Bulkhead Waterproofing: Why Bulkheads Leak and How to Fix It

Most bulkhead leaks don't come through the door itself. Water usually gets in because a downspout or the ground sends it toward the bulkhead, because the joint between the door frame and the concrete sill has failed, because the stairwell walls are cracked, or because the bottom of the stairs has nowhere for water to go. Bulkhead waterproofing means finding which of those it is, then fixing them in order: water source first, then seals, then masonry, then the door.

Waterproof bulkhead doors are part of the answer, but no sloped bulkhead door is watertight on its own. Here is how to find your leak and what fixes each kind.

Watch it leak first

Go look during a steady rain, or run a hose over one area at a time while someone watches from inside. Note where water first appears:

• Dripping at the top, under the door frame: the frame-to-sill joint, or the joint where the bulkhead meets the house wall.
• Running down the side walls: cracks in the walls or failed sealant at the frame.
• Coming in at the seam where the two door leaves meet: worn weatherstrip, bent leaves or rust holes.
• Pooling on the bottom step and under the inside door: surface water running into the stairwell, or groundwater, with no drain to carry it off.
• Only during snowmelt: snow piled on or against the bulkhead, or a frozen drain at the bottom.

Step 1: Move roof and surface water away

Check for a downspout emptying near the bulkhead, soil that slopes toward it, and a walkway, patio or driveway that pitches toward it. Any of these can send far more water at a bulkhead than a door is built to shed. Fixing them often stops the leak with no work on the door at all. Our guide to drainage around the house foundation covers downspout piping and regrading.

Step 2: Find out which part is letting water in

The door

Look for rust holes, leaves that are bent so they don't meet, and worn or missing weatherstrip. Sloped bulkhead doors are designed to shed rain, not hold back standing water. Even a new door can let some wind-driven rain past its seams in a heavy storm, which is why the stairwell also needs a way to get rid of water.

The frame-to-sill joint

The door frame sits on the concrete sill at the top of the stairwell walls, and the joint between them is sealed. That sealant breaks down with sun, cold and movement. Resealing it with a polyurethane sealant made to bond to both metal and concrete, applied to a clean, dry surface and within the temperature range the maker lists, fixes many leaks. If the sill itself crumbles when you scrape it, the sealant has nothing to hold onto and the sill needs repair first.

The stairwell walls and steps

Map the cracks. Hairline cracks in poured concrete are common. Wider cracks, stair-step cracks in block walls, or walls that have moved point to a bigger problem, and a patch alone won't hold. Our post on bulkhead stair replacement covers when the stairwell should be rebuilt.

The bottom of the stairwell

Some water reaching the bottom of the stairs is normal. The question is whether it can leave. A drain at the bottom step, piped to a dry well or to daylight, keeps it from building up against the inside door. If there is a drain, make sure it isn't clogged with leaves.

Are fiberglass bulkhead doors waterproof?

Fiberglass, aluminum and some coated steel doors don't rust, which removes one cause of leaks over time. They still depend on the same things as any bulkhead: a sound sill, a sealed frame, good grading and a way for water to leave the bottom of the stairs. A new door of any material on a cracked sill will leak. For choosing a door type, see our post on bulkhead doors for basements.

Basement weatherproofing at the bulkhead

If the bulkhead area is cold and drafty, the inside door at the bottom of the stairs does more than the bulkhead lid. A solid, weatherstripped exterior-grade door into the basement keeps out cold air, and it gives you a second line of defense when water reaches the bottom step.

A homeowner checklist

• Note when the leak happens: rain, wind-driven rain, or snowmelt.
• Check downspouts and grading near the bulkhead.
• Look at the door seams and weatherstrip.
• Scrape the sill and check the frame sealant.
• Map any cracks in the side walls and steps.
• Find the drain at the bottom, if there is one, and see if it is clear.
• Keep shoveled snow off and away from the bulkhead.

When to call a mason

Call when the leak continues after the water source is handled, when the sill or walls are cracked, or when the stairwell needs a drain. Gerrior replaces bulkhead doors, rebuilds sills and stairwells, and fixes the grading and drainage around them. Bilco and Gordon are among the door brands shown on our site, and owner Joseph Gerrior oversees each job. See our foundation and bulkhead repair page and the bulkhead replacement cost guide. One bulkhead customer wrote:

"Gerrior replaced our bulkhead and the surrounding blocks and refinished the steps. They started and finished in a very timely manner. Extremely pleased with the quality of their work, and they left our property in excellent shape." Bulkhead replacement customer (review on gerriormasonry.com)

Common questions

Why does my bulkhead leak when it rains?

Usually surface water aimed at it, a failed seal between the frame and the sill, cracks in the stairwell, or no drain at the bottom. The door itself is the cause less often than people expect.

Can I just caulk my bulkhead?

Resealing the frame-to-sill joint is worth doing, and it fixes many leaks. Caulk won't fix a crumbling sill, a cracked wall or water running into the stairwell from outside.

Will a new bulkhead door stop the leak?

Only if the old door was the cause. Check the sill, walls, drainage and grading first, or the new door will leak the same way.

Does a bulkhead need a drain?

Not every bulkhead has one, but a stairwell that collects water does. A drain at the bottom step piped to a dry well or daylight is a common fix.

If your bulkhead leaks, we can find where the water is getting in and tell you whether it needs a seal, masonry repair, drainage or a new door. Gerrior Masonry & Landscape Construction Corp. is a family-owned company in Woburn, MA, with over 30 years in masonry and drainage work. We are fully insured, our work is guaranteed, and estimates are free. Call (781) 933-4157 or request a free estimate.