Window leaks in driving rain

Problem occurs only in north wind and rain, in only one north-facing window, a non-opening half-moon over a large sash window. There is a substantial windowsill below the half-moon and above the sash window, and water enters where this horizontal sill meets the vertical part of the window.
This leak first appeared last fall, when I tried to fix it by silicone caulk outside, finger-smoothed into two small visible cracks in exterior finish (oil-based stain) in the vertical/horizontal corner. This seemed to work OK but the problem recurred recently (2 inches of rain in a day in north wind.)
But I now see outside no visible cracks down in the corner -- only cracks along the edge of the putty (20 years old) that holds the window glass, extending about half the width (3 ft. overall.) Could rainwater enter at this point and travel down the wood (under the finish) at least one inch, and then another two inches horizontally to enter the house?
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Don Phillipson
Carlsbad Springs
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Water comes in all cracks and goes anywhere
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Sure.
Could easily be a roof leak, too. Check out your vent pipes going thru the roof.
On Wed, 6 Apr 2005 06:55:01 -0400, "Don Phillipson"

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[snip]

That's possible, but somewhat unlikely IMO unless you have some pretty large gaps in the putty. I think you should be looking higher up, maybe even as high as the eaves or the roof. Water could be getting behind the siding, and running down between the sheathing and the siding, until it reaches the windowsill, where it has a point of entry to the inside.
The first place I'd look is the casing around the window. Make sure the gap between that and the siding is caulked properly. If that looks good, then check the siding above the window for cracks or gaps. Go all the way up to the roof if you need to - I think you'll find a point of entry somewhere, that allows water behind the siding.
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
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Drain holes on the window plugged?

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