Any experience with winter roosting box? (1 Viewer)

After acquiring some basic woodworking tools in the last few month, I can whip one up pretty quickly. However I'm not sure it would be useful given my location.

I'm located in the suburbs so bird species are limited, no forest dwellers like bluebird and woodpeckers, and winter population is mostly composed of cardinals, dark eyed junco, common redpoll, and house sparrows. I do have row of eastern white cedar around the (tiny) yard which birds seem to like use as shelter all year round.

My two major concern is that birds would prefer the cedar and not bother with the box, and it would be taken over by house sparrows.

So should I bother with one?

Montreal winters are hard on birds, they can use all the help you can give.
Downy Woodpeckers sheltered in my bird boxes while living in Connecticut, so anything goes. You might be surprised at how well your boxes are received.
Some roosting box designs have the hole at the bottom, with perches inside. With your tools, you can create variants of your own. Experiment to see what works best.
If House Sparrows are a problem, the Van Ert trap has worked well for me. See:
http://www.vanerttraps.com/universal.htm

Well just bought the wood, the "lumberyard" doesn't have 1x10 that I'd prefer so I ended up getting 2x6, will have to rip it to 1x6 and glue it into board, either butt joint or rebate joint, haven't decided yet.

I thought about doing a hollow wall with frame and veneer, since air's thermo conductivity is about half of wood so it would essentially double the insulation value without being any thicker. But I'm concerned about mold growth in the hollow core since I would have no access once it's glued up, so I think I'll stick with a simple one for now.