Adding Depth to Casement Window for Mounting Mini Blinds

Bonnie Morris
by Bonnie Morris
3 Materials
1 Week
We have casement windows throughout our home. Because of the window construction there is minimal to no room on the inside of the window to install 1" wide blinds. I could use outside mounted blinds but I think they just look better if mounted inside; consequently, I needed to add depth to the window.
Original window trim has been removed.
Step 1: First trick is to remove all the window trim without destroying it. I only shattered one of the four pieces but was quite happy that it was just one of the shorter sides. The top and bottom pieces were over 8 feet long and thankfully I saved these. I also found that once the trim was off, I found several areas that needed more insulation. Nice thing about painted trim is that it is easily patched and repainted and it will look just like new!
1x3 added around entire window
Step 2: I purchased primed 1x3 MDF boards and cut these to fit around the entire window. I found it easiest to install the two horizontal pieces first which allowed the two vertical pieces to line up more easily. Since I did this myself and the horizontal pieces were very long, I temporarily nailed a shim at the each end to keep the trim piece lined up properly. I could then push the trim up against the shim and attach the trim piece knowing that I had it in the correct position.
Significantly built up center trim.
Step 3: The center of this 8' wide window posed a slightly different problem. The center was already recessed about another 1 1/2 inches; consequently I had to really build this center up to match the rest of the window. I found a scrap piece of 3/8" thick trim, trimmed the same width as the 1x3, added another piece of the 1x3, and topped it off with a decorative 1x3. Now it matched the rest of the window.

Finished Product with Blinds
Last step was recut the original trim, put it back up, paint it and then install the mini blinds.
Close up view of inside mounted blinds.
As can be seen in this last view, the mini blinds easily fit into the now deeper window wells.
Suggested materials:
  • 3 pieces of 1x3x8 MDF board   (Menards)
  • Pair of navy blue mini blinds   (
  • 1 - 8' primed colonial door/window trim   (Mendards)
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