Although I would rather see the water intercepted before it hits your basement wall, you need to have a place to drain it to that is lower than the elevation of the basement floor. Harold's suggestion of intercepting it inside the wall and running it to a sump is valid as well, especially since this is an intermittent occurrence.

When you get around to finishing the basement walls, make sure you allow for the circulation of air behind the new finish assembly so that the small amount of water that does come in on occasion is allowed to evaporate. Think vertical supports for your drywall and some sort of opening bottom and top. If you seal up the wet area, you will be creating a very good habitat for nasty molds and other undesirable organisms, (sow bugs, carpenter ants).

Excuse the timeliness of my response to your ongoing issue. Looking at your 2 follow up photos of the subject area, I see as follows:

Photo 1: Fence appears to be wet along side of the bottom. Ground visibly slopes towards your house. Downspout. There is a garden hose.

Photo 2: In-ground irrigation box. Hose bib riser. Some strange water connection at the hose bib riser. Wood post on the left appears to have water damage on the bottom of the post.

Both photos give me "wet" feeling. Do you water that area a lot ?

Do this on non-rainy days: Remove hose. Put it in the garage, so nobody will use it. Cap off that hose bib. Thoroughly inspect underground plumbing at and around the irrigation box, hose bib, and that strange connection. If possible, cut off water to it completely. Don't water the plants of grass. . Leave it like that for 2 weeks. I bet you that mysterious basement leak will disappear.

From my experience, I would concentrate on the hose and / or the irrigation box. A small, drip will produce exactly the same basement wetness as you are describing. The drip is probably going on for weeks w/o you noticing it. Ground saturates and water shows in the basement. Even badly attached hose, dripping at the connection while it is being periodically used for washing your driveway or car will eventually show up in your basement.

Irrigation plumbing leaks all the time. Above ground and under ground. Again, a small, persistent drip at a connection will saturate ground over the time showing up in your basement.

Furthermore, that downspout is not installed properly. It has to be lowered, terminating right above the ground. Then, extend it as far away from that area as you can. Best would be to install 4" underground pipe and lead it towards the street / curb. Attach the down spout directly into the discharge pipe. Use Schedule 40 PVC and GLUE all joints. Use 4"PVC-to-Downspout transitional fitting to assure proper fit and minimize spill. Pouring 24" of concrete slab around the building, sloping away, would not be a bad idea at all.

If you really like plants in that area then use drought-resistant species.

When we work on new houses we never install hose bibs or irrigation system by basement areas. They are always a problem. Always. Gutters and Downspouts are a must over basements. French drains are installed regardless as extra precaution. Strips of concrete flat work along side of the basement walls is poured in areas where eves are less then 24".

Good luck...

Question: doesn't that undermine any fire-blocking built into the framing and wall?

Nope, almost never. It is heavily shaded and hardly ever goes really dry. Not wet, but not dry... moist is a good word.


No leaks there. The problem is only on heavy rains.


The irrigation is not running this year -- no water in the pipes -- shut at the main valve.


Yes, that is to be corrected in short order. Without running a 100 ft trench to the street, I will try to drain it about 10 ft away and see if this helps.


Thanks

FYI -- I have a few drainage guys coming in for estimates to talk about my options. I'll keep you all posted on what an in-person assessment says.

WWPiere: have you ever heard "mold" ?

Antipode12: That's great. You've done your "homework". So you have pretty much isolated your problem. There is lots of good suggestions in this blog as to how to proceed with installation of de-watering system. Proceed as suggested and you should be fine...

So, I had a pro come out to evaluate.
1) He's going to grade the ground to drain away from the basement.
2) Then, the gutters will connect to a dry well about 15 feet from the basement.

If this doesn't alleviate, he believes the best bet is to dig out the foundation and seal the wall.

I just thought everyone would like to know. Thanks for you ideas.

Yes, of course that is why I specified ventilation of the finish assembly. As for the lack of firestops, Antipode12, in the event of a fire in the basement, the heat would quickly concentrate at the ceiling, and there would be no opportunity to initiate the chimney effect.

In any case, You have decided upon the very best course of action: to intercept the water before it hits the wall. Once you have done the remediation, and monitored it through a few "high water" events, as long as there is no sign of dampness, you could slap up 1x4s or 2x2s (or whatever) strapping on 16" centers and hang whatever finish you want.

If there IS any dampness, (moisture in the soil can wick through the concrete blocks, which is why basements are usually cool) put your strapping on vertically, hang your finish paneling leaving a 1/2" gap top and bottom, then space your baseboard 1/4" above the floor, and disguise the gap at the ceiling with a crown moulding spaced 1/4" down. That way, air can circulate between the damp wall and the finish paneling, taking away moisture before it can accumulate, causing a chance for mould to grow.

A high-quality post that I will definitely save for future reference. Thanks.