So I've read many diy ways to prevent the draft of an used fireplace. Mine is not in a working condition and I don't know if the previous owner of my home had ever used it. It's very very cold. I've had the house 18 years and I just want to block out the cold. I don't know about damper or the terms. Any suggestions are welcome. I read one idea with insulation but how and what kind I'm stumped
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Draft from fireplace
fireplaceinsulation
Related Solutions
Did the transparent glass "back wall" explode because you added the front side glass doors and as a result the temperature in the fire box area went way up???
You need to consider carefully the airflow and draw requirements of the fireplace and the chimney that vents it out through the roof. Changing the design can really change the temperatures of the internal space!!
I would think that if you were to block off the far side with bricks that you may need to line the inside of the brick with special heat resistant fire bricks. Regular bricks could get extra hot and shatter too.
If you really need to have the front side glass doors make sure that there is a part of the design that permits the proper amount of air flow in around the sides of the door assembly for the chimney draw to work correctly.
Similar to @BMitch's answer, I used a magnetic cover to cover the vent below my fireplace. We found this was the primary cool air leak for our fireplace and I bet it is yours too. It works great, and is very simple to remove before starting a fire. Since it is black like the fireplace, it is not even noticed. I bought one from this site selling the exact size I needed and in black.
Here is my fireplace with it on and removed.
Best Answer
Since you say it's not working, I assume you mean disused fireplace.
Two insulation approaches (which don't depend on there being an operable damper, though closing a damper if you can figure out how will certainly help.)
Neither of these need (nor should) be visible when looking at the fireplace normally.
You can also fill the fireplace front opening itself, but that is more of a visual impact on the room with the fireplace in it and may be unacceptable as a result.
If you have not used it for at least 18 years and don't intend to, you might want to consider having the chimney externally capped off, as well, or even taken down, but those are more extensive projects rather than quick DIY solutions.