New one for me

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cowboyjwc said:
Just had a contractor call me and stated that the he was going to run some exposed PVC and that the HO wanted the straps "glued" to the structure and not mounted with a screw or such.

While it seems strange to me I can not find anything that prohibits this. I'm sure I would need some sort of listing for the product (wet location, sunlight resistant).

Or he could just use that stuff that they advertise on TV.

Any thoughts?
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Is there any other equipment along with the PVC?reading thru the lines,- glue may be acceptable but I dont think it should be used.The holes in clips/straps are put there for a reason-to put a fastener thru...
 
Rather than glue, I would try to locate a supply of the double sided foam tape of the type that is used to attach wire mold type conduit and/or 'sticky back' tie strap mounts.

Any glue that is strong enough to make a reliable attachment is going to make a much bigger mess of the siding than a small hole. The goo from double sided tape can be removed with products such as 'Goo Be Gone' or even mineral oil for that matter.
 
In another thread about "Protector Plates", I referenced UL2239, which also covers straps.

Adhesive as a fastener is not an option in this specification, only metal fasteners of a certain size and able to handle a certain torque/pull force are specified.

I would tell the HO that there really is no UL-listed way to "adhere" UL-Listed straps to a surface, as the UL-listing for the straps was obtained using standard metal fasteners. Also, the design of the strap is intended to use a metal fastener such as a screw or a bolt, not a pad of adhesive.

As a previous poster indicated, Stainless or other corrosion resistant fasteners (i.e. galvanized) are the only option if rust streaking is a concern. Brass is probably too soft to handle the required mounting torque and loading. If water penetration is a concern, I would drill a pilot hole first, apply caulking in the hole and then attach the strap.

Good Luck!:cool:
 
cowboyjwc said:
UPDATE: Just got a call from the EC, said the reason was the HO didn't want any hole drilled in his walls. I'm thinking if the "glue" is strong enough to hold the straps, why not just glue the pipe to the wall.
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Now that I think about it there is a type of pvc strap that just might work. You mount the strap and then snap the Conduit into the strap and snap the cover closed. I haven't used these in years but if I remember correctly the base of the strap is over an inch square ( depending on conduit size) which would give a large surface area for the glue to bond.

We were useing these in a chemical environment with stainless steel mounting screws but I guess they could have been glued. They are probably not all that cheap but they do look good.

This would allow the conduit to expand and contract.
 
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LJSMITH1 said:
In another thread about "Protector Plates", I referenced UL2239, which also covers straps.

Adhesive as a fastener is not an option in this specification, only metal fasteners of a certain size and able to handle a certain torque/pull force are specified.

I would tell the HO that there really is no UL-listed way to "adhere" UL-Listed straps to a surface, as the UL-listing for the straps was obtained using standard metal fasteners. Also, the design of the strap is intended to use a metal fastener such as a screw or a bolt, not a pad of adhesive.

As a previous poster indicated, Stainless or other corrosion resistant fasteners (i.e. galvanized) are the only option if rust streaking is a concern. Brass is probably too soft to handle the required mounting torque and loading. If water penetration is a concern, I would drill a pilot hole first, apply caulking in the hole and then attach the strap.

Good Luck!:cool:
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Good call, that's exactly what I told the EC this morning including the caulking part, but less the UL part.
 
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iwire said:
You 'stole' my question. :cool:
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Now I'm thinking LJSMITH answered your question.
quote: --------------------------------------------------------------------------------

In another thread about "Protector Plates", I referenced UL2239, which also covers straps.

Adhesive as a fastener is not an option in this specification, only metal fasteners of a certain size and able to handle a certain torque/pull force are specified.

I would tell the HO that there really is no UL-listed way to "adhere" UL-Listed straps to a surface, as the UL-listing for the straps was obtained using standard metal fasteners. Also, the design of the strap is intended to use a metal fastener such as a screw or a bolt, not a pad of adhesive.
 
LJSMITH1 said:
In another thread about "Protector Plates", I referenced UL2239, which also covers straps.

Adhesive as a fastener is not an option in this specification, only metal fasteners of a certain size and able to handle a certain torque/pull force are specified.
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Sure wish I could see that with my own eyes.

Is adhesive prohibited, or is it just not mentioned?

To say that no adhesive can do the job is ridiculous, airplanes are put together with adhesives. (It just sounds so much better when you say 'chemical fastener' instead of 'glue'. :D ) If anything it will be that adhesive has not been tested for the application.

I think it's also a ridiculous request by the homeowner but I am fine with doing whatever they want as long as it is within the rules.
 
I would forget the glue angle and consider the siding itself.

I wonder what the siding manufacturer would say about using the siding itself as the support means for anything?

Usually we support to the sheathing under the vinyl.
 
cowbowjwc said:
Not that was told to me. My first thought was that if he removed it he didn't want holes left in his "stucco", but then I thought if these straps came off they would really leave a mess.
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Is this stucco, vinyl siding, brick?
 
1st thought: The straps are listed to be used with screws, not glue. Installing them with glue is not installing them according to the listing and labeling.
2nd thought: PVC conduit is required to be "securely fastened and supported". If the surface is vinyl or aluminum siding I cannot understand how gluing to the thin siding meets this requirement. The mounting screws will penetrate the siding and "secure" to conduit to the particle board or other substructure. I know this is a matter of interpretation but I don't think that siding is capable for providing adequate support.
 
iwire said:
Sure wish I could see that with my own eyes.

Is adhesive prohibited, or is it just not mentioned?

To say that no adhesive can do the job is ridiculous, airplanes are put together with adhesives. (It just sounds so much better when you say 'chemical fastener' instead of 'glue'. :D ) If anything it will be that adhesive has not been tested for the application.

I think it's also a ridiculous request by the homeowner but I am fine with doing whatever they want as long as it is within the rules.
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I think the real question here is if you (or the AHJ, or HO) want to use UL listed products in the installation. By that I mean that all products are used in accordance with the way they were designed/intended to be used as applicable to the UL standard. I can tell you that the straps that are available today are in no way listed for use with a 'chemical fastener'. I'm just the messenger...don't shoot me:)

I didn't really say that an adhesive would not do the job. Sure, there might be an adhesive mounting pad system available that might work, but the odds that it would be UL-listed and designed to work with this exact application is very slim.

What if the surface is stucco over styrofoam insulation? How secure would you think that cement coating is on the styrofoam? What if the surface layer (stucco, paint, etc.) had bond issues with the substrate below? While your clamp adhered to the stucco, the stucco layer pulled off the block/concrete below. Either way, your conduit would not be adequately supported as required by the NEC.

UL2239 does not mention adhesive as a fastening method for straps and hangars. If there is such a method, someone should petition UL to have it specifically defined and included as a fastening option in the specification. This way, when manufacturers like us make a strap, we can test it to make sure it works with all fasteners defined.

Pull tests are only as good as the strength of the fastener AND the surface that it is mounted on.

:cool:
 
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