Bay Window-No Sill Muffler

[fqp25]

This window was installed in late Novemeber. The owners were gone the whole month of Dec. The house temp was set to 58 - 60 degrees. The company who did the install (A Reputal Company) sent out a manger, his explaination is:

There is no Sill Muffler, plus the driving winds from the Southwest is causing the moisture build up, (Condensation). There is also a small pond 30-40 feet from the window, this could also be a factor.

The sill is 9 ply birch, and moisture readings range from 15 - 35, along the outer part of the sill. They're going to open it up in a day or two. Does the moisture level seem a liitle high just for condensation, from driving winds?

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little mold on this side

[mthomas1]

"Sill muffler" is a new term to me - GOOGLE turns up several references, but no picture.

[Scottpat]

Yep, that's a new one on me. When I think of a muffler (not the car type), I think of scarves to keep the wind from blowing down your neck. Never knew windows had mufflers!

The pond is a Red Hearing, it should have nothing to do with that window.

An improper install is the problem. It could be from the lac of insulation, bad seals or the lack of sealants. Or whatever the window guy said about the sill scarf![:-bigeyes

[AHI in AR]

As a common sense matter, if the installation is the EXACTLY the same on both angled sides of the bay, and there is noticeably higher moisture on one side, then it seems likely that directional orientation may be a factor in causing condensation.

BUT...if there is a difference in air flow across the interior of the windows then orientation is less of a factor. If there is not dryer, warm air flowing equally across both the windows that may be the real issue. I would also suspect that poorly sealed gaps around the exterior may allow wind-driven moisture to permeate the area.

That said, I wonder what interior sources of moisture there would be to form condensation in an unoccupied home during winter... in a cold climate where the thermostat is kept low. No cooking, no breathing, no showers, etc. Any humidifiers in use?

Bottom line as I see it is that there are too many variables to call this with the information given. From where I sit anyway.

Oh yeah...I have no idea what a sill muffler is either. Maybe it quiets the sound of the wind whistling through a poorly sealed sill...

[kurt]

How do driving winds cause condensation?

Anyone that uses a term like "sill muffler" shouldn't be listened to. I'm betting a dime there's no flashing, or some other very simple thing.

[chrisprickett]

Speaking of red herrings... Eliminate the possibility that the window was left, even slightly, open during the rainfall. It wouldn't be the first time that a newly minted bay window owner did not know how to latch that type of window.

[fqp25]

I'm pretty confident the window was never open, no water marks on the unfinished birch.

Sill Muffler, is pretty much (as I understand it) a big piece of Styrofoam under the sill, increasing it's R-Value. If you Google it you'll probably see a few product lines offering a Sill Muffler as an option for "Underside Weather Protection".

The wind explanation is making less & less sense the more I think about it, especially if the interior was not that warm for the majority of the time. My first instinct was a flashing/caulking defect during the installation, and I bet the underside of the sill is soaking wet.

[AHI in AR]

Originally posted by kurt

How do driving winds cause condensation?

Anyone that uses a term like "sill muffler" shouldn't be listened to. I'm betting a dime there's no flashing, or some other very simple thing.

The only way I could see winds as a factor is if the window is improperly sealed and cold air is being forced in around it, thereby cooling the inside of the window frame enough to allow condensation to form.

[Les]

sure looks like improper installation. I think the pond, sill muffler, wind, etc is over thinking it. The window allows water to accumulate on interior sill. Lots of cheap windows do that. I would be curious what the cross section of bottom sill looks like and method of assembly. Could be just a missing gasket on operator.

I have had 10-15calls about Thermastar windows and interior water.

[chrisprickett]

You might also want to see if some knucklehead caulked over any weepholes in the bottom of the window track or an alarm guy who drilled for his contacts.

I know these (along with the open window theory) are pretty obvious, but I'm just thinking through all scenarios I've seen over the years.

[Les]

Clear thinking Les and Chris "The bane of Builders everywhere!"

[Eric B]

Condensation has been known to drive moisture levels to an amazing 100%. What people often don't understand is how much water can be generated by condensation.

BTW - I started a collection of documents written by contractors. I tip my hat to these guys for the crap they think of.

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[kurt]

Isn't that a vinyl window? You're not going to get condensation on a vinyl window, no?

[Scottpat]

I just noticed the shape of the mold in the picture. It is the same shape as the mechanical operator for that type of window. I'm thinking missing gasket around the mechanical opening.

[Les]

Jeezzzzzzzz now I have to add Scott to the list of clear thinkers!

[Terence McCann]

Originally posted by fqp25

This window was installed in late Novemeber. The owners were gone the whole month of Dec. The house temp was set to 58 - 60 degrees. The company who did the install (A Reputal Company) sent out a manger, his explaination is:

There is no Sill Muffler, plus the driving winds from the Southwest is causing the moisture build up, (Condensation). There is also a small pond 30-40 feet from the window, this could also be a factor.

The manager, from the company that did the installation, said that there is no "sill muffler"?

Is a "sill muffler" an option that is presented to the home owner during the selling cycle or did they just forget to install it?

"We always advise our clients to get the undercoating, rust proofing and a sill muffler but sadly, these are extra. Upon signing you decided against purchasing these options, with the free set of steak knives, in favor of our econo-vision model."

I left my bs horn around here somewhere.