Crawlspace installations - new code

[fatboy]

Thanks for the update!

 

[ICE]

I knew I was going to get all kinds of responses on how crazy this code may sound. So I got some clarification from a fellow contractor who went to the building department last week. I was wrong on my original post and the actual code states that if the floor joist are less then a "true 2x8" then that is when this sheetrocking is to be enforced. So a 2x8 this is actually 1.5 x 7.5 would be required to sheetrock the crawlspace. An inspector told me what some contractors are doing is building an encloser around the furnace that is sheetrocked, so that seems to satisfy the code.

As ridiculous as this sounds, I will find out soon because today I just finished installing a furnace and ductwork in a crawlspace that has floor joist that are 7.5". But on my proposal, I stated I was not responsible if sheetrocking was required on this job, that the general contractor would have to do it. Will find out soon when I schedule my inspection.'

Thanks for reading

Back up to rogerpa's post and you will see that it is 2"x10" and dimensions in the code are nominal unless noted otherwise.

Some inspector is pulling your leg with this one: "An inspector told me what some contractors are doing is building an encloser around the furnace that is sheetrocked, so that seems to satisfy the code."

It sounds like a common way to ruin a furnace in your area. I have seen maybe two in my career and one was a floor furnace being replaced with another floor furnace. Are floor furnaces still being produced?

R501.3 Fire protection of floors. Floor assemblies, not required elsewhere in this code to be fire-resistance rated, shall be provided with a 1/2-inch (12.7 mm) gypsum wallboard membrane, 5/8-inch (16 mm) wood structural panel membrane, or equivalent on the underside of the floor framing member.
Exceptions:
1. Floor assemblies located directly over a space protected by an automatic sprinkler system in accordance with Section R313, NFPA13D, or other approved equivalent sprinkler system.
2. Floor assemblies located directly over a crawl space not intended for storage or fuel-fired appliances.
3. Portions of floor assemblies can be unprotected when complying with the following:
3.1. The aggregate area of the unprotected portionsshall not exceed 80 square feet per story
3.2. Fire blocking in accordance with Section R302.11.1 shall be installed along the perimeter of the unprotected portion to separate the unprotected portion from the remainder of the floor assembly.
4. Wood floor assemblies using dimension lumber or structural composite lumber equal to or greater than 2-inch by 10-inch (50.8 mm by 254 mm) nominal dimension, or other approved floor assemblies demonstrating equivalent fire performance.

And because R302.11.1 is mentioned above, here it is below:

R302.11.1 Fireblocking materials. Except as provided in Section R302.11, Item 4, fireblocking shall consist of the following materials.
1. Two-inch (51 mm) nominal lumber.
2. Two thicknesses of 1-inch (25.4 mm) nominal lumber with broken lap joints.
3. One thickness of 23/32-inch (18.3 mm) wood structural panels with joints backed by 23/32-inch (18.3
mm) wood structural panels.
4. One thickness of 3/4-inch (19.1 mm) particleboard with joints backed by 3/4-inch (19.1 mm) particleboard.
5. One-half-inch (12.7 mm) gypsum board.
6. One-quarter-inch (6.4 mm) cement-based millboard.
7. Batts or blankets of mineral wool or glass fiber or other approved materials installed in such a manner as to be securely retained in place.
8. Cellulose insulation installed as tested for the specific application.
R302.11.1.1 Batts or blankets of mineral or glass fiber. Batts or blankets of mineral or glass fiber or
other approved nonrigid materials shall be permitted for compliance with the 10-foot (3048 mm) horizontal fireblocking in walls constructed using parallel rows ofstuds or staggered studs.
R302.11.1.2 Unfaced fiberglass. Unfaced fiberglass batt insulation used as fireblocking shall fill the entire cross section of the wall cavity to a minimum height of 16 inches (406 mm) measured vertically. When piping, conduit or similar obstructions are encountered, the insulation shall be packed tightly around the obstruction.
R302.11.1.3 Loose-fill insulation material. Loose-fill insulation material shall not be used as a fireblock
unless specifically tested in the form and manner intended for use to demonstrate its ability to remain in
place and to retard the spread of fire and hot gases.

 

[ICE]

The scope of work matters to the application of the CRC. Are you replacing a floor furnace with a forced air unit? Are you replacing a FAU with another FAU? Are you installing a FAU where there was no furnace previously? Are you replacing a floor furnace with a floor furnace?

 

[linnrg]

for discussion: if a person created a small crawl space Mechanical room with studs and gypsum around the equipment (w/ proper service/clearance space) would it then meet the fire blocking exception? And then possible having the rest of the i joist or less than 2x10 floor systems area over the crawl space be unprotected.

The original post did sound like a new install so would have been the type that would have triggered the requirement.

 

[mtlogcabin]

I believe It is an acceptable alternative that meets the intent of the code.

We have allowed this where mechanical systems are installed in ICF foundation crawlspaces and in R-2 where the mechanical is installed in the crawlspace to avoid sprinklering the entire crawlspace

 

[my250r11]

2. Floor assemblies located directly over a crawl space not intended for storage or fuel-fired appliances.
3. Portions of floor assemblies can be unprotected when complying with the following:
3.1. The aggregate area of the unprotected portionsshall not exceed 80 square feet per story
3.2. Fire blocking in accordance with Section R302.11.1 shall be installed along the perimeter of the unprotected portion to separate the unprotected portion from the remainder of the floor assembly.

IMO yes if it meets the exceptions

 

[ICE]

for discussion: if a person created a small crawl space Mechanical room with studs and gypsum around the equipment (w/ proper service/clearance space) would it then meet the fire blocking exception? And then possible having the rest of the i joist or less than 2x10 floor systems area over the crawl space be unprotected.

Only if the aggregate area of unprotected area is less than 80 sqft.

 

[linnrg]

ICE where are you getting the 80 sf from? sorry I found it but not so sure that is applies. The 80 sf is under the exception of the fire protection not the fireblocking