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No sill plates at the top of CMU for the attachment of trusses

jar546

jar546

CBO
Joined
Oct 16, 2009
Messages
12,789
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Not where I really want to be
Instead of a sill plate, there is a 30# piece of felt paper used to separate the truss from the CMU. The entire perimeter is a tie-beam poured solid with embedded tie downs for the truss connection to resist uplift. How do you do this in your area where CMU meets wood trusses?

IMG_2949.JPG
 
I’ve never seen it done like that. What about blocking? Seems to me that it would require blocking and it would go in prior to the sheathing.
 

2021 IRC - R802.6 Bearing​

The ends of each rafter or ceiling joist shall have not less than 1-1/2 inches (38 mm) of bearing on wood or metal and not less than 3 inches (76 mm) on masonry or concrete. The bearing on masonry or concrete shall be direct, or a sill plate of 2-inch (51 mm) minimum nominal thickness shall be provided under the rafter or ceiling joist. The sill plate shall provide a minimum nominal bearing area of 48 square inches (30 968 mm2). Where the roof pitch is greater than or equal to 3 units vertical in 12 units horizontal (25-percent slope), and ceiling joists or rafter ties are connected to rafters to provide a continuous tension tie in accordance with Section R802.5.2, vertical bearing of the top of the rafter against the ridge board shall satisfy this bearing requirement.

R606.11 Anchorage​

Masonry walls shall be anchored to floor and roof systems in accordance with the details shown in Figure R606.11(1), R606.11(2) or R606.11(3). Footings shall be permitted to be considered as points of lateral support.

FIGURE R606.11(1)
ANCHORAGE REQUIREMENTS FOR MASONRY WALLS LOCATED IN SEISMIC DESIGN CATEGORY A, B OR C AND WHERE WIND LOADS ARE LESS THAN 30 PSF​
1695166667284.png
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
Note: Where bolts are located in hollow masonry, the cells in the courses receiving the bolt shall be grouted solid.

FIGURE R606.11(2)
REQUIREMENTS FOR REINFORCED GROUTED MASONRY CONSTRUCTION IN SEISMIC DESIGN CATEGORY C
1695166812240.png
​
 
Edit: Sorry, did not thoroughly read the initial post. I would think that would work fine.

I have never seen this, I have only seen a treated sill plate bolted down to the top of the CMU wall with hurricane ties at each truss.
 
The difference between a tie beam and a bond beam is a tie beam is formed concrete with 4 horizontal bars and stirrups. A bond beam uses multiple CMU's designed for the placement of rebar which is typically horizontal but can also be diagonal in design.
1695241069993.png

1695241126339.png
1695241819228.png
 
I believe it is complaint. You have the tie downs & the felt gives the barrier between the two so it doesn't need to be pressure treated.
 
classicT said:

2021 IRC - R802.6 Bearing​

The ends of each rafter or ceiling joist shall have not less than 1-1/2 inches (38 mm) of bearing on wood or metal and not less than 3 inches (76 mm) on masonry or concrete. The bearing on masonry or concrete shall be direct, or a sill plate of 2-inch (51 mm) minimum nominal thickness shall be provided under the rafter or ceiling joist. The sill plate shall provide a minimum nominal bearing area of 48 square inches (30 968 mm2). Where the roof pitch is greater than or equal to 3 units vertical in 12 units horizontal (25-percent slope), and ceiling joists or rafter ties are connected to rafters to provide a continuous tension tie in accordance with Section R802.5.2, vertical bearing of the top of the rafter against the ridge board shall satisfy this bearing requirement.

R606.11 Anchorage​

Masonry walls shall be anchored to floor and roof systems in accordance with the details shown in Figure R606.11(1), R606.11(2) or R606.11(3). Footings shall be permitted to be considered as points of lateral support.

FIGURE R606.11(1)
ANCHORAGE REQUIREMENTS FOR MASONRY WALLS LOCATED IN SEISMIC DESIGN CATEGORY A, B OR C AND WHERE WIND LOADS ARE LESS THAN 30 PSF​
View attachment 11507
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
Note: Where bolts are located in hollow masonry, the cells in the courses receiving the bolt shall be grouted solid.

FIGURE R606.11(2)
REQUIREMENTS FOR REINFORCED GROUTED MASONRY CONSTRUCTION IN SEISMIC DESIGN CATEGORY C
View attachment 11508
​
Click to expand...
I don't like top plates because most of the time it is the weakest link because of problems with the bolts being embedded properly and tying to the horizontal Bond beam.
 
my250r11 said:
I believe it is complaint. You have the tie downs & the felt gives the barrier between the two so it doesn't need to be pressure treated.
Click to expand...
Wood and contact with concrete products does not have to be pressure treated if the concrete is not in contact with the ground.
 
2018 IRC
R802.6 Bearing.
The ends of each rafter or ceiling joist shall have not less than 11/2 inches (38 mm) of bearing on wood or metal and not less than 3 inches (76 mm) on masonry or concrete. The bearing on masonry or concrete shall be direct, or a sill plate of 2-inch (51 mm) minimum nominal thickness shall be provided under the rafter or ceiling joist. The sill plate shall provide a minimum nominal bearing area of 48 square inches (30 865 mm2).
 
ICE said:
Use it or lose it.
Click to expand...
I forgot to add that the sill must be pressure treated if in contact with concrete or masonry and any wood in contact with concrete or masonry that is in direct contact with the grade like basement furring strips. But strangely beams pocketing into concrete above grade don't need to be pressure treated.
 
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