sill rot on older Anderson windows

[BAlmnd]

On 1/3/2021 at 9:08 PM, Johnnybull said:

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. 

Any luck with your project?

[Chuck L.]

I have a house full of 1993 Andersen Narroline 200 series windows. Many sashes were replaced free of charge by Andersen earlier under the 20 yr. warranty because the gas between the panes leaked out. But I still have the original frames and several of the sills are rotted out. Since Andersen is no longer supporting these windows with replacement sills, and dismantling the window and trim inside and out is an undesirable approach, here's my idea: Tell me what challenges this will present. Solutions to refine are invited and welcome. 1. Slit the vinyl sill cover from above and remove rotted wood. 2. Close cover back over and fill cavity with foam. (drill multiple holes if needed similar to what would be done in an epoxy foundation repair). 3. Cover sill with a thin sheet of moldable plastic or fiberglass or other, that is attached to and molded to the shape of the existing sill. 4. Paint repaired sill cover.    

Edited May 4 by Chuck L.

[Tom Raymond]

20 hours ago, Chuck L. said:

I have a house full of 1993 Andersen Narroline 200 series windows. Many sashes were replaced free of charge by Andersen earlier under the 20 yr. warranty because the gas between the panes leaked out. But I still have the original frames and several of the sills are rotted out. Since Andersen is no longer supporting these windows with replacement sills, and dismantling the window and trim inside and out is an undesirable approach, here's my idea: Tell me what challenges this will present. Solutions to refine are invited and welcome. 1. Slit the vinyl sill cover from above and remove rotted wood. 2. Close cover back over and fill cavity with foam. (drill multiple holes if needed similar to what would be done in an epoxy foundation repair). 3. Cover sill with a thin sheet of moldable plastic or fiberglass or other, that is attached to and molded to the shape of the existing sill. 4. Paint repaired sill cover.    

It will be less labor intensive to remove and replace the window.

[hausdok]

That is similar to a problem that we had around here. There was a high-end window builder from the Midwest that had a lot of success marketing wood-framed windows from the 80s. That is, until it was discovered that the wood they'd used is not naturally resistant to local forms of wood rot fungi and they began to rot. Lawsuits eventually drove that company out of business (I forgot the name but I'm sure it wasn't Anderson, and you can find it here if you search the archives way back.). In any event, Anderson has apparently tried to best wood rot by manufacturing its new line with Fibrex, a fiberglass replacement.

A cottage industry began here with a local company or two that would remove the window, disassemble them, and completely rebuild them using locally grown and naturally rot resistant wood and then reinstall them. This was done by expert woodworkers working in woodworking shops equipped with all they'd need to completely emulate the eastern white pine and replace it with locally grown cedar. The rebuilt windows were indistinguishable from the original except for the species of wood.

I've been away from the home inspection business for a few years, so I don't know how this has worked out. Perhaps this approach worked or perhaps it wasn't long-lived. In any case, I don't know how one would approach these vinyl-wrapped windows without doing something similar and I think the cost involved, unless it's a high-end home where the cost involved might make it worth it, would be prohibitive.

You can certainly preserve what's left by hardening it and then rebuild the windows with epoxy, using Abatron's Liquidwood and Woodepox, but first you'd need to completely remove the vinyl. That's a whole lot of work and if it isn't done by a very experienced specialist the results would probably appear abysmal.

The bottom line is this - if the wood were properly primed and painted in the first place it wouldn't have rotted because the paint would have kept oxygen from getting to it and feeding wood rot. A lot of builders seem to forget that when a window comes pre-primed that it is not waterproofed. They leave those windows in the primed state and deliver the house. New owners that don't know any better are blown away by the nice pristine white primer and they don't say anything about it. Later, when the water-and-air-permeable primer doesn't prevent the wood from rotting, they try and weasel out of their own stupidity.

Anderson is doing the same if the wood of a window casing is only wrapped with vinyl, inside of an unsealed sheath, water eventually will get inside, soak into that wood and cause the wood to rot. That wood needs to be sealed or immunized against rot before it is wrapped. You'd think a company with such a huge name would have figured that out before they did it.

[Chuck L.]

On 5/5/2024 at 11:07 AM, Tom Raymond said:

It will be less labor intensive to remove and replace the window.

Thanks for weighing in. That may be true for easily accessible single windows. But when we have to consider triple mullioned windows, only one of which needs replacement, 2 story foyer windows, and the labor involved with removing interior trim and sill, then re-caulking after reinstalling trim, hoping that touch-up paint of the interior color matches, etc., it's worth exploring options that don't include that.

[Chuck L.]

23 hours ago, hausdok said:

That is similar to a problem that we had around here. There was a high-end window builder from the Midwest that had a lot of success marketing wood-framed windows from the 80s. That is, until it was discovered that the wood they'd used is not naturally resistant to local forms of wood rot fungi and they began to rot. Lawsuits eventually drove that company out of business (I forgot the name but I'm sure it wasn't Anderson, and you can find it here if you search the archives way back.). In any event, Anderson has apparently tried to best wood rot by manufacturing its new line with Fibrex, a fiberglass replacement.

A cottage industry began here with a local company or two that would remove the window, disassemble them, and completely rebuild them using locally grown and naturally rot resistant wood and then reinstall them. This was done by expert woodworkers working in woodworking shops equipped with all they'd need to completely emulate the eastern white pine and replace it with locally grown cedar. The rebuilt windows were indistinguishable from the original except for the species of wood.

I've been away from the home inspection business for a few years, so I don't know how this has worked out. Perhaps this approach worked or perhaps it wasn't long-lived. In any case, I don't know how one would approach these vinyl-wrapped windows without doing something similar and I think the cost involved, unless it's a high-end home where the cost involved might make it worth it, would be prohibitive.

You can certainly preserve what's left by hardening it and then rebuild the windows with epoxy, using Abatron's Liquidwood and Woodepox, but first you'd need to completely remove the vinyl. That's a whole lot of work and if it isn't done by a very experienced specialist the results would probably appear abysmal.

The bottom line is this - if the wood were properly primed and painted in the first place it wouldn't have rotted because the paint would have kept oxygen from getting to it and feeding wood rot. A lot of builders seem to forget that when a window comes pre-primed that it is not waterproofed. They leave those windows in the primed state and deliver the house. New owners that don't know any better are blown away by the nice pristine white primer and they don't say anything about it. Later, when the water-and-air-permeable primer doesn't prevent the wood from rotting, they try and weasel out of their own stupidity.

Anderson is doing the same if the wood of a window casing is only wrapped with vinyl, inside of an unsealed sheath, water eventually will get inside, soak into that wood and cause the wood to rot. That wood needs to be sealed or immunized against rot before it is wrapped. You'd think a company with such a huge name would have figured that out before they did it.

Agree. This Narroline 200 series was an abysmal failure with gas leak, sash rot, and sill rot being major issues. At the time, Andersen had a stellar reputation. I would not buy an Andersen product after this experience.