Help with Low Attenuation

We brewed the True Brew Red Ale kit one week ago; our beginning
gravity was quite low (1.034) and the beer only actively fermented
(visible bubbling in the airlock) for about 24 hours. The temperature
in our apartment dropped considerably with the first freeze of the
year, and we fear that the yeast may have been too cold to properly
ferment. The final gravity, after checking today, is 1.015, which
means that we've had 55% attenuation in our brew.

This is one of our first attempts at brewing beer, and we're not sure whether to leave the brew for a few more days, in hopes that the yeast may consume more sugar, or whether we should simply toss this brew out. Our low beginning gravity may be a sign that we've done something wrong. It tastes OK, just fairly watery.

Any advice would be appreciated!

Do NOT throw it out. Even though your attenuation is low, you don't want to go too much lower anyway. Beer has residual sweetness and some complex sugars that don't ferment out, so 1.015 is a reasonable FG.

Watery and thin can be two things- either the original recipe is at fault, or it's just young and uncarbonated beer. (Or a combo of both!).

Keep it in the fermenter at least one more week- at 65 degrees if you can manage it with the weather. Then check the SG again. If it's still 1.015, bottle it! If it's lower, wait another day and recheck it. When it's the same at least three days in a row, then you can bottle it.

With such a low OG from a kit I would wager two things: first that this was an extract brew and second that the wort was not thoroughly mixed in the carboy which gave you an off OG reading.

1.015 is a decent FG so I am also betting that everything happened as it should have and your beer will be fine.

Thanks to you both for your advice! It's been really helpful (we're so happy to find a good resource like this!). We actually discovered what the problem was a few minutes ago. We siphoned our beer from the plastic fermenter bucket into a glass carboy, to let it continue fermenting for another week or two. When we did this, we realized that we actually added too much water at the beginning -- our plastic bucket is a 6 gallon bucket, and we filled it all the way, instead of stopping at the 5 gallon line. That's probably why our gravity was low to begin with. We'll still see it through, though we assume it'll always be more watery with a lower alcohol content...