Fireblocking

hello and welcome to building codes for basement finish this session is on fire blocking with fire blocking we're going to talk about its purpose the approved materials and the locations that fire blocking is required if we look at an example of a home and unfortunately a fire breaks out in the basement fire blocking is meant to keep that fire from spreading up through the concealed open cavities within the home and turning the home into a chimney that quickly is in flames specifically the IRC states in combustible construction fire blocking shall be provided to cut off both vertical and horizontal concealed draft openings and to form an effective barrier between stories and between a top storey and the roof space so the first thing to take note is that this is for combustible construction only concrete or steel framed structures would not be required to follow the fire blocking requirements there are certain materials that are specifically approved for fire blocking first you can use two-inch nominal lumber or you can use two layers of 1-inch nominal lumber except you've got to make sure that it has broken lap joints between each ply you can also use 20 to 30 seconds Wood structural panel like this OSB or plywood you can also use 3/4 inch particle board using these board products you've got to have backed joints so if the seams between two pieces don't fall over a framing member they'll need to be backed or doubled up somehow half inch gypsum board is an approved fire block as well as quarter inch cement based mill board typically used behind showers bats or blankets of mineral wool or glass fiber insulation is also allowed but there was rather specific requirements when using insulation that we'll discuss in this video the IRC States batts or blankets of mineral wool or glass fiber or other materials shall be installed in such a manner as to be securely retained in place retaining in place is important if it falls out of the cavity like this it won't be a very effective fire block Louisville insulation has also got some specific words from the IRC Louisville insulation material shall not be used as a fire block unless specifically tested in the form and manner intended for use to demonstrate its ability to remain in place and to the spread of hot gases that's a mouthful from the IRC that's basically requiring some specific data from a manufacturer if you're to use loose fill insulation on the other hand dense filled insulation like this is not specifically discussed in the IRC but could be approved as an other approved material like it is here where it's installed very packed into the cavity and will be retained in place by the drywall however a bird's nest is not typically going to be an other approved material cellulose insulation can be used as a fire block but is also got to be tested very specifically by the manufacturer cellulose insulation installed as tested in accordance with ASTM e 119 or UL 236 for the specific application now there are certain locations where fire blocking is going to be required specifically in the basement finish but first of all it's always going to be a concealed location in a wall like this that is not drywalled on the other side the cavities are not concealed and fire blocking is not required the first location we'll look at is in stud walls at 10-foot horizontal intervals if we were to cover drywall on this side of the wall then we would have a concealed space and we would not be able to have a horizontal space more than ten feet in length in this case each 2x4 stud 16 inches on center would break it down to conceal displaces less than 10 feet however in this wall where the cotta found the wood-framed wall is held off the crooked foundation there is a cavity behind that's longer than 10 feet and it would need to be fire blocked again here's a photo of another concealed area between a walkout basement wall and a newly framed wall also to be fire blocked at at least 10 foot intervals staggered walls like this that are usually larger for sound or insulation reasons also create a cavity behind that must be fire blocked in this example we see a piece of OSB installed down the length of the stud and tight to the other studs behind and this blocks off that 10 foot horizontal distance here's another example where OS B is used between the two walls however here it's not 20 to 30 seconds as is required this is only 7/16 OS B and would not be compliant sometimes insulation is used for as a fire block for the 10-foot horizontal rule as we see here however in most interpretations of the IRC provisions it refers to a bat or blanket and generally would want to see a bat installed down that cavity for this full depth and full thickness now in this case we see a foam used behind a stud as an attempt to as a fire block this foam is not tested or intended for fire blocking as you see here but some are and they could be approved as other approved material here's an example of a product called great stuff by dow intended for fire blocking but there are limitations if we look at the specifications it's only allowed for gaps up to a half inch something to be careful of when using these types of products another location for fire blocking is at the tops and bottoms of walls at floor levels this is basically at the plates of the walls where electrical wires are plumbing pipes are passing through and the space around them would allow the hot gases to pass fire blocking foam like this is commonly used as it's also a good air sealant for insulation values however tightly-packed mineral wool or fiberglass insulation can always also be used around these gaps around these pipes and wires the final location is at interconnections between vertical and horizontal spaces in this example you see a vertical cavity of the wall and a horizontal cavity of the floor had this dropped soffit not been built the top plates would have been the fire block but with the soffit airflow can now pass from the wall to the floor cavity one way to fire block this would be to cover this region here you can see this being done in this photo and in this photo where the fire blocking is incorporated into the construction of the Sophos another way to block off this connection would be to put blocks in the walls at this location this you can see done here on the right side of the photo however there is a breach in that fire blocking in this region or the curved concrete wall is behind the framed wall insulation was used as an attempt for fire blocking for that problem but would not be approved by under the IRC provisions here's another example where insulation is improperly used to fill a large gap between two walls and similarly here at a soffit level some insulation is folded up to use insulation in these applications as a fire block it would need to be at least 16 inches of vertical height and to fill the cavity completely you see that done correctly in this photo where fiberglass is used for a 16 inch depth to completely fill the cavity back to the other wall behind sometimes basements get done and fire blocking wasn't done correctly or perhaps it was completed without permit in this exploratory photo it was discovered that fire blocking had not been installed with this basement one way to solve these problems after the fact is with dense field insulation in like in the entire cavity will also bring the basement up to compliance with energy codes here's an example of OSB used at the top plates as a fire block put on after the wall was installed and notched around the studs except unfortunately it's not 20 to 30 seconds OSB it's 7/16 and would not be compliant a better way to do this is in this photo where the OSB is installed before the wall is put in place and thus the notching is not required the OSB is extended all the way back to the sill plate and the fire blocking seals off the entire top of the wall however again this is 7/16 and not 20 to 30 seconds this is a common mistake that's made in the field fire blocking can be tricky to notice sometimes and it takes a little time to look around a project and make sure that all breaches have been covered in this soffit built a bit above a small and innocent art niche in the corner of a hallway the curved radius was built with this plywood and it allows for this OSB and it allows an air passage from the cavities adjacent through the soffit and up to that top piece this top piece was used to create the arch form however it's also functioning as a fire block and again it's not 20 to 30 seconds the final spot for fire blocking requirements are at stairs stairs allow passage for people from one floor to the next and if their construction allows airflow within the concealed cavities of the stairs it may require fire blocking my name is Glen Mathewson and I thank you for learning with me today

Channel: Glenn Mathewson

Views: 86,834

Rating: 4.9002771 out of 5

Keywords: basement finish, building codes, glenn mathewson, fireblocking, fire stopping, fire blocking, draft stopping, construction, wood framing, basement framing

Id: dSRpUvSD0l4

Length: 10min 49sec (649 seconds)

Published: Sun Mar 22 2015