Attachment of fixed roof access ladder to masonry cavity wall 2

[Jc67roch]

Any recommendations on how to attach a roof access ladder to the exterior cavity wall of a building (one story)? In particular, the wall is constructed of 4" split face cmu veneer, with an 8" cmu backup wall. I am debating use of epoxy adhesive anchors in just the 4" exterior veneer, run long with a backup nut to hold the plates off the split face surface. OR run an epoxy anchored threaded rod all the way thru both the veneer and the backup wall? Suggestions?

 

[KootK]

Do you know what the buildup between the veneer and backup looks like? Would your bolts be penetrating the building envelope?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[manstrom]

I would run it all the way into the 8" cmu and epocy it. The veneer is probably fine, but you are talking about a handful of bolts.

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[JAE]

I would use something like HILTI's HIT HY70 anchors. These use a mesh sleeve tube (they have them almost 8" long) that can extend through the veneer, air space and into the block backup.
With the injection of the resin, the resin forms "mushroom" heads in the cavity and into the block wall as well. This would tie in the two wythes at the connection.

HILTI HIT HY70 link

I think they have specialty tubes that go longer as well - you'd have to call a rep to find out.


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[XR250]

As others have said, might as well get into the 8" cmu. The 4" may not even be attached to the 8" (been there done that)

 

[thaidavid40]

Use L3x3x5/16" standoffs, each welded to an end plate. Turn the legs out, and space them at 24" clear inside. That way, they will fit in the corners of mortar joints 1-1/2 blocks wide (16" + 8"). You don't even need to cut any blocks to do this. Bolt through the 8" backup wall with a short-legged channel backup (web against the wall, legs out), which can hide behind the interior wall finish. Let the standoffs project out of the finished exterior veneer, and later field weld to the ladder rails. No block cutting, no joints, and no sealing to worry with (except a little bead of RTV around the standoff legs).

Thaidavid

 

[hokie66]

Do as JAE suggested. You don't want to support a ladder solely on the veneer.

 

[KootK]

@thaidavid: I want to understand your detail but I don't. Would you be willing to post a sketch?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Ron]

Agree with JAE as well. I've done lots of these using screen tubes and epoxy for hanging canopies. Don't depend on the veneer at all. Make sure everything is waterproofed.

 

[Jc67roch]

Thanks All! Great responses! I had forgotten about the Hilti screen tubes (have seen them but never used them). Excellent suggestions!

 

[thaidavid40]

KootK,
Hopefully, the attached sketch will help clarify what I so inelegantly put into narrative above.
Dave

Thaidavid

 

[JAE]

thaidavid40 - looks pretty good - the only thing I'd suggest is making sure that the sideways sway on the ladder is sufficiently controlled by the extended angles through the veneer. Those angles are probably stiff enough but the flat plate between the veneer and back-up wall may not be. You could see some wiggle in the ladder sideways. I suppose the brick veneer could be mortared solid around the two extended angles to help.


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[KootK]

Thanks David. A friend who will run to the scanner for you during a work day is a friend indeed! Into the vault she goes...

The install would require the removal and reinstating of some of the veneer to access the bolts between wythes though, right?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[thaidavid40]

KootK
This was developed mostly for new walls, though we have used it for modifications on existing walls. Anything the steel people do, regardless of the detail, almost always ends up needing some attention from the masons anyway. This at least makes the masonry repairs modular, so the reinstalled blocks (or brick, or stone, or whatever) go back in whole pieces, and they look less affected. Fortunately, most ladders go on the less desirable side of most buildings anyway! The USACE guys have always seemed okay with this detail.
Dave

Thaidavid

 

[thaidavid40]

JAE,
You have at least four of these on every ladder, and sometimes six or eight, depending on the ladder length. I've climbed on these details before, and I'm 6'-2, 210#. I couldn't make them budge an inch. If there's any wiggle in them, I couldn't squeeze it out of them.
Dave

Thaidavid