I agree. This doesn't look like a cladding related issue. It looks like an install issue as I previously noted. It is also possible the compression seal degraded or was torn somehow. It's very likely water became trapped between the sash and frame somehow.

Thank you for your comments and insight. Perhaps you are right. I do know that 15 of 21 sashes are in varying stages of decay. The good ones are in perfect condition. The rotting is either at the bottom corners, (usually the hinge side) or on the under side. They were installed by the Marvin Dealer installers in 1999. Also, they are extruded aluminum, primed and painted with Oil paint or stained and sealed with polyurethane. The worst damage is on the West and North sides, with the least damage on the east.

I suspected the seals, but they are pliable, not buckled or damaged. The windows that I routinely open are damage free, hence the thought that moisture was trapped. The sills and wood that houses the hinges are in perfect shape. The internet is riddled with rotted wood stories. I just hope Marvin has improved it's technology.

I mentioned this a bit earlier, but the entire industry uses much better wood preservatives than were available in the 90s...Marvin included. I personally don't feel regular venting of windows is needed or even beneficial.

+1

This was not a vapor issue. This is a bulk water or installation issue.

Windows (as components themselves) do not need to breathe.

Most wood windows do not have weep holes. What is probably happening (and I have seen it ) is that water is being trapped because the seal between the glass and the cladding has deteriorated. The water has no where to go so it rots the sash. Put a business card between the glass and the sash and if you get no resistance, the sealant is gone. Run a bead of clear silicon along the horizontal and up each vertical leg enough to keep water out. Also check the bottom of the sash to see if it has been painted or stained. You can do this with a mirror. If it hasn't, chances are the top and maybe even the sides weren't done. Get the windows painted now before the wet weather sets in. These simple steps should help prevent long term problems if you don't already have them.

JIMT, I didn't have the time to read this entire thread but I had Pella sliding doors that rotted out on the bottom. The doors were 15 + yrs. old. We contacted Pella and they sent us replacement doors/parts. We had to pay for labor. It is my understanding that they changed the way the doors were made since this was a problem.

In inspecting the photo of the rotted bottom rail of the sash, I notice a dark line where the sash closes into the frame. Above this line is a darkened stain from water. This should have been evident way before the rotting, and would have been a good indicator that something was amiss - that water was present where it should not be. That would have been a good thing to have not ignored.

I agree with the folks here. Water looks like it got behind the sash from above, and then sat trapped at the bottom.

I also would like to suggest another possibility. This looks very much to me like possible insect damage. I have seen this before, where opening a window that had not been opened in a long time revealed a colony of wood eating ants. I have seen whole houses munched on by insects, and termites are not the only culprits.

I should add that if no insects were present when this was discovered that does not mean that for some reason they didn't flee on their own.

Just saying that is another possibility. You want to make very certain about this, because if it might likely be the case, then you will want to make sure to have your house treated by professional pest people.

I've never seen that kind of rot in a window unless there was a major leak of some kind. You should have your attic and roof inspected to make sure there is not water running down the walls and getting trapped above the window frames and working down into the frame behind the sash. I have seen that happen many times.

Other than those things, my only other comment would be towards the wood and the preservative. The reason old windows don't rot isn't because they were better. It's because they were made out of old growth trees. They were slower growing, had denser rings and harder cores. Trees now are fast growing re-forested trees and the wood is very very soft. It plays a factor in moisture absorbency.

Wood must be maintained, including the bottom. I suspect a leak more than anything. And failure to check the windows out once in a while, open them up and clean them out and make sure everything is ok.

UPDATE: Marvin Windows is replacing EVERY sash even though we are two years past our warranty. It turns out that the wood preservative used the year my windows were made was bad. Even the fixed picture windows were rotted. After prying away the panel at the bottom of every fixed window, the rot existed on the bottom, particularly in the corners. So the failure was a manufacturing problem. I DID open nearly every window every year to clean so I didn't think inattention was an issue.

I have to pay for the install and new paint and stain, but as I read online, I am getting a better deal than those in years past.

thanks for everyone's opinion, but the fault was bad preservative.
I am grateful that Marvin has been very pleasant to work with thus far. The new sashes are to be delivered in late March - post winter.

Good news and good for you. Another reason pros like and recommend Marvin as they will behind their product, even when technically their product did not fail.

+1

Great outcome here.

Glad to see they are stepping up.

Andersen replaced millions of double hung sash that had a similar problem with NO WARRANTY.

Sold Andersen for years and I have never heard of such a "similar" issue?

Neither have I

3rd that hasn't heard of this either.

UPDATE: I posted the photos above of rotted Marvin case master Alum. Clad sash.
My 1999 windows failed due to a poorly engineered GLAZING BEAD. The windows were re-engineered sometime in the mid 2000's. Marvin has replaced all of my sash. They have just been delivered and are waiting installation. I am having to pay for the delivery, installation and painting of my new sash. All in all, I am I guess I feel lucky compared to other customers.

Marvin has been excellent to deal with thus far. I'll post one more time after installation.

Excellent, glad this is working out for you and as I stated another reason we recommend Marvin products. (On another note still waiting for for jumppilotmdm's reply on the rotting Andersen sash being replaced?)

Good update.

Keep us posted and I am glad to see Marvin step up.

Solid company and certainly part of the reason that they are often recommended.

+1. Great example of how all manufacturers should treat their customers.

I have this same problem and came across this thread when searching for solutions. My Pella not so old Pella windows have been going bad for years (urethane pealing off) but I didn't do anything about it. I didn't know the warranty was 10 years so now that they're so bad the wood is falling apart I finally made a call. I'm just outside the warranty and Pella basically told me to go F... myself. They want me to buy entire new windows that would cost me a fortune even after the "discount" they're offering. Has anyone had better luck dealing with this company?

If the frames of the windows are okay just have them replace the sash. From my memory they have extruded frame so I'd hope they'd still be in tact. That roll formed sash really is an issue. Hopefully some day they catch up with the rest of the brands and go to an extrusion. But like I said, see if they can simply do a sash replacement. It will save you a lot compared to a whole new window.

I personally would look into another brand if I were you unless they were to give them to you for free.

If you are forced to do a full replacement, like millworkman said you'd be better off with a better brand like Marvin or Kolbe....

If the frames are ok, I would look into a quality vinyl replacement unit.

Pella is quoting me $272 for a ProLine 35 X 65 "Replacement Sash" and they tell me this is after a 30% discount. Labor is extra. Does this sound right? TY

Likewise, I am on the water in Florida, and have huge issues with rot. Have had to replace several and Pella is very difficult to work with. Maintenance advice is appreciated.

Also, I need new trolley parts for a couple of my Pella sliding screen doors (Pella part #80-054). Any advice where I can get these small chrome pieces for less than $140 each? (I could probably get a different screen door for the same price!)

Try Strybuc, for the screen parts. Other than these guys I would say you are stuck with Pella. As far as maintenance and rot, not much advice can be offered with out more info and pictures.

Like most posts I have rotting Pella windows in a 23 year old house. But the first failures were within 6 years. Also I have owned and operated a wood treating facility for 37 years. The failures are caused by not properly treating the wood. Penta has not been outlawed, except for certain usages (dwellings). Pella has replaced windows on two occasions, with me paying the labor. This after the warranty had expired. Could never confirm the reason, but believe it was because Oklahoma has a law concerning treated wood products. Most states have statues that have triple damages for selling products that do not meet the advertised item ( pressure treated wood). I believe there is ample grounds for a class action suit.

Pella Sucks - Have windows from 1999 that the aluminum cladding failed and have wood rot. They want to screw us on the pricing of replacement sashes since they know that it's the cheaper way to go vs tearing out and replacing with a new window. $150 service call

Maybe they have changed over the years? We have our original Pella Windows (21) installed 31 years ago. They have been wonderful and show no signs of rotting.

I have Eagle aluminum clad casement windows installed in 1988. I have had similar rot issues on the sash but have been able to replace the wood. The aluminum clad sill portion of the frame has a hinge track screwed to it. The screws have rusted and the wood under the aluminum is soft, giving very little to nothing to secure the hinged track in place. What would be the best way to address the rotting wood in the sill and secure the hinge track without removing the entire frame?

Replace the window

Yep. You will be spending good money chasing bad at this point.

I have 20 windows and a bid for $24K to replace them. I have rebuilt all of the sashes for under $200. The hardware is all in good shape. After reading reviews of issues with new windows I am hesitant to spend such a large amount of money on new windows just to end up with the same problem I have now. I don't mind at least trying to find a solution, even if it is just temporary. It has been suggested to drill out the screw hole, treat the soft wood with a wood hardener and then fill the opening with an epoxy product. The sill seems solid everywhere except the screw holes. What problems could there be to this approach?

It's a band aid, it may work just fine for what your expecting . I prefer to cut out sections of bad wood and replace with a section of new vs the epoxy.

I agree, new wood is preferable. I 'm not sure of the best way to get to the bad wood short of removing the aluminum around the frame and then replacing it. I am just trying to get a few more years out of the windows until I am ready to salvage them for another project. Thank you for your help!

Dig in and see what you got left, then make you're decision

I have Pella Proline windows from 1998. The sash has the rotting issue, but the rest of the frame is good. I have a quote from Pella with a 35% discount for new sashes. If the rest of the window is good, should I just get new sashes or would a whole new window be best? I really don't want to spend 5K (for about 10 windows + labor and caulking the other windows) now, then a whole new window project in a couple years.

Also, if I go the whole new window replacement route, would they need to take the trim off inside and outside?

Just do the sashes

With a 35% discount that's the way to go for sure. I just paid $350 and $545 for some 29x59" and 29x 73"s and they took just under 4 weeks, I hated paying that much they don't even come primed or with any hardware FYI.

That is interesting about the prices the the supposed 35% discount (Looks more like a 22% discount).

the 29x73 was $427

I didn't have the other size, but 29x53 was $254 (for a fixed window it is $376) and 29x65 was $291 ($423 for fixed).

Prices above are with me doing the staining and top coats.

I too had a hard time getting them to respond initially. I think posted a comment on their FB page and got a call within 5 minutes.

I would NEVER EVER buy Pella doors or windows again! They're designed to rot out, and the markup on replacement doors and sashes is obscene. The ~20 year-old active leaf pictured here cost >$1,100 to replace, and I provided the labor. Replacement upper sash was quoted @ $467.43 plus $160 labor if they installed.

Pella SUCKS:

did anyone file for the class action settlement Pella has for casement, awning and transom windows. It expires 6/20/2018.

Purchased a home in 2014. The windows were Pella proline aluminum clad/wood. the home was built in 1999, so at the tie of purchase, the house was approximately 15 years old. we received a $1500 write off for the 2 windows that were rotted at closing. the home inspector stated that the pella proline was probably one of the worst windows ever built. the class action suit closed in 2013 , so we could not take advantage of the settlement.

we are now looking at a couple of other windows that have severe rot in the bottom rail.

I have already replaced several of the cranking mechanisms. My question is , is there a none Pella version of the sash that I could have installed ? the frames are (to my surprise) in fairly good shape. A sash replacement is more cost effective this point in our lives. we are both retired and on fixed incomes.

Thanks

Art and Helen

Not to my knowledge, I’d contact Pella and check out pricing and options.

I’d check for any water issues also , this could be anything from drip caps on the exterior to condensation problems. I have seen Pella’s with problems just as youEd and I have seen many also stand the test of time with know issues.

Pella pricing has gone rogue!!!
They just quoted me $800.00, tax and shipping NOT INCLUDED!!! FOR A 29"X59" SASH ONLY!!!!!
CRIMINAL!!!!! HATE PELLA!!!! NEVER EVER AGAIN!!!

Typical Pella. The cladding leaks, the bottom rail rots out, and they do nothing for you except charge you a bundle for a replacement sash, door, etc. When I called about my sliding door active leaf with the rotten bottom rail, they told me it was my fault for not putting a bead of clear silicone caulk b/w the cladding & the glass, even though there's nothing in the user manual about it. The rep said "All of our technicians know to do it," and I got stuck for >$1,100 for another active leaf.

Pella REALLY SUCKS.

I don't know where you all buy but I just got quote for replacement and it's $5000. This includes labor. The window 29"29"x53" and the price includes screen & if I could find price like above I could replace the rest of them. I got the same story about how I was supposed to be caulking them every year all this time. No mention of that when I bought. None of my neighbors&guess what, they're not up there caulking their windows every year either but neither are their windows turning to sawdust. Run from !!!

meant none of myneighbors have them. Lucky me I thought it was a good decision to get them.