Loose Guitar Braces

Loose Back Brace

Braces reinforce and strengthen the top and back of most acoustic instruments. The braces on an acoustic instrument bare the brunt of string tension placed on the instrument and it is essential that they be securely glued in place. Because most acoustic flat tops are no more than say .100+/- of an inch, braces play a huge role in keeping everything together.

Signs of Loose Bracing:

Checking Braces

Some times we aren't aware of loose braces. They are usually discovered by inspection after a bulge is noticed, a rattle is heard or perhaps a bridge repeatedly comes loose.

A thin feeler gauge will slide under
a loose brace.

I start by inspecting the interior of the guitar with a light and mirror, but sometimes that isn't enough. Loose and split braces that have no visible gap can be difficult to spot.

After eyeballing it I turn to my favourite brace checker, a simple feeler gauge. A thin feeler gauge will easily slip between a loose brace and the top or back.

Cracked / Split Braces

A cracked/split brace can elude even the best eagle eyes. While inspecting the braces with an interior light and mirror a split brace may give no cosmetic clue as to it's whereabouts. Handling each brace is sometimes necessary to locate the mystery brace as the crack can be very fine with no gap or separation.

Paper strip shows location of a hidden crack

Even though these braces are radiused (shaped to render the top/back slightly arched) this one has begun to curl up excessively. Warping can occur when a brace is left loose for a long period of time or the instrument is subjected to a dry environment.

Gluing Loose Braces

Before gluing the brace, old glue must first be removed to insure good adhesion. I go to great lengths to avoid leaving glue behind which would make these kinds of repairs most obvious.c clamps

Loose top braces are often glued using deep c-shaped clamps available thru luthier supply companies.

Back braces are often glued with the use of interior "jacks". On occasion I may use an interior jack in combination with an exterior clamp. This allows me to place greater pressure on a back brace without the risk of damaging the instrument.

I use a small nylon wedge to lift the brace away from the panel and permit glue application.

What glue is used to repair loose braces? In most cases an aliphatic resin glue such as Titebond regular water soluble glue is used. Some vintage instruments may warrant using hide glue.
jacks wedged between top and back brace
"Jacks" are often used to glue loose back braces

Replacing Braces

When left un repaired a loose brace can actually come completely free from the top or back. On many occasions I have inspected a guitar only to find a missing brace, one can only wonder where it got off to.

When dealing with flat top acoustic guitars with typical, round soundholes, most braces can be repaired without removing the back.

As seen in a previous photo, a loose brace can warp over time. Excessive warping can make the brace far to stiff to be clamped back into position. In such cases removal and/or replacement is often necessary.

I have successfully made an installed many top and back braces without removing the back. This excludes the X brace, it is two braces where one lies over another. This is tedious work as the radius must be copied and the brace positioned while placing ones hand, clamps, mirror and light inside the sound hole all at once. Difficult access does require the back to be removed for some repairs.

Types of Braces


By far the most popular top bracing pattern on flattop guitars. This X pattern was invented/accredited to C.F. Martin in the mid 1800's. The two primary top braces intersect to form the shape of an X. The point of intersection and it's degree vary amongst instruments.

Ladder Brace

There are top braces which run parallel to themselves like the rungs of a ladder. They run from treble to bass side. This pattern does not yield the strength that the X pattern does and instruments with ladder bracing are normally strung with light or extra light gauge strings to avoid overstressing the top.

Fan Brace

A bracing pattern which fans out like a hand spread open. Commonly found on classical style guitars.

Lattice Brace

Bracing crosses over to form small squares or diamond like pattern.

Scalloped Brace

A technique used to decrease the mass of a brace and change the stiffness of the top. A scalloped brace often appears to dip down towards it's center and peak on either end.

Tone Bar

These braces are found behind the bridge area on an acoustic guitar top...you may find 1, 2 or even 3 though 2 is most common.

Finger Brace

These are found on either side of the sound hole, short, small braces.

Popsicle Brace

A flat brace which runs from treble to bass side directly under the fingerboard extension.

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