IBC requirements - Reroofing

[RHTPE]

The 2003 IBC, paragraph 1510.3.3, requires that: "Where the existing roof has two or more applications of any type of roof covering", all existing layers of roof covering must be removed.

I am working with a client who markets a single ply membrane roofing system (no ballast). We contend that the removal of the uppermost roofing membrane (and its ballast if it exists) and its replacement with a new membrane (no ballast system) should be acceptable, assuming that there are no structural deficiencies. The cost savings involved to eliminate the removal of all layers of roofing would be significant.

Does anyone have any thoughts on how to battle a building official on this?

Ralph
Structures Consulting
Northeast USA

 

[Ron]

Why would you want to? If you have two roofing systems on there and you remove one (dubious delineation), then theoretically, you could comply with the intent of the code, if not the letter.

It doesn't cost much if any more to remove both of the old systems.

Roof system manufacturers are notorious for unfounded claims of performance. It has been that way for many, many years....yet we continue to have premature roofing failures of many systems. Granted, application deficiency is the most common failure, but part of it is because the manufacturers claim that their roofing systems can be installed by untrained monkeys, will cure all ills, and will last for 20 years, yet they have no history or data to support such.

Take the existing roof systems off. Start with a good substrate, apply the materials properly and then let the manufacturer's claims evolve or not.

 

[RHTPE]

Ron,

The IBC REQUIRES that ALL roofing be removed when there are 2 existing layers. Building inspector in MA would NOT accept just removing one layer because the Code says otherwise.

Tearing off the top membrane, patching the insulation/substrate as required, and installing new membrane is far less costly when you consider all of the costs involved (debris removal, temporary protection from rain, insulation, etc.).

So the contractor is doing a "repair" to replace deteriorated membrane in some areas.


Ralph
Structures Consulting
Northeast USA

 

[Ron]

RHTPE...I understand the code provision, but in my experience, it costs little if any more to remove the whole system rather than trying to selectively remove a membrane on top of another and then patch the existing membrane.

I am a licensed roofing contractor as well as an engineer. I would remove it all and start over. If you have had an evaluation done of the existing insulation and it is in good condition, I would make that argument, but otherwise I'd remove it all and move on. If you have two membranes, it is likely that the original would not comply with current uplift requirements (assuming wind is an issue in your area).

 

[RHTPE]

Ron,

I do not disagree with anything you have presented. If it were my choice and my choice alone, I would take it down to the roof deck. But, I am investigating what my client has asked.

The key question - what means exist to challenge a requirement of the IBC? Does it go state-by-state - CT's 2005 version of the 2003 IBC rewrites the entire Section 112, or does one have to appeal to the ICC directly.

Is the local building inspector in a position to allow a deviation from a code-specified requirement?



Ralph
Structures Consulting
Northeast USA

 

[msquared48]

With a 15 psf dead load for the design, you have allowed typically for one, and only one, re-roofing. Anything more than that is an overload in the dead load region, effectively taking away from the REQUIRED live load capacity for the roof. Hence, the IBC requirement.

Don't argue here. Just do it.

Mike McCann
MMC Engineering

 

[RHTPE]

Glad to see that everyone here is open to thinking outside of the usual paradigms.

No argument intended. Let's not go back & forth over the loads or the wisdom (or lack thereof) of an owner's desires. As I said, I do not disagree with the comments & opinions thus far.

I'm just asking what you all would do when a code requirement conflicts with common sense combined with a solid structural engineering evaluation.

Can an Engineer of Record prevail over the local builder inspector and the Code?

Ralph
Structures Consulting
Northeast USA

 

[msquared48]

In some circumstances, but not in this case.

Mike McCann
MMC Engineering

 

[Ron]

RHTPE...it's not that we don't think "outside of the usual paradigms", it's that we've dealt with these issues before and hopefully can offer you some insight.

Yes, you can "prevail" over the local building inspector. Your appeal is to the local Building Official, not the ICC. They only provide a model code for the "Authority Having Jurisdiction" to adopt by ordinance or statute. Winning the battle might cost a lot of time and effort, and you won't win the war. The code is what it is (minimum and conservative).

I see your point clearly and have been down that road. I've rarely been able to get the Building Official to acceed. Interestingly enough, he could make the decision and shift all the liability to you...'cause he has no liability anyway. That leads us to your liability and the standard of care.

When you deviate from the code, you are often hanging yourself out there for liability and for a deviation from the accepted standard of care. That's fine if you know all you need to know about your system and are sure of your design. But do you know all there is to know about the system? Have you sampled the system for unit weight confirmation? Do you know how the bottom layer of insulation is attached? Do you know the integrity of the deck and its attachment to the structure? Do you know if the 2nd roof is properly adhered/attached to the 1st one? Can you reasonably separate the two roof systems and prove you've done it? Do you have any wet insulation? Does the existing insulation comply with fire and energy codes? Has there been any deterioration of the structure as a result of roof leaks? Do you have proper drainage on the existing system?

You need to be able to positively answer and document each of these questions for your protection. If anything ever goes wrong with the roof or the structure afterwards, you'll be looked at critically, whether you are right or wrong. If you're wrong, they'll hang you. If you're right, you'll spend a lot of money to prove it.

Good luck.