Originally Posted by lonepalm
Basement! have watched with the heat doesn't get over 70 degrees
That's ok for an ale, but no good for a lager. Most lagers need to ferment in the mid 50s and be lagered at near freezing. So, do you have controls in place to handle those perameters?
Otherwise, making a 10 gallon batch by doubling a 5 gallon recipe is just fine. Provided you can chill it.