Why did they do that when they wired?!

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Having almost had the house burn down on me today due to an electrical short in some old wiring (no blazing fire, just sparks and a scorched timber thank God!), I decided to do some electrical work today.

Anyway, what I was wondering is WHY did the old timers put a cross member between the studs everytime they mounted an electrical box? Some boxes just have a single piece of 2 X 4 under them, while other boxes have a piece of 1 X 6 above and below them. Some boxes are nailed only to the studs, and other boxes were nailed to the studs and the cross members.

-- Eric in TN (ems@nac.net), June 01, 2000

Answers

our old house(built during the depression), had these type of walls. they are called fire walls, or fire blocks. supposedly they contain the fire in the wall and keep it from traveling up to the next floor. maybe a carpenter can explain it better, but that was what i was told. and it is a bitch to install new wiring in. laura

-- laura cavallari (ladygoat13@aol.com), June 01, 2000.

Eric, I've given it alot of thought and believe they did it just to irritate you!

But seriously, are you replacing aluminum wire? It is much more likely to cause fires, so it would make sense about the "firewall" idea.

I had to rewire my house and I cursed a whole lot.

I wish you the best of luck on the project and thank God your home didn't burn!

-- Doreen (livinginskin@yahoo.com), June 02, 2000.


Yeah! The board is letting me post again! Eric, without checking, I'm thinking houses were built using what is called the balloon method starting about 1850. Roughly it means that they would build the stud walls as high as they were going (2 floors, 3 floors, etc) then go back and put in floor joists. This means that you have what are basically chimneys surrounding your house's exterior and possibly chimneys in any interior load bearing walls. Newer houses (maybe starting 1930's or 1940's) are built using the platform method. This means they build up the foundation walls, clap a floor across it. Build the first floor walls on the floor, clap the 2nd floor across the walls. It makes the house much more "compartmentalized".

What happens when a fire gets started in a ballon-framed house is that the fire can either start in or get sucked into the wall "chimneys". Worst case, the fire starts low and gets sucked into all the "chimneys", (depending on a lot of factors of construction and decorating). Usually it isn't quite that bad. But to imagine what it would be like, turn on a gas stove burner and pretend you're an inch tall and standing in the center of the burner. Not good.

Fires in balloon framing without fire stops are bad for two broad reasons. Whatever stud spaces have fire in them are like blow torches, tremendous heat from the ignition point up. The easiest things to burn in a house are what you add-window treatments, wall paper, paneling, plus your movable possessions. Fire in the walls ignites the finished wall, and fire rapidly moves through the paneling, plaster/lath, wall paper, dry wall (sorry folks, slower but it burns) and catches the window treatments, pictures, furniture, etc. Because unfire-stopped walls could have roaring fire in them from basement to attic, the house rapidly becomes engulfed in smoke and fire. Tough to get out of.

The other, and even worse problem with un-fire-stopped walls is that it puts intense heat on the structural bones of the house immediately. You need structural integrity to get yourself out, and hopefully firefighters in. Think about trying to start a pile of 2x6s on fire. You basically can't do it with a match. You need tinder. However, hit that same pile of 2x6s with a torch for long enough and you'll have a nice roaring blaze. Remember I told you the spaces between the studs would be like blow torches? As soon as fire gets into the stud spaces, it is weakening and destroying the basic structure of the house. In platform construction, structural damage (at least in the early stages) remains compartmentalized.

I'm glad you caught your fire in time. But as aggravating as they are, if you're in a balloon frame house, NEVER remove the fire stops. And it is possible that they weren't installed originally, or have been removed since. PUT THEM BACK. Gerbil

-- Gerbil (ima_gerbil@hotmail.com), June 02, 2000.


It's not a fire stop. I talked with someone else today, and they said their dad used to do that too - ONLY where and electrical box was, did he put in a 2 X 4. And they don't know why he did it either.

A fire stop would make sense, where the 2 X 4's are used, and that was what I thought too at first. But where there is no electricla box, there is no "fire stop". FYI - this is also a single story home, no basement, no true attic, and was built in the 2 stages - the first half was built in 1950 and the 2nd half sometime in 1960.

And the 1 X 6's that are set in between the 2 X 4's don't make sense (they are set "on edge" so that the top of the board is the 1" side, and the 6" side is what is vertical). They aren't structural in any way. It just aggrevated me and made what should have been a 2 hour job into a 6 hour job, not counting the drywall I need to repair now... 8-(

-- Eric in TN (ems@nac.net), June 02, 2000.


Sounds like somebody thought they needed the extra wood to fasten the electrical boxes to, possibly to get them placed exactly where they wanted them. The one by sixes on edge may have been placed to be nailers for something that was planned for that location on the wall? We've done things like that, when we knew something was going to be too heavy for the sheetrock.

-- Kathleen Sanderson (stonycft@worldpath.net), June 03, 2000.


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