Blanco County News
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A Guide to Historic Wood Windows Restoration
Wednesday, December 8, 2010 • Posted December 7, 2010

A Timeless Building Material – The second article in a series.

Last week we learned that many remodelers, building owners, and homeowners are ripping out historic wood windows from old homes and historic structures. They have become the most vulnerable architectural elements of the historic buildings and historic homes.

Historic wood windows were handmade, precise and the tolerances tight, there were no gaps in the joinery, and constructed of old-growth wood. Lastly, we learned that replacement windows – wood, vinyl, metal – are generally warranted from 5 to 20 years depending on the window manufacturer.

The replacement window industry says that wood with a single-pane glass cannot be energy efficient and they must be replaced. Yet, nationwide the towns and cities historic district design guideline says that historic windows must be retained. As a homeowner myself are we caught in the middle without the facts?

The truth is that old wood windows are a natural insulator material and attractive material. Wood is the standard material for residential windows. It can be painted or stained, and is strong and easy to work with. With regard to energy efficiency, few sash and frame materials are better insulators than wood.

Here is a list of 6 usual culprits for wood window rotting or malfunctioning:

1. Lack of paint. Peeling paint is more than an eyesore, it’s a sign that wood is being exposed to weather such as sun, wind, rain, and dust which will ultimately cause it to rot or breakdown; a properly maintained wood window could last hundreds of years.

2. Foundation movements will cause the walls to lean, bent, and twist so the windows and doors will also become out of line and will separate. Remember your grandparent’s or the local carpenter’s simple solution? Take it off and plane it down till it fits. Was it the windows fault?

3. Water and mold is the window’s worst enemy. Water retainage on the exterior wood, this can be from a window ac unit as it drains on the window sill, a poor sloped thus it will have an standing water issue, a wooden screen frame that fits way-too tight that traps water, ice or snow, and again a lack of a good coat of paint.

4. Wood-loving insects can contribute to windows deterioration.

5. Aging, abandonment, and lack of an annual scheduled maintenance.

6. Lastly, broken sash cords.

Blanco’s historic preservation and design guidelines will also be explicit about saving all original fabric where possible on all historic homes and buildings. Can your old windows be saved? If they are saved, can they be made as energy efficient as modern windows? The answer is “yes” and “yes”.

Let’s start fixing the wood windows. First, wood window problems are not hard to fix, but you should leave it to a very skilled carpenter, window maker, a cabinet maker. It may not be a good ‘do it yourself’ weekend project. Primarily the sashes and stool or sill of the window are not hard to fix. If the problem is minor, and exterior (which is where it usually is), then a little outdoor spackling and some new paint solve it.

Replacing the rotted wood portions of an external wood window always, go back with a good hardwood, since they are better for exterior trim. Some of the hardwoods are; ponderosa pine, poplar, white pine, cedar, mahogany and oak wood trims are highly resistant to sun bleaching, moisture damage and warping. But, do not use a pressure-treated lumber since they will crack, twist, and some are a #3 lumber.

Fixing decayed and rotted wood windows where is not necessary to replace any wood, instead you can make repairs with a specialty epoxy penetrants called consolidants they are designed for restoring wood damaged and for sealing hair line cracks, end grain and porosity in wood. Not only is this faster, but the fixed wood is stronger than the original. This will not only strengthen the wood, but also give it complete protection from moisture for decades once it is primed and painted. Completely saturates the wood fibers, encapsulates and permanently hardens dry rot areas. Working time is approximately 60 minutes at 70°F and a hard cure is obtained overnight the cost for an quart is about $35.

Next week will upgrade your windows to save you money on your heating and cooling bills.

Rudy Nino, a member of the Blanco’s Historic Preservation Commission and a local remodeler. We do not endorse any product or service in these articles.

Web sites to keep you in touch:,,

The Historic Preservation Commission meets on the last Monday of the month at the Byars House. The Design Guidelines draft is online:

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