Egress from sleeping rooms on 3rd floor in R-3 existing structure

[dillehayarch]

I have an existing 2 story w/ attic wood framed house that currently has 6 sleeping rooms. The owner wants to convert the building into 2 dwelling units with 3 sleeping rooms each. Dwelling unit 1 is on the first floor. Dwelling unit 2 would take up the 2nd floor and attic, with the sleeping rooms in the attic.

There is one stair for the upstairs dwelling unit.

My question:
Are Egress compliant windows sufficient for the sleeping rooms on the third floor, or will I require an additional means of egress for the rooms (i.e. exterior stair)

The building is not sprinklered.

Thank you for your assistance in reviewing this.

Respectfully,
Sam

 

[mtlogcabin]

Are Egress compliant windows sufficient for the sleeping rooms on the third floor,

Yes. The attic space is not a "story" If you meet R325.6. # 1 thru 4.
Will the existing ceiling joist support the 30 PSF required for a sleeping area?

R304 and R305

R325.6 Habitable attic.
A habitable attic shall not be considered a story where complying with all of the following requirements:

1. The occupiable floor area is not less than 70 square feet (17 m2), in accordance with Section R304.

2. The occupiable floor area has a ceiling height in accordance with Section R305.

3. The occupiable space is enclosed by the roof assembly above, knee walls (if applicable) on the sides and the floor-ceiling assembly below.

4. The floor of the occupiable space shall not extend beyond the exterior walls of the floor below.

Table 602.3(5)
c. A habitable attic assembly supported by 2 × 4 studs is limited to a roof span of 32 feet. Where the roof span exceeds 32 feet, the wall studs shall be increased to 2 × 6 or the studs shall be designed in accordance with accepted engineering practice.