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Plumbing Penetration Through The Roof - How High Is Too High?

Plumbing penetration through the roof - how high is too high?

Looking up at the rear roof of this new construction I saw the plumbing penetration was very high.

This particular tubing was 27" high.

Is that too high?

The usual height above a roof is the 10" to 12" range.

But that depends on the local area, climate and rules.  Some jurisdictions want particular lengths to accommodate for frequent, deep snow falls.

It's also made of PVC tubing.

While there is the general thought out there that PVC is degraded by sunlight and UV rays, I have never seen evidence of it.

Some builders will paint the tubing with black latex paint, or use ABS tubing, which is a black plastic.  But I seldom see ABS tubing penetrate roofs.

However, what problems can happen if the plumbing penetration is too high?

1.  It can freeze inside, and clog.  While I have heard that, in this area I have never seen it happen.  But I have read where it happens further to the north.

2.  It becomes wind vulnerable and can be deflected and move.  That can loosen the rubber collar at the roof line, and cause cracking or leaks.  Plus, the older the rubber collar gets the more brittle it becomes and therefore more prone to cracking.  So movement from high winds could be even more damaging.

The fix here is simple - cut the tubing back to the 12" height and be done with it.

My recommendation:  home inspectors need to have forethought when investigating houses.  Placement of trees, shrubs, dryer vents, how shingles are placed and cut, and even the height of plumbing penetrations need to be looked at in the context of time.  Why not forestall the aging or potential damage of anything by handling it properly at the outset?  I can tell you that comments on inspection reports about "minutia" like plumbing penetration height will bother a builder to no end.  But over time the client is benefited, and in my opinion the client rules.



Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560


Comment balloon 4 commentsJay Markanich • November 16 2016 03:30AM


We very much appreciate you sharing this information with us today.

Posted by Harry F. D'Elia III, Investor , Mentor, GRI, Radio, CIPS, REOs, ABR (RentVest) about 4 years ago

Great call, Jay Markanich and I would think the latter reason is one of the more valid ones to apply anywhere in the U.S. Nothing worse than leaking boots!

Posted by Sandy Padula and Norm Padula, JD, GRI, Presence, Persistence & Perseverance (HomeSmart Realty West & Lend Smart Mortgage, Llc.) about 4 years ago

I have seen them pretty high here, even some with guide wires! With evaporative coolers, the air intake is up there and in cases with plumbing penetrations beside the units... they have to be higher than the air intake! But when it comes to those coolers... that's a whole different story!

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) about 4 years ago

That's why I come here, Harry.  Hope my posts are instructive.

S&N - and I see them all the time.  And leaking is slow and damaging.

If they are that high it would explain the guide wires, and necessarily as I understand you have windy days out there that are unusually persistent Fred.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 4 years ago

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