What Grade Is 3105 Aluminum Sheet? And Why It Matters for Builders
Aluminum is strong, light, corrosion-resistant, and easy to work with. But here’s the catch — not all aluminum sheets are the same. If you’re a builder, contractor, or fabricator, understanding the grade of aluminum you’re using is everything. Today, we’re diving into one of the most widely used grades: 3105 aluminum sheet. So, what exactly is it — and why should you care?
Aluminum is strong, light, corrosion-resistant, and easy to work with. But here’s the catch — not all aluminum sheets are the same. If you’re a builder, contractor, or fabricator, understanding the grade of aluminum you’re using is everything. Today, we’re diving into one of the most widely used grades: 3105 aluminum sheet. So, what exactly is it — and why should you care?
What Is 3105 Aluminum Sheet?
Let’s start simple. 3105 aluminum sheet is part of the 3xxx series of aluminum alloys, known for excellent corrosion resistance and good formability. It’s a non-heat-treatable alloy that gets its strength through cold working processes.
You’ll often find it in construction and architectural applications, and that’s not by accident — it’s a great performer in tough conditions.
Understanding the Grade “3105”
The “3” in 3105 stands for the 3xxx series, which means the primary alloying element is manganese (Mn). This gives it high corrosion resistance.
The rest of the number (105) is simply a way to identify the specific alloy in that series. So, 3105 is a unique blend of aluminum with just enough added elements to give it enhanced performance — but without getting overly complex or costly.
Chemical Composition of 3105 Aluminum
Aluminum (Al): 95.0 – 96.5%
Manganese (Mn): 0.3 – 0.8%
Magnesium (Mg): 0.2 – 0.8%
Iron (Fe): Max 0.7%
Copper (Cu): Max 0.3%
Chromium, Zinc, Others: Trace amounts
The key takeaway? It’s mostly aluminum with just the right sprinkle of manganese and magnesium for added strength and corrosion resistance.
Mechanical Properties of 3105 Aluminum Sheet
Tensile Strength: Around 150 MPa (can vary based on temper)
Yield Strength: Typically 130 MPa
Elongation: 12% – 20% depending on thickness and temper
Hardness: Brinell 47 (in H14 temper)
These numbers might seem abstract, but what they mean for builders is: 3105 aluminum is strong enough for most architectural uses, but still flexible enough to shape and form.
Corrosion Resistance of 3105 Aluminum
Thanks to its manganese content, 3105 offers excellent corrosion resistance, especially in atmospheric conditions. Think humid environments, rainy seasons, coastal areas — 3105 doesn’t rust or corrode like steel does.
It’s especially popular for roofing, siding, and gutters because of this durability.
Workability and Weldability
3105 aluminum is highly workable, which means it’s easy to cut, punch, and bend into complex shapes without cracking.
It’s also weldable, especially using common welding methods like TIG or MIG. Though it’s not the best for high-strength welded structures, it gets the job done for architectural needs.
Surface Finish and Paintability
It takes paint exceptionally well, making it perfect for pre-painted aluminum sheets. Whether it’s a bold roof color or a decorative panel, 3105 holds its finish beautifully over time.
This makes it ideal for both aesthetic and protective coatings.
3105 Aluminum vs. Other Grades
3105 vs. 3003
Both are part of the same series, but 3105 has a bit more magnesium, giving it slightly better strength and corrosion resistance.
3105 vs. 5052
5052 is stronger and more suited to marine environments, but it’s also more expensive. If you don’t need marine-grade durability, 3105 is a better value.
3105 vs. 6061
6061 is a heat-treatable alloy with higher strength, but lower formability. It's great for structural components, whereas 3105 is better for cladding, roofing, and siding.
Common Applications in the Construction Industry
Roofing panels
Siding systems
Gutters and downspouts
Cladding and curtain walls
Mobile homes and RV panels
Soffits and fascia boards
If it’s flat, needs to look good, and stand up to weather — 3105 is a solid pick.
Why Builders Prefer 3105 Aluminum
Affordable without compromising performance
Lightweight, reducing structural load
Long-lasting in outdoor applications
Easy to fabricate and install
Aesthetic versatility (painted, anodized, or brushed)
Sustainability and Recyclability
In today’s eco-conscious world, sustainability matters.
3105 aluminum is 100% recyclable without losing performance. Using recycled aluminum also saves up to 95% of the energy required to produce new aluminum — win-win for the environment and your project budget.
Limitations of 3105 Aluminum Sheet
It’s not all sunshine, though.
Lower strength compared to 5xxx or 6xxx series
Not ideal for high-load structural parts
Limited machinability compared to harder alloys
If you need brute strength or precision machining, 3105 might not be your go-to.
Selecting the Right Aluminum Grade for Your Project
Is the material exposed to weather? → 3105 is perfect.
Need to paint or coat the surface? → 3105 loves paint.
Heavy structural loads involved? → Consider 5052 or 6061 instead.
Tight budget but need reliability? → 3105 is a smart balance.
FAQs
1. What is the weight of 3105 aluminum sheet?
The weight depends on the thickness, but on average, it’s about 2.71 g/cm³. For example, a 1mm thick sheet weighs approximately 2.71 kg per square meter.
2. Can 3105 aluminum be anodized?
It can be anodized, but it’s not ideal for decorative anodizing. For color consistency and finish, painting is a better option.
3. Is 3105 aluminum considered marine grade?
Not exactly. While it has good corrosion resistance, it’s not classified as marine grade. 5052 or 5083 are better suited for marine environments.
4. What thicknesses are available for 3105 sheets?
Common thicknesses range from 0.2mm to 6mm. Custom gauges are also available depending on supplier capabilities.
5. Does 3105 aluminum require surface treatment?
It doesn't require it, but surface treatments like painting or coating can enhance its appearance and lifespan.