"Walter Cohen" wrote in
:

No - a hole saw is $4 and $10 for shipping on Ebay.
I don't have a sawzall. I only have a jig saw.

Walter
"RBM" wrote in message
...
If you want to do it with a hole saw, use a 4 1/2", but it'll cost
you. You could do it with a sawzall or similar.


"Walter Cohen" wrote in message
...
Due to logistical reasons in my attic I need to route the new
bathroom fan exhaust duct up through the roof instead of out the
side wall. It's also a shorter run if I go vertically instead of
horizontally. I'll be buying 4" aluminum ducting so when I buy a
hole saw to cut the roof hole do I buy one that's 4" round, 4 1/4",
or 4 1/2"?

Anything else I should do or watch out for?

Thanks.
Walter




A jig saw will work fine. Use a blade with coarse cut.

Don't cut any holes until you get the roof fixture. Check instruction
recommendations first. Easier to make a hole bigger than smaller.

I assume you mean the 4" rigid aluminum and not the foil stuff.

Good part going through roof: Shortest run is usually best. If you go by
code there is often a max run length (for dryer vent anyway). Each bend
shortens the max length.

Bad part: May be harder to insulate. Regardless, you MUST insulate or you
will have water dripping out of the fan in the bathroom.

Going out the gable end the wall fixture usually has flaps that are closed
when not in use. Keeps wind from blowing back into the bath. Going out the
roof you may just have an upside down J type with a screen. I would think
wind could get in there. Also, snow buildup could block it if the exit is
low and you are in that climate. I hear there is a higher neck rise type
but I could not locate one locally.

Just some thoughts to keep in mind.