Expansion Anchor Connection to Concrete Wall

[Bedrock1977]

I have a wood beam running parallel to a concrete wall. The beam is an edge beam for a new deck design and need to know how to properly design the expansion bolts connecting the beam to the wall. Can someone please offer some help?

Thanks!
Chris

 

[steellion]

Expansion anchors are proprietary and vary by manufacturer. Get a free catalog from a manufacturer and it will be filled with allowable loads and design procedures. Since your specific case involves a wood connection, I recommend Simpson Strong-Tie.

 

[southard2]

Also check out Hilti. They have a program that you can use which will really help you in learning how to apply their reduction factors. Once you see how the factors are applied it is usually easier just to apply them yourself. I like Simpson but I usually use Hilti products for my concrete bolt connections.

John Southard, M.S., P.E.

http://www.pdhlibrary.com

 

[Ron]

Chris,
Are you a contractor or an engineer? Just curious.

As steellion pointed out, wood connections are a specialty of Simpson StrongTie, so an appropriate hanger or connector can be selected from their catalog based on your loading. The connector can then be fastened to the masonry with a variety of fasteners, from expansion anchors to TapCon-style fasteners.

Ron

 

[paddingtongreen]

Around here, the wood beam would be called a "ledger".

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[DaveAtkins]

The expansion bolt can be chosen from any manufacturer's catalog--Hilti, Powers, Simpson, etc. But the capacity of the bolt in the concrete will not control in this case. You need to check the ledger itself, and to do that, you should use the NDS.

DaveAtkins

 

[Bedrock1977]

Thanks for everybody's input.

No, I am not an actual Engineer or Contractor. I am working on an Architecture degree but really enjoy the structural side of things. Unfortunately, the college I go to does not offer more than just a basic structural theory class. I have taken it upon myself to go beyond what they taught us in class by reading books and asking questions here.

 

[msquared48]

Watch out here.

If the application would put the expansion anchors very close to a concrete edge, I would resommend a chemical anchor to avoid spalling the concrete.

If that is not the case here, then no worries.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[JLNJ]

You said the wall is concrete and for concrete there are many many good options for anchorage.

One of the posters above mentioned a masonry wall. If the wall is indeed masonry and it is hollow be very careful. There are few anchors suited to hollow CMU construction and those that are have small allowable loads.

 

[RHTPE]

If this is an exterior application, which I presume it is, I would recommend using spacers (say 1/2" x 3" PT plywood strip vertically) at your bolts to provide an air space between the concrete and the wood. Helps to minimize the trapped moisture that will ultimately rot the ledger.


Ralph
Structures Consulting
Northeast USA

 

[MultiVar]

... I would recommend using spacers (say 1/2" x 3" PT plywood strip vertically) at your bolts to provide an air space between the concrete and the wood. Helps to minimize the trapped moisture that will ultimately rot the ledger.

Wow, this whole thread is 5-star suggestions, incl. this one. Kudos to all.

Hopefully not a hijack, but a corollary: in my sub-tropical zone (Miami), the PT wood spacers would indeed extend the life of the ledger, but the spacers themselves would succumb, in an unacceptably short time, and probably even start conducting moisture into the ledger. Is there an approved spacer made of PVC/polymer, masonry, or other impervious material that can do the job?

Thanks in advance.

 

[Ron]

MultiVar...there are plastic spacers that are used for window and storefront installation. They come in color coded thickness increments of 1/8". They will work for ledger and other wood spacer applications.

Ledgers and other wood/timber applications in contact with concrete or masonry should be pressure treated with an appropriate level of preservative for the application.

 

[hokie66]

Why not use galvanized steel plate for the spacers?

 

[Ron]

Hokie66...those will work as well, but corrosion is a factor here in Florida, so the plastic works well.

One thing I forgot to point out is that when you use spacers/shims, you can induce bending in the fasteners so that has to be checked. If less than 1/4", usually not an issue.

 

[MultiVar]

Why not use galvanized steel plate for the spacers?

Coastal S. FL is the most aggressive (in terms of CORROSION) environment in CONUS, i.e. combo of high temps, high humidity, and salt spray. Exposed galvanized doesn't do well; neither do most stainless alloys for that matter.

For the ledger app of this thread, the spacer needs to be part of the protective "sheath" for the anchor bolt, along with quality caulk, or, increasingly, anchoring epoxy (e.g. Simpson Strong-Tie ET/SET).

 

[hokie66]

Fair enough if severe corrosion conditions exist, but the OP gave no indication that he is in Florida. Mine was a generic suggestion.

 

[msquared48]

If you periodically use a steel angle ledger under the wood ledger that is afterset bolted to the concrete and lagged to the wood ledger, then the presence of spacers between the wood ledger and concrete wall will not affect the bolts through the wood ledger in bending. You can then use whatever type of shim that will work for your environment.

(run-on sentence here - sorry)



Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[RHTPE]

My advice, from the big picture - change the direction of your deck framing members. Instead of a ledger along the concrete wall, support the main carrying beams at the concrete wall - simple connection, many commercially produced framing connections available. Run the joists parallel with the concrete wall, keeping the first joist 6" or so from the concrete. Cantilever the decking material to the wall, but hold the ends back enough to avoid debris & moisture accumulation along the wall.

Did this on a deck I replaced many years ago. The original was built with a ledger and joist perpendicular on a wood-framed wall. I thought it was going to be a simple deck replacement until I removed the ledger. Water had worked its way down between the ledger and the wall due to accumulated debris. Carpenter ants had found it to be a perfect environment - the damage was extensive.

Ralph
Structures Consulting
Northeast USA