The size of a ridge beam needed for a 24′, 22′, 20′, 18′, 16′, 12′ and 10-foot span depends on several factors, including the type and load of the roof, snow load, dead load, live load, local building codes & regulation, roof pitch, design and construction requirement.

A ridge beam is a horizontal structural member that runs along the peak of a roof, providing support for the roof rafters and helping to distribute the weight of the roof to posts evenly. To determining the appropriate ridge beam size you should consider various factors.

A ridge beam in construction provides support and stability to the roof structure by connecting the tops of opposing roof slopes. It helps distribute the weight of the roof and prevents sagging or spreading of the walls.

**Here’s is the general guideline for ridge beam size and their span for Douglas Fir lumber:-**

- For a 24 foot span:- The size of a ridge beam for a 24-foot span need to be 3-1/2″×16″, made of Glulam or LVL or engineered wood or 4-2×16 dimensional lumber
- For a 20 to 22 foot span:- The size of a ridge beam for a 20 to 22-foot span need to be 3-1/2″×14″, made of Glulam or LVL or engineered wood, or 4-2×14 dimensional lumber
- For a 18 foot span:- The size of a ridge beam for a 18-foot span need to be 4-2×12, made of dimensional lumber or wood
- For a 14 to 16 foot span:- The size of a ridge beam for a 14 to 16-foot span need to be 3-2×12, made of dimensional lumber or wood
- For a 12 foot span:- The size of a ridge beam for a 12-foot span need to be 2-2×12, made of dimensional lumber or wood
- For a 10 foot span:- The size of a ridge beam for a 10-foot span need to be 2-2×10, made of dimensional lumber or wood
- For a 28 foot span:- The size of a ridge beam for a 28-foot span need to be 4-2×18 dimensional lumber or wood or 5-1/4″×14″ Glulam or LVL
- For a 30 foot span:- The size of a ridge beam for a 30-foot span need to be 4-2×20 dimensional lumber or wood or 5-1/4″×16″ Glulam or LVL.

**What size ridge beam do i need to span 30′, 28′, 24′, 22′, 20′, 18′, 16′, 12′ and 10-foot**

Determining the size of a ridge beam for a span depends on various factors, including the type of wood, local building codes, and the load it needs to support.

In general, the size of ridge beam needed to span a 30-foot should be 4-2″×20″ lumber, while the size of ridge beam needed to span a 24-foot should be 4-2″×16″ lumber. Likewise, the size of ridge beam needed to span a 18-foot should be 4-2″×12″ lumber, while the size of ridge beam needed to span a 16-foot should be 3-2″×12″ lumber. In addition, the size of ridge beam needed to span a 12-foot should be 2-2″×12″ lumber, while the size of ridge beam needed to span a 10-foot should be 2-2″×10″ lumber.

**What size ridge beam do i need for a 24-foot span**

The size of the ridge beam needed to span a 24 foot should be 16 inches deep and 8 inches wide. So, you would need something like 4-2″×16″ size of wood ridge beam or 3-1/2″×16″ size of engineered lumber (LVL, Glulam) for a 24 foot span used for residential application.

**What size ridge beam do i need for a 20-foot span**

The size of the ridge beam needed to span a 20 foot should be 14 inches deep and 8 inches wide. So, you would need something like 4-2″×14″ size of wood ridge beam or 3-1/2″×11-7/8″ size of engineered lumber (LVL, Glulam) for a 20 foot span used for residential application.

**What size ridge beam do i need for a 28-foot span**

The size of the ridge beam needed to span a 28 foot should be 18 inches deep and 8 inches wide. So, you would need something like 4-2″×18″ size of wood ridge beam or 5-1/4″×14″ size of engineered lumber (LVL, Glulam) for a 28 foot span used for residential application.

**What size ridge beam do i need for a 30-foot span**

The size of the ridge beam needed to span a 30 foot should be 20 inches deep and 8 inches wide. So, you would need something like 4-2″×20″ size of wood ridge beam or 5-1/4″×16″ size of engineered lumber (LVL, Glulam) for a 30 foot span used for residential application.

**What size ridge beam do i need for a 16-foot span**

The size of the ridge beam needed to span a 16 foot should be 12 inches deep and 6 inches wide. So, you would need something like 3-2″×12″ size of wood ridge beam or 3-1/2″× 9-1/2″ size of engineered lumber (LVL, Glulam) for a 16 foot span used for residential application.

**What size ridge beam do i need for a 18-foot span**

The size of the ridge beam needed to span a 18 foot should be 12 inches deep and 8 inches wide. So, you would need something like 4-2″×12″ size of wood ridge beam or 3-1/2″× 11-7/8″ size of engineered lumber (LVL, Glulam) for a 18 foot span used for residential application.

**Conclusions:-**

The size of a ridge beam for a 24-foot span need to be 3-1/2″×16″ engineered wood, a 3-1/2″×14″ for a 20-foot span, a 4-2×12 for a 18-foot span, a 3-2×12 for a 16-foot span, a 2-2×12 for a 12-foot span, a 2-2×10 for a 10-foot span, and a 5-1/4×16 size ridge beam for a 30-foot span.