Replacing Tile Interior Window Sill with Wood

justinswartsel · 10-06-2009, 09:47 AM

Hi,

Firstly let me say that I am very new to house repair and rennovation, but have been "cutting my teeth" on a few projects at my house. I own a concrete-block home and all the windows have ceramic sills on the interior. In our master we're hoping to replace this tile with a wood stool and trim around the window.

It appears that the window doesn't have any wood framing underneath it, only concrete block that the tiles are mortared to. What will I need to do to install a wooden stool in their place? The window itself sits ON TOP of the tile. It is a metal horizontal-sliding window roughly 105 inches wide by 25 inches tall. The interior sill measures 3 1/4" from the window to the wall edge.

One suggestion was to put a pressure treated 1x4 on the concrete and install the stool on top of it. Any other ideas or suggestions?

Thanks!

Justin

inspectorD · 10-07-2009, 06:35 AM

My opinion, don't install any wood to the block. your asking for trouble from somewhere down the road with condensation or wicking water.

When we trim a block area, usually around a basement window around here, we build the interior trim box.
The window will need extension jambs to get the trim out flush to the interior wall because of the thickness of the block. Build a box to fit the window size where the reveals are good. Then shim the box with a few cedar shims.
The last thing is to foam the box in place with low expansion foam in the can. Just be sure to cut a few sticks to keep the jambs in place while the foam sets up, or the foam will bow the jambs inward.
I have had great results with this method, and actually it is less work.