What type of walls should be used for the separation of duplex?

[amateurdesigner]

Hello,
What is the most common way to separate two units, such as a duplex or condos side to side?

Would it be one single wall,,or use two 'interior-4' walls next to each other with an air gap?

Or use firewall ?

cheers.

[POLARA500]

This would be determined by the building classification according to the applicable building code. Whether you will need just a fire separation wall or fire wall again will be a code requirement.

Richard

[lbuttery]

they are known as party walls or zero lot line

see this thread

http://www.chieftalk.com/showthread....ighlight=PARTY

check with your local building dept and determine what is required and then make a new wall in chief with the needed layers

Lew

[MTH]

You should check on parapet wall requirements too.

[AcadMaster]

the official term is DEMISING WALL.

[amateurdesigner]

thanks for the replies everyone.. i chatted with a builder in the area and he said that the separation of 2 units should use 2 standard interior walls with 1" air gap. Both walls with drywall on both sides.

so here in Chief there are 'firewall-4' wall types and so what I did was made 2 of those walls and put them side by side and Chief automatically made the 1" air gap. Then I selected both walls and made them 'double wall' in the wall specifications dialog box.

But do you think I need drywall on the insides of the 2 walls in between the 1" air gap? I would guess that it would be necessary and add more firewall protection.

thanks again

[Joe Carrick]

What the builder told you is very difficult to actually build. Mainly because it's really hard to get in that 1" air space between the walls to attach the drywall.

Generally, the one of the walls will be built with drywall on both sides (this would be the firewall) and then the second wall would be built with drywall just on the finish room side.

The reason for air space is to prevent sound transmission thru a solid connected wall. There are many different configurations of wall construction that give lesser or better STC (Sound Transmission Classification) ratings.

The Fire Rating is also dependent on the materials used (5/8" Type-X Drywall on both sides will give a 1-Hr Fire Rating) but technically the drywall must be continuous from floor to roof. (There are some ways to avoid that requirement).

It would be a good idea to consult with your local building department to get their requirements - your project may require more or less depending on the occupancy.

[amateurdesigner]

@Joe,
haha, maybe a very skinny man can get in between that 1" air gap to attach the drywall?

But that makes sense to have at least one of the sides drywalled with the 5/8" as you mentioned.

I read your old thread from 2006, how did you end up doing that with the property line?

[Joe Carrick]

@Joe,
haha, maybe a very skinny man can get in between that 1" air gap to attach the drywall?

But that makes sense to have at least one of the sides drywalled with the 5/8" as you mentioned.

I read your old thread from 2006, how did you end up doing that with the property line?

Too long ago - I don't remember.

[POLARA500]

Samantha,

Whatever separation or fire walls are required make sure you use walls that have the proper UL designated rating.

Richard

[Allen Brown]

The way we do it here is (2) 4" walls with a 1" air gap. We place 5/8" rock on one side, completely fill the 8-1/2" cavity with stabilized blown cellulose, then place 5/8" rock on the other side.

Fire-proof, bug-proof, sound-proof.

[amateurdesigner]

@Allen,
so you only have 2 sides with with drywall total? (the interior finish sides of each unit?)

and then you just fill the walls and in between the walls (1" air gap) with stabilized brown cellulose?

Wouldn't that be just an 8" cavity ?

5/8" < (3.5" + 1" + 3.5") > 5/8"

[Allen Brown]

Yes it would be, my math was off. And yes, there are only two layers of drywall, one on the inside of each unit.

[amateurdesigner]

Does anyone know if plumbing is allowed to be ran within the party walls?

Basically, I have a 3 floor mirrored duplex, and the bathrooms of each unit are against the party walls. (the sink and tub)

Can plumbing be ran vertically within the party wall from upstairs to downstairs?
how about horizontally from unit to unit?

[lbuttery]

Samantha:

I seriously doubt if it would be allowed

the idea of party firewalls is to prevent the spread of a fire from unit A to unit B

any penetrations into that fire barrier would have to be fire-blocked and sealed and rated etc

but who knows - some jusrisdications may not care ???

Lew