In general terms, joists spaced 16 inches on center **can span** 1.5 times in feet their depth in inches. A **2×8** up to 12 feet; **2×10** to 15 feet and 2×12 to 18 feet.

Also, How far can a triple 2×6 beam span?

A **triple 2×6 beam** over a **span** of 10′ feet should be more than sufficient for normal deck loads.

In this way, What size lumber can span 20 feet?

**20**foot clearspan beam

**size**

In that case, you need something like a 12-16″ GLULAM or LVL to **span** the **20**‘ and **can** use simple 2×8-10 dimensional **lumber** 16″OC as floor joists.

**20 Related Questions Answers Found**

Table of Contents

**How far can you span a 2×6?**

Joist Spacing (o.c.) | 12″ | |
---|---|---|

Species | Size | Allowable Span |

Southern Pine | 2×6 | 9′-11″ |

2×8 | 13′-1″ | |

2×10 | 16′-2″ |

**How far can you span a 2×6 ceiling joist?**

**Joist** spacing of 24 inches is allowed for **spans** between 16 to 20 feet using 2-inch by 10-inch lumber of these three grades.

**How far can a 2×6 Rafter span without support?**

The table states that 2 X 6 **rafters** spaced 16 inches on center (o.c) **can span** a maximum **distance** of 13 feet 5 inches. Another option are 2 X 8 **rafters** spaced 24 inches o.c.

**What is the maximum span for a 2×6 floor joist?**

Maximum Span (ft – in) | ||
---|---|---|

Nominal Size (inches) | Joist Spacing Center to Center (inches) | Lumber Grade |

2 x 8 | 12 | 15′ – 10″ |

16 | 14′ – 5″ | |

24 | 12′ – 4″ |

**How far can you cantilever a 2×6 deck joist?**

Looking at the table below, **we** see that **2×6** floor **joists can** be cantilevered up to 2 feet and 6 inches (2′-6″) when the **joists** are spaced 16″ apart.

**How many footings do I need for a 10×10 deck?**

For our 12 x 12′ **deck**, we’ll use 12” round **footings**. Based on the dimensions in our example, the 12 x 12′ attached **deck** will need three 12” diameter **footings**, plus at least two more if you’re planning on building stairs.

**What size joist to span 20 feet?**

Maximum Span (ft – in) | ||
---|---|---|

Nominal Size (inches) | Joist Spacing Center to Center (inches) | Lumber Grade |

2 x 10 | 12 | 20′ – 3″ |

16 | 18′ – 5″ | |

24 | 15′ – 0″ |

**How far can a double 2×8 span?**

**How much weight can 2×10 floor joists hold?**

-Firit need not be Doug. Fir-Larch. In fact, each **2×10 will** support 1,200 lbs. To be clear, spans are measured as “clear spans”.

**Can I use deck pier blocks instead of footings?**

A **deck pier block** is in many ways just a simplified version of a “precast foundation”, a foundation type recognized by building codes. They’re subject to all of the same requirements as a typical **footing**, regardless of not being cast-in-place. The small bearing area of **pier blocks** is limited in supporting much load.

**How far can a 4×6 span without support?**

Obviously, the larger the beam, the greater the **distance** it **can span** between posts. A Redwood **4×6** beam should **span** no more than 6′ between **supporting** posts.

**How far can a 2×8 deck joist cantilever?**

If the code span tables allow a **2×8** to span 12 feet, then the **cantilever can** be 3 feet.

**How many screws go in a 2×6 deck?**

The basic rule of thumb here is 350 **screws** for every 100 square feet of **deck** surface for standard 6” wide boards (5.5” actual width) and 16” spaced joists. If you aren’t using these standard sizes, use an online **deck** calculator to determine **how many** you’ll need.

**How far can a 4×6 span without support?**

Obviously, the larger the beam, the greater the **distance** it **can span** between posts. A Redwood **4×6** beam should **span** no more than 6′ between **supporting** posts.

**Do you need pressure treated wood for a deck?**

According to the new span tables and IRC provisions, cantilevers **can** extend up to one-fourth the backspan of the **joist**. This means that **joists**, such as southern pine 2x10s at 16 inches on-center, spanning 12 feet are allowed to **cantilever** up to an additional 3 feet (see illustration, below).

**Do you need pressure treated wood for a deck?**

**Wood** is the usual material **used for decking**. The **lumber should** be pressure treated to avoid rot and decay. Some of the most common **wood used** are cedar, redwood, fir and pine. There are **decks** that **use** concrete posts for support but **wooden** posts are the usual.

**Should you countersink deck screws?**

If **you** are face-driving **deck screws**, it is acceptable to “self-**countersink**” them. Some **deck screws** even have a little cutter head built into the **screw**, to facilitate **countersinking**.

**How much weight can a 2×4 deck hold?**

A 10 foot long **2×4** carrying a uniform **load** of 40 pounds per foot (400 lbs total **load**) **will** have a maximum bending moment at the center of the span of 1000 ft-lbs.

**How wide is a 2×6?**

Same for 1×4, 2×4 and 4×4 etc. Actually, the nominal **size** is often never the actual **size**. 1×4 are 3/4″ x 3–1/2″, 2×4 are 1–1/2″ x 3–1/2″. Again, **2×6** are 1–1/2″ x 5–1/2″.

**What is the gap between decking boards?**

**SPACING BETWEEN DECK BOARDS**

Ensure there is a minimum **gap** of 5-6mm **between** each **deck board**.

**How far apart do footings need to be for a deck?**

For our 12 x 12′ **deck**, we’ll use 12” round **footings**. Based on the dimensions in our example, the 12 x 12′ attached **deck** will need three 12” diameter **footings**, plus at least two more if you’re planning on building stairs.

**Will pressure treated wood expand?**

Regular **pressure treated wood** tends to be somewhat wet when it’s new. That means, as it weathers in the sun and the heat, it **will** dry out some and shrink slightly. In this case, some space between the boards is a good idea because the **wood can** actually **expand** slightly over time.

**What size wood do you use for decking?**

For the **deck** surface, **you can use** 2x4s, 2x6s, or 5/4x6s. The 5/4 **decking** (pronounced “five-quarter”), available in cedar and pressure-treated fir, is 1 inch thick and 5-1/2 inches wide with rounded edges that make for a splinter-free surface. Cedar 1x **lumber** usually has one rough side and one smooth side.

**What size wood do you use for decking?**

**Pressure**–**treated lumber** is the logical choice for the structural part of your **deck**—the posts, joists, beams and other members **you** normally don’t see. **Pressure**–**treated lumber** can support more weight and span longer distances than cedar, redwood or other woods commonly used for building **decks**.

**Should I stain deck joists?**

It is not necessary to **stain** the underside of your **deck** for protection from the elements, especially if you use pressure-treated wood, which helps keep wood-boring insects out.

**How much weight can a 2×8 joist hold?**

some of it gets pretty technical in nature, and mostly relates to pounds / square foot of loading. 2x6s are generally used for ceiling **joists**, esp since you said 24″ oc and reallllly short spans only (5 or 6 feet ). Most floor loads would be a minimum of **2×8** @ 16″ oc and most preferbaly 2×10.

**Which direction should deck boards run?**

A **board** that is correctly installed right side up (or bark side down) will form a crown and allow water to **run** off the edges. If the **board** is installed wrong side up (or bark side up) it will curve up on the edges when dry and water can gather and sit in the cup. That is a recipe for wood rot and problems.

**How far can I span a double 2×8?**

No, you cannot **span** 23 feet with conventional lumber, even doubled. It’ll be as bouncy as a trampoline and won’t meet code, and that’s if you **can** find such lengths. You’ll need at least a 12″ (nominal) I-joist or an engineered floor truss to **span** that **far**, or you’ll need an LVL or steel beam midway.

**How many footings do I need for a 10×10 deck?**

some of it gets pretty technical in nature, and mostly relates to pounds / square foot of loading. 2x6s are generally used for ceiling **joists**, esp since you said 24″ oc and reallllly short spans only (5 or 6 feet ). Most floor loads would be a minimum of **2×8** @ 16″ oc and most preferbaly 2×10.

**Can you use a 2×4 as a joist?**

**2×4** are fine if span was like under 5 ft. If the span was say 4 or 5 feet (max.) **2×4** are suitable for ceiling **joists** where the LL is like 20 Lbs. If **you** got a good species with the highest Modulus of Elasticity and Best grade and **use** like 12″ o.c. – **you** might get 8” span.

**Can I build a deck out of 2×4?**

For our 12 x 12′ **deck**, we’ll use 12” round **footings**. Based on the dimensions in our example, the 12 x 12′ attached **deck** will need three 12” diameter **footings**, plus at least two more if you’re planning on building stairs.