## What is the maximum span for a 2×8 ceiling joist?

A rule of thumb is 1.5 times a joist’s depth but in feet when spaced at 16” centers. In general, a 2×8 will span 1.5 x 8, so **12-feet**.

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

2-grade 2×6 joists can span up to **10 feet 9 inches** from beam to beam when spaced the standard 16 inches apart with a maximum live load of 30 inches per square foot. In comparison, No. -1 grade lumber can span slightly further to 10 feet 11 inches under the same parameters.

## What size joists should I use?

Commonly used joist sizes are **2-by-6, 2-by-8 and 2-by-10**. For example, when you space joists 16″ apart — which is standard for residential decks — a deck spanning 9 1/2′ would require 2-by-6 joists, a 13′ deck would need 2-by-8 joists and a 16′ deck calls for 2-by-10 joists.

## How do you determine the number of joists required?

For example, assume the clear span is 15 feet 6 inches. **Round up to 16 and divide this span by 2, giving you 8.** **Next, add 2 to get the required joist depth**. In this example, 8 + 2 = 10, so a 2×12 floor joist will be required (it’s important to use the actual lumber dimensions, not the nominal dimensions).

## Can I use 2×8 for deck joists?

**2×8 for joists will be fine, with 16″ OC**. Should use 2×10 for beams but 2×8 will be fine as well. If you are worried you can triple the 2×8 for the beams but double will be sufficient. You should put the beams at 7 and 14 feet out from the house, with the piers you should do 3 per beam with spacing of 1, 7, 13.

## What will a 2×10 span?

How Far Can a 2×10 Beam or Header Span? A 2×10 beam – made up of two 2x10s nailed together – can span **up to 11′** without support beneath a deck that is 4′ wide. For a more normal-sized deck, the same beam can span 8′, supporting a deck that is 8′ wide.

## Are 2×6 OK for floor joists?

**2x6s may be used for floor joists, ceiling joists, or rafters** and have differing spans for the same grades and species. Loads are divided into live or snow loads and dead load considerations. A plank used for a floor joist commonly has different load factors than a ceiling joist or rafter.

## Are 2×6 strong enough for deck joists?

**You can use 2×6 as deck joists if the deck is low enough to the ground as not to require guard railing**. When using S-P-F 2×6 deck joists, the span must not be greater than 9’0″ (2.73m) with joists at 16″ o.c. (400mm), and 9’10” (3.01m)with spacing at 12″ (300mm).

## Should deck joists be 2×6 or 2×8?

For upper-level decks, **2×10 is recommended as the minimum size to use for strong guard post connections**. 2×6 joists should only be used on ground-level decks that do not require, and will not provide for, any guards.

## How many joists is 16 feet?

**Nine joists** will be needed for the 16-foot width.

## How many joists is 12 feet?

A 12-foot long deck with joists 16 inches on center will require **10 joists**.

## What size joist do I need for a 12 foot span?

Thus you will need a **2×6 (2-by-6)** size of floor joists for 12 foot span at standard 12 inches spaced.

## How long can joists be without support?

The maximum span for a floor joist that needs to support a 40 psf live load would be **just over 23′**.

## How far can 2×8 span 12?

Max. Live Load 30 lbs/ft2 (1436 N/m2)

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

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

2 x 10 | 24 | 15′ – 0″ |

2 x 12 | 12 | 24′ – 8″ |

16 | 21′ – 4″ |

## How far can a 2×12 span for floor joist?

A 2×12 (2-by-12) floor joists can span up to **23 feet 3 inches**, 2×10 (2-by-10) up to 19 feet 1 inches, 2×8 (2-by-8) up to 15 feet & 2×6 (2-by-6) up to 11 feet 4 inches at 16″ spaced by using southern yellow pine graded as #1 when live load of 30 lbs/ft^2 & dead load of 10 lbs/ ft^2.

## How big of a beam do I need to span 20 feet?

For a 20-foot spans, the wood beam has to be **at least 16 inches in depth and 8″ in width** (4-2×16) used for residential building or projects.

## How big of a beam do I need to span 16 feet?

For a 16 foot span, you will need atleast **3-2×14 or 6×14** size of wood beam. Thus, a 3 nailed 2×14 or 3-2×14 or 6×14 wood beam can allow to span 16 feet. For a 16-foot spans, the wood beam has to be at least 14 inches in depth and 6″ in width (3-2×14) used for residential building, wood frame structure or projects.

## Do floor joists have to sit on a beam?

Floor joists spread the loads bearing from above, and must be framed adequately to complete the load paths. Ideally, **if a load-bearing wall runs parallel to floor joists, then it should sit directly over a beam** or a joist supported by a load-bearing wall below.

## Do walls sit on joists?

**All exterior walls are bearing walls**. They support the roof at the ends of the joists. The interior bearing walls support the floors above and the attic weight. They support the joists at midpoint.

## Should I use treated lumber for floor joists?

Generally, building codes require pressure-treated or naturally durable wood for the following applications: **Joists or the bottom of structural floors without joists that are within 18″ of exposed soil**. Beams or girders closer than 12″ to exposed soil.