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Unit separation 1979 UBC

New postPosted: Mon Oct 25, 2021 6:30 pm
by mtCDCcb
We have a 4-unit townhome complex that was built under the 1979 UBC. An owner of two adjoining units has combined portions of his 2 units. He has essentially taken the upstairs of one unit, removed the stairs, and made it part of the adjacent unit. To do this he had to compromise and put an opening in the units' demising wall. Was this demising wall required to be fire rated under the 1979 UBC. I can't find it under the table for chapter 5 or Chapter 12. Any assistance would be appreciated. Thanks in advance.

Re: Unit separation 1979 UBC

New postPosted: Mon Oct 25, 2021 10:03 pm
by Jerry Peck - Codeman

I didn't see a reference to, or definition of, "townhouse" in the 1979 UBC.

- Part II
- - Definitions and Abbreviations
- - - Chapter 4
- - - - Definitions and Abbreviations
- - - - - A
- - - - - - Apartment House is any building, or portion thereof, which is designed, built, rented, leased, let, or hired out to be occupied, or which is occupied as the home or residence of three or more families living independently of each other and doing their own cooking in the said building, and shall include flats and apartments.
- - - - - D
- - - - - - Dwelling is any building or any portion thereof which is not an "Apartment House," "Lodging House" or a "Hotel" as defined in this code, which contains one or two "Dwelling Units" or Guest Rooms," used, intended or designed to be built, used, rented, leased, let or hired out to be occupied, or which are occupied for living purposes.
- - - - - - Dwelling Unit is a single unit providing complete, independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking and sanitation.

If the building is a one or two-family building, then the One- and Two-Family Dwelling Code would be applicable.

If there are three or more "dwelling units" in the building, it is an Apartment House

Are you referring to a building which has more than two dwelling units (your description indicates that there are at least two dwelling units side-by-side, however, your description does not indicate whether or not there is a third dwelling in that building - that would the the initial starting point on which code to apply.

Presuming ... that there are more than two dwelling units ...

Chapter 12
- Requirements For Group R Occupancies
- - Group R Defined
- - - Sec. 1201. Group R Occupancies shall be:
- - - - Division 1. Hotels and apartment houses.
- - - - - Covenants and monasteries (each accommodating more than 10 persons)
- - - - Division 2. Not used.
- - - - Division 3. Dwellings and lodging houses.
- - - - - For occupancy separations, see Table No. 5-B.
- - - - - For occupant load, see Section 3301.

Sec. 1201, Division 1. Hotels and apartment houses, would apply. Your description indicates the building is two-stories ... is that correct?

(bold and underlining are mine)
- 1202.(b) Special Provisions. has an Exception
- - Exception: Dwelling units within an apartment house not over two stories in height may have nonbearing walls of unprotected construction, provided the units are separated from each other and from corridors by construction having a fire-resistance rating of not less than one hour. Opening to such corridors shall be equipped with doors conforming to Section 3304(h) regardless of the occupant load served.

The Exception above indicates that if the apartment house is greater that two stories in height ... load bearing and nonloadbearing walls all require construction having a fire-resistance rating of not less than one hour. It also indicates that load bearing walls (walls other-than-nonloadbearing walls) require construction having a fire-resistance rating of not less than one house as the only walls being excepted out are nonloadbearing walls in apartment houses not more than two stories in height. This is actually more than "indicated", it is actually stated in (b) Special Provisions. Group R blah, blah, blah ... shall be not less than one-hour fire-resistive construction throughout.

They key will be two dwelling units or less, and, more than two dwelling units: you stated "We have a 4-unit townhome complex" - does that mean a 4-unit building, or a complex of 4 buildings? I think you are saying it is a 4 dwelling unit building, which would be an apartment house.

The One and Two Family Dwelling Code is referenced at the top of page 6, the last item in the list of Related Publications, which starts on page 4.

One and Two Family Dwelling Code. This code is jointly sponsored by the Internation Conference of Building Officials, Building Officials and Code Administrators International, Inc., and Southern Building Code Congress International, Inc. It eliminates conflicts and duplication among the model codes to achieve national uniformity. Covers mechanical and plumbing requirements as well as construction and occupancy.

Re: Unit separation 1979 UBC

New postPosted: Tue Oct 26, 2021 8:37 am
by Jerry Peck - Codeman
A follow-up question:

When he combined the upper level of two units together into one, did he also combine the lower level of the two units into one, making two "flats".

If so, the roof-ceiling assemblies and floor-ceiling assemblies would also need to be at least 1 hour rated assemblies.

If you have a 4-unit building, either a quad or 4 units in a line, the simplest solution may be to combine 1/2 the quad (two adjacent units), or two adjacent units in a line together as a single unit.

That would reduce the areas of concern to the walls which connect that one unit to the adjacent units ... presuming, of course, that the demising walls would need to extend from foundation to roof (i.e., no unit is over or under another unit as that would complicate the issue).