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

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

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

"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

For size measure the flange on the vent fitting you will be using on the
roof and add about a 1/4 to 3/8 to allow the clamp to fit into the hole.

I would not use a hole saw to cut through the roof. The tar in the shingles
will grab the hole saw of that size and tear the tool out of your hands, the
grit in the shingles will destroy the teeth on the hole saw. Take a jar lid
or some other template of the correct size and a Magic Marker to the roof,
use a drill to start the hole and cut along the line with a very coarse
tooth jig saw blade -- the blade will most likely be destroyed cutting the
hole and you will probably toss it when finished, but they are cheap.

I have installed several this way.

Walter Cohen wrote:
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

Make sure you insulate the duct. If you don't, the moist air will condense
in the duct (because of the cooler air in the attic) and run down the sides
and drip in the fan.

a

"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?



I use a 4 1/4" hole saw in my angle drill at slow speed. You don't want to
go too fast with a puppy this big.

On Feb 9, 1:13�pm, "EXT" wrote:
"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

For size measure the flange on the vent fitting you will be using on the
roof and add about a 1/4 to 3/8 to allow the clamp to fit into the hole.

I would not use a hole saw to cut through the roof. The tar in the shingles
will grab the hole saw of that size and tear the tool out of your hands, the
grit in the shingles will destroy the teeth on the hole saw. Take a jar lid
or some other template of the correct size and a Magic Marker to the roof,
use a drill to start the hole and cut along the line with a very coarse
tooth jig saw blade -- the blade will most likely be destroyed cutting the
hole and you will probably toss it when finished, but they are cheap.

I have installed several this way.

i would prefer to run exhaust thru sidewall..........

be certainto well insulate any exposed line in attic so condensarttion
doesnt cause water damage

"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.

Here's an excellent video on how to install a roof vent by Tim Carter.
After I saw this , it made installing mine easier.

http://www.youtube.com/watch?v=gee3itzjOG0

Thanks John.
Some have suggested NOT to use a hole saw but instead a jig saw or sawzall.
Mostly because of tearing through roof shingles once it pokes through.
Thoughts on this?

Walter
"John Grabowski" wrote in message
...

"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?



I use a 4 1/4" hole saw in my angle drill at slow speed. You don't want
to go too fast with a puppy this big.

Thanks Red!

Walter
"Red Green" wrote in message
...
"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.

Thanks John.
Some have suggested NOT to use a hole saw but instead a jig saw or sawzall.
Mostly because of tearing through roof shingles once it pokes through.
Thoughts on this?


The hole through the roof will not be round, but an oval due to the slope of
the roof. The higher the slope, the longer the oval. I just hold a piece of
pipe vertcally in position on the underside, and trace the outline with a magic
marker, this will give a nice clearance. You can start with a hole saw, but you
will need a drill with a side handle to hold one that large. I only use a heavy
duty angle drill for holes this large. Better to use the jigsaw.

Drill a couple of locating holes from the underside, then go on the roof and
mark the oval by placing a piece of ductwork vertically and tracing again. Cut
away the shingles with a razor knife, than cut the hole with the jigsaw. The
hole throguh the shingles will be larger than the one through the roof, so that
the flange of the flashing will fit.

--
Dennis

"Walter Cohen" wrote in message
...
Thanks John.
Some have suggested NOT to use a hole saw but instead a jig saw or
sawzall.
Mostly because of tearing through roof shingles once it pokes through.
Thoughts on this?


I've done it both ways. I think the jig saw is a little more time consuming
and the hole may not come out as perfectly round as you like. You could
drill a pilot hole through the center from below and then go up on the roof
and start the hole using that center mark. However you do want to position
the roof cap flange so that it aligns with the shingles and can slide under
for best water protection.

As I said before, drill at a slow speed and take your time. If drilling
from below, when you start to see the the roof shingles stop the drill and
try to remove the wood by hand. If you can't at this point, drill a little
more until you can. You can then cut the shingles from above by hand with a
good knife or compass saw. Push a coat hanger through the pilot hole to
find the center on the roof.

I try to do it in this order when possible:

1. Drill pilot hole from below and push wire through hole.
2. Using pilot hole as a reference, position center of roof cap to align
best with shingles and keep pilot hole within roof section to be removed.
3. Drill hole with slow speed, high torque drill until you are through
roofing materials.
4. Remove roofing materials from hole saw.
5. Continue drilling hole saw through wood.
6. Set roof cap using roof cement as needed. Roof cement should go under
shingles and cap.

This way only one trip up to the roof is required. A five gallon bucket is
useful for carrying items at once.



Walter
"John Grabowski" wrote in message
...

"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?



I use a 4 1/4" hole saw in my angle drill at slow speed. You don't want
to go too fast with a puppy this big.

On Feb 10, 10:33*am, (DT) wrote:
Thanks John.
Some have suggested NOT to use a hole saw but instead a jig saw or sawzall.
Mostly because of tearing through roof shingles once it pokes through.
Thoughts on this?

The hole through the roof will not be round, but an oval due to the slope of
the roof. The higher the slope, the longer the oval. I just hold a piece of
pipe vertcally in position on the underside, and trace the outline with a magic
marker, this will give a nice clearance. You can start with a hole saw, but you
will need a drill with a side handle to hold one that large. I only use a heavy
duty angle drill for holes this large. Better to use the jigsaw.

Drill a couple of locating holes from the underside, then go on the roof and
mark the oval by placing a piece of ductwork vertically and tracing again. Cut
away the shingles with a razor knife, than cut the hole with the jigsaw. The
hole throguh the shingles will be larger than the one through the roof, so that
the flange of the flashing will fit.

--
Dennis

Let me understand - when outlining the hole to cut (whether inside the
attic or outside on the roof) does the traced item (pipe, coffee can,
etc) lay flat with the angle of the roof against the wood/shingles or
do I need to hold the traced item vertically against the roof slope
and then trace it. The first way gives me a round hole but not at the
correct angle. The second way gives me the correct angle with an
oblong hole (but just a bit more difficult to trace). I think that if
I trace the outline flat against the roof with an extra 1/4" or so
then I'd be ok. After all, the roof cap would cover any minor
"mistake" I make on tracing/cutting.

Walter

On Feb 12, 2:25*pm, Wally wrote:
On Feb 10, 10:33*am, (DT) wrote:





Thanks John.
Some have suggested NOT to use a hole saw but instead a jig saw or sawzall.
Mostly because of tearing through roof shingles once it pokes through.
Thoughts on this?

The hole through the roof will not be round, but an oval due to the slope of
the roof. The higher the slope, the longer the oval. I just hold a piece of
pipe vertcally in position on the underside, and trace the outline with a magic
marker, this will give a nice clearance. You can start with a hole saw, but you
will need a drill with a side handle to hold one that large. I only use a heavy
duty angle drill for holes this large. Better to use the jigsaw.

Drill a couple of locating holes from the underside, then go on the roof and
mark the oval by placing a piece of ductwork vertically and tracing again. Cut
away the shingles with a razor knife, than cut the hole with the jigsaw. The
hole throguh the shingles will be larger than the one through the roof, so that
the flange of the flashing will fit.

--
Dennis

Let me understand - when outlining the hole to cut (whether inside the
attic or outside on the roof) does the traced item (pipe, coffee can,
etc) lay flat with the angle of the roof against the wood/shingles or
do I need to hold the traced item vertically against the roof slope
and then trace it. *The first way gives me a round hole but not at the
correct angle. *The second way gives me the correct angle with an
oblong hole (but just a bit more difficult to trace). *I think that if
I trace the outline flat against the roof with an extra 1/4" or so
then I'd be ok. *After all, the roof cap would cover any minor
"mistake" I make on tracing/cutting.

Walter- Hide quoted text -

- Show quoted text -

Here is Broan's installation guide for a bath roof vent
http://www.broan.com/ImageLibrary/br...s/99041929.pdf
It says to cut the hole 1/2" larger than the duct size. This is what I
did when I installed mine. Then I filled the gap around it with low
expanding Great Stuff foam. I also drove 2 screws from the inside
securing the duct to the roof plywood. It turned out great, no leaks.
So in general, just cut the hole 1/2" larger. This will compensate for
the roof slope.