[Mystriss]

I've been searching the interweb for the past two days trying to figure this out. Does UBC allow me to notch and fire resistant foam a draft stop [AKA fireblock between floor/ceiling joists to prevent/limit horizontal flow] for circular electrical boxes?

OR can I relocate the draft stop blocking a bit to the right or left in the 5 joist bays I need to put the light boxes in?


More info. This is what I've got in the floor/ceiling:

And, of course, those draft stops are EXACTLY where I need to center my pool table lights downstairs - because, why would they POSSIBLY be anywhere else, or offset by a couple inches?!?

Typical. :vs_laugh:

Anyway, as I understand it code requires draft stops to break things up into 1k sqft or less open areas. Since my upstairs is just over that in total, and there's at least one more* draft stop "row" up there, seen there:

[*] The blocking there is just about directly above the center of the upstairs joist spans/2nd floor platform so there may even be a third row of them on the other side of that. Which kinda makes me think that maybe they put these in as combo draft stops and "floor bounce" stabilizers.

 

[ront02769]

Having a hard time visualizing but if that is your ceiling Standing sideways the blocking there is not fire blocking. Just standard blocking to stabilize the floor. If that sideways picture was a WALL, then that might be sheer wall blocking or fire blocking if your ceilings are over 10’ or if yuo are balloon framed, neither likely. Ron

 

[Nealtw]

I don't think it is fire stopping in a floor, it is usually bridging and it should be with in 7 ft of bearing wall and or no more than 7 ft apart. So yes you can move them a few inches .

 

[Mystriss]

I figured as much but thought I would check before we get to removing them.

For clarity though in case anyone wants to change their mind Both pictures are the space between the first and second floors.

Game room downstairs and that sub-floor board (directly over top of the pool table) being removed [pool table lights need to go roughly where the blue tape is, which is exactly where the blocking/draft stop is heh]

The other row of blocking (pic two of my initial post) looks to be directly above the right wall of the game room. I was looking under the wall on the left above

The upstairs bedroom is about 12 foot wide so that blocking is at about 6 foot from the exterior wall as your stabilizer theory Nealtw

 

[Nealtw]

I have not changed my mind. I would not be concerned. The replacement blocks don't need to be full height but they should be close to the bottom of the joist. The subfloor holds the top in place.

 

[Mystriss]

Ah cool, we happen to have some 2x6's on hand so that'll save us a trip to find 2x10s

 

[ront02769]

No worries.

 

[Mystriss]

I have not changed my mind. I would not be concerned. The replacement blocks don't need to be full height but they should be close to the bottom of the joist. The subfloor holds the top in place.

I was meaning to ask elsewhere, but I guess here is as good a thread as any. Looking at the joist structure there, do you still think, or can you tell if I've got balloon framing? Like where would I look to figure that out?

I'm curious about that kinda stuff. Like, I've figured out that my structure wood is probs from Alberta, Canada "Weyerhaeusser 4 Square" - https://www.weyerhaeuser.com/woodproducts/lumber/western-lumber/weyerhaeuser-4-square-j-grade/

Then I read that j-grade is popular with modular homes and I got to wondering if she might be one of those DIY kit houses. I hunted around and I can't see any re-construction marks on any of the exposed lumbers. I'm not sure if they put those in back then though. Either way, its apparently good quality lumber so that's a bonus

 

[Nealtw]

I was meaning to ask elsewhere, but I guess here is as good a thread as any. Looking at the joist structure there, do you still think, or can you tell if I've got balloon framing? Like where would I look to figure that out?

I'm curious about that kinda stuff. Like, I've figured out that my structure wood is probs from Alberta, Canada "Weyerhaeusser 4 Square" - https://www.weyerhaeuser.com/woodproducts/lumber/western-lumber/weyerhaeuser-4-square-j-grade/

Then I read that j-grade is popular with modular homes and I got to wondering if she might be one of those DIY kit houses. I hunted around and I can't see any re-construction marks on any of the exposed lumbers. I'm not sure if they put those in back then though. Either way, its apparently good quality lumber so that's a bonus

Most if not all balloon framed house were built before the mills planed the lumber down to the sizes we see today, there are places in many new houses that use the method as it works best but for the most part all are platform based.
In a balloon the studs are full height often 16 to 20 ft and the floors are hung from them




platform framing, each floor is built most often with pre cut studs and each floor is built as a box on top of the bearing walls. They have rim joists.

 

[Mystriss]

@Nealtw

Ah I see, well then I'm just about positive I have platform construction then, the boards are clearly dimensional lumber, the exterior walls aren't continuous from first to second floor, and we do have insulated rim joists.

Upon a further investigation of the center support wall downstairs here (right game room wall) I am positive that the joists for the second floor are continuous from wall to wall vs being hung from a beam in the center of the house. I had thought that would change the location of my drill holes through the joists for cables, but through some magic we end up having to drill in the exact same location (RE no holes in the center third of joists) - happy little accidents



As a secondary question though; do ya think I should put in some fire blocking while I've got the floor open? I suspect we don't have any as the blocking between the kitchen and game room isn't at all air tight (in fact it's barely even secure in there lol)

 

[Nealtw]

@Nealtw

Ah I see, well then I'm just about positive I have platform construction then, the boards are clearly dimensional lumber, the exterior walls aren't continuous from first to second floor, and we do have insulated rim joists.

Upon a further investigation of the center support wall downstairs here (right game room wall) I am positive that the joists for the second floor are continuous from wall to wall vs being hung from a beam in the center of the house. I had thought that would change the location of my drill holes through the joists for cables, but through some magic we end up having to drill in the exact same location (RE no holes in the center third of joists) - happy little accidents

As a secondary question though; do ya think I should put in some fire blocking while I've got the floor open? I suspect we don't have any as the blocking between the kitchen and game room isn't at all air tight (in fact it's barely even secure in there lol)

Floors are not usually fire blocked that I know of. They are usually common thru out the house and are used for plumbing and Hvac and wires.

The firestopping is the top and bottom of the walls so a fire in a wall doesn't spread to the floor or from the floor to a wall. Mostly what you are after is no air feeding a fire. An open wall like you have in a balloon frame would draw air from the basement and feed and spreed a fire to all floors, all walls and the attic in minutes. :wink2:

 

[Nealtw]

@Nealtw

Ah I see, well then I'm just about positive I have platform construction then, the boards are clearly dimensional lumber, the exterior walls aren't continuous from first to second floor, and we do have insulated rim joists.

Upon a further investigation of the center support wall downstairs here (right game room wall) I am positive that the joists for the second floor are continuous from wall to wall vs being hung from a beam in the center of the house. I had thought that would change the location of my drill holes through the joists for cables, but through some magic we end up having to drill in the exact same location (RE no holes in the center third of joists) - happy little accidents


As a secondary question though; do ya think I should put in some fire blocking while I've got the floor open? I suspect we don't have any as the blocking between the kitchen and game room isn't at all air tight (in fact it's barely even secure in there lol)

When we build boxes like this, the box is common with the floor structure above, so we are required to fire stop and that is done by started with plywood, osb or drywall against the wall and then build the box if we built it like this we would have to put solid blocking between the studs just below the box.

 

[Mystriss]

@Nealtw hmmm well our walls are built on top of the "platform" on the second story so there's not a "chimney" effect there. I plan on/want to spray closed cell in the exterior stud bays eventually so that'll help regardless. I kinda want to put in rockwool to cut down on the noise, but we didn't buy any and I'm not sure we'll be able to with everything getting shut down :/

 

[Mystriss]

When we build boxes like this, the box is common with the floor structure above, so we are required to fire stop and that is done by started with plywood, osb or drywall against the wall and then build the box if we built it like this we would have to put solid blocking between the studs just below the box.

Yeah we don't have anything at all like that, baseboards rather than central air.

 

[Nealtw]

@Nealtw hmmm well our walls are built on top of the "platform" on the second story so there's not a "chimney" effect there. I plan on/want to spray closed cell in the exterior stud bays eventually so that'll help regardless. I kinda want to put in rockwool to cut down on the noise, but we didn't buy any and I'm not sure we'll be able to with everything getting shut down :/

I have added a few basement suites to my own houses and have always put in about 6" of fiberglass with out a lot of complaint about noise.

In this house we were told 9" of rock wool would out perform the fiberglass.
I can not claim that was true. I would spend less on insulation and more on resilient channel if I did another.

 

[Nealtw]

Yeah we don't have anything at all like that, baseboards rather than central air.

Same applies for boxes around beams and plumbing.

Other people read this stuff. :wink2:

 

[Mystriss]

I have added a few basement suites to my own houses and have always put in about 6" of fiberglass with out a lot of complaint about noise.

In this house we were told 9" of rock wool would out perform the fiberglass.
I can not claim that was true. I would spend less on insulation and more on resilient channel if I did another.

I've always heard that rock wool is def. better than fiberglass for "quiet" due to the density hampering sound waves. (air pockets in fiberglass batts give sound waves an easy pathway.) IIRC rockwool stops 10db vs fiberglass is like 4-6db

*Of course, if you don't really address the joists themselves you're results will be limited since they transmit sound too, I think wood only blocks like 6db of higher tones, and basically serve as an echo box for lower tones heh