[jjeglbs]

I'm not sure if the subject line describes this correctly, but hopefully the picture will help. I've got a big picture window with mullions separating the center window from the two side windows.

I'm planning on installing plantation shutters on the inside, directly mounting shutters on each side to the side trim and then directly mounting two shutters to the mullions for the center window. As you can see, the mullion is recessed back and needs to be built out to the edge (about two more inches). My question is, how best to do this.

Do I cut down a piece of solid wood and fit it in? Seems like the wood would move a lot with changes in humidity.

How about pressing to together 1x4s? Or filling with plywood strips trimmed out with 1x wood?

Any advice would be appreciated. Thanks.

 

[kwikfishron]

I'd remove the mullion trim that you have now and add jamb extensions to push the trim out. You basically end up with a three sided box not a solid piece of wood.

 

[jjeglbs]

Ah, that makes sense. Thanks! Will it be strong enough to support the weight of the shutters (each one will be about 36" x 56")? I imagine I could beef it up some.

I'd remove the mullion trim that you have now and add jamb extensions to push the trim out. You basically end up with a three sided box not a solid piece of wood.