Altering existing type V-B house to V-A Health Facility

[Yikes]

I've just taken on a Southern California client who built a large single family (R-3) home several years ago with the intent to converting it into a Congregate Living Heath Facility (R-2.1) once the years-long planning approval was complete.
They have planning approval, but an inspector has reminded them that the California Building Code does not allow R-2.1 occupancies in nonrated (type B) construction.

Unfortunately, their original stamped plans for the (wood frame + stucco) house call it out as type V-B construction, so they have a fundamental problem of the old plans only requiring nonrated gyp board. One option is to either replace the existing gyp board, or simply add another layer of fire rated gyp board.

Question: would another option for achieving 1-hour walls be to apply intumescent paint to the face of the gyp board?

 

[RLGA]

Intumescent "paint" is intended to improve the flame spread characteristics of the substrate--it is not intended to be a fireproof material.

There are intumescent fire protection coatings, but I do not believe there are any tested assemblies where it is used on a gypsum board wall assembly.

With Type VA construction, only load-bearing walls are required to be 1-hour rated. For ranch-style residential construction, this is usually the exterior walls and a select few interior walls.

For the exterior walls, they probably only need to be rated for interior exposure if the fire separation distance is more than 10 feet. Assuming 2x6 construction, 16" o.c. with fiberglass blanket insulation and 1/2" gypsum board on the interior, this would give you 50 minutes using the calculated method in Chapter 7:

• Framing - 20 minutes; Table 722.6.2(2)
• Insulation - 15 minutes; Table 722.6.2(5)
• 1/2" Gypsum Bd. - 15 minutes; Table 722.6.2(1)
• Total = 50 minutes.

If you add a 3/8" layer of gypsum board, that will give you the additional 10 minutes you need for a 1-hour wall per Table 722.6.2(1).

If the exterior wall is less than 10 feet from the lot line, then you will have to worry about exterior fire exposure. Since I do not know what the construction of the exterior wall cladding is, I cannot advise you on that.

For interior load-bearing walls, you can do the same thing; however, you have to figure out how to get insulation into the wall to get that additional 15 minutes. This may be done by pumping in cellulose insulation. The 3/8" gypsum board will need to be applied to both sides of the wall.

Ceilings may require an additional full layer of 5/8" Type X gypsum board to create a 1-hour horizontal membrane:

• Framing (must be 16" o.c.) - 10 minutes; Table 722.6.2(2)
• 1/2" Gypsum Bd. - 15 minutes; Table 722.6.2(1)
• Insulation (cannot use for horizontal assemblies if it exists)
• New 5/8" Type X Gypsum Bd. - 40 minutes; Table 722.6.2(1)
• Total = 65 minutes

 

[Yikes]

The exterior is 7/8" stucco.

 

[RLGA]

The exterior is 7/8" stucco.

What is the sheathing, if any?

 

[Yikes]

According to the city's record drawings, on 2 sides of the house, it's 15/32" plywood. On the other 2 sides, it's 3/8" plywood. So it sounds like this will work. Thank you so much for your response!

On a related note, for my own education:
All walls are 11'+ from any adjacent property lines. However, I don't see in Table 601 or 704.10.2 where this distance from property line allows me to only protect the exterior side and not the interior side.
- Are the load bearing studs in structural walls considered to be "structural members" for purposes of apply 704.10.2?

Regarding the interior walls: the house was originally built under the locally adopted version of the 2012 IBC. During that era, a full NFPA 13 sprinkler system could substitute for all 1-hour construction except exterior walls per Table 601 footnote (d).
Since an R-2.1 requires sprinklers anyway, I may ask the city for a modification request to allow the interior+ ceiling 1-hour substitution. The owner is quite keen on not disturbing the interior walls if it can be avoided.

The house is one-story, slab-on-grade, so one-hour floor construction is not an issue.

 

[RLGA]

All walls are 11'+ from any adjacent property lines. However, I don't see in Table 601 or 704.10.2 where this distance from property line allows me to only protect the exterior side and not the interior side.
- Are the load bearing studs in structural walls considered to be "structural members" for purposes of apply 704.10.2?

Refer to Section 705.5. If the lot line is more than 10 feet from the exterior wall, only the interior face needs to provide the one-hour rating. Where the exterior wall is 10 feet or less from the lot line, both the interior and exterior sides need to provide one-hour protection.

Studs would be considered structural members (not the structural frame, however) and would be part of the exterior wall per Sections 704.10.2 and 704.10.3, whichever requires the highest rating.