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butterkups 02-05-2013 04:56 PM

Proper techniques to install fire blocking
I've got a 1901 Victorian that I'm restoring and wanted to know a technique of putting in fire blocking at floor level (and ceiling on first floor).

I've got the exterior walls opened and I'm using barrier paper (to keep out draft), insulation, running

butterkups 02-05-2013 05:00 PM

Tips on fire blocking 1901 victorian
I've got my exterior walls opened up from the inside and I need to fire block both at floor level and ceiling height on first floor. Any tips to make it easy?

I'm also installing tyvek paper to keep out draft, insulation, new retro fit windows and a title 24 upgrade on electrical.

joecaption 02-05-2013 05:05 PM

Got a picture? How tall are the ceilings?
Simple wooden blocking top and bottom, if the walls over 8' tall put one in the middle.
FIll any gaps with fire rated caulking.

hand drive 02-05-2013 08:54 PM

fire blocking separates the air between structural cavities. Floor and ceiling cavities can share air space with attics and crawlspaces but the air must not be transferred through a wall cavity to another floor system of the home. look at how a typical wall is built with the bottom wall plate and upper top plates, the plates are the fire blocking basically because they stop air from the bottom of the house to the top and all floors in between. if you have to install blocking inside of wall stud bay then do the blocking just like a wall plate, it's just cut into single stud bay pieces instead of a full length plate as normally used. check with the tradesmen before adding your blocking. in general it is better to have the blocking installed before mechanical and electrical but some spots the tradesmen may need access to before you plug the spot with blocking,so check with them about it. otherwise the blocking is always in first and then tradesmen show up to drill holes and notch the blocking to pieces and then the firestop is added :)

Gary in WA 02-05-2013 09:45 PM

You can also use drywall, structural plywood, etc.;

Check with local AHJ;

Hit "next section" (few more times) for fiberglass requirements after this one:


danpik 02-06-2013 05:58 AM

Old houses like that have framing that is not standard sizes compared to what we have today. 2 x 4's are actually 2" x 4". You will need to make some blocking to fill the tops and bottoms of the bays to be the width of the opening in both directions. Basically you need to block off the tops and bottoms of the bays to not allow air movement out of the cavity. No real easy way, just repetitive cutting and fitting

butterkups 02-06-2013 05:23 PM

2 Attachment(s)
Is this the right way to fire block the second floor exterior walls?

rebelranger 02-06-2013 08:32 PM

Add Roxul insulation too. Otherwise that is fireblocking but those 2x4s still burn.

Gary in WA 02-07-2013 12:23 AM

The flooring should have been cut back flush and the blocks dropped down next to the ribbon board- esp. if wall drywall is held up 1/2" SOP.;

Roxul is good...

danpik 02-07-2013 05:20 AM


Originally Posted by butterkups (Post 1111162)
Is this the right way to fire block the second floor exterior walls?

In my area the inspector would want to see those blocks down against the floor boards or up against the bottom. Also at the top the same at the ceiling. Basicaly set up so there is no passage from the joist bays to the wall bays.

Maintenance 6 02-07-2013 06:37 AM

Your fire blocks should be down against the floor joists. You have a gap at the baseboard level that would allow fire and combustion gases to escape into the room from the wall cavity below.

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