Exposed wood roof joists on a single story masonry building

[Yayi Colombo]

Hi everyone,
Im new to the forum and this is my first tread

For 2020 NYS Code, I have a single story commercial building, it has a CMU exterior walls and wood ceiling joists – the client is asking me if he can have a dropped ceiling and not have to have to sheetrock the underside of the wood beams. Im looking in the code because I have read on that there are certain exception on buildings of a certain height and # of stories but I cant seem to find it. Is anyone familiar with this?

 

[cda]

Welcome

Does the building have a fire sprinkler system?

 

[Yayi Colombo]

Hi!! Thank you!!
There is no sprinkler system in the building.

 

[Mark K]

There is no structural reason why you have to have sheetrock under the roof joists and beams. Depending on your building and the occupancy there may be fire rating requirements or energy provisions that may dictate the need for sheetrock.

 

[cda]

Hi!! Thank you!!
There is no sprinkler system in the building.

Would you label it Heavy Timber????

 

[Yayi Colombo]

There is no structural reason why you have to have sheetrock under the roof joists and beams. Depending on your building and the occupancy there may be fire rating requirements or energy provisions that may dictate the need for sheetrock.

Fire requirement is what im trying to figure out. Contractor will be installing closed cell foam between joists to take care of ECC requirements.
Building will be used as occupancy B and as per table 601, if constructiion is type IIIB you do not require a fire rating on the roof. Im not sure where is the differernce in requiring type A or B for the buidling.

 

[Yayi Colombo]

Would you label it Heavy Timber????

i dont think so, its standard 3x9 joists.

 

[cda]

Fire requirement is what im trying to figure out. Contractor will be installing closed cell foam between joists to take care of ECC requirements.
Building will be used as occupancy B and as per table 601, if constructiion is type IIIB you do not require a fire rating on the roof. Im not sure where is the differernce in requiring type A or B for the buidling.

A = Protected - Protected means that all structural members of a building or structure has an additional fire rated coating or cover by means of sheetrock, spray on, or other approved method. This additional fire rated coating or cover extends the fire resistance rating of structural members at least 1 hour.



B = Unprotected – Unprotected means that all structural members of a building or structure has no additional fire rated coating or cover. Exposed members are only fire resistant according to their natural ability and characteristics.

 

[steveray]

The foam would be the only reason I could think of....The wood itself should not require drywall...

 

[Paul Sweet]

IBC 2603.4 requires a 1/2" gypsum board or other thermal barrier to separate the foam plastic from the interior of the building.

​

 

[fatboy]

Agree, the foam is an issue regardless, must have a thermal barrier.

 

[mtlogcabin]

2603.4 Thermal barrier.
Except as provided for in Sections 2603.4.1 and 2603.9, foam plastic shall be separated from the interior of a building by an approved thermal barrier of 1/2-inch (12.7 mm) gypsum wallboard, heavy timber in accordance with Section 602.4 or a material that is tested in accordance with and meets the acceptance criteria of both the Temperature Transmission Fire Test and the Integrity Fire Test of NFPA 275. Combustible concealed spaces shall comply with Section 718.

 

[JPohling]

Use a different method for insulation if you do not want to install gyp.

 

[mtlogcabin]

Or but the foam on the roof deck

 

[Yayi Colombo]

Thank you very much for all the useful information and recommendation guys.

 

[patrickjames]

DC315 is a single component, water based intumescent coating tested to meet Building Code requirements for the fire protection of for Spray Polyurethane Foam (SPF).

ESR-3702 - ICC-ES​

This could be an option to submit to the inspector for approval.

 

[Yayi Colombo]

DC315 is a single component, water based intumescent coating tested to meet Building Code requirements for the fire protection of for Spray Polyurethane Foam (SPF).

ESR-3702 - ICC-ES​

This could be an option to submit to the inspector for approval.

will have owner inquire about which of the 2 options may be less expensive as the intumescent may require spsecial inspection.

 

[cda]

will have owner inquire about which of the 2 options may be less expensive as the intumescent may require spsecial inspection.

You might talk to the building official first

Bring them some pictures of the condition and simple proposal of what you want to do,,,,
They may let you go as is and as you propose