Rotting Window Frames

[Peter H]

I hope that someone from the excellent group can help me with this one.

We've bought a 22 year-old house in the greater Toronto area. The window frames on the western side of the house are beginning to rot out. We had a home inspection done and the inspector suggested that the windows should be replaced next year or the year after at the very latest.

I'm wondering if there isn't some way to save the windows, or at least delay the work. The windows are thermapane (sp?) and the seals are all still good.

Could we not have the frames injected with a resin or something and then seal them. It seems such a waste to trash the whole set of windows because of this problem... not to mention the expense.

Thanks for all replies.

Peter H

[Tony Hwang]

Hmmm, Looked into a cladding possibility?

[Ed Pawlowski]

Yes, I saw something done on This Old House when they were doing some restoration. It was an epoxy material that dried hard and could be shaped and sanded to match.

It is also important to find out the cause of the rot and eliminate the problem. Windows should last much longer with proper care and a coat of paint.

Probably other materials available too.

[hrhofmann]

Bondo as used in auto body repair works quite well and is commonly available. Also you must find out if something happened to the wood that made it rot. It might just be a case of the west exposure and not painting/repainting the wood often enough as some people just don't realize that painting is a routine chore.

[aemeijers]

Cladding is a cosmetic fix only, and often causes rot by trapping water and condensation behind it. (Field-applied cladding, not the factory stuff where no wood is exposed to water.) Not a fan. Besides, if the rot is advanced enough, the window will still fail.

-- aem sends...

[David Nebenzahl]

On 11/16/2009 6:58 PM Peter H spake thus:

Having had recent experience doing just this, yes, it is possible to save windows this way. Depends, of course, on the extent of the rot.

The window I rebuilt was a standard double-hung sash (single glazed), but there's no reason the same technique shouldn't work for your windows.

The stuff you want to use is epoxy made for such purposes. I used something called PC-Woody, basically epoxy mixed with wood dust to about the consistency of peanut butter. I also embedded some steel hardware (all-thread rod and an angle bracket) to restore structural integrity to the corner that was completely rotted out.

It takes a bit of doing: I ended up making a crude form to mold the stuff in. But it does work well.

[Bob F]

Git-Rot or some other penetrating epoxy would be a better solution than bondo.

[ransley]

Why did they rot, the west side has enough sun to dry things out, is it the whole frame. First dig out whats loose and kill the rot with bleach. Minwax has a liqued hardener to be used on soft wood, you drill holes and inject the liqued. I think a syringe would be best. For holes ive used Bondo as that is the cheapest. A few other products mentioned might cost you 2-5x as much and do no more. Covering it all in aluminum will only hide the problem and cure nothing. But a question remains, what caused them to rot?

[ransley]

I use a belt sander and usualy 80g , cleans it fast

[dadiOH]

Yes, there are epoxies for that purpose; as mentioned, Git Rot is one.

The success in using them depends on the extent and type of rot; the epoxy needs to penetrate into the entire rotted area. If the rot is "wet" rot and superficial they would work IF the wood is completely dried first. If the rot is deep "dry" rot, you would need to drill numerous holes and fill them with epoxy...all the fungus causing the rot needs to be encapsulated. In either case, any missing wood can be replaced with Bondo after the epoxy sets.

How practical it is to do that is impossible to say without knowning the extent of the rot. Quite possibly it would be cheaper to replace the windows considering the amount of work to fix them, prime and paint. Especially if the rot is also in the overhead member of the frame...try getting thin epoxy into *that* :)

[Jim Elbrecht]

-snip-

first you need to find out why they only lasted 22 years. Once that's fixed, I love this stuff;

It is expensive, and not that easy to use-- but given all the things that replacing otherwise good windows entails, it is probably a good idea.

I fixed the bottom of my garage door with it 10[?] years ago & there is no sign of rot returning.

Jim

[Jim Elbrecht]

-snip-

Before you do that- take some yellow pine, weigh it, take a chunk of bondo and weigh it. Put both in water for a while & see how much more water the bondo holds than the wood.

Auto-body bondo is not for wood. Bondo *does* make a wood repair product though. I've never used it- but note that the directions say "For Rotted Wood Problems, Use After Applying Rotted Wood Stabilizer."

Jim

[ransley]

Bondo doesnt absorbe water its plastic, their 'wood' line is just bondo, I used it this summer and compared it to regular bondo which is alot cheaper.

[salty]

Bondo absorbs moisture very easily. It is like a hard, open cell, sponge. Very porous.

[dadiOH]

You must be using a different kind of Bondo...mine is talc (absorbs nothing) bonded together with polyester resin (absorbs nothing), and a small amount of magnesium carbonate. If it was porous it would make a lousy auto body filler which is its primary use.

[ransley]

Bondo is solid, hard as a rock with no cells visable, if it absorbed moisture it would rot your cars steel from holding moisture, you must be thinking of something else like foam.

[salty]

Nope. Bondo is quite porous and absorbs water easily. That's why anyone who knows what they are doing immediately coats it with primer when doing autobody. You should never leave unprimered bondo on a car even inside overnight. Otherwise, it absorbs moisture that causes problems with subsequent finishing.

You might think nylon is waterproof as well. It isn't. When immersed in water for any length of time, it absorbs moisture and SWELLS.

[Don Phillipson]

1. The home inspector could have answered your questions about repair rather than replacement. Rot signals damage by moisture, and long-term repair requires eliminating the source of this damage. Plastic and metal-covered windowframes are much easier to clean and maintain than (cheaper) wood.
2. You should be aware of the government-subsidized "Eco- Energy" programme for Ontario, see This subsidizes (0) an "energy audit" of your house (cost 0 to 0) and provides for part payment of upgrades that improve your energy economy. The federal government announced in 2008 (as an economic incentive) extra tax deductions for home improvements, but this has not yet been enacted for tax year 2009.

[salty]

Nope. I'm talking about BONDO.

Do a google search for

"Bondo" "moisture"

and learn something useful.

[EXT]

What caused them to rot. That is a good question. I have a similar problem on south facing windows. It appears that the window company used a very susceptible piece of wood. The wood next to it and touching it is fine. The windows are aluminum clad at the factory. There is nothing on the outside to paint, however, aluminum venetian blinds on the inside can cause considerable condensation in winter. This soaks into seams and swells the wood which causes the paint to crack allowing more water to penetrate. The bad piece of wood over the years retains the water for months and has started to rot in spots after 25 years. I have soaked in epoxy penetrant and used epoxy putty to level the lower frame and it is still quite sturdy and useable. The window next to this one, made by the same manufacturer, facing east is fine. Sometimes a bad piece of wood is used when making the frame. It looks OK when new, but just does not hold up over time.