Is Ice and Water Shield Required in Oklahoma?

In valleys and at changes of roof pitch, yes, and unconditionally. Oklahoma requires a 36 inch wide ice barrier in both places, and unlike the national code’s eave requirement, the Oklahoma rule is not conditioned on the area having any history of ice dams. That is the detail almost nobody knows, and it is precisely why the requirement bites in Tulsa, where ice dams are rare. Arrowhead Roofing has installed leak barrier in Tulsa valleys since long before anyone asked us to explain why.

Note: this is a general guide only. Code editions and local amendments change, and your installer should verify the requirements in force in your jurisdiction on the date the work is done. Manufacturer installation instructions may require more than the code does.

Three separate requirements are at work and they have different triggers, which is where the confusion comes from.

The Short Answer

The national code frames this entirely as an ice problem. Its requirement opens with the words “in areas where there has been a history of ice forming along the eaves causing a backup of water”, and whether that applies is a local designation.

Oklahoma added two paragraphs that do not carry that condition. One requires a 36 inch barrier in all valleys, run the length of the valley and centred on it. The other requires 36 inches at every change in roof pitch where the lower roof is shallower than the upper.

No ice dam history required. No local designation required. In a valley on an Oklahoma roof, it is simply required.

Why Valleys, in a Place Without Ice Dams

Because in a valley the problem was never ice. It is water volume.

A valley is where two roof planes drain into one channel. Everything that lands on both slopes above it funnels through a strip a few feet wide, at speed, and it does that during every storm rather than during a rare winter event. Add wind driving rain up the slope and the valley is the hardest working few square feet on the roof.

The industry treats it that way too, and the pattern is consistent. The National Roofing Contractors Association ties its eave membrane recommendation to a temperature threshold, and recommends membrane in valleys and at penetrations on their own merits, separately. The asphalt roofing manufacturers’ body describes self-adhering membranes as excellent secondary protection at ridges, hips, valleys and around penetrations, without a climate qualifier.

So the code, the contractors’ association and the manufacturers’ association independently arrived at the same structure: eaves are a climate question, valleys are not.

How a Leak Barrier Goes On

Watch this short video for how the membrane is rolled into a valley and lapped before anything else goes over it.

The Name Is the Problem

Worth saying plainly, because it causes a genuine misunderstanding.

The product standard governing these membranes is titled for ice dam protection. The common name is “ice and water shield”. Everything about the vocabulary points at winter, in a state where the winter case is the least of it.

A more accurate name would be a leak barrier, which is what the manufacturers increasingly call it, and what it does in Tulsa is stop water that gets past the shingles in a valley, at a pitch change, or around a pipe, from reaching the deck.

What the Manufacturer Requires, Separately

Code is a floor. Manufacturer instructions run alongside it, and on this subject they are stricter in a specific way.

GAF’s field guide requires leak barrier in valleys for its enhanced warranty tiers, at the full 36 inch width for the entire length of the valley, and requires it around plumbing vents on those tiers as well. Notably, GAF’s eave requirement is written for regions affected by ice dams, while its valley requirement carries no such qualifier. The same split as the code, arrived at independently.

Two honest limits on that. It is a condition of the enhanced warranty tiers rather than a rule for every installation, and we have verified it for one manufacturer rather than for all of them. Anyone telling you that every manufacturer requires it on every roof is going further than the documents do.

Why It Turns Up on an Estimate for a Roof That Never Had It

This is the question behind the question, and it comes up on almost every claim.

Most Tulsa roofs built before the current requirements do not have leak barrier in the valleys. So when it appears on a replacement estimate it reads like an addition, an upsell, something the old roof managed without.

Andy Anderson at Arrowhead puts it the way it should be put: “Even if a roof doesn’t have ice and water shield in the valley, when we go back with it, it’s required.”

A code required item on a replacement is not an upgrade to the old roof. It is what the new roof has to be.

What Changes the Answer

Three things affect how much membrane a specific roof needs.

How many valleys it has

A simple gable may have none. A cut-up roof with dormers can have a hundred feet of valley, and every foot of it takes a 36 inch strip.

Whether the roof has pitch changes

A porch roof meeting a steeper main roof, or a shallow addition below a steeper original, triggers the second Oklahoma requirement. Plenty of roofs have one without anybody thinking of it as a feature.

Which warranty tier the job carries

Enhanced manufacturer warranties impose their own requirements on top of the code, and they are conditions of the coverage rather than suggestions. A job specified to a higher tier gets more membrane.

Related Questions

What else does Oklahoma change in the roofing code?

Four amendments in total, including a prohibition on laying shingles over shingles. What building code applies to roofs in Oklahoma? sets them all out.

Does my carrier have to pay for it?

Oklahoma’s regulator has instructed carriers to treat every building code as strictly enforced for ordinance or law purposes, even where a city does not inspect roofs. Does insurance have to pay for building code upgrades on a roof in Oklahoma? covers it.

Can they leave the old roof on underneath?

Not on a shingle roof in Oklahoma. Can you put a new roof over an old one? covers the state amendment and the physical reasons behind it.

What protects a wall or a chimney joint?

A different detail entirely, in two pieces, and one without the other is the most common reason a chimney leaks. What is step flashing and counter flashing? covers both pieces and why the code will not let a tear off reuse them.

See Also

The two answers on either side of this one are the Oklahoma code framework, and what has to come off before any of this goes down.