Using Structural Columns for Roof Drains

[JAE]

I couldn't find anything in the search here.

What has been the experience and viewpoint of allowing steel pipe roof drains to extend through the walls of structural columns (larger pipe columns - say 10 to 16 inch diameter) and extend down through the base plate and out the footing or pedestal?

Assuming you can manage the structural strength/buckling issues, has this been successfully done in the past?

We have a concern that if there ever was a leak in the internal pipe there would be no way to fix it short of shoring the roof and re-building the whole assembly.

Galvanizing? "leak-proof" pipes within the structural column?

??

 

[Ron]

JAE, we've routinely done this with aluminum columns, but I have not done it with steel. Corrosion is the primary reason for not doing it in steel. I agree with your concerns.

 

[Jc67roch]

This was historically done with cast iron columns.

 

[MikeHalloran]

You won't know the drain pipe has failed until the water compromises the structural column. It will probably last through any warranty period, but you can expect aspersions in your direction someday.



Mike Halloran
Pembroke Pines, FL, USA

 

[cvg]

add a weep hole at the bottom of the column and you'll know when it leaks

 

[BAretired]

Knowing when it leaks is helpful, but you still can't repair the drain pipe through the wall of the column, so unless there is a method of repair, I would be leery about using the system.

There must be similar concerns about water filled columns for fire protection which concept has been used successfully on a number of buildings.

http://www.cookeonfire.com/pdfs/17.pdf

BA

 

[dhengr]

JAE:
I guess I’ve seen that done, Archs. like it because it’s out of sight and out of harms-way. But, I’ve also seen roof drains leak, and appreciate your concern about what would you do then. I’ve also seen the drain pipes embedded in a conc. col. with varying, good, bad, freezing results. Maybe you explaining the two options to the Arch. or owner and have them send you a letter identifying the choice they want to live with. I don’t quite understand Ron’s rationale, that his would be o.k. in an alum. col., since the steel pipe might still leak, and you would have the same problem, except less internal col. corrosion. Unless he means that the alum. col. interior is the water carrier, with some sort of piping connections atop the cap pl. and below the base pl. And, I would provide the weep hole suggested to show any problem immediately.

Maybe this is a belt and suspenders approach, but is there any fairly flexible plastic pipe, PEX or otherwise, and large enough, and code compliant for a roof drain? Proved holes in the cap pl. and the base pl. and a light gage conduit to thread the plastic pipe through; that is down, through the cap and base pls. and a large sweeping conduit elbow, and out the side of the pier, to a connection make-up box or point below the slab.

 

[Ron]

dhengr....we don't put a steel pipe in an aluminum column. We do one of two things....let the column be the pipe and put a deflector above the base plate and a hole in the column to direct the water outside, or provide a welded "snorkel" to which PVC pipe can be threaded into, top and bottom, through the top plate and base plate. This has been done on thousands of columns for large aluminum canopies and it works fine.

My problem, as the structural, is making the column work with a big hole in its side...sometimes a challenge!

 

[dik]

A little frozen water will go a long way to splitting the HSS tube...

Dik

 

[JedClampett]

Isn't that a standard design in the Gas Station Canopy design? I've seen several drain pipes poking out of those cantilever columns.

 

[shobroco]

I've done it in steel and wood columns with different materials, with all of the concerns noted by everyone, but using plastic pipe is the best guarantee against corrosion, and if the columns are exterior in freezing country, heating cables inside the drains are mandatory.