Question: I need to vent a room in an uninsulated cabin - the ceiling is also the roof - so I don't need soffit tubing or anything like that. I am looking for a fairly cheap item that has a large cfm ability.

(This is for venting steam from a maple syrup evaporator)

EDIT

We ended up just putting in two vents in the roof. (Maybe 12"x12" each - though maybe a little smaller than that)

We did not need a fan. We still get a tiny bit of condensation on the ceiling but not even close to what it was before. We are happy with the two vents but may add one more. 

First we put in one vent and it was FAR superior to just having windows open. We could actually see across the room when boiling/evaporating. Then we put in a second vent and that made a difference too. 

The next vent will be fed directly from a steam hood we will put over the evaporating pan.

Answer: 
You'll want to use glazing compound, which comes in both oil-based, and latex, and can be found in both cans or tubes.

Once you have the glass removed, and the frame cleaned up. 

* Run a bead of glazing compound around the frame (where the glass will sit).
* Set the glass in the compound giving it a little wiggle to work out any air bubbles, and to make sure the glass is set in properly (don't worry about a little excess oozing out, you can trim it off later when it cures).
* Using a putty knife push in glazing points every 6-8 in.

![Glazing point](https://i.stack.imgur.com/4Yi5U.jpg)

* Install the interior trim, and wait for the glazing compound to cure.
* Once the compound has cured enough (24-72 hours), using a utility knife carefully trim off any compound that has oozed out.
* If you are not using interior trim, you will want to apply a bead of glazing compound to the interior side of the frame, and use a putty knife to smooth it to a nice finish.
* After 7-10 days you can paint the glazing compound to match the frame.
You should use putty to bed the glass into the frame.

This will form an air- and water-tight seal.

You could even put the wood strips back on.