Fireblocking......bracing or stiffners

[pioneergal]

What is the correct spacing of the fire blocks on the exterior wall and is it necessary to do this on the interior walls?

I read somewhere that if the local code did not require fireblocking on the interior walls to omit it because fireblocking the interior walls would cause sound to travel more easily thru the room.


PS.....the reason I used the terms bracing and stiffners is an elderly gentleman friend said he had never heardof fireblocking.....it was stiffners...Ha!

[jraabe]

Most codes require fire blocking in the outside walls only. In platform frame construction the top plates stop the communication of fire and hot gasses between floors and walls and ceilings. Thus you normally have the blocking already done for you.

If you have balloon framing between floors then you will need fireblocking between the studs at the floor line. In the 1 - 1/2 story plans I place the fireblocking so that it also serves as a nailer for the wall finish.

If you have very tall cathedral type walls you may also need fireblocking at around the 8' height.

Stiffeners at 1/2 up the wall were used in old framing when board sheathing was used. Plywood and OSB have eliminated that need.

[pioneergal]

Thanks John for the info.

We plan to start blocking in the next week.

The weather in Texas has been very nice and cool this week so we are trying to catch up on some much need ed yard work.

[manhattan42]

Codes require fireblocking is every wall and partition, exterior and interior, and elsewhere.

As John says, with platform framing, some of the fireblocking is provided by the top and bottom plates in the walls.

But this is not entirely what fireblocking is or needs to be.

The International Residential Code defines 'fireblocking' as "Building materials installed to resist the free passage of flame to other areas of the building through concealed spaces."

Structural sheathing, drywall and other materials play as much a part in fireblocking as do the studs themselves and top and bottom plates in walls.

Here is what the Code states about fireblocking:

R602.8:

"Fireblocking shall be provided to cut off all concealed draft openings (both vertical and horizontal) and to form and effective fire barrier between stories and between a top story and roof space. Fireblocking shall be provided in wood-frame construction in the following locations:

1. In concealed spaces of stud walls and partitions including furred spaces and parallel rows of studs or staggered studs; as follows:
 1.1 Vertically at the ceiling and floor levels
 2.2 Horizontally at intervals not exceeding 10 feet

2. At all interconnections between concealed vertical and horizontal spaces such as occur at soffits, drop ceilings, and cove ceilings.

3. In concealed spaces between stair stringers at the top and bottom of the run.

4. At openings around vents, pipes, and ducts (and wires) at ceiling an floor level, with an approved material to resist the free passage of flame and products of combustion....."

There are also specialty requirements for fireblocking regarding two family dwelling conices and fireblocking around chimneys.

In addition, 'draftstopping' is also a required part of fire suppression by limiting large open spaces behind framed walls such as are installed in basements in front of masonry walls or above suspended ceilings when the area exceeds 1500sf.

This cuts down on the available air that can be drwan in to feed a fire.

For proper fire and draftstopping requirements consult your local building code office or fire marshall.

Here is a very helpful link:

http://www.awc.org/HelpOutreach/eCourses/MAT110/Section10-Firestopping.pdf