Water dripping from basement ceiling during heavy rain

Question

I would appreciate direction on investigating this water issue further:

I have had water dripping (from ceiling) during heavy rain , along inside wall of basement only on one side of the house. Fortunately, this is also not a chronic issue. It happened only during two spring/summer seasons in past 7 years.  Only after super heavy rain I saw this 3-5 times one year, and 1-2 time the next year spring. Dripping along the wall, stops after the heavy rain stops. For past two springs, it has been dry along that wall and now I am finishing the basement, so could use help on what preventive/investigative steps I could take before framing the inside wall. My plumber ruled out any water pipe leak. It is a 1950 cape in northeast, with poured concrete basement wall.

Visuals below:

• The first image shows the stain on the wall from the ceiling, from water drippings. You can see the same basement window in the second image from an outside view. Since the basement ceiling is well over 18 inches above ground level, I ruled this out as collected ground water coming back in.  

• The second image is an outside view of the same basement window: The water dripping along inside wall is isolated to the right of this window, in this view.

• The third image shows the full view of the outside wall, including the gutter & pipes on roof. I believe the gutters are fine, and water discharges about 21 feet away from the basement though a buried gutter extension. There is no other puddle or wet wall outside I could detect during rain.

I am suspecting the problem is some leakage around the flashing on the roof coming down alone inside of exterior wall, or some seepage along the cracks on the outdoor wood shingles.

Suggestions on other areas I could investigate, are very much appreciated. Right now I am think of calling a chimney professional to check flashings on the roof, as the next step to investigate.

Answer 1

I know you say the guttering is fine, but my advice to all homeowners is: "never check the gutters when they are dry". Always check them when it's pouring with rain, the harder the better. There is no better way of seeing exactly where the water is going.

My thoughts are that if the roof or chimney were leaking, you'd see evidence long before the water hits the basement ceiling, no?

The fact the water leak is above the ground level means the water is likely getting past the cladding. The fact it only does it during extreme rain points to the gutter system overflowing (IMHO).

The problem may then be twofold; the gutter (as it is) can't cope with heavy rain, and second, there is a breach in the cladding and/ or membrane behind the cladding.

Answer 2

I would consider the fasteners for the low bracket on the downspout. How far do they penetrate the outside wall?

They could act as a pathway for rainwater to follow. I would expect the amount of water in a light rain to be insufficient to make the basement ceiling wet. A heavy rain on the other hand might be enough.

Answer 3

I just saw something similar in a parking garage stairwell. See the attached picture. There is definitely no plumbing anywhere near the wall, and there is no leak in the roof. It is called basement wall sweat.

This happens if your home is too humid, the concrete walls touch the air, and the concrete is colder than the air. Concrete warms up slower than the rest of your home. So if your home temperature increases even a small amount, the concrete will be the coldest point; so it becomes the first point to collect dew.

Check your dryer vent. If a bird made a nest in there, you might not be venting water vapor properly. Clean your dryer lint trap after each load. Keep windows and doors closed at all times to keep out humidity, even when the outside weather seems nice. Turn down your humidifier or throw it away.

Your ac and furnace both dry out your air, so they can help.

Search the net for "basement wall sweat". Insulation can help, but you have to install it right, or it will make things worse.