Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Chemical timber fastening epoxy???

Chemical timber fastening epoxy???

Chemical timber fastening epoxy???

I am an Australian forum user and I was after some info on the existence of a timber epoxy used to fasten threaded rods into timber beams. Does it exist? Are there technical resources available with design pullout values etc? I know tasbeam used to publish design data years ago using a hilti and ramset product. They don't do that anymore. I haven't seen anything used since. Maybe there is a reason for that?????

RE: Chemical timber fastening epoxy???


RE: Chemical timber fastening epoxy???

google Rotafix, a UK company. Sika also makes suitable products. We have done this since the 1970s in Canada with Sika products.

RE: Chemical timber fastening epoxy???

check out the following:
I have not investigated where they are getting the values from but the fine print says "testing divided by a reduction factor of 4." Probably worth it to look up the Code Evaluation report. Essentially they are assigning a withdrawal value of 4490 lbs for a 10" embedment with epoxy.


RE: Chemical timber fastening epoxy???

Boy, despite the cited testing results, I have real reservations regrding that connector, and the use of epoxy in that regard.

The AITC has long recommended against the use of any tension values for nails in end grain, which, in effect, the rod becomes. Just feels funny to me and I would never use it without further justification beyond any report from Simpson and the State of Florida...

Mike McCann
MMC Engineering

RE: Chemical timber fastening epoxy???

There is a big difference between the friction holding a nail and an adhesive that develops a greater strength than the fibre strength of the wood. The wood around an epoxied rod will fail, not the adhesive bond, so the strength of the connection depends upon the length and area (diameter) of attachment, and the strength if the wood in shear parallel to the grain, not on withdrawal like a nail.

RE: Chemical timber fastening epoxy???

OK, but in both cases, you are still pulling with the grain, not across it, so any allowable tension should be much less for the same fastener. With the 4K or so capacities being generated in the Simpson table, I just do not sense that.

I guess I will have to check my old tables the pullout for the same diameter and depth lag screw in side grain when I get back into the office. I have to prove this to myself, one way or the other.

Mike McCann
MMC Engineering

RE: Chemical timber fastening epoxy???

Not pointed by the above responders is the effects of shear forces perpendicular to the end grain of the wood.

RE: Chemical timber fastening epoxy???

As the wood dries, it will shrink away from the adhesive and fastener. A nail or screw hasn't removed wood, only compressed it, but drilling makes a hole that will grow over time. Especially if you are subject to tangential shrinkage - wood shrinks across the grain more than along it. I would look to install a mechanical fastener at some depth, rather than relying on adhesive, unless you have a way to key the (creep-free) adhesive into the wood, creating a mechanical bond.

RE: Chemical timber fastening epoxy???

Any hole parallel to the grain will most often get smaller, not larger if the wood dries, depending upon its location with respect to growth rings. Also, the wood in question is existing in its existing service conditions and is unlikely to change much. Trust me, 35 years of experience with this method shows up most of the situations that you will encounter.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close