Should you insulate the attic ceiling?

This answer is half right

"You do not want to insulate your attic ceiling unless you use some special means to allow for ventilation, installed by an expert. Insulating by regular means can cause moisture problems for your roof since the air will be trapped below the roof and the insulation. Also, if your roof becomes to warm it can cause the snow on the roof to melt during cold periods and refreeze under shingles or in gutters."

I posted this originally

"Almost always yes. Its the highest area for heat loss. There are 2 ways, batt, & blown. Ventilation is also an important consideration. There should be vents low, at the soffiets/ overhangs to let cooler air in & vents near / at the ridge to let hotter air out. This also allows mosture that may get in there to escape. If doing blown, make sure that any soffiet vents that might be there are protected by baffles to prevent blown insulation from covering them up. R-38 is code in my area, Washington, it may vary in different areas. It can be hard work, but will pay off on heating & cooling costs."

Read more: http://wiki.answers.com/Should_you_insulate_the_attic_ceiling#ixzz1ibhRcmJr

I will also add this

The lack of insulation can very well lead to ice damming. As heated, moist air leaves the living space, it travels thru the unisulated attic and raises to warm the under side of the roof. as it melts, it travels to the unheated overhangs & refreezes, and thus, can lead to ice damming. If you have no insulation, I would recommend starting of with Kraft faced insulation, this will provide a vapor barrier. Then you can add additional batts or blown on top. Be sure not to block any vents that may exist. Even without vents, you'll almost always, be better off.

Make no mistake, ventilation is good & important. Most composition roofing requires proper ventilation to maintain the warranties. A rule of thumb is 1 sf of venting per 150sf of ceiling / attic area. You can go 1 / 300 sf if you have a balanced system. This is 50% ridge vent (The baffled vent matrix that's installed under the ridge cap shingles, is by far the best.) & 50% soffiet vent (low point).

You can also use temperature & moisture activated solar & electrical power attic vents(follow there recommendations).

In summary, as a building contractor, I recommend

1) Insulate

2) Ventilate, this includes venting bath / stove fans & driers to the outside