How much weight can a 4x6 support


  • 4×4 vs 6×6 Deck Post: Which is Better?
  • Sleepyhead™ Original - Orthopedic Memory Foam Mattress
  • Lumber Weight & Volume Calculator for Any Wood Species
  • Calculate the Weight of Wood
  • Question: How Much Weight Can A 4×6 Beam Support?
  • 4×4 vs 6×6 Deck Post: Which is Better?

    Print What to look for when calculating deck load. As homeowners enter the summer months, many are looking into DIY projects that will allow them to upgrade their outdoor living space.

    The answer you give a customer will never be as simple as just telling the customer that their deck can hold 2, pounds. The primary reasons that a customer may want to learn more about the weight load of their deck has to do with the current trends toward outdoor living.

    Many customers nowadays are looking at adding a hot tub to their deck, or an outdoor kitchen space complete with appliances.

    Of course, there are regional factors at play as well. Where I live and work, in the Minneapolis area, we need to build decks to support 50 lbs. To support 50 lbs. Well, since none of us weigh 10 lbs.

    Also look up in your building code book, or ask your local inspectors for a chart that shows the species of wood that you want to use.

    How close together you place the joists also plays a role. So, you have to put this together as an entire package and find out why the customers are asking the question. And, pardon the pun, but boards are only the surface of the issue. You also have to factor in joist hangers, fasteners, footings, and soil.

    You can make your joists able to hold thousands of pounds of weight and your footings could sink into the ground. As you can see, the answer to the question is far more than just how much weight can a deck hold. The best thing you can do is to consult your local building codes and utilize resources available to you such as NADRA.

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    There are many terms that have different meanings, and span is one such word. Span, in construction, means the distance a structural member traverses from support to support. It is measured from the center of one support to the center of the next. The span differs, however, if it is horizontal like a joist or beam, or diagonal for rafters.

    Loads limit joists to shorter spans than rafters of the same grade and species. Rafters span greater distances from support center to support center, but the horizontal distance from centerline to centerline is often the same as that of a joist.

    To add to the confusion, there is the effective span which is measured from the center of one support to the center of the next support. The clear span is the space between adjacent support faces. Plus, there is the free span or long span that commonly refers to structures without intermediate internal supports, so all loads are carried on exterior walls. This provides larger unobstructed spaces or rooms.

    Hockey arenas, gymnasiums, and airplane hangars are examples of long span construction. The allowable distances it can span without support are identified in National, State, Provincial, and Local Building Codes. Wood species and grade identify strength, which in turn determines load capacities and deflection over distance.

    Location frequently has load variables too. 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. Floor joists may support drywall ceilings on the underside and marble tile and furniture on the top, which are all factors affecting the dead load.

    People and animals are live load factors, and snow can be a separate load consideration or part of the live load. Spacing between joists and rafters contributes to load variables too. The location of the weight in relation to any supports or span needs to be considered too. The distribution of weight with other support members, bracing, and sheathing, plus the duration the weight is carried are also determining factors.

    On an 8-foot span, that would be about 30 pounds in one location before bending beyond acceptable deflection values. Span increases as the spacing decreases but it decreases as loads increase. The grade and wood species also determine how far the joist can span. The required span, spacing between floor joists, and load requirements often determine the dimensional lumber used.

    Always check the current local building code for span values. Drywall and plaster are two common ceiling finishes and affect dead load differently. A dead load of 5psf is common for drywall while plaster generates a dead load of 10psf.

    Ceiling joists without living or storage above commonly have a dead load of 5psf and a live load of 10psf. Attics with some storage have a dead load of 10psf and a live load of 20psf.

    If the attic has a living or sleeping space, then the ceiling joists become floor joists and must be spanned accordingly. Ceiling joists should be continuous or properly joined above interior walls according to the codes. They should also connect to rafters at the top plate when run parallel to the rafters and fastened to the top plate if not parallel.

    A rafter span is measured from the center of the ridge or ridge beam to the outside face of the supporting top plate, or the outer edge of the birdsmouth or cleat.

    How far a rafter can span is determined by the wood species and grade, spacing between rafters, and the loads it must support. The load includes factors such as whether the ceiling is finished or not, weight of roofing asphalt vs metal vs slate vs tile , wind loads, and snow or live loads. The span decreases as the spacing and load increase and is dependent on the type and grade of timber.

    The stronger the species and higher the grade, the farther it can span. Roofs with lightweight roofing and no ceiling commonly have a dead load rating of 10psf and those with heavy roofing are rated at 20psf. However, rafters with light-weight roofing and a drywall ceiling have a dead load of 15psf while a plaster ceiling is 20psf. Heavy roofing changes the dead load rating to 25psf and 30psf respectively. Decking is the material that spans and fastens to the joists upon which you walk and place furniture.

    Interior decking today is usually plywood or OSB. Loads affect joist spacing and span which also impact decking choice. Hot tubs require additional support, so always reference your local building code when building a deck. Pressure-treated lumber is often made from the most available local rated material, which in my area is SPF spruce-pine-fir. Joist spans for exterior decking differ from interior spans of equivalent species and grades too. Most decks are rated for a 10psf dead load and a 40psf live load, or a total load of 50psf.

    Exterior decks are commonly rated for a live load LL of 40psf and a 10psf dead load DL , for a 50psf total load. The wood species, grade, and spacing between joists determine the distance a joist can span.

    The building code span tables for deck joists include the cantilever distance. The cantilever is how far a plank can extend beyond the beam without support.

    It should be noted that deck joists span shorter distances than interior joists with equivalent factors. So, make sure to reference the correct span tables. Beams support the joists, decking, and furnishings on the deck, known as the dead load DL , and people, pets, and snow, known as the live load LL. Beam construction, dimensions, and spans are all addressed in the building code. Beam span is also determined by the deck joist span.

    Increasing the joist span decreases the beam span, so always check the codes. Headers are specialized beams over window and door openings in wall framing that support and transfer loads above them to other structural members below. Location and load are the main determining factors in the header span. The span differs for headers in interior and exterior walls and is affected by the building width, number of floors, floor structure and support, and snow load. In most cases, as the building width and number of floors increase, the header span decreases, so check the building code.

    Building width and the number of floors are the main factors that affect header spans for interior walls. Realistically, it would be easier and probably cheaper to substitute a double or triple header of greater dimensional lumber.

    To ensure the span is compliant with the code, always reference the building code, your local building department, or a Structural Engineer. Leave a Comment.

    Lumber Weight & Volume Calculator for Any Wood Species

    Also look up in your building code book, or ask your local inspectors for a chart that shows the species of wood that you want to use. How close together you place the joists also plays a role. So, you have to put this together as an entire package and find out why the customers are asking the question.

    And, pardon the pun, but boards are only the surface of the issue. You also have to factor in joist hangers, fasteners, footings, and soil. You can make your joists able to hold thousands of pounds of weight and your footings could sink into the ground. Interior decking today is usually plywood or OSB. Loads affect joist spacing and span which also impact decking choice. Hot tubs require additional support, so always reference your local building code when building a deck.

    Calculate the Weight of Wood

    Pressure-treated lumber is often made from the most available local rated material, which in my area is SPF spruce-pine-fir. Joist spans for exterior decking differ from interior spans of equivalent species and grades too. Most decks are rated for a 10psf dead load and a 40psf live load, or a total load of 50psf.

    Exterior decks are commonly rated for a live load LL of 40psf and a 10psf dead load DLfor a 50psf total load. The wood species, grade, and spacing between joists determine the distance a joist can span. The building code span tables for deck joists include the cantilever distance. The cantilever is how far a plank can extend beyond the beam without support.

    It should be noted that deck joists span shorter distances than interior joists with equivalent factors. So, make sure to reference the correct span tables.

    Beams support the joists, decking, and furnishings on the deck, known as the dead load DLand people, pets, and snow, known as the live load LL. Beam construction, dimensions, and spans are all addressed in the building code. Beam span is also determined by the deck joist span. Increasing the joist span decreases the beam span, so always check the codes.

    Headers are specialized beams over window and door openings in wall framing that support and transfer loads above them to other structural members below. Location and load are the main determining factors in the header span. The span differs for headers in interior and exterior walls and is affected by the building width, number of floors, floor structure and support, and snow load. In most cases, as the building width and number of floors increase, the header span decreases, so check the building code.

    Building width and the number of floors are the main factors that affect header spans for interior walls. Realistically, it would be easier and probably cheaper to substitute a double or triple header of greater dimensional lumber. Concentric compression forces are vertical or axial and pass through the axis of the post — top to bottom.

    Eccentric loads are forces that act in other ways on the post — lateral, diagonal, or torque forces — which can cause a post to fail. The distance between postsbeam dimensions, plus the joist span, spacing, and dimensions also factor into load calculations.

    However, for most decks, 50psf is a safe load value.

    Question: How Much Weight Can A 4×6 Beam Support?

    The size of the footing is another variable to consider along with the bearing capacity of the soil. The type of wood and length of post influence how much it will support before snapping. Another factor is the tributary area of the deck being carried by a post. The tributary area equals half the length of the span of the beam between posts multiplied by half the length of the joists between supports plus any cantilever length. Posts at the end of a beam carry less than the posts in the middle of a beam or deck, so the middle posts may need to be thicker than the end posts.


    How much weight can a 4x6 support