I'm in upstate NY and we've been having January-like weather for the past month, with temps running on some days 10-15 degrees colder than normal. We've also had very short periods of normal, warm-for-early-winter days with occasional highs in the 40-57 range. Then followed by 7-10 days of below freezing days and nights at or or below zero.
I have three hives (Langs of various heights from 2 X deeps to 2 deeps plus 1 med.) that are snuggled together on a raised platform. On top of each stack is a "quilt box" made up from an old comb-honey depth box filled with pine shavings.(Box size chosen by what I had on hand more than anything else.) On the bottom of the box is a very tightly stretched layer of unbleached muslin for a floor. Some people have reported using wire screening as the floor, but I was worried the wires might be a condensation plane and create drips, so opted for fabric instead
Below the quilt box (just above the top most frames) is a shim with a semi-occluded top entrance, I use this space for winter feeding; above the box is a 1 7/8th" shim with two vent holes 1.5" diameter, one closed and one open. Above it all is a tel. cover with 1.5" of foam insulation stuck up under its rim.
The quilt boxes have been on the hives for about six or seven weeks. Whenever I've had a chance to peek in the hives, they seemed quite dry. I have a sticky board inserted at the bottom and I see no evidence of any drips or moisture there.
Today I opened and examined the quilt boxes after 10 days of very cold weather. There was condensed moisture on the bottom side of the insulation close to the position of the open vent hole in the front. The shavings on the top (where condensate from the underside of the insulation had dripped down on them) were palpably damp: slightly darker color and more flexible than totally dry ones. In the center of the hive (above the cluster space) the shavings all the way to the fabric floor felt slightly damper, although the fabric itself felt , and looked, dry.
The temperature of the shavings was warm to the touch, and really quite warm at the layer just above the fabric over where the cluster is. In fact, it felt so warm I am revising my earlier belief that the quilt boxes were almost entirely moisture management tools, not also thermal barriers. They are clearly containing some of the heat from the cluster, while still doing exactly what I had hoped: allowing vapor dispersion through the shavings to be vented to the outside. And being an absorptive barrier for any drips from condensation on the under surface of the top.
My boxes were filled above the rim into the shim space and I only had one vent hole opened, so perhaps I wasn't venting as much as possible the way it was set up. I opened the other vent hole.
And I replaced the slightly damp shavings today with fresh ones and brought the damp ones in to dry in a wood heated room. I didn't fill them as high as I did the first time, hoping to increase the vapor loss somewhat.
So far, I am happy with how the quilt boxes are working, though I won't know for months if the hives survive. My reason for posting an interim report is that other beekeepers in cold areas may be wondering if there is anything else they can still do, at this stage of the winter, to increase protection for their hives. Quilt boxes are one such tactic. And they appear to be working very well for me.
Materials needed: a shallow-height box (normal shallow or a comb-depth box, even a medium would do in a pinch, I think); enough plain cotton fabric to stretch across the bottom; 1/2" staples and staple gun; (optimal, but not necessary: plastic greenhouse batten tape as an edge-maker for the fabric margins); dry wood shavings (I got mine at Tractor Supply for about $6.00 and one bale has filled 3 quilt boxes, twice, and I still more left over); and an extra shim with at least one large, preferably two, holes in it. Two of my comb-honey boxes are so old and over-used they are in bad shape on the bottom edge so they didn't make good contact with the new shim below. I solved this with that stick-on, 1/2"-wide foam insulation used for tightening up leaky windows. It closed the gaps nicely and also had the beneficial effect of anchoring the boxes better in the stack since the bees aren't going to stick them togther with propolis at this time of year. But if your boxes are in better shape than mine, I wouldn't bother.
If you made and filled the boxes ahead of time, you could pop them on in a very short interval with the hive top open. With two people working together, it probably could be done is less than 15 secs., so doable even in pretty cold weather.
(I should also add that I have foam side insulation panels -inside and outside of the hives - and additional layers of wool blankets and a loose tarp around the whole shebang. I don't think any of this somewhat eccentric arrangement has any effect - for good or ill - on the function of the quilt boxes, except perhaps to slightly impede the flow through ventilation of the top holes above the quilt box. I remove the tarp on days when there is no precip. I don't have the hives wrapped in tar paper or a plastic bee-cozy)