How To Add Glass To A Solid Wood Door

Today Jacky emailed me with a very interesting question and design idea about modifying salvaged doors. Jacky said “We live in 1940 house, and are remodeling our unfinished half-lit basement. Currently we are in search of interior door w/small glass for our new 2nd bathroom. Since the bathroom has a big window, would like to use some of sun light thru its entrance door’s glass panel to the dark hallway area. We have found a couple of salvaged doors we love, but they are solid hemlock/fir doors without glass. Now we are wondering if we could cut the top panel out and install a reed glass instead. I know we could just order brand new one like that, but it will cost $400/door, it’s outside our budget.

Well I’ve never done this but I have seen it done a few times and it’s a great way to recycle / salvage a great solid wood door and give it new life and some added functionality. Solid wood doors are very expansive and honestly aren’t as good as the older doors. This modification will work well because the doors back then were indeed made out of solid wood and built with craftsmanship.

The process is actually pretty simple. First you’ll need to remove the wood panel that will serve as the window pane. This can be done several ways. Probably the best two ways that I can think of are to use either a circular saw or a router with a straight cutting bit. If you’re going to use a router you could make a simple jig to clamp to the door that would ensure you cut the exact size you want. The key here is to make sure you don’t cut too far into the corners. With both methods you’ll need to finish the corner cuts with a handsaw in order to get nice clean corners.

Once you cut out the panel you’ll want to sand the edges and treat the raw wood with either paint or urethane in order to protect the wood from rot. Next you’ll need a piece of glass thats slightly smaller than the window opening. I suggest making the glass approximately 1/4″ smaller in height and width to accommodate thermal movement in the wood. It’s important to note that most codes require tempered glass in doors. You may even want to purchase an insulated piece of glass (this could be quite expensive for a custom size).

In order to hold the piece of glass in place you’ll need to use some decorative moldings. The moldings will need to be sized based on the thickness of the door. For instance, if you have a 2″ thick door with a piece of glass that’s 1/8″ thick, you’ll need the moldings to be no greater than 7/8″ thick. You’ll also want to try and find a wood species thats similar to the native door species.

Nail the decorative trim into the opening on the outside of the door (you’re creating a sandwich effect, wood stop – glass – wood stop). You want to make sure that the molding is positioned so that when you insert the glass it’s centered in the door. Next apply a bead of silicon caulking around the inside of the molding. Set the glass inside the opening up against the first row of molding. Apply another bead of silicone caulking around the edge of the glass. Finally install the inside layer of molding up against the glass panel to complete the sandwich.

Once you’ve finished installing the glass you can apply a finish to the door to match it’s existing finish or you can re-finish the entire door. I hope this explanation offers sufficient information for you to try this interested door conversion.

Have any of you tried this? Do you have any before and after pictures? Email them to me and I can post them for others to see.