Client Question: When you inspected our home, we told you about our plan to make a door through the garage into the crawl space under our stairs. We’re at the point where we’ve cut the hole, and we’re contemplating our choices for finishing it with a door.
Can you tell us more about the code related to this project? We’re trying to consider cost both now and in the future, if we sell our home and have to pay to bring it up to code.
Answer: To clear things up a bit (I had to go back and read your report after we emailed), your home doesn’t have a crawlspace in the technical sense. A crawlspace is an area below a house that has a raised or pier and beam type foundation. You’ve essentially added an opening in the garage wall to gain access to the dead space below your stairs.
I can’t tell from the image that you sent, but I’m guessing that you can now see the wall studs and the wood that forms the stair treads and risers? In this instance, you’ve basically extended your garage. You could add a door, but due to the location of the opening, you’ll still need to protect the now exposed walls.
You’d also need to protect the now exposed stairs; therefore, any type or style of door would be acceptable, provided you followed through with protecting this newly exposed area in your extended garage. To be clear, adding a door won’t change the requirement that the now exposed garage walls and exposed stairs be appropriately covered.
Why Do We Use Fireblocking Below Stairs & in a Garage?
To restore the fire barrier on both the walls and the underside of the stairs, you’d need to add a minimum 1/2 inch thick drywall/sheetrock/gypsum board to cover this new storage area completely. The reason that we need to cover this area in 1/2 inch drywall is for fire safety.
All of the other walls in your garage have 1/2 drywall to help slow the spread of fire from the garage to the living space. By opening the wall up, you’ve exposed the wood studs to fire damage, which hastens the spread of a garage fire. As for the stairs, they’ve been exposed as well, and are now subject to fire damage, which could cause them to collapse before the 2nd-floor occupants escape.
Typically Used Code Standards for the City of Houston and Surrounding Areas
2012 International Residential Code R302.6 Dwelling/garage fire separation
“The garage shall be separated as required by table R302.6. Openings in garage walls shall comply with Section R302.5. This provision does not apply to garage walls that are perpendicular to the adjacent dwelling unit wall.”
2012 International Residential Code R302.7 Under-stair protection
“Enclosed accessible space under stairs shall have walls, under-stair surface and any soffits protected on the enclosed side with ½ inch (12 .7 mm) gypsum board.”
2012 International Residential Code R302.11 Fireblocking“
In combustible construction, fireblocking shall be provided to cut off all concealed draft openings (both vertical and horizontal) and to form an effective fire barrier between stories, and between a top story and the roof space. Fireblocking shall be provided in wood-frame construction in the following locations: In concealed spaces between stair stringers at the top and bottom of the run.”
2012 IRC Section R302.5.1 Opening Protection
Openings from a private garage directly into a room used for sleeping purposes shall not be permitted. Other openings between the garage and residence shall be equipped with solid wood doors not less than 1 3/8 inches in thickness, solid or honeycomb-core steel doors not less than 1 3/8 inches thick, or 20-minute fire-rated doors, equipped with a self-closing device.