First of all, screwed in trim molding is unusual. It is generally attached with finish nails.
This sounds like a flashing issue. Removing the interior molding will not expose the source of the problem. The source is on the exterior. Water can infiltrate on the exterior at a higher elevation and get in lower down. Do you have an exterior shot of the window? Looks like the fascade is brick. What sort of sealant was used around the perimeter of the bank of windows? Not the caulk, but where it is attached to the sheathing.
Was this a problem before you caulked all the windows?
Why did you caulk all the windows?
Ron

We recaulked all of the windows because the builder had used a inferior caulk which left gaps big enough to put your fingers in around most of the windows. It was awaful. We had company come out and cut out all the caulk and redo it. It now is smooth, and completely sealed. An interesting side note, we have had two days of torrential rain and not a drop in the house...

Here are some of the exterior photos I took:
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Bottom corner of one of the triple windows:
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Right side of one of the triple windows where it meets the surrounding frame:
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Top of the triple windows where they meet the frame of the arch above. Note that gap is not black caulk, it is a gap about 1/4 or more wide in the frame:
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Bottom of the triple windows:
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This is the window pre caulking. You can make out the huge gaps. The first time it rained water came in everywhere.
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We spoke to a glass company and showed them the photos. They seemed inclined to caulk the mitred corners where it shows a gap and see if that does the trick. We are also in contact with the warranty/repair office of Norco. Hopefully this is a small fix.

The open mitered corners on a window with wood as a base is a problem. Norco became a Jeld-Wen company in 1996. On the J-W site they mention welded seams for their vinyl line. Couldn't find a specific vinyl clad wood section, only aluminum clad wood.
Andersen has vinyl clad wood, casements and awnings, and the corners are welded shut on the sashes and on the frames are seamless . I think any vinyl clad window with open corner seams is in the initial stages of failure. Caulking this is stupid and the companies way of putting off responsibility. Any open seam window should be replaced.
Ron

i was aware that Norco was bought by Jeld Wen. We've not heard a response back from them but we've only contacted them today. I agree this is a defect one should not see in windows less than 10 years old. However it is what it is. If they choose not to replace them, then we still have to fix the problem somehow.

On further inspection I think these are aluminum clad and not vinyl clad, on the outside.

You just answered my first question. I thought they looked like they were aluminum clad. The miters show the material being thinner than any vinyl product.

Finding a leak in a multiple mulled unit is very troublesome at times. The leak can be coming in at a higher level and working it's way down. The best way to try and dial in on the area it's leaking from is water testing. Get out the old garden hose and ladder. I would also remove that trim board on the inside below the triple unit. Take the garden hose and start on one of the outside triple units. Set your nozzle on stream and spray the window straight on. Hit each corner and then along the brick. Do this for around two minutes or until you see a leak forming. Do this with all three windows and don't spray above them yet. If a leak occurs while spraying then you'll know where to look. You can try and track it down by looking in the cavity you pulled the trim off. Just use the process of elimination to spray the window down and hopefully you'll find it. Then let me know what you find.

The problem with open seams on wood windows is the wood gets wet and swells. Once it swells, it never goes back to it's original size. The wood stays wet a long time because the water only has the crack to evaporate from, sort of like a terrarium in a bottle. Caulking the seam will trap the moisture in the window.
If you have paperwork on the window, check to see what the guarantee covers. Website says 20 years on the glass. I thought some of the lines mentioned a lifetime guarantee. Whatever that means.
If they start a down the path of,"Well that's not covered", or some such drivel, I would casually mention how you will be(might be) posting on the Internet about the companies policies and the lack of cooperation you are getting. I would look into legal ways you could get their attention. I don't know if you have Small Claims court up there in Canada.
I would prepare for less then full cooperation, but hope for the best.
Ron

Where are the backer rod and sealant joints? Not just a fillet joint of caulk. What kind of moisture barrier is on the house?

Did they tape over the bottom nail fin of the windows creating a funnel into the door?

Here is a link that might be useful: X-Ray

Hi

I am not in Canada so not sure about that part...

My husband spoke with the national rep for Norco/Jeld Wen and also the local glass/window/door place. Both of them felt that the plan was right and that likely the friction fit of the triple windows has shifted due to masonry shifting or weather extremes. They all agree the problem is not major and only when driving rain from the right direction. So the plan is to fix the few areas which appear separated and water test it. If that does not work, there is apparently some sort of gasket around the entire frame where the triple windows fits. This can be replaced. So we are preapring to try that.

More rain and nothing came in, despite the fercocity. Am very glad at least for small favors.

If it happens again,it might mean the caulking or any part of windows have continuing pressure of water from a small laek in the roof which can travel down joists and inside of exterior siding,brick,isulation.etc...(which show no visible damage to ceiling or inteiror walls)..and puddle.Eventualy seeping through the little cracks it has caused in time from erosion.

Sorry if I am hijacking the thread, but I have a somewhat similar problem. My leak at the shoulder of a palladium window. Exterior is brick. Caulking reduced but did not eliminate the leak. No sign of a roof leak seen in attic above. I do not know the window manufacturer. Builder is long gone. So far, I have not been able to replicate the leak with a garden hose, but the window is pretty high and the leak is pretty slow even in a heavy, driving rain.

I can't seem to solve the problem myself, but I'm not sure who to call. A window company? A general contractor? I'll get local references if someone can point me toward the right profession. Thanks.

By gosh I would check the roof first. Several years ago I had a drip at a window and after several attempts at repairs to the window itself my guy found that there was a nail popped thru the asphalt shingle directly above the window and approx 10 ft from the roof edge. Apparently the water was running down the top of the felt paper until it found a spot inside then it ran down the interior of the wall and out of the window trim. There was no visible sign of a leak inside the attic.

I think before we start with the roof we cross off the more obvious causes--like the seams that may need caulking. Or the gasket in which theese three windows sit may have torn or moved as the house settled. The roof is the least likely cause as the water comes in over the first and second panel of french doors (see first photo) and no where else. It would have to make a pretty circuitous and gravity defying route to get there. The glass company is coming on Friday and we'll see what they say.

Update:

We had the window contractor come out and inspect the window. He was able to determine the gasket surrounding the three window unit had deteriorated. We all decided to completely seal in the units. We had them caulk the complete exterior against the brick and also seal with silicone the glass to the clading. Both sets over both doors. It looks very nice. They had a very competent caulk guy come out. So far so good!