Best Grade 5 Lag Screws: How to Choose the Right Wood Fastener
If you need a true SAE Grade 5 fastener, check the product specification carefully: the lag screws listed here are not identified as SAE Grade 5. Lag screws are wood-threaded fasteners, while Grade 5 is a strength marking used for certain bolts. For wood projects, the best choice depends on diameter, length, coating, and installation style. The options below include galvanized and coated screws for outdoor use, stainless steel for corrosion resistance, and conventional hex-head lag screws for wood connections.
| Product | Best For | Key Detail |
|---|---|---|
| Makers Bolt 3/8 x 5 Kit | Outdoor projects needing washers | Hot-dip galvanized; 50 washers included |
| Prime-Line 3/8 x 5 | Standard heavy-duty wood fastening | A307 Grade A, hot-dip galvanized |
| LIONMAX 5-Inch Screws | Star-drive installation | Heat-treated steel with double coating |
| BNUOK #14 x 5 | Exterior projects using a T30 bit | Epoxy coating and washer-style head |
| Makers Bolt 1/4 x 5 | Smaller connections needing stainless steel | 18-8 stainless; 25 per pack |
Makers Bolt 3/8 x 5 Galvanized Kit
This kit includes 50 3/8-inch-by-5-inch lag screws and 50 USS flat washers. The screws are described as Grade 307A and meet ASME B18.2.1, with a hot-dip galvanized finish for rust resistance.
Best for: Buyers making outdoor wood connections who want washers included and need a larger 3/8-inch diameter. It was selected for its complete kit and clearly stated dimensions. Limitation: Grade 307A is not SAE Grade 5, and the product is a lag screw rather than a conventional nut-and-bolt assembly.
Prime-Line 3/8 x 5 A307 Lag Screws
These heavy-duty wood screws measure 3/8 inch by 5 inches and have a six-sided hex head with deep wood-screw threads. The listed material is A307 Grade A steel with a hot-dip galvanized finish. The product information specifies that the fastener does not accept a nut.
Best for: Wood projects that call for a conventional hex-head lag screw and a galvanized finish. Choose this if you do not need washers included in the package. Limitation: The listing identifies A307 Grade A, not SAE Grade 5, and does not provide a stated pack quantity in the supplied details.
LIONMAX 5-Inch Black Lag Screws
LIONMAX supplies 50 black screws measuring 5 inches long, with a listed 0.25-inch thread diameter. They use a T30 star bit and heat-treated steel. The product description cites double corrosion-resistant coatings, a 1,000-hour salt spray test, knurled shanks, deep threads, and a Type 17 point.
Best for: Buyers who want a star-drive screw designed for wood installation and value the manufacturer’s stated coating and point features. Limitation: The listing does not identify an SAE Grade 5 rating; its corrosion-test claim does not by itself establish suitability for every environment.
BNUOK #14 x 5 Exterior Wood Screws
This package contains approximately 24 carbon-steel screws measuring #14 by 5 inches and includes a T30 star bit. The screws have a black epoxy exterior coating and a wide washer-style head. The manufacturer states that they passed a 2,000-hour salt spray test.
Best for: Exterior wood projects where a T30 drive and wide head suit the installation. It was selected as a coated alternative with a bit included. Limitation: The product data does not state an SAE Grade 5 classification or give a diameter in inches, so verify that the #14 size matches the project requirements.
Makers Bolt 1/4 x 5 Stainless Lag Bolts
This 25-pack contains 1/4-inch-by-5-inch lag bolts made from mill-certified 18-8 (304) stainless steel. The listed head size is 7/16 inch, and the length is measured from the bottom of the head to the point. The product also lists ASME B18.2.1.
Best for: Buyers seeking stainless-steel lag screws in a smaller diameter for projects where that material choice is appropriate. Limitation: The product is not identified as SAE Grade 5, and its 1/4-inch diameter may be too small where a larger fastener is specified.
Buying Guide: Choosing a Lag Screw
Does “Grade 5” apply to lag screws?
Do not assume that a lag screw is Grade 5 because it is called heavy-duty or industrial. SAE Grade 5 is a bolt strength classification, and none of the products above is listed as SAE Grade 5. The listed grades include A307 Grade A and Grade 307A, which are different designations. If plans or an engineer specify Grade 5, confirm the required fastener type and marking before buying.
Which dimensions should you compare?
Match both diameter and length to the project specification. A 3/8-inch screw is wider than a 1/4-inch screw, while #14 is a numbered size that should not be treated as interchangeable without checking the applicable sizing information. Confirm how the manufacturer measures length, and consider the head and washer arrangement when planning the connection.
Which coating is right for outdoor use?
Hot-dip galvanized, stainless steel, and coated carbon steel are different material and finish choices. The listings describe corrosion-resistance features, but the best option depends on exposure, connected materials, and project requirements. Follow applicable building plans and manufacturer guidance, especially for structural or harsh-environment installations.
What drive style and installation details matter?
Hex heads are tightened with a compatible wrench or socket; star-drive models require the specified bit, such as T30. Type 17 points and self-tapping descriptions may help with starts in wood, but do not assume predrilling is unnecessary for every wood species or connection. Check installation instructions and avoid substituting a different size or fastener type.
Frequently Asked Questions
Are any of these products confirmed SAE Grade 5?
No. The supplied product details do not identify any of these lag screws as SAE Grade 5.
Is A307 Grade A the same as Grade 5?
No. A307 Grade A and SAE Grade 5 are different fastener designations. Do not treat them as interchangeable.
Which listed option includes washers?
The Makers Bolt 3/8 x 5 kit includes 50 lag screws and 50 USS flat washers.
Which listed products specify a T30 star bit?
The LIONMAX and BNUOK listings specify T30 star-drive installation; BNUOK also states that a T30 bit is included.