with several elements to mitigate the risk, such as as rated from the underside, with 4' FRT plywood and solid blocking at the plate in the rafter cavity. If that is actually the situation this should have been identified and proposed as an alternate long ago (the CBO has already indicated he would consider it as an alternate request). We'll see what happens.

 

[ADAguy]

Yes there is a lot line, but I haven't considered that it wouldn't be a two-family building. I don't see a definition for two-family dwelling that specifies this. I see what you are saying, just not a definition, such as the one for town-homes. If they are just single family homes the projection question is still relevant though.

BTW, I have been confused by their fire separation design uses 2-hr shaft wall where they abut, and a 1-hr wall where they do not. Maybe the idea that they are two single family units tight to each other helps clarify that. But then the projections would definitely be enforced from the single family perspective.

IF I get what you saying, we have two single family homes side by side, each with it's own 1-hr wall because there is a lot line between them. But, if no lot line, the same two families could live there but only have a common 1-hr wall separation. Does the property line offer a greater risk?

So now I have two questions: Is it a two-family dwelling? Are the projections allowed? (pretty sure that is put to bed either way)

We use to call them Duplexes back in the day and triplexes too.

 

[Sifu]

Ooooh, we aren't "allowed" to call them that now!

 

[steveray]

I guess you could use this from the 2018 IBC and have no rating between them.....

706.1.1 Party walls. Any wall located on a lot line
between adjacent buildings, which is used or adapted for
joint service between the two buildings, shall be constructed
as a fire wall in accordance with Section 706.
Party walls shall be constructed without openings and
shall create separate buildings.
Exceptions:
1. Openings in a party wall separating an anchor
building and a mall shall be in accordance with
Section 402.4.2.2.1.
2. Fire walls are not required on lot lines dividing a
building for ownership purposes where the aggregate
height and area of the portions of the building
located on both sides of the lot line do not
exceed the maximum height and area requirements
of this code. For the code official’s review
and approval, he or she shall be provided with
copies of dedicated access easements and contractual
agreements that permit the owners of
portions of the building located on either side of
the lot line access to the other side for purposes of
maintaining fire and life safety systems necessary
for the operation of the building.

 

[Paul Sweet]

If there is a property line there should be deed restrictions to allow the overhangs, allow owners to go over the property lines to maintain them, and prevent the owner of the property they project over from cutting them off. The builder should request a code modification and demonstrate how he is providing fire safety for the overhangs.

 

[Mr. Inspector]

This could be a problem if there is a property line for this twin house

 

[Sifu]

Just had a conversation with the designer of these projects. They are using a method of fire protection that does not meet the restriction of projections. He explained what I thought, that they are using a protected eave and solid wood blocking at the wall line inside the eave, as well as 4' FRT. They are basically using the townhome provisions, with the modification of a rated eave and blocking instead of running the rated wall to the bottom of the sheathing. I think it is probably a fair equivalent, but probably should have been addressed a little differently long ago. I will put it to the CBO for his blessing. BTW, He said this question was asked by another AHJ about three years ago, and this was the way they answered. I guess it just became a part of their standard design because of that. As far as the neighbor owning a little piece of the house next door....not my problem. I asked our planning and zoning if/how/why. Typical "it depends" and "maybe" were all I got.