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John Dirks Jr

sill rot on older Anderson windows

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The older Anderson wood frame windows are the topic here.  Not just the windows but also the framework surrounding the windows.  Most of the time I see these windows they are in homes built in late 80's and throughout the 90's.  They have a wooden frame and sill that is encased in vinyl.  The corners of the wood sill are exposed and I assume a point of water intrusion.  Sometimes there's significant rot of the sill and sometimes not, even mixed on the same house.  Sometimes the sill is completely rotted and all that is left is the hollow vinyl cover.

What allows the water intrusion that causes this rot? 

For those of you who have removed these windows with the rotted sills, what condition have you found the surrounding framing in?

 

Edited by John Dirks Jr
wordy

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John, anecdotally we started writing the open sill ends and were corrected by the local distributor.  We had advised simply caulking them.  He, informally, told us that was designed to be open, but offered no real scientific reason.  Mentioned it may be for ventilation or prevent the water that may have penetrated the horizontal sill becoming seal into wood.

we still mention it.  we have found, like you, many rotted and many nothing.

 

interested to see what others post. 

 

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I find that older wood windows from the 80s and earlier are doing just fine and I assume it's because of the chemicals used to treat the wood. The 1990s had horrible problems with rotting wood and not just Anderson but, Norco, ROW, Marvin, etc.  I think the windows are clad with aluminum and not vinyl. Regardless, water gets behind the cladding and sits there and the poorly treated wood rots rapidly. I believe there was a class action suit against Marvin.  I make a point to check all windows carefully especially at the lower corners of the sash. 

Blackening is the prelude to rot and I always point that out in the report. Here are some recent pictures of a 1990s condo.

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When I arrive at an 80's or 90's house for an inspection,  rotted wood on windows is one of the things I immediately look for, as well as PB pipe.  Methods and Materials, Les said, and some are particular to a certain era.  Some day I'm going to make a timeline, putting down all the era-specific methods and materials I know.

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I've experienced many time what you're referring to with these Anderson windows. It's not just the single/double hung windows, but also the casement windows. I always do the "push" test where I open the window and push on the sill to feel for rot. Also, as you open the windows you can usually see the hardware is loose from the rot.

My theory with the casement windows is the water penetrates around the lower hardware and cracks that form in the vinyl cladding. The moisture and rot at the single and double hung windows is likely from the exposed corners. Most windows I see are exposed to an extreme beach climate so the damages are pretty bad.  

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I have some Marvin casements on my master suite addition.  I have to ride herd on the inside wood and recoat it with spar varnish every few years.

Edited by Jim Baird

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10 hours ago, Jim Baird said:

I have some Marvin casements on my master suite addition.  I have to ride herd on the inside wood and recoat it with spar varnish every few years.

 

Edited by Jerry Simon

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