Backyard Lagering

Ok, riddle me this ye of much collective knowledge. I have a shed in my backyard, and I was wondering if I was to build a box to contain my carboy and blowoff bucket, would lagering in here during the colder months (southeastern PA) work? Or would the raising temps during the day mess it up?

I would imagine the constant changing of temps would give it some off flavors, but i'll let somebody more experienced with lagers chime in.

Fluctuating temperatures (sometimes as low as +/- 5F, but usually in the 10-20F range) can cause the yeast to go into shock, create off flavors and all sorts of other problems.

It may be doable if you keep it in a large, cheap Styrofoam container inside the shed so the fluctuations are minimal. A great way to test that would be to put the cooler in your shed and, if you have one of those weather stations with a remote temperature sensor, put the sensor in the cooler and monitor what the temperature fluctuations are a few times a day. If they stay in an acceptable range I would say you should be fine.

Lager fermentation is (relatively) easy to do this way. Get a big laundry tub, put your carboy/bucket in it and fill the tub with cold water. the bigger mass will buffer temperature fluctuations pretty well as long as outside temps aren't swinging wildly or we have a heat wave...if so, you can try throwing frozen water bottles into the tub to keep temps down, but you will really have to nurse it to keep the temp constant.

Lagering will be harder, but not as critical to be absolutely stable (IMHO). you really need to keep the temps down around 35 if you do it in the dead of winter and we have a few REALLY cold weeks here in PA you might be okay, but often we have temps that go into the 40's or 50's for a few days.

I have read of a few folks that will bury their carboy in snow to lager it. the snow should keep it at 32 as it will insulate colder air temps and as long as it is buried in a snowbank and the surrounding snow doesn't melt your beer shouldn't raise above 32-ish. Of course this relies on us having a decent snowfall.

I'd say give it a shot, but you are a bit at the mercy of mother nature. Let us know how it turns out.

With a water bath it is very possible to keep temperature fluctuation within reason

See this blog post:
http://woodlandbrew.blogspot.com/2012/11/lagering-outside.html