Step-by-step fix
Step 1: Confirm the membrane is the real problem
- Check where the leak or staining shows up inside, then trace that area upslope on the roof. Ice and water shield problems usually show up near eaves, valleys, roof penetrations, or other low, vulnerable sections.
- Look for clues that point to failed membrane coverage rather than a simple missing shingle: repeated winter leaks, water backing up at the edge, torn underlayment, wrinkled self-stick material, or signs that the protected area was never covered far enough.
- Lift the lower edge of a few shingles carefully in the suspect area and inspect for brittle, torn, or poorly bonded membrane underneath.
- Pick a dry day with mild temperatures so the roof surface and deck are dry before you open anything up.
If it works: You have a specific roof section where the membrane is damaged, missing, or clearly not sealing water out.
If it doesn’t: If you only find a few damaged shingles or exposed fasteners and the membrane below looks intact, repair the roofing surface first instead of replacing the membrane.
Stop if:- The roof is steep, high, wet, icy, or unsafe to stand on.
- You find widespread soft decking, sagging, or signs of structural damage.
- The damaged area extends far enough that a larger reroof section is needed.
Step 2: Open the roof area and expose the old membrane
- Set the ladder on stable ground and work from the bottom of the damaged section upward.
- Use a flat pry bar to lift shingles or other roofing material carefully so you can remove nails without cracking surrounding pieces more than necessary.
- Stack reusable shingles flat and in order if they are still in good shape. Set aside any pieces that are torn, curled, or too brittle to reinstall.
- Peel back enough roofing to expose the full damaged membrane area plus solid material around it so the new membrane can overlap onto sound surfaces.
If it works: The damaged section is fully exposed, and you can see the old membrane, roof deck, and surrounding roofing layers clearly.
If it doesn’t: If shingles break apart as you lift them, plan to replace those pieces during reassembly so the new membrane is not covered by damaged roofing.
Stop if:- You uncover hidden rot, moldy sheathing, or framing damage instead of a simple membrane failure.
- Water damage extends beyond the area you can safely open and dry in one repair session.
Step 3: Remove failed material and prepare the roof deck
- Cut and peel away the old roof ice and water shield membrane from the damaged section. Remove any loose underlayment, old sealant lumps, and remaining fasteners that would keep the new membrane from lying flat.
- Scrape off stuck debris and sweep the deck clean. The surface should be dry, solid, and smooth enough for the new membrane to bond well.
- Replace any small sections of damaged sheathing if needed so the membrane is not bridging over soft or crumbling wood.
- Measure the repair area and plan your new membrane so each piece sheds water downhill and overlaps onto sound membrane or underlayment.
If it works: You have a clean, dry, solid roof deck with the failed membrane removed and the repair area measured.
If it doesn’t: If the deck is still damp, let it dry fully before installing the new membrane. Self-adhering material will not bond well to a wet surface.
Stop if:- The roof deck is rotten over a broad area.
- You cannot create a clean, solid surface for the new membrane to adhere to.
Step 4: Install the new roof ice and water shield membrane
- Cut the new membrane to length before removing the release film. Dry-fit each piece so you know where it will land.
- Start at the lowest part of the repair area and work upward so upper pieces lap over lower pieces and shed water correctly.
- Peel back the release film gradually while pressing the membrane onto the deck. Smooth it by hand first, then use a hand roller to press out air pockets and improve adhesion.
- Wrap the membrane tight into corners, valleys, or edge transitions as needed, and keep seams flat and well overlapped onto sound surrounding material.
- Trim excess neatly so the roofing above can sit flat without ridges or bunching.
If it works: The new membrane is fully adhered, flat, and lapped so water will flow over it instead of under it.
If it doesn’t: If the membrane wrinkles badly or sticks in the wrong position, cut out the misapplied section and patch with a properly overlapped new piece rather than leaving a channel for water.
Stop if:- You cannot get the membrane to bond because the deck is dirty, wet, or too cold for safe installation.
- The repair area includes complex flashing details you cannot rebuild correctly.
Step 5: Reinstall the roofing over the repaired section
- Reinstall underlayment or roofing pieces in the same water-shedding order they were removed, starting low and working upward.
- Nail shingles or other roofing material where they will be covered by the next course whenever possible. Avoid unnecessary fasteners through exposed membrane areas.
- Seal any exposed nail heads or small lifted tabs with roofing sealant where needed, but do not rely on sealant as the main waterproof layer.
- Check that courses lie flat, edges align with the surrounding roof, and nothing blocks normal drainage at the eave or valley.
If it works: The roof surface is back in place, lies flat, and covers the new membrane without obvious gaps or lifted edges.
If it doesn’t: If the old roofing no longer sits flat or has become too brittle to reuse, replace those pieces before calling the repair complete.
Stop if:- You cannot restore the roofing surface so it sheds water properly.
- Large sections of surrounding roofing are too worn to reinstall reliably.
Step 6: Test the repair in real conditions
- After the repair is complete, inspect the area from the ground and from inside the attic or ceiling below for any immediate signs of gaps or missed openings.
- If conditions are dry, run a controlled hose test starting low and moving slowly upward while someone inside watches for leaks. Do not spray uphill under shingles.
- Check again after the next heavy rain or freeze-thaw event if ice dams were the original problem.
- Watch for recurring stains, damp insulation, drips at the roof edge, or water tracking farther downslope than before.
If it works: The repaired area stays dry during testing and after normal weather, with no new interior moisture or visible roof-edge leakage.
If it doesn’t: If water still gets in, reopen the area and check for missed overlap, damaged flashing, or a leak source higher up the roof.
Stop if:- Leakage continues after the membrane replacement and basic water test.
- Water appears to be entering from a valley, chimney, skylight, or other detail outside the repaired section.
Replacement Parts
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FAQ
Can I patch roof ice and water shield instead of replacing it?
Yes, a small damaged section can often be cut out and patched if the surrounding membrane is still well bonded and the roof deck is sound. The patch needs proper overlap onto solid material so water cannot track under it.
Do I have to remove shingles to replace the membrane?
Usually yes. The membrane sits under the roofing, so you need to lift or remove the roofing above the damaged area to reach it and reinstall everything in the right order.
What if the old membrane is stuck hard to the roof deck?
That is common. Remove as much failed material as you can without destroying sound sheathing, then clean and smooth the surface so the new membrane can lie flat and bond well.
Can I install new membrane over wet wood?
No. The roof deck should be dry and solid. Wet or dirty wood can keep the membrane from adhering and can trap moisture under the repair.
How far should the new membrane overlap?
Use enough overlap to extend onto sound surrounding membrane or underlayment and maintain a clear downhill water path. Follow the overlap guidance printed for the membrane you buy.