Question: I have a Vermont Castings Winter Warm Large fireplace insert. It was installed by professionals 2 years ago. The unit works well, but I have a problem. The surround does not block the entire opening of the existing fireplace. I have approximately 3 inches of space at both sides. Recently this winter, I've noticed I've got some draft coming through these openings. The insert does not fill the entire fireplace cavity, but tapers to the rear. After looking on your site, I can see that my installers should have created a blocking plate at the flue. (Yet, I had the entire chimney lined with a stainless steel liner, which is connected directly to the insert. Why am I getting this draft in the first place?) My question is this: What can I use as insulation to fill the spaces at the sides of my insert? The insulation will be in contact with the insert's sheet metal exterior. Also, what can I use to conceal the insulation? I have large stone facing over my existing brick, so my clearances between the stone and the insert are not even. Any ideas? Answer: The draft you are feeling may be from the stone conducting cold if your fireplace is an exterior fireplace where the back is actually exposed to the outdoors. If your fireplace is an interior one, then the draft is air movement coming down the flue meaning that the seal around the damper plate is not tight. It's a difficult job to get a great looking appearance with uneven stone. Based on your description, if it were my fireplace, I would use a combination of insulation & steel. If you are in agreement, you can try the following. Make a cardboard template of the stone shapes on each side of the Front or surround. Measure the distance to the Front or surround as well. Have a sheet metal specialist fabricate these pieces, with enough overlap for a secure fit. Treat the galvanized for painting. Paint the pieces black. Silicone some insulation to the back of these pieces. Pull the insert out enough to work just behind it. Secure the pieces. Push the insert back.