Timber bolts are also referred to as dome head, fender head, safety head, and mushroom head bolts. In the Pacific Northwest, they are referred to as an economy bolt. They are used in marine and wood applications.

The underside of the large, rounded, low-profile head of a timber bolt has two nubs or fins which prevent the bolt from turning in the timber. The oversized timber bolt head eliminates the need for a malleable iron washer, and therefore reduces costs.

Manufacturing

Portland Bolt manufactures timber bolts from 1/2″ diameter through 1-1/2″ diameter in most ASTM, AASHTO, and SAE specifications. Special timber bolt tooling can be created to produce nonstandard head dimensions or bolt heads with your company’s name and/or logo.

Standard Thread Length

Bolt lengths ≤ 6″: Thread length = (2 X diameter) + 1/4″
Bolt lengths > 6″: Thread length = (2 X diameter) + 1/2″
Note: Most stock timber bolts longer than 12″ in length will have either 6″ or 8″ of thread.

Stock

Grade: A307
Diameters: 3/4″
Lengths: 8″ – 36″ in 2″ increments
Origin: Domestic
Finish: Hot-dip galvanized

Stock Thread Length

Bolt lengths ≤ 12″: 4″ thread
Bolt lengths 14″-16″: 6″ thread
Bolt lengths ≥ 18″: 8″ thread

Timber Bolt Dimensions

Click table to show drawing
Bolt Diameter D F H
Body Diameter Max Head Diameter Head Height
12 0.515 112 14
58 0.642 11516 516
34 0.768 214 38
78 0.895 258 716
1 1.022 278 12
118 1.149 278 12
114 1.277 278 12
138 1.404 3 38
112* 1.531 3 38
* No nubs on underside of head

Stock Timber Bolts

Length Diameter
3/4"
Galv.
8 18549
10 18553
12 18557
14 18561
16 18565
18 18569
20 18573
22 18577
24 18581
26 18583
28 18585
30 18587
32 18589
36 18595
Other sizes and finishes available on request.