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QUESTION: Hello John,

     I have had this problem on and off ever since I bought this house for over 20 years, its a nice house to me. I would also like to add; a picture is worth a thousand words lol. Well, at the drip edge of my steep roof there is a gutter of course! PLUS the gutter 90 degrees around to the side of a add-on laundry room. I believe they may of added this to solve the basement leak problem but guess what, it still did not help matters. Well I thought the water was coming from the down spout so I put an 4" corrigated flex black, above ground 10' extensition on it. I thought that solved the problem however when big rains came I got a small puddle in my basement. THEN I thought OK well this 4" corrigated I'm going to OR someone may trip over this so I dug a french drain 20' away and ran 3" schedual 80 pipe underground. GUESS WHAT same problem on heavy rains SOOOOOO one day after the rain I noticed spots on my grass where there was NO grass close to the border of the roof eaves over hang PLUS its a mildew stain; been there ever since i had this house  but after 20 years it finally rang a bell to me. SOOO I put large plastic containers down and after a rain they FILLED UP hmmmmmmmmm but no water in basement well any way I wanted to know a clever idea what to put on my roof. Hmmmm when I was at my dentist office i just happend to look out the window and low and behold i saw something i never noticed before i been going there since 1964 .... lol i saw a exstention off a building with a small room BUT a STEEP roof above BUT it looked like a triangular shaped device with a provision to connect a down spout pipe to hmmmmmm is this my answer? The triangular device had vertigal metal extending upwards about 1" do you think if I fabricated a device like this it could solve my long long long basement water leak problem? Perhaps you have a different idea this kind of stuff is very difficult to put in to words John

ANSWER: I assume you are talking about a rain diverter that will drain the water to another area of the roof or a separate downspout. I am still in the dark as I assume you placed the buckets on the grass where the mildew stains existed.

does your basement also leak when a driving rain hits that side of this house? You probably have a foundation problem where the addition ties into the existing home. Are they both concrete block or both concrete?

If possible you should see if you can see where the water is entering the basement. Through the wall or from under the floor? More to it then just diverting water away.

Water test the foundation with a hose and see if the leak re-occurs.

---------- FOLLOW-UP ----------


     The mildew stains are on the side of the house on the stucco and the water is coming in at the base of my foundation right in the corner whenever its a driving rain. I never saw how the water comes down in a driving rain. this is a cinder block wall. The cinder blocks are not wet what I can see its just water that use to come in at the floor level. It seems like after I put the plastic storage bins out there they catch the water thus its not coming in my house. Well so far it hasn't come in and ONCE one bin was about full that's why I thought it was too much water coming down in this one corner area of the roof and spewing over the drip edge and over the gutter, then on the stucco which makes these mildew stains. I am sure if I put a water hose out there and just ran water in that area continuously water WOULD come in. I have clay soil here :-(
On just a normal rainfall it will not leak. I really did not want to dig down to the foundation and try to repair it if I can just get the gutter or down spout to work better in that area I believe even if I dug that one area up and repaired that with this clay soil water would find another area somewhere else in several more years.

Questions for you as you have not stated a question herein but observations.
Is your foundation damp-proofed or waterproofed? Has this leak occurred only since the addition or since day one?

If the soil is clay water should theoretically stay away from the basement as clay acts as a water barrier.

Mildew on the wall denotes water. Is water running down the inside of the wall from the roof?
Too many variables to formulate a pausible answer.


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D. John Henderson


My 33 years in the building science business has involved air barriers, waterproofing, and flat & steep slope roofing systems.


My roofing encompasses commercial systems (BUR, mod-bit, single-ply) and residential applications (asphalt shingles, cedar shingles, slate and metal. I am cognizant of code stipulations in regards to FM and UL for commercial roofs.

Attended numerous courses offerd by Roof Consultants Institute, Roofing Industry Educational Institute, Factory Mutual Research Corporation, University of Wisconsin, and BURSI. Lectured for RCI and mentored at a local university for a Building Science Certificate.

Past/Present Clients
Government, commercial businesses such as The GAP, hospitals, school boards as a roof designer.

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