# Replacing Tile Interior Window Sill with Wood



## justinswartsel (Oct 6, 2009)

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


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## inspectorD (Oct 7, 2009)

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.


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## Evan (Jul 17, 2010)

inspectorD said:


> 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.
> ...



I have the same issue, concrete block home with tile.  It was good info to hear about the condensation and wicking effect, but I honestly do not understand the rest of your post!  Are you suggesting we remove the window and build a windowbox, then replace the window into the box?  My windows do not sit on the tile, yet I don't like tile or marble and miss the look of a wood interior sill.  

I like the idea of seating the sill on a treated plank.  This would seem to take care of the condensation/wicking effect.  What do you think?
-Evan


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## inspectorD (Jul 17, 2010)

Sure, you can use a piece of PT wood tho secure it to the trim, It just makes the opening smaller in my Opinion. I like to get as much window glass as I can for the opening.
And the vinyl window itself usually can be made to the exact measurements of the concrete opening, and a couple of concrete screws applied through the sides. Then some eurathane caulk or silicone to seal the edges.

The foam nowadays is extremely sticky and bonds well to everything. So if you can build you window extension jambs and trim as one piece,, foam it in. Whan I remove this "great stuff " on jobs when someone foams in a window, I usually need a quick run with a sawzall to cut away the foam.

Hope this helps.


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## SillMaster (Dec 3, 2010)

Hello,

You might take a look @ Sill Masters - Premium Quality Vinyl Window Sills for a solid vinyl window sill.  You can glue this right to the block with poly urethane construction adhesive.  The sills are waterproof.


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