Beam Pocket Bearing on CMU Wall

[cxagent]

I have a residential dwelling utilizing wood beams (multiple 2x10) resting in a beam pocket in the CMU foundation wall.
IRC R502.6 and IBC 2304.11.2.5 require a min 3 inch bearing and 1-1/2 inch air clearance for decay control.
I am searching for requirements on 2 other issues:
- Is a bearing plate of some sort required in this beam pocket for the wood beam to rest on? The contractor is planning to use a 2x4 treated wood as a bearing plate to rest the non-treated wood beam on. Would this meet Code requirements?
- Are there requirements to grout the CMU cells below and to the side (45 deg angle) from the beam bearing? if so, any particular distance from the bearing point?

Thanks.
John.

[Jerry Peck - Codeman]

Hi John,

Either a steel plate or a pressure treated 2X may be used to separate the non-treated wood from the masonry/concrete.

Typically, a steel plate is used as it does not increase the height of the beam like a 2X would.

I'm not completely understanding your second question as the top course where the beams and joists are is filled solid with concrete, anchor bolts/straps are typically embedded in the concrete. Also, typically, there would be a filled cell at the beam location to carry the load down to the footing as the concrete block face shells are not designed or intended to carry that concentrated load at the end of the beam.

[cxagent]

Thanks Jerry:

Your 3rd paragraph about grouting of cells, anchor bolts, etc.
Where in the ICC Codes could I find these requirements?

John.

[Jerry Peck - Codeman]

All I can do is speak in general terms as I do not know any of the conditions or specifics of your construction or lot - and those conditions and specifics can make for many critical changes in my generalizations made below.

The foundation walls are, I presume, the walls enclosing a basement or crawlspace.

The design of the wall is based on many things, such as the height of the masonry wall, the thickness of the masonry wall, and the unbalance fill height.

Let's say you have an 8 foot high masonry foundation wall and there is 1 foot of wall above the finished grade, the unbalanced fill height is 7 feet, depending on the soil type the load applied per linear foot along the top of that wall would be between 214 plf to 322 plf to 429 plf, and that load will need to be resisted by support and bracing the wall. Not knowing your soil type, let's select the center soil type with a load of 322 plf. The joists will rest on a sill plate on top of that wall, the joists will be attached to the sill plate with the joists a maximum of 24" on center to support that wall, the method of attachment of the joists to that sill plate would be 'C' - from Table 404.1(1) - and 'C' is "1-1 /4-inch thick steel angle. Horizontal leg attached to sill bolt adjacent to joist/blocking, vertical leg attached to joist/blocking with 1/2-inch minimum diameter bolt." The sill plate is to be anchored to the top of the foundation wall in accordance with Table R404.1(2), and for the center column soils I selected, with an 8 foot tall wall with 7 feet of unbalance fill, the sill plate anchor spacing would be 12 inches maximum bolt spacing "Spacing is based on 1/2-inch diameter anchor bolts. For 5/8-inch diameter anchor bolts, spacingmaybe multiplied by 1.27, with a maximumspacing of 72 inches."

The only way to achieve the above anchoring of the framing to the foundation walls is by embedded anchor bolts for the sill (which are embedded in the filled/poured top course) or anchored by metal ties (which may also be embedded in the filled/poured top course or which may be attached to the sill plate which is attached by embedded anchor bolts).

(bold and underlining are mine)
R404.1.1 states: "Concrete masonry and clay masonry foundation walls shall be constructed as set forth in Table R404.1.1(1), R404.1.1(2), R404.1.1(3) or R404.1.1(4) and shall also comply with the provisions of Section R404 and the applicable provisions of Sections R606, R607 and R608."

I do not know if you are in a seismic design area or not, if so, there are additional requirements.

The reference to R606 (General Masonry Construction) above directs us to here:
- R606.1 General. Masonry construction shall be designed and constructed in accordance with the provisions of this section or in accordance with the provisions of ACI 530/ASCE 5/TMS 402.

And ACI 530 will specify the bond beams (the filled/poured top course).

If you follow that, then you will not require an engineer:
- R606.1.1 Professional registration not required. When the empirical design provisions of ACI 530/ASCE 5/TMS 402 Chapter 5 or the provisions of this section are used to design masonry, project drawings, typical details and specifications are not required to bear the seal of the architect or engineer responsible for design, unless otherwise required by the state law of the jurisdiction having authority.

There are ways to construct the wall without doing as stated above, not required a bond beam, and not require an engineer. You could build the foundation wall under "Plain Masonry Foundation Walls", Table R404.1.1(1).

Using the same soil column used above, an 8 foot high plain concrete wall with 7 feet of unbalanced fill would require the use of 12 solid masonry units, or you could use the 12 inch hollow masonry units and solid grout the entire wall - and not have to install any steel reinforcing bars. You would not be allowed to use the standard 8 inch hollow masonry units.

Or, you could use an engineer and whatever the engineer designs, signs and seals. Provided the engineer did not make such horrific mistakes that the local building department catches. Most smaller building departments do not have engineers on staff, many smaller building departments will have a working relationship with an engineer who will review suspect plans for the building department. Most large building departments have engineers on staff who will make an effort to catch the stuff some engineers may try to slip by them.

For the most part, engineers are reliable and effective, after all, *THEY* become responsible for the structure after it is built should there be a problem during or after construction and their design is at fault.

[Marc M]

Hi John,

Either a steel plate or a pressure treated 2X may be used to separate the non-treated wood from the masonry/concrete.

Typically, a steel plate is used as it does not increase the height of the beam like a 2X would.

I'm not completely understanding your second question as the top course where the beams and joists are is filled solid with concrete, anchor bolts/straps are typically embedded in the concrete. Also, typically, there would be a filled cell at the beam location to carry the load down to the footing as the concrete block face shells are not designed or intended to carry that concentrated load at the end of the beam.

Hey Jerry...am I missing the part where it requires PT wood at the beam pocket
R502.6 Bearing. The ends of each joist, beam or girder shall
have not less than 1.5 inches (38 mm) of bearing on wood or
metal and not less than 3 inches (76 mm) on masonry or concrete
except where supported on a 1-inch by 4-inch (25.4 mm
by 102 mm) ribbon strip and nailed to the adjacent stud or by
the use of approved joist hangers. The bearing on masonry or
concrete shall be direct, or a sill plate of 2-inch-minimum (51
mm) nominal thickness shall be provided under the joist,
beam or girder. The sill plate shall provide a minimum nominal
bearing area of 48 square inches (30 865 square mm).

Bold is mine.

[Jerry Peck - Codeman]

John,

I am searching for requirements on 2 other issues:
- Is a bearing plate of some sort required in this beam pocket for the wood beam to rest on? The contractor is planning to use a 2x4 treated wood as a bearing plate to rest the non-treated wood beam on. Would this meet Code requirements?

The code requirements are only minimum requirements - thus the code is only going to address separation of the wood from the concrete, which includes 'something' to separate the wood beam from the concrete at the bearing surface. However, unless the 2x4 height was allowed for in the height of the beam pocket, that 1-1/2 inch thick 'separation' bearing plate will likely affect the height of the beam to its intended finished-height-to-top or finished-height-to-bottom of the beam and could throw off all other measurements.

Possibly a better separation plate is galvanized steel as that would be thin and not affect the height of the beam with the galvanization providing corrosion resistance for the steel while serving to separate the beam from the concrete bearing surface.

- Are there requirements to grout the CMU cells below and to the side (45 deg angle) from the beam bearing? if so, any particular distance from the bearing point?

Concrete block by itself is not suitable for support of a load bearing member. Typically, the top one or two courses of block are filled to make a bond beam, then vertical cells filled as specified spacings - the filled cells provide the vertical load support for the bond beam, and, again, typically, any concentrated loading point will have a filled cell under it for support. Think of the concrete block wall as being a wall with columns (the filled cells) and a poured beam (the bond beam) with no other concrete block in the wall, the other areas are 'openings'. The spacing of the fill cells are as required to create short enough spans of the beam above to reduce the size of the beam (or spaced further apart and the beam is made taller (two or three courses instead of one or two) to reduce the number of vertical filled cells required for the beam. The spacing and location of the filled cells (and installation of vertical steel reinforcing) should all be shown on the approved plans.

If there is no code in your area, then a structural engineer should design the construction documents and sign and seal those documents, that will provide backup documentation that someone is responsible for the design of the structural aspects of the building.

Is there a code in your area? You referenced the IRC, which is a good code reference, I'm just curious if it is an enforceable reference or not in your area.

[Marc M]

Hey JP its Marc M.. i saw this and was just commenting on it. Im in CA as you may know..that code was from CRC 2013

[Jerry Peck - Codeman]

Hey JP its Marc M.. i saw this and was just commenting on it. Im in CA as you may know..that code was from CRC 2013

Marc,

Oops! I also just realized that I went back and replied to the original question - me bad.

I'm getting ready to leave the office now, so I will reply to your follow-up when I get back.

[Jerry Peck - Codeman]

Hey JP its Marc M.. i saw this and was just commenting on it. Im in CA as you may know..that code was from CRC 2013

Marc,

Oops! I also just realized that I went back and replied to the original question - me bad.

I'm getting ready to leave the office now, so I will reply to your follow-up when I get back.

Marc,

Hey Jerry...am I missing the part where it requires PT wood at the beam pocket R502.6 Bearing.

That section only addresses the minimum amount of bearing required, not protection from decay or termites.

Check out this section (from the IRC, not sure about the CRC):
- SECTION R317 PROTECTION OF WOOD AND WOOD BASED PRODUCTS AGAINST DECAY
- - R317.1 Location required.
- - - Protection of wood and wood based products from decay shall be provided in the following locations by the use of naturally durable wood or wood that is preservative-treated in accordance with AWPA U1 for the species, product, preservative and end use. Preservatives shall be listed in Section 4 of AWPA U1.
- - - - 1. Wood joists or the bottom of a wood structural floor when closer than 18 inches (457 mm) or wood girders when closer than 12 inches (305 mm) to the exposed ground in crawl spaces or unexcavated area located within the periphery of the building foundation.
- - - - 2. All wood framing members that rest on concrete or masonry exterior foundation walls and are less than 8 inches (203 mm) from the exposed ground.
- - - - 3. Sills and sleepers on a concrete or masonry slab that is in direct contact with the ground unless separated from such slab by an impervious moisture barrier.
- - - - 4. The ends of wood girders entering exterior masonry or concrete walls having clearances of less than 1/2 inch (12.7 mm) on tops, sides and ends.
- - - - 5. Wood siding, sheathing and wall framing on the exterior of a building having a clearance of less than 6 inches (152 mm) from the ground or less than 2 inches (51 mm) measured vertically from concrete steps, porch slabs, patio slabs, and similar horizontal surfaces exposed to the weather.
- - - - 6. Wood structural members supporting moisture-permeable floors or roofs that are exposed to the weather, such as concrete or masonry slabs, unless separated from such floors or roofs by an impervious moisture barrier.
- - - - 7. Wood furring strips or other wood framing members attached directly to the interior of exterior masonry walls or concrete walls below grade except where an approved vapor retarder is applied between the wall and the furring strips or framing members.

Keeping in mind that the code is only the minimum requirements, not 'good, better, or best' building practices.

Note that 2. above addresses those which "rest on", while 4. above addresses "ends of", and then 7. above which addresses many things not included in 1 through 6 above.