# Thermally Modified Wood

- Link: https://www.oldhouseguy.com/thermally-modified-wood/
- Published: 2012-07-11T22:21:00-04:00
- Author: Ken Roginski

I try to get my larger projects completed by end of June to better enjoy the summer
and here it is July and I am way behind!

My current project is the restoration of a large attic dormer window with 20 True
Divided Lights.

During the winter I noticed rain entering the window lights, so I had someone cover
the entire window (minus a 2 inch gap at the bottom for air circulation) with plywood.
This looked ugly but was not easily visible from the street. This was just a way
to temporarily protect the window until the warm weather when it could be repaired.

The window glazing failed.  The window is in an out of the way location so I never
noticed any problem until it was too late. The last painter I used was a very bad
choice for this issue should have been found and fixed by him when the house was
painted.

Once the warm weather arrived there were many projects to do and finally this window.
The window was removed and put in the garage to be restored and re-glazed.

[⌊Rotted wood window will be fixed using thermally modified wood.⌉⌊Rotted wood window
will be fixed using thermally modified wood.⌉[

Rotted wood window will be fixed using thermally modified wood.

In this photo you can see the rotted wood on the lower rail of the window.  Small
areas of rot on the lower corners of the stiles were repaired with a wood filler
made by [Conserve – a wood epoxy filler. ](http://conservepoxy.com/)  However, for
such a large area as you see in the photo above, a Dutchman repair seemed like the
best option.

The problem was deciding on what type of wood to use to patch this old pine window.
Modern pine  is not much different from cardboard and would never hold up.  My answer
was to use Thermally Modified Poplar.  Basically soft wood is cooked and the result
is a strong, weather resistant wood that smells like beef jerky that will last a
long time.

[⌊thermally modified wood dutchman patch⌉⌊thermally modified wood dutchman patch⌉[

Rot is cut out and thermally modified wood is used as a dutchman patch.

Here is my Dutchman repair before trimming off the bottom.  The piece of thermally
modified wood is 2 feet long and 1 1/4 inch thick.  Two pieces were glued together
for me to get the desired thickness.  For this special order, I paid $32.00. I was
instructed to glue the Dutchman repair with Marine Epoxy. (Note it is brown from
the cooking process – the bacon scent filled the car on the ride home.)

## Here is an article in PDF format that tells you all about Thermally Modified Wood.

[About Thermally Modified Wood ](https://www.oldhouseguy.com/assets/UltimateOutdoorWood.pdf).
[

Remember, wood windows are made to be repaired.  [Learn about wood windows here ](https://www.oldhouseguy.com/windows).

My next step is glazing.  Then I can get this window out of the garage and get my
jeep back inside with the top down and doors off and enjoy the summer!