Recently, a reader asked us, if we had any suggestions or explanation for the crumbling wood window frames on her 1887 home. Though we can’t promise an easy fix to the problem, we can offer an idea of what is causing it, and what it will take to address the underlying issues that are causing those window frames to fall apart.
First, wood window frames suffer a constant barrage of changing humidity and moisture levels. In our reader’s case, her home’s frames have held up for well over 100 years—an impressive feat. Though those window frames may have faithfully kept moisture from entering when they were new, time has a way of breaking down those defenses. If the moisture levels in your window frames reach 20% or higher, they become a prime environment for the fungus that causes wood rot—characterized by discolored or crumbling surfaces. This is probably our reader’s culprit, though any signs of insect damage from termites, carpenter ants, or powderpost beetles should be taken into consideration as a possible contributing factor.
If the rot is contained in one area, you may only need to remove the rotted portion (and a little of the healthy wood, just to be sure you got it all), and replace it. Cut a piece of wood to fit the void (try to use the same wood species used in the existing frame) and apply construction adhesive to lock it into place. A little putty, sanding, and paint will make the old and new areas appear uniform. If you have stained window frames, matching the patch to the original frame will be more difficult.
Unfortunately, when you remove the rotting portions of your frame, you may find that the rot extends into the surrounding wall. If that’s the case, you could be looking at significant repair and replacement costs. It also means that you have underlying moisture issues that need to be addressed before you repair or replace the window frame.
Wood treatments available at home and garden centers can help prevent and solve future rot problems. Try to use products formulated with propylene and polyethylene glycol, as they work well and are believed to be safer to use than typical rot-prevention products.
It might be time to replace your windows entirely. If you do purchase new windows, be sure to buy ENERGY STAR qualified windows—they can save you energy and money, and might make you eligible for additional federal tax credits.
We certainly hope this helps!