Ice and Water Shield Is a Line Item, Not a Free Extra

Most roof quotes list shingles, tear-off, disposal and a line for underlayment. Somewhere between those lines sits a membrane that costs real money and is easy to miss: self-adhering ice and water shield, the sticky rubberized sheet laid under the shingles along the eaves. In a St. Louis winter, where the freeze and thaw cycle can push meltwater up under shingles at the lower edge, that strip is often the difference between a roof that sheds water and one that backs it into the soffit and the wall. Before you compare totals, you need to know whether the membrane is in the price, how much of it there is, and where it stops.

Why it shows up as a cost

Ice and water shield is priced by the roll and by the labor to lay it under shingles that will be installed on top. It takes more time than felt, it has to be cut and pressed tight to the deck, and it usually cannot go on in cold or wet conditions without extra care. A bid that treats it as a small add-on can understate the work. A bid that leaves it out entirely can make the price look lower than a roof that will actually keep water out.

Membrane is also one of the lines that changes after you sign. If the crew finds soft decking at the eave, the membrane area may grow because the deck has to be replaced first. If the drip edge is changed or the eave is rebuilt, the strip may need to go wider. Those are normal changes, but they are only fair to a homeowner who knows the starting quantity.

Where the code points

Many jurisdictions follow the International Residential Code, and that code asks for an ice barrier in areas where ice forming at the eaves is expected to cause water to back up under the roof covering. The common reference is a strip that reaches from the eave edge to a point at least 24 inches inside the exterior wall line. Whether your particular address needs it, and which edition of the code applies, depends on the city or county that issues the permit. Ask the permit desk for the adopted rule in writing rather than relying on what a roofer remembers from another suburb.

Code is a floor, not a ceiling. A roofer may run the membrane farther up the slope where the roof is low, where a valley drains into the eave, or where an old ice dam has left staining on the soffit. Those choices are sound, and they add cost. The point is to see them on the bid.

How a bid hides the membrane

Membrane usually does not get its own line on a roof quote. It may appear inside a general line called underlayment, be folded into a "roofing system" price, or be mentioned only in the scope text as "ice barrier at eaves." None of those wordings tells you the length, the width, or whether valleys and pipe penetrations are included. Two bids can both say ice barrier and mean very different amounts of material.

This is the same problem the square count creates. You cannot compare two prices until both are measured the same way. For the membrane, the measure is linear feet of eave and the width of the strip. A bid that states the roll count and the coverage zone is easy to check. A bid that says "ice protection included" is not.

What to ask before you compare totals

• How many linear feet of eave will receive the membrane, and how many rolls or squares of material that represents?
• How far up the deck does the strip run from the eave edge, measured from the exterior wall line?
• Does the membrane also cover valleys, the lower edge of any low-slope section, and the area around pipe boots or a chimney base?
• Is the membrane a separate line, or is it inside a larger underlayment price? If it is inside, which line?
• If the deck is soft at the eave, what is the rate for replacing it, and does the membrane area change with it?
• Will the membrane be installed in cold weather, and does the crew have a plan for it, such as hand sealing the laps?

Those six questions produce answers you can write down. If a roofer cannot answer them on the spot, ask for the revised scope in writing before you decide.

What the membrane will not do

Ice and water shield does not stop wind-driven rain from reaching a bad flashing, and it does not fix a gutter that is pouring water against the fascia. It does not replace a proper vent plan in the attic, which matters because warm attic air is one of the drivers of ice at the eave in the first place. Treat it as one part of the water path, not a guarantee against every leak.

It also does not change which shingle you buy. The membrane sits under whatever shingle is specified, and the shingle line should still show the exact product and the color you chose. If you are comparing bids, make sure the membrane is named in both and that the shingle is named too, so the two totals are for the same roof.

Putting it on the bid sheet

When you lay two quotes side by side, add a row for the eave membrane. Write the linear feet each roofer states, the depth up the slope, and whether the price is separate or inside underlayment. If one bid is much lower and does not list the membrane at all, the gap may be the membrane. That is not proof of a cheaper roof, but it is the first thing to check.

Keys Roofing can walk the eave with you, measure the strip, and put the membrane quantity and coverage zone in a written scope with photos. For questions about your address, call the office at (314) 220-2333.