firewall oops

**John Arnold** · 06-21-2007, 02:16 PM

11 year old townhouse. Firewall was just a little off.

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**Jerry Peck** · 06-21-2007, 02:39 PM

John,

Nope.

My guess is that is the way the block mason always does it (and that's true everywhere I've been in Florida), then, someone follows behind them, installs forms, and pours a solid concrete rake/bond beam.

Did you feel down inside those blocks? Bet they were hollow, no bond beam (which is required).

Bet it's a bigger problem than you first thought.

**John Arnold** · 06-21-2007, 02:59 PM

Thanks Jerry -
Here's another view where the block appears to be full height at the lower right.

**Rick Cantrell** · 06-21-2007, 03:22 PM

I think the firewall should go through and 2 feet above the roof.

**wayne soper** · 06-21-2007, 05:21 PM

Jerry, Why block all the way up? Besides the concrete and mexican thing.
Can't they use sheetrock? Seems like alot of work with a little result.

**Jerry Peck** · 06-21-2007, 06:21 PM

Originally Posted by Rick Cantrell

I think the firewall should go through and 2 feet above the roof.

Not needed *IF* the roof sheathing is fire retardant treated for 4 feet out from each side of the wall ... that means you cannot lay an 8 foot sheet down, it needs to be 4 feet *from each side*, and that wall is 8" thick.

OR.

If (obviously, it was not) the roof sheathing is protected by gypsum board for 4 feet out from each side of the wall.

**Jerry Peck** · 06-21-2007, 06:27 PM

Originally Posted by wayne soper

Jerry, Why block all the way up? Besides the concrete and mexican thing.
Can't they use sheetrock? Seems like alot of work with a little result.

First, set aside the fire rated wall aspect.

You have a concrete block wall which does not have any reinforcement at its top, meaning it could tip over and fall, and, if there is a fire, IF the heat does not make it fall on it own, one blast from a fire hose and the wall comes tumbling down ... onto the property which was not on fire.

Not a real good thing.

Secondly, that *could be* a frame wall with 1 or 2 layers of 5/8" Type X, and, when constructed in accordance with the UL design for that type of wall, you could make that a 1 or 2 hour rated wall, BUT ...

It is block ... only part way up ... with (most likely) no reinforcement along the top ...

Just not a pretty sight. And not a real easy fix.

Depends to some extent on if the wall has reinforcement and a poured bond beam along its top, I'm betting it does not.

**Michael Thomas** · 07-16-2007, 05:31 AM

Can someone suggest a link to a comprehensive outline of the requirements for town home common walls the the associated attic/roof areas?

Later.... after finding the right GOOGLE search, answering my own question:

http://www.ci.blaine.mn.us/_docs/_Bu...-Townhomes.pdf

**John Arnold** · 07-16-2007, 06:04 AM

2006 IRC Section R317 Swelling Unit Separation, which you can find online at
Seattle Residential Code in Chapter 3.

**Michael Thomas** · 07-16-2007, 06:18 AM

Thanks, John.

In the above link:

"R321.3.2 Membrane penetrations. Membrane penetrations shall comply with Section R321.3.1. Where walls are required to have a minimum 1-hour fire-resistance rating, recessed light fixtures shall be so installed such that the required fire resistance will not be reduced..."

How is a "membrane" defined ... how is it different from a "wall" in R321.2: "fire-resistance-rated wall assemblies"?

**Jerry Peck** · 07-16-2007, 04:14 PM

Fire rated walls, ceilings, floors, etc., have a fire rating by design, and that fire rating applies to both sides of the 'separation'.

A "through penetration" is one which penetrates one side and goes all the through and out the other side. An example of a through penetration is a duct 'going through' a wall or floor/ceiling assembly.

A "membrane penetration" is one which penetrates one side ... and stops. An example of a membrane penetration is an electrical box, tub/shower control valve, something for which a hole is only cut into one side of the wall. I.e., one "membrane". A fire rated assembly has a membrane, something else (could be air and studs), then another membrane.

Joe Nernberg · 07-17-2007, 09:02 AM

Found flex duct through the firewall at 3 areas of the garage. This photo is from a 17-year old house. 9100 square feet in Bel Air, CA. Biggest fixer this year for me. Sub panel in the master bedroom closet. No electrical receptacles at the island counter. Three inoperable package units at the roof. Gas was off and the valve was locked. My comment: "Inspector's return trip fee shall be $300.00 or client may rely solely on seller and listing agent disclosures."

**Jerry Peck** · 07-17-2007, 09:41 AM

Originally Posted by Joe Nernberg

Found flex duct through the firewall at 3 areas of the garage.

Even in CA I think that wall between the house and the garage is not a "firewall". It is a wall with 5/8" Type X on the garage side and had a self-closing and latching door, but not a true "firewall".

Even the IRC, which only requires a "separation" wall with 1/2" gypsum board (does not have to be Type X) requires metal duct when duct penetrates through that "separation" wall.