sill rot on older Anderson windows

[John Dirks Jr]

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 April 27, 2018 by John Dirks Jr
wordy

[Les]

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. 

 

[Mike Lamb]

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.

[Marc]

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.

[palmettoinspect]

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.  

[Jim Baird]

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 September 22, 2018 by Jim Baird

[Jerry Simon]

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 September 22, 2018 by Jerry Simon

[Rob H]

John Dirks, thanks so much for your post re Andersen vinyl clad windows and exposed ends of the sill. We’ve got a home completed in 1989, and are finding some sills rotted significantly, whereas others appear to be completely intact. 
Have you come upon a good solution for diagnosing the extent of and repairing this sort of damage?

Rob

[ejager]

On 4/27/2018 at 7:41 AM, Marc said:

Some day I'm going to make a timeline, putting down all the era-specific methods and materials I know.

How goes work on this great idea? I suspect it would be a best seller. 😄

[enfd240]

Hello all - I came across this thread while looking for replacement sills for my 1989 vintage 200 Narrolines.  One sill, as described above, has significant wet rot inside the vinyl casing.  Anyone familiar on where to get a replacement sill?  I spoke with Andersen today and they don't carry replacement sills for the 200s anymore.

If replacements are not available, any thoughts on digging out the rotted wood through the end openings and filling with something in it't place? (wood putty?)

 

thanks

 

[Rob H]

Hi, enfd240.

I’m hoping to get in touch with our Andersen rep soon. I’ll plan to post something here when I do.  

[Jim Katen]

On 4/20/2020 at 11:38 AM, enfd240 said:

If replacements are not available, any thoughts on digging out the rotted wood through the end openings and filling with something in it't place? (wood putty?)

Try using architectural epoxy. Go here: http://www.smithandcompany.org/products.html

Dig out as much rot as you can, soak everything else with Smith & Company's "Clear Penetrating Epoxy Sealer," then, after a day, fill everything with their "Fill-it Epoxy Filler." 

Lots of companies out there make epoxies for architectural work, but Smith & Company's are the best. I've been using their stuff for close to 30 years now. 

[John Kogel]

Thanks, Jim. A brand I'm familiar with is JB Woody. Two jars of putty, mix equal parts together.

It sets up hard enough to sand in a few hours, but won't take a stain, has to be painted.

[fred wark]

I put Narroline vinyl clad windows on my home while renovating it, in the 1980s.  Most of the exposed ends of the sill plates seem okay, but I am going to put some exterior paint on them to try to keep them that way.  However, the windows on the south facing side which get direct sunlight, and most of the rain are in bad shape.    This weeks project during this quarantine is to look close at them, and try to figure out how deep the decay is, how to remove as much as possible without disturbing the vinyl cladding, and how to seal it up.  It might involve removing a few pieces of vinyl siding off the wall to get better access.  I will follow this thread.  thanks.      It is good to know that I am not the only one with this issue

[BAlmnd]

I too have this issue. One window is fine and one is terrible. Would like to know what anyone finds and how they fixed it. I do appreciate what’s been provided above. This will also be a COVID-19 project. Hoping I don’t have any structural problems. 

[enfd240]

First off thank you all for your insight.  So today i started digging out the rotted wood from the end openings with a coat hanger with a little half loop bend...  Was getting the wood out, but it was a tedious process...

 

After 45 minutes i decided to go another route.  I slit the vinyl along the bottom edge.  There's a groove so the blade went right along it.  Once slit open, my wife lifted the vinyl up from inside the window.  I was able to then get my hand inside and using a screwdriver, removed all the wood in larger pieces.  The entire wood sill was wet rotted, nothing left of it.

Luckily the bottom of the jambs are in pretty good shape. Little rot that I'll hit with wood hardener. 

 

Next step. .  I'm figuring that now that I have access to inside the vinyl, I'll rip a piece of pressure-treated wood to the right size and slide it in, then with epoxy fill in any gaps.

Edit:. Added a picture of the largest pieces of the still... 

Edited May 3, 2020 by enfd240

[Jim Katen]

At that point, why not just fill it with high-density spray foam? 

[enfd240]

3 hours ago, Jim Katen said:

At that point, why not just fill it with high-density spray foam? 

Do you think it would be solid enough that when the bottom sash is closed it forms a tight seal?

[Jim Katen]

It's worth trying on one. If it doesn't work, you haven't lost much. If it does work, you can go into business fixing these all over the country. 

[enfd240]

🤔

[BAlmnd]

Thanks enfd240 for that write up. Not sure if I have the skills to go so far as to open up the sill. My windows are about 20 yrs old and some are pretty rough. But I wanted to comment also that it appears the windows should be / need to be re-caulked periodically where the horizontal vinyl jamb meets the sill. I’m in the process of cleaning, inspecting and re-caulking using DAP Ultra Clear. It’s pretty sticky, dries fast and as the name implies it’s crystal clear. Hope this advice (from those folks above) and my actions buy my another 15 years on these windows. 
 

Also wanted to mention that I’m using the Bondo products - wood hardener and exterior wood filler to repair my windows. So far so good.

Thanks again everyone. 

Edited May 8, 2020 by BAlmnd
Capitalization and clarity

[Brkstr]

Hello all,

I have experienced same problem with my Andersen 200 narrowline double hung windows circa 1981.  The bottom sash is vinyl clad with wood interior with the ends exposed wood.  The wood is almost completely gone from rot.  I only have two windows with this problem.  They are on the south side of my house and are the most exposed to the weather.  The rest of the windows in my house are under a significant overhang and protected from the weather so no problem with those yet.  
On one of the windows I removed the interior trim of the window covering the bottom sash this exposed the front side of vinyl clad sill.  I drilled 8 holes using a 1/4 inch bit in the front of the sill.  I sprayed window and door foam filler in all the holes.  It filled the vinyl sill pretty effectively.  Quite a bit flowed out the exterior corners so if you do this either cover the corners or have something catch the foam as it spills out.  After the foam dried, I cutoff the exposed foam that expanded out the holes.  Then I put the interior trim back on covering the holes.  This seems to have worked.  
 

I’ve read on other forums that foam might prevent proper drainage of the window   This is weird how Andersen might have designed a window that requires drainage around a piece of wood.  I’m not sure if the foam will cause a drainage issue or not.  I’m waiting for some heavy rain storms to try and inspect before I do my other window. Has anyone else tried this solution and have had problems with drainage or any other thoughts?

[Elrod]

I have the same problem on several of my Anderson narroline window.  I replaced the window sills with PVC board.  Just uploaded a video to You Tube.  Search for “replace rotted Anderson Window sills.

[SueMusic]

On 5/4/2020 at 4:10 PM, enfd240 said:

🤔Hi,

Like everyone here, I have wood rot, but mine goes the entire length of the sash.  I can put a piece of rebar all the way through each end of the double wide window and can put a screw driver straight through under the sill area between the window and screen location.  I have no idea how much damage is under the window and am told that I would need a full window replacement (that includes a palladium on top) so it's pretty expensive.  I had carpenter ants entering through the wood rot.  Although my house was now treated, and I've cleaned out all the the wood (which was at the point of dirt), I don't know what to fill the sill with because it's completely an empty void.  I heard that using a low expansion foam won't solve my problem because it will absorb water.  I'm not sure I can use the epoxy mentioned by Jim Katen because there is no wood left.  I don't see any water coming into the house, but who knows what awaits underneath? 

I am interested in the idea of sliting the underside of the exposed sill and lifting it up to see what damage is however, I don't see how it can be lifted with the edges tucked under each side.  Do you have any pictures to help explain that more?

When I asked a Renewal by Anderson salesman about why the ends weren't capped, he simply said that it was an installation problem and was anxious to sell me new windows which of course wouldn't solve the problem since the sill is incorporated into the poorly designed frame. 

I would appreciate any guidance you can.  Thank you!

 

[Johnnybull]

We have a house that the Andersen Narrowline 200 windows were installed in the mid 1980’s. I have replaced three widows due to the bottom sash rotting out across the bottom edge. I used a kit by Andersen that converts sashes to tilt windows. I have come across a couple of sills that are rotted, one at edges, I will probably try epoxy to cover those exposed ends. The other is completely rotted out, I am trying to locate an opportunity resin, that I can mix and inject with a large syringe and a tube and hopefully completely fill the void.