How to Properly Brace Roof Trusses

Roof truss instal­la­tion can be one of the most dan­ger­ous parts of the home build­ing process. Col­laps­es from improp­er­ly braced truss­es can result in dis­as­ter. Despite this, many builders are either unaware or sim­ply over­look the need to ade­quate­ly brace the roof struc­ture dur­ing construction.

Builders often rely on their per­son­al expe­ri­ence, result­ing in a false sense of secu­ri­ty that can have cat­a­stroph­ic con­se­quences. Just because some­one is used to doing things a cer­tain way, this does not nec­es­sar­i­ly mean it is the right way.

There are mul­ti­ple ways to safe­ly secure a roof truss set. Regard­less of the brac­ing method, it’s always impor­tant to fol­low the truss manufacturer’s instruc­tions, as well as indus­try best prac­tices when it comes to set­ting and brac­ing trusses.

Traditional 2x4 Lumber Bracing

One of the most com­mon meth­ods for brac­ing roof truss­es is using 2×4 blocks of lum­ber to pro­vide tem­po­rary sup­port before the sheath­ing is installed

How to Install Tra­di­tion­al Lum­ber Bracing:

1. Pre­cut blocks of 2×4 lum­ber to span from the top chord of one truss to the top chord of the next (See green block­ing in Dia­gram 1). Each end of the block should extend at least ¾” beyond the out­side edge of each truss. When spaced at a typ­i­cal 24” on cen­ter, this means cut­ting blocks to at least 27” in length.
   • Often builders fail to extend their blocks beyond the end of each truss, cut­ting them to only 25½”. This puts the blocks at risk of split­ting dur­ing installation. 
   • Alter­na­tive­ly, blocks can be cut to 22½” and insert­ed into the spaces between the top chords of each truss, instead of on top of each truss.
2. Nail the brac­ing into the top chord of each truss, mak­ing sure to fol­low the truss manufacturer’s lay­out while set­ting trusses.
3. Install diag­o­nal brac­ing, rep­re­sent­ing a ​“W” pat­tern through­out the struc­ture (See red block­ing in Dia­gram 1).
   • Lat­er­al brac­ing alone is not ade­quate to secure roof truss­es before sheath­ing. Imag­ine putting togeth­er a book­shelf. Dur­ing assem­bly, the hor­i­zon­tal shelves will sup­port the spac­ing between the ver­ti­cal walls of the shelf, but until the back pan­el is installed, the shelf will be unsta­ble – sub­ject to twist­ing and racking. 
   • An unsheathed roof is sim­i­lar, with much more dire con­se­quences. Until the diag­o­nal brac­ing is installed, the whole truss set can sim­ply rack over like a line of dominoes.
4. Remove the block­ing as the sheath­ing is installed.

It’s impor­tant to fol­low your truss manufacturer’s lay­out and the BCSI when using wood brac­ing to set roof trusses.

Diagram 1

Ben­e­fits of using tra­di­tion­al block­ing to brace roof trusses:

• Mate­r­i­al is inex­pen­sive and easy to obtain (2×4 lumber).
• Most builders are used to brac­ing roof truss­es this way.
• If done cor­rect­ly, this pro­vides an ade­quate­ly sta­ble truss set.

Draw­backs of using tra­di­tion­al block­ing to brace roof trusses:

• It takes time to pre­cut blocks to the cor­rect length.
• Blocks must be removed pri­or to sheathing.
• Addi­tion­al diag­o­nal brac­ing is required to secure the structure.

Metal Bracing

Some builders opt for met­al brac­ing to secure their roof truss­es. Often designed to space truss­es at 24” on cen­ter, these meth­ods elim­i­nate the need to cut blocks of lum­ber and pro­vide a strong con­nec­tion between truss­es. How­ev­er, most met­al brac­ing meth­ods fail to pro­vide diag­o­nal sup­port, requir­ing the same ​“W” block­ing as tra­di­tion­al lum­ber bracing.

There is one met­al brac­ing solu­tion that pro­vides both lat­er­al and diag­o­nal sup­port in one appli­ca­tion – FastenMaster’s new Truss­BRACE sys­tem. Truss­BRACE is installed in the place of tem­po­rary lat­er­al and diag­o­nal brac­ing in a frac­tion of the time. 

FastenMaster TrussBRACE Roof Truss Support

How to Brace Roof Truss­es Using TrussBRACE:

1. Set the first 3 truss­es using both Truss­BRACE and diag­o­nal web mem­ber brac­ing (See Dia­gram 2). Truss­BRACE is installed eas­i­ly on the top chord or oth­er web mem­ber using 3 nails.
2. Set the next 12 truss­es using only TrussBRACE. 
3. After the 15^th truss, the next 3 truss­es should be secured with Truss­BRACE and diag­o­nal web mem­ber brac­ing, and the process is repeat­ed through­out the struc­ture. If few­er than 30 truss­es are being used, apply diag­o­nal brac­ing at the mid­way point of the truss set.
4. Apply sheath­ing to the top chord of the truss direct­ly on top of Truss­BRACE. There is no need to remove Truss­BRACE pri­or to sheathing.

Always refer to the com­plete manufacturer’s instal­la­tion instruc­tions and the truss lay­out for prop­er spacing.

Diagram 2

Ben­e­fits of met­al bracing:

• No need to cut blocks to the cor­rect length.
• Met­al braces are sim­ple and easy to install.
• The Truss­BRACE sys­tem pro­vides both lat­er­al and diag­o­nal sup­port in one application.
• Truss­BRACE can be left in place dur­ing sheath­ing, act­ing as per­ma­nent brac­ing which is some­times required by the truss manufacturer.

Draw­backs of met­al bracing:

• Not all met­al braces are made equal­ly – some do not pro­vide diag­o­nal support.
• Most met­al braces are only designed for brac­ing truss­es that are spaced at 24” on center.

For more infor­ma­tion on how to prop­er­ly brace roof truss­es dur­ing con­struc­tion, refer to the BCSI or to the Truss­BRACE instal­la­tion instruc­tions.