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Old 12/22/07, 7:42 PM
Bruce A. King's Avatar
Bruce A. King Bruce A. King is offline
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Default Max load allowed on 2x2 ledger

I see decks at times with the joists running parallel with the house.

The center of the deck has a girder (perpendicular to the house) with the joists connected to both sides.

The girder rests on a post at the rear but only has a 2x2 ledger (with 3- 16d nails under the girder) at the house end.


If the deck is 10x20, the tributary load area on that half of the girder is exactly 50sf. If the deck needs to handle 50psf total, this puts 2500 lbs as a point load on the 2x2 ledger.

I say this is incorrect but don't have any 2x2 ledger specs to prove it.

Anyone have any data for this?



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  #2  
Old 12/22/07, 8:57 PM
Marcel R. Cyr, CMI's Avatar
Marcel R. Cyr, CMI Marcel R. Cyr, CMI is offline
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Default Re: Max load allowed on 2x2 ledger

Quote:
Originally Posted by bking
I see decks at times with the joists running parallel with the house.

The center of the deck has a girder (perpendicular to the house) with the joists connected to both sides.

The girder rests on a post at the rear but only has a 2x2 ledger (with 3- 16d nails under the girder) at the house end.


If the deck is 10x20, the tributary load area on that half of the girder is exactly 50sf. If the deck needs to handle 50psf total, this puts 2500 lbs as a point load on the 2x2 ledger.

I say this is incorrect but don't have any 2x2 ledger specs to prove it.

Anyone have any data for this?
Bruce;

I think eliminating the guess work, unless a structural engineer dose the calculations, I would recommend using the proper ledger and girder attatchment to the house using the proper Simpson beam hangers. It takes all the guess work out of the equation. If you know what I mean.

5 Steps to a Safer, Stronger Deck


Download Deck Framing Connection Guide
This guide provides step-by-step information on how to make your deck safe, secure and code compliant. You can download and print a PDF of the guide or request a copy by mail.
Download 5 Steps for a Safer and Stronger Home - Decks (PDF)
Also see:
What you need to know to make your deck strong and safe.
  1. <LI style="PADDING-BOTTOM: 10px">Check Out Your Deck
    The first step in making your deck safe is knowing that it may not be. Decks are potentially the most dangerous part of the house, according to some experts. Factors, such as improper construction, exposure to the elements and lack of maintenance can make your deck unsafe. It’s important to look for the warning signs: missing or loose connections, corrosion, rot and cracks. If you are unsure about the safety of your deck, consult with a professional such as a structural engineer or contractor. <LI style="PADDING-BOTTOM: 10px">Carry the Weight
    For most homeowners, the deck is a popular gathering place for friends and family. Like a house, a deck must be designed to support the weight of people and objects placed on it as well as the forces of Mother Nature like wind, snow and earthquakes. Knowing how weight and other forces can affect the safety of your deck is important. There are three types of forces that put pressure on your deck, causing strain to the critical connections that keep it together:
    • Gravity – downward pressure typically caused from people standing on the deck or from snow and ice.
    • Lateral – a back and forth (horizontal) motion caused by people walking on the deck and/or leaning on a railing. Wind and earthquakes can also create lateral movement.
    • Uplift – wind flows under the deck creating a lifting effect. People standing on the overhang of the deck also creates upward pressure on the connection that attaches the deck to the adjacent support structure (typically your home).
    <LI style="PADDING-BOTTOM: 10px">Create a Path
    A continuous load path, that is. A continuous load path is a method of construction that creates a series of solid connections within the structure of the deck that transfers load through its frame to the ground and adjacent support structure (commonly your home). If your deck is built with a continuous load path, it will be better equipped to resist the forces that can weaken your deck. <LI style="PADDING-BOTTOM: 10px">Combat Corrosion
    Decks and the metal connectors that keep them connected and safe are exposed to the elements. Over time, metal connectors, screws and nails can corrode and weaken the structure of your deck, especially if the right product is not used. If you live in an area prone to moisture, such as along the coast or near bodies of water, the risk of corrosion is much higher. Chemicals in pressure-treated woods and other corrosive elements can also damage your deck. Using connectors, screws and nails that are made from stainless steel is the best way to combat corrosion. When choosing connectors, take into account where you live and how weather and the environment may affect your deck. For critical information about corrosion and connector selection, click here.
  2. Maintain a Safe Deck
    Just like other parts of your home, regular maintenance and inspection are required. To prolong the life of your deck, you need to check for things like loose boards or protruding nails. You should also keep your deck clean from debris and depending on type of deck boards used, keep them sealed to protect against water and sun damage.
Next: Is Your Deck Unsafe? Look for the 5 Warning Signs...

Just a little information for you to use.

Merry Christmas

Marcel



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  #3  
Old 12/23/07, 12:17 AM
Barry Adair's Avatar
Barry Adair Barry Adair is offline
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Default Re: Max load allowed on 2x2 ledger

Bruce,

I concur with McHammer.............
I find it hard to believe, afterthought, not really, anyone would even conceive this being OK.

Sure would like to see detail photo(s) of this install



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Old 12/23/07, 6:51 AM
Richard A. Hetzel Richard A. Hetzel is offline
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Default Re: Max load allowed on 2x2 ledger

The ledger construction was used decades ago, before the introduction of joist hangers. The joists are not fully supported by the ledger, because they are also toe-nailed into the structure, Neither toe-nails or the 2x2 ledger can carry the full load, but together they barely manage to work. The method should no longer be used, but is still found on older decks.

However, supporting a GIRDER only on the 2x2 ledger is...well, a little nuts. There are specifications for the amount of load a particular nail size will hold. I can't put my finger on them at the moment, but there are other problems, such as bearing surface...2500 pounds on 1 1/2 x 1 1/2 inches is over 1100 psi.

Last edited by Richard A. Hetzel; 12/23/07 at 7:00 AM..
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Old 12/23/07, 2:05 PM
Marcel R. Cyr, CMI's Avatar
Marcel R. Cyr, CMI Marcel R. Cyr, CMI is offline
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Default Re: Max load allowed on 2x2 ledger

Addittional information to the subject.

Floor Framing and Connections

Fasteners & Connections
Sill Plates
Sill Beams
Beams & Girders
Floor Joists
Notching & Boring of Joists
Subflooring
Framing of Floor Openings
Support of Partitions
Framing Details
Floor framing consists of a system of sills, beams, girders, joists, and subflooring, all properly sized and connected together. Floor framing provides support for floor loads, and gives lateral support to exterior walls.

Fasteners and Connections

Proper design, specification, and installation of fasteners and connections is crucial to the long-term performance and structural integrity of any structure. Nails, used alone or in combination with metal framing anchors and construction adhesives, are the most common method of fastening framing lumber and sheathing panels. Nail joints provide best performance when loads are applied at right angles to the nails. Nailed joints with the load applied parallel to the nail (in withdrawal) should be avoided. Metal products in contact with pressure-treated wood must be corrosion resistant. See the Advisory on Fasteners and Connectors for Treated Wood.

Sill Plates on Foundation Walls

Sill plates resting on continuous foundation walls (stem walls) are generally of nominal 2x4 or 2x6 pressure-treated lumber. They are anchored to concrete, masonry, or wood walls with steel anchor bolts or proprietary metal anchor straps. The required size and spacing of the bolts or straps is dependent upon the forces acting on the building.

Typically, 1/2"-diameter anchor bolts are placed within 12" from each end of the sill plate and then spaced a maximum of 6' on center. These bolts are usually embedded at least 7" in concrete or masonry (15" in masonry for uplift loads). Proprietary metal anchor straps providing equivalent anchorage may also be used in lieu of anchor bolts. Closer anchor bolt spacing and/or a larger bolt diameter may be required in seismic design categories D1 and D2 and where the design wind speed exceeds 110 mph. Consult the ANSI/AF&PA Wood Frame Construction Manual from the American Wood Council or your local building code official for specific anchorage requirements.

Sill Beams on Piers or Piles

Sill beams supported by freestanding piers or piles must be of adequate size to support imposed loads between piers. They must also be adequately attached to the supporting piers. In addition, sill beams must be preservative treated if bearing on concrete or masonry, or if closer than 12" to exposed soil.

Sill beams are generally of solid-sawn lumber (typically 4x6) or timbers (typically 6x6 or 6x, or glued-laminated timber.

Beams and Girders

Beams and girders are generally of solid-sawn lumber or timbers, glued-laminated timber, or structural composite lumber. They can also be built-up (nail-laminated) with multiple pieces of nominal 2" lumber nailed together with the wide faces vertical. These multiple pieces should be nailed together with two rows of 20d nails — one row near the top edge, and the other near the bottom edge. Nails in each row are spaced 32" apart. End joints of the nailed lumber should occur over the supporting column or pier.

Beams and girders must be adequately attached to supports, and should be tied together across supports if they are not continuous members. Beams and girders must be preservative treated if entering exterior masonry or concrete walls without a minimum 1/2" air space on top, sides and end, or if closer than 12" to exposed soil.

The allowable load tables provide maximum pounds per lineal foot (plf) and required bearing lengths for the following Southern Pine beam and girder options:
  • Solid-sawn, heavy dimension lumber or timbers (Table 12)
  • Glued-laminated timber (Table 13)
  • Nail-laminated, built-up lumber (Table 14)
For additional information, refer to the SPC publication, Southern Pine Headers & Beams.

Floor Joists

Floors are commonly framed with solid-sawn lumber, floor trusses, or wood I-joists. Joist end-bearing should not be less than 1-1/2" on wood or metal, or 3" on masonry. Joists are usually attached to sills by toe-nails or by metal framing anchors. Table 10 provides the typical nailing schedule for floor framing, while Figure 17 illustrates floor framing connections. Floor joists must be preservative treated if closer than 18" to exposed soil.

Table 10 Nailing Schedule for Floor FramingJoint DescriptionNumber and Size
of Common Nails Nail Spacing Joist to Sill, Top Plate or Girder (toe-nailed)4- 8dper joist Bridging to Joist (toe-nailed)2- 8deach end Blocking to Joist (toe-nailed)2- 8deach end Blocking to Sill or Top Plate (toe-nailed)3- 16deach block Ledger Strip to Beam (face-nailed)3- 16d each joist Joist on Ledger to Beam (toe-nailed)3- 8dper joist Band Joist to Joist (end-nailed)3- 16d per joist Band Joist to Sill or Top Plate (toe-nailed)2- 16d¹per joist Source: Wood Frame Construction Manual, 2001 Edition, American Wood Council, Table 3.1.
1 Nailing requirements are based on wall sheathing nailed 6" on-center at the panel edge. If wall sheathing is nailed 3" on-center at the panel edge to obtain higher shear capacities, nailing requirements for structural members shall be doubled, or alternate connectors, such as shear plates, shall be used to maintain the load path.

Joists should be placed so the top edges provide an even plane for the subfloor and finish floor. See Tolerances and Techniques for Flat Floors. Preferably, joists should be attached to the sides of girders as shown in Figure 22, Figure 23 and Figure 25. This will reduce the cumulative amount of shrinkage as lumber dries to its in-place moisture content.


Construction adhesive is applied to floor joists before subfloor sheathing is installed. Gluing improves floor stiffness, reduces floor vibration, and helps eliminate squeaks.Proper alignment of the upper edges of floor joists is maintained by adequately nailed subflooring. Nailing the ends of joists to band joists or headers provides additional joist support. These typical construction techniques usually eliminate the need for intermediate bridging. Where the nominal depth-to-thickness ratio of lumber joists exceeds six, intermediate bridging is installed at 8' intervals. Bridging may be accomplished with solid 2" blocking or 1x4 cross braces as illustrated in Figure 17, and helps reduce floor vibration. See Reducing Floor Vibration.

The Span Tables — Floor Joists and Trusses provide maximum allowable spans for the following Southern Pine joist options:For additional information, refer to the SPC publication Maximum Spans for Southern Pine Joists & Rafters, Span Tables for Joists and Rafters from the American Wood Council at www.awc.org, or the Metal Plate Connected Wood Truss Handbook from the Wood Truss Council of America at www.woodtruss.com.

Notching and Boring of Joists

Figure 18 illustrates joist notching and boring limits for solid-sawn joists. Do not cut notches in the top or bottom edges in the middle one-third of the joist span. Notches in the outer thirds of the span cannot exceed one-sixth the actual joist depth, and cannot be longer than one-third the depth. Notches made at a support, such as shown in Figure 23 for joists supported by ledgers, cannot exceed one-fourth the actual joist depth.


Bored holes are limited in diameter to one-third the actual joist depth, and the edge of the hole cannot be closer than 2" to the top or bottom edges of the joist.

No boring, cutting or other modification of wood trusses is allowed. For rules on modification of I-joists, refer to I-Joists for Residential Floors at www.apawood.org or to the manufacturer's requirements.


Workers install subfloor sheathing over floor trusses of a 5,000 sq. ft. assembly building. See Assembly Building case study.Subflooring

Subflooring, also commonly called "rough floor," is the material applied over floor joists to provide a base for the finish floor. The subfloor also works as a horizontal diaphragm in high-wind and seismic areas, transferring lateral loads from the wall system to the foundation below.

Structural wood panels (e.g. plywood, OSB) commonly form the subfloor of a raised floor system. These panels are typically manufactured in 4x8 sheets. The panels are then applied to the floor joists with 1/8" gaps left between the sheets to allow for expansion and to prevent buckling. Table 11 provides a nailing schedule for properly attaching wood structural panel subflooring to the top of the floor joists.

APA-rated Sturd-I-Floor is a combined subfloor-underlayment product designed specifically for single-layer floor construction beneath carpet and pad. When other subfloor products are used, builders often install a separate underlayment grade of plywood over the subfloor to provide a proper base for the finish flooring.

Table 11 Nailing Schedule for Wood Structural Panel Subflooring¹Panel
Span RatingPanel
Thickness
(inches)Maximum Span
(inches)Nail Size and Type4Supported Paniel Edges6
(inches)Intermediate Supports
(inches)24/16 7/16 16 6d common 6 12 32/16 15/32, 1/2 16 8d common²6 12 40/20 19/32, 5/8 20³8d common 6 12 48/24 23/32, 3/4 24 8d common 6 12 60/325 7/8 32 8d common 6 12
Source: APA Design Construction Guide — Residential & Commercial; APA — The Engineered Wood Association, (www.apawood.org), Table 11.
1 APA Rated Sturd-I-Floor may be substituted when the Span Rating is equal to or greater than tabulated maximum span.
2 6d common nail permitted if panel is 1/2 inch or thinner.
3 Span may be 24" if a minimum 1-1/2 inches of lightweight concrete is applied over panels.
4 Other code-approved fasteners may be used.
5 Check with supplier for availability.
6 Supported panel joints shall occur approximately along the centerline of framing with a minimum bearing of 1/2". Fasteners shall be located 3/8 inch from panel edges.

The quality of the subfloor and underlayment layers is fundamental to having a floor that is plumb and stable. See Tolerances and Techniques for Flat Floors. Regardless of the type of flooring used, subfloor and underlayment rules are basically the same. They should be stable, clean, smooth and level. If a subfloor becomes wet during construction, it should be allowed to dry prior to the installation of any finish flooring material.

For more information on subflooring, refer to the Engineered Wood Construction Guide available from APA — The Engineered Wood Association at www.apawood.org.

Framing of Floor Openings

Headers, trimmers, and joists form the framing for floor openings. Trimmers and headers are doubled when the header span exceeds four feet. Headers more than six feet in length are supported at the ends by joist hangers or framing anchors unless they are bearing on a partition, beam, or wall. Tail joists that exceed 12' in length are supported on framing anchors or on ledger strips not less than 2x2 (nominal).

Support of Partitions

Bearing partitions are normally placed over girders or walls that support the floor system. Where floor framing is adequate to support the added load, bearing partitions may be offset from supporting members by no more than the joist depth, unless floor joists are designed to carry the increased load. Where nonbearing partitions run parallel to floor joists, the joist under the partition is doubled to support increased loads frequently occurring adjacent to the partition.

Framing Details

Figure 19, Figure 20, and Figure 21 provide floor framing details. Figure 22, Figure 23, Figure 24, and Figure 25 illustrate various methods for supporting floor joists. Figure 26 and Figure 27 provide stair framing details, with emphasis on floor framing support.



















Marcel



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