Retrofit your wood-burning fireplace with the safety of glass doors
A cozy fire on a cold night is a delight. But it loses its charm when you must wait for it to burn out before heading to bed. A wood fire left untended isn’t safe. Unlike a gas fireplace, which can be switched off, the only way to leave a wood fire is to close it off with glass doors.
Most new fireplaces come with glass doors. But if you want to add this safety feature to an existing fireplace, retrofitting them isn’t difficult. The doors come in standard sizes that fit in any flat firebox opening.
We asked Justin Calemmo, of Five Sons Chimney Service in Brookfield, Connecticut, to show how to retrofit new doors on an old fireplace. Our 1848 fireplace has a surround that’s undersized, so the glass doors make it safer by blocking the fire from the too close wood floor and mantel.
Glass Fireplace Doors Overview
Installing a fireplace door is simply a matter of fitting the door unit into the firebox opening and attaching it to the masonry. The process is fairly simple when you’re dealing with a squared-off brick firebox. If you have a firebox made of rough-textured material, such as fieldstone, you won’t be able to use a standard door because it can’t overlap the opening’s edge.
If you’re dealing with an older fireplace, you’ll want to be watchful when drilling into the brick, in case it’s brittle.
Attach lintel clamps to door
Stand the door on its bottom edge and either lean it against your leg as you work or have a helper hold it for you.
With a Phillips-head screwdriver, remove the four screws located on the back of the door where the floor brackets (bottom) and lintel clamps (top) will go. Set these aside; you will need them later to attach the brackets and clamps.
Assemble the two lintel clamps and attach them to the door at the top.
Adjust the clamps
As you tighten the screws that hold the lintel clamps to the upper, rear frame of the doors, note that the screws fit into a slot milled in the clamps. This slot allows you to adjust the clamps up or down to precisely align them with the underside of the lintel that runs across the top of the firebox opening.
Next, screw the two L-shaped floor brackets in place at the bottom of the door.
Tip: Never lay the glass-door unit on its front or you will damage the doors.
Mark for screw holes
Carefully fit the door into the firebox opening, making sure not to scratch the finish. Align the unit snugly into the opening.
Hang a droplight inside the firebox to light your work.
Holding the unit in place, reach inside to mark where the bottom brackets meet the floor of the firebox. Use a thick marker, such as a Sharpie, and mark through the grooves in the brackets.
Drill holes for lead anchors
Carefully remove the door from the firebox and set it aside.
Using a drill/driver fitted with a 5/16-inch masonry bit, drill a 2-inch-deep hole at each of the two bracket marks.
Insert lead anchors for screws
Use a wet/dry vacuum to pick up the dust left from drilling the holes. Be sure to vacuum out the dust in the holes, too.
Using a hammer, gently tap a lead anchor into each hole until it’s flush with the surface of the surrounding brick.
Tip: Always drill into brick, not mortar, which crumbles easily and won’t hold the anchor. Make sure to drill straight down or you may have trouble getting the screw into the hole.
Put on a pair of gloves and unrollthe fiberglass insulation that comes with the door. Tear off pieces to fit into the channels at the two sides and the top of the unit.
Stuff the insulation into all three channels. Don’t worry about keeping the fiberglass fluffy, as you would with wall insulation—it’s mainly there to seal the door and keep smoke from seeping out, and to protect any finish on the door frame from the heat.
Screw door to firebox floor
Carefully slide the door into the firebox opening. Check that no insulation is sticking out around the edge of the frame.
Make sure the door is flush to the face of the firebox. Reach inside and twist sheet-metal screws through the bottom brackets and into the lead anchors.
Using a socket wrench, tighten the screws to secure the unit to the brick.
Tip: Be careful not to tighten the screws too much or you may loosen the anchor in the brick or break off the head of the screw.
Clamp door to lintel
Finger-tighten the thumbscrew to clamp the hardware onto the lintel. When you can’t turn the thumbscrew anymore, use a pair of pliers to give it another quarter-turn.
Tip: Don’t tighten the thumbscrew too hard or you will bend the clamp.