Strut Finishes & Materials Guide
Strut and its accessories come in several finishes, and picking the right one is mostly about the environment: how wet, how corrosive, indoors or out, near salt water or chemicals. Choose too light and it rusts; choose too heavy and you overpay. This guide compares the common strut finishes so you can match the finish to the job.
Finish Comparison
| Finish | Best For | Corrosion Resistance | Notes |
|---|---|---|---|
| Electro-Galvanized (EG / zinc) | Interior, dry — the default | Low-moderate | Thin zinc coating; lowest cost; not for sustained wet or outdoor |
| Pre-Galvanized (mill galv) | Interior, light humidity | Moderate | Zinc applied to coil before forming; cut edges exposed |
| Hot-Dip Galvanized (HDG) | Exterior, damp | High | Thick zinc, coats cut edges; the workhorse outdoor finish |
| 316 Stainless | Coastal, washdown, chemical | Very high | Best chloride resistance; highest cost |
| Aluminum | Lightweight, corrosion-prone but non-marine | High (non-chloride) | Light, non-magnetic; lower strength than steel |
How to Pick
- Indoors, dry (offices, dry plants): electro-galvanized is fine and lowest cost.
- Outdoors, general: hot-dip galvanized — the thick zinc handles rain and humidity and covers cut edges.
- Wet / washdown (food plants, pools, kitchens): 316 stainless resists frequent water and cleaning chemicals.
- Coastal / marine (within a few miles of salt water): 316 stainless; chlorides will eventually pit lesser finishes.
- Weight-critical or non-magnetic: aluminum, where loads allow.
Does Strut Rust? Will It Work Outside?
Plain and electro-galvanized strut will rust if left wet or outdoors — the thin zinc is meant for dry interiors. For outdoor use, choose hot-dip galvanized or stainless. Yes, strut works outside, you just have to match the finish to the exposure. A common mistake is using EG strut outdoors and watching it rust within a season; HDG or 316 stainless avoids that.
Mixing Finishes & Galvanic Corrosion
Where dissimilar metals touch in a wet environment, galvanic corrosion can occur (for example a bare steel clamp on copper tube). Two fixes: keep finishes consistent, or isolate the metals — a cushion clamp with its plastic insert is the easy way to separate a copper line from a steel clamp. For stainless runs, use stainless nuts such as STR4168S2.
Frequently Asked Questions
Is strut galvanized?
Most strut is galvanized in some form. The standard interior finish is electro-galvanized (a thin zinc plating). For outdoor use it is hot-dip galvanized (a thick zinc coating). Strut is also made in 316 stainless and aluminum. Bare/plain strut without a finish exists but will rust if not painted or coated.
Can strut be used outside?
Yes, with the right finish. Use hot-dip galvanized for general outdoor exposure or 316 stainless for coastal and chemical environments. Do not use plain or electro-galvanized strut outdoors; the thin coating will rust.
Does strut rust?
Plain and electro-galvanized strut rusts when exposed to moisture or weather. Hot-dip galvanized resists rust outdoors for many years, and 316 stainless resists rust even in wet and salty conditions. Match the finish to the exposure to prevent rust.
What is the difference between electro-galvanized and hot-dip galvanized?
Electro-galvanized has a thin zinc plating applied electrically, good for dry interiors and lowest cost. Hot-dip galvanized is dipped in molten zinc for a much thicker coating that also covers cut edges, making it suitable for outdoor and damp use.
When do I need 316 stainless strut?
Choose 316 stainless for coastal/marine areas, pool decks, food and pharmaceutical washdown, and chemical environments — anywhere chlorides or frequent water would eventually corrode galvanized. It costs more but lasts where lesser finishes fail.
Related Guides
- Strut Channel Accessories Guide
- Channel Nut & Spring Nut Guide
- Strut Brand Cross-Reference
- Shop Strut Channel