Built up roof penetration detail. 2

[WARose]

I am going through a built up roof to anchor a guard rail post. The roof is a "Single-Ply Roof Membrane on Densedeck Board & Rigid Insulation" (2 boards). The detail I normally use for something like this isn't applicable (because the anchor plate is wider than the board). So can someone suggest a detail? What do I fill the hole in with? Thanks.

 

[lexpatrie]

Built up roof and single ply isn't the same creature. You fill the hole with "Roofing contractor to patch and flash in accordance with workmanlike practices, NRCA recommendations, and manufacturer's published installation instructions for penetrations, and warrant work against leakage."

If you mean the structural connection, what's it look like so far?

 

[WARose]

You fill the hole with "Roofing contractor to patch and flash in accordance with workmanlike practices, NRCA recommendations, and manufacturer's published installation instructions for penetrations, and warrant work against leakage."

That's no good. Have to give a detail here. Every detail I am finding is for a object that has a constant width. Obviously not the case here since we are talking a post with a base plate.

If you mean the structural connection, what's it look like so far?

Basically the current roof is a concrete slab (with the roof system I talked about in my OP on top of it). So we are talking about removing a section of what is above the slab & anchoring the post with a baseplate and Hilti anchors. But that will (of course) leave a hole where the Densedeck was....and we are talking about a hole with a uneven bottom. (Which would mean cutting holes in the Densdeck....which I don't think is allowed.)

I was thinking about in-filling with concrete and using a sealant around the edges (maybe chamfering the top perimeter edges of the concrete to better facilitate the sealant). But trying to decide if the Densedeck will make a good form.....I've seen people do this.....but wonder if that was a issue.

 

[lexpatrie]

I still don't see how what you're discussing isn't roofing versus structural engineering.

 

[WARose]

Actually what I am talking about is probably more close to an architectural detail than anything else.....but that is what I have been asked to provide.

 

[lexpatrie]

I wouldn't expect an Architect to get obsessed with the means and methods of sealing the roof penetration, either. They might show something, sure, but like I mentioned earlier "roofing contractor's job to do it correctly and warrant the penetration" language would (or should) appear. If you want the densdeck and insulation removed, sure, show that, so the building official can make sure of it (provided they even get called). I wouldn't bother with specifics on how to seal the penetration besides pointing at it and obligating the roofing contractor to design and install appropriate flashing for a waterproof/weathertight condition, etc.

Your (structural) guardrail connection is going to depend on the substrate, which you mentioned is concrete. If you want to approach it as a grout pad then you could do self-consolidating non-shrink grout under it to whatever thickness you prefer, etc. I'd galvanize the whole steel piece. Strength testing for the epoxy and special inspection as well. Given the nature of the connection being life-safety.

If I recall correctly, the Morabito drawings for Champlain Towers South, Surfside, FL had roof anchorages into concrete, if you wanted to refer to those, look them up.

 

[Greenalleycat]

Are you installing a post for fall arrest/abseiling?
If so, I have worked on very similar projects - concrete substrates with insulated roof systems over, and using a 600mm proprietary post anchor to clear the roofing
Waterproofing has always, always been tagged out as the responsibility of the contractor

 

[hokie66]

Not 'always, always'. Only since architects abdicated their responsibility for watertightness.

 

[lexpatrie]

In 1960?

 

[Greenalleycat]

Hokie, we work direct with the contractor and there is very rarely an architect, so I will give them a pass this time

 

[dvd]

Adapting a pitch pocket seems like one way to go -

 

[WARose]

Thanks dvd.....that's a good suggestion. EDIT: any recommendation for the "pourable sealer".

 

[lexpatrie]

Pitch pockets are no longer recommended by NRCA there are better options.

Manual Elements, Professional Roofing, April 2005

 

[phamENG]

Manual Elements, Professional Roofing, April 2005

So...a pitch pocket with a hat?

 

[WARose]

The thing I have to wonder is: do I even need a pitch pocket? With a pourable sealant with the right viscosity, you'd think the Densdeck could the form. The hole filled will be the same height before it was cut.

 

[hokie66]

If you do that, I would use a flexible collar above the sealant, something like this.

https://trade.tradelink.com.au/application/files/3216/2918/3440/Aztec_-_ProFlash__Roof_Collar.pdf

 

[WARose]

Thanks hokie66.....what would be the purpose for that?

 

[XR250]

Tell them you cannot provide a detail because it is out of your area of expertise.

 

[lexpatrie]

Yeah, fair comment Pham.

 

[hokie66]

WARose,

Because pitch pockets are not foolproof. Belt and braces, I suppose. Roof leaks are nasty things.