I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?

thx!

you could take a bubble level and draw some short lines. Make several of
these along the entire length (like a dashed line). Then use any straight
edge to extend the dashes to the full 27' so the full line is parallel to
all of them. You might be able to use the top edge of the panel as a
vertical guide..

I would measure down from the soffit about every 6 feet. You need
to pull a lot of tension to keep the say out of a line 27' long,
plan on several snaps.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"ben" wrote in message
...
I'm cutting off the bottom 20" of my t1-11 panel siding to
replace it
and want to cut it off straight. The bottom edges of the siding
are
rotten, so I can't just measure up from those 20" as a guide.
So I
bought a chalkline but I now realize, I don't know how I can
make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?

thx!

Use a water level . It is easy to use and is available at any tool
supply store.

On Jun 16, 4:16*am, ben wrote:
I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. *The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. *So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. *The length will be about 27'.

How can I level this? *Or is there a better way to do this?

thx!

Don't know if this helps but kids bought me a laser Straightline.
Laser light puts out a straight line and the small unit has leveling
bubbles. Don't think they are expensive.

In article , ben wrote:
I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?

With a water level.

If the line needs to be 27' long, then get about 30' - 35' of clear vinyl
tubing, and an assistant. Fill the tubing with water (stick one end in a
bucket of water and suck on it til you get a mouthful), then let a little bit
run out. You want a few inches of air space at each end. Make a pencil mark at
one side of the shed where you want the cut line to start. Hold one end of the
tube against the shed, and adjust it until the water level lines up with the
pencil mark. Have your assistant take the pencil and the other end of the tube
to the other side of the shed. Double-check to make sure the water level at
your end is still aligned with the pencil mark, and readjust as needed. When
the water level is stable, have the assistant mark the water level at that
side of the shed. Pull a chalk line across the two marks, and make it tight --
it's going to sag some over 27 feet -- then snap it. Done.

ben wrote:
I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?

thx!

Measure down the same distance from the fascia or top of siding (it
might not be level but will look level compared to other lines of the
house). Tack the chalkline at that measured point. Check with bubble
level to see how the line lays. Snap.

"ben" wrote in message
...
I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?

thx!



Use a rotating laser like ceiling hangers use.

On Jun 16, 8:41*am, (Herb Eneva) wrote:
Use a water level . *It is easy to use and is available at any tool
supply store.

Yes and can be made up (and/or lengthened) by yourself using a hose
pipe and two pieces of clear hose. Tint the water with food colouring
if you wish. The techie modern way of course is to use a laser-level;
a tool which may very useful later on inside and outside a building!

On Jun 16, 1:38*am, "iwdplz" wrote:
you could take a bubble level and draw some short lines. *Make several of
these along the entire length (like a dashed line). *Then use any straight
edge to extend the dashes to the full 27' so the full line is parallel to
all of them. *You might be able to use the top edge of the panel as a
vertical guide..

For 27' feet? You won't even be close at the end.

Harry K

On Jun 16, 4:30*am, (Doug Miller) wrote:
In article , ben wrote:

I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. *The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. *So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. *The length will be about 27'.

How can I level this? *Or is there a better way to do this?

With a water level.

If the line needs to be 27' long, then get about 30' - 35' of clear vinyl
tubing, and an assistant. Fill the tubing with water (stick one end in a
bucket of water and suck on it til you get a mouthful), then let a little bit
run out. You want a few inches of air space at each end. Make a pencil mark at
one side of the shed where you want the cut line to start. Hold one end of the
tube against the shed, and adjust it until the water level lines up with the
pencil mark. Have your assistant take the pencil and the other end of the tube
to the other side of the shed. Double-check to make sure the water level at
your end is still aligned with the pencil mark, and readjust as needed. When
the water level is stable, have the assistant mark the water level at that
side of the shed. Pull a chalk line across the two marks, and make it tight --
it's going to sag some over 27 feet -- then snap it. Done.

Water levels are a great tool and is the only way I know of to level
around a corner but need some care.

1. The entire line must be in the same condition, i.e., all in sun or
all in shade.
2. There can be no air bubbles in the line.

Personally, I would use a laser for the OP's use. They are not
expensive and will be used many times if the OP does much carpentry
over the years.

Harry K

In article , harry k wrote:
Water levels are a great tool and is the only way I know of to level
around a corner but need some care.

1. The entire line must be in the same condition, i.e., all in sun or
all in shade.

Utter nonsense.

2. There can be no air bubbles in the line.

If you fill it the way I described, there won't be.

Personally, I would use a laser for the OP's use. They are not
expensive and will be used many times if the OP does much carpentry
over the years.

Phooey. Even the "cheap" ones are an order of magnitude more expensive than 35
feet of vinyl tubing, and they're MUCH less accurate. With a steady hand and a
sharp eye -- and a sharp pencil -- it's easy to get +/- 1/32" with a water
level. Ever look at the specs on the consumer-grade laser levels they sell at
home centers? Typical is +/- 1/4" at 25 or 30 feet; I saw one at Sears a few
years ago labelled as "accurate within 1/2%". That doesn't sound too bad until
you do the math: that's an error of an INCH AND A HALF at 25 feet. To get the
kind of accuracy with a laser level that can be easily achieved with a water
level, you need to go beyond consumer-grade units to professional gear costing
many hundreds of dollars.

In article , "Bob M." wrote:
"ben" wrote in message
...
I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?

Use a rotating laser like ceiling hangers use.

Not very accurate, and probably not visible outdoors....

In article , Hipupchuck wrote:
ben wrote:
I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?

A laser level.

See my response to Harry K regarding laser levels...

On Tue, 16 Jun 2009 01:16:58 -0700 (PDT), against all advice,
something compelled ben , to say:

I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?



http://www.diyinfo.org/wiki/How_To_B...ve_Water_Level





--

Don't worry about people stealing an idea. If it's original, you will
have to ram it down their throats.
- Howard Aiken

On Jun 16, 3:16*am, ben wrote:

snip

*So I bought a chalkline but I now realize, I don't know how I can make sure
it's level. *The length will be about 27'.

How can I level this? *Or is there a better way to do this?


I have a small 'line level' that simply hooks into the center of the
chalk line. With one end firmly attached, the other end of the line
can be raised or lowered incrementally until level. Only takes
minutes, seems perfectly accurate and IIRC it cost about $5 or so at
local lumber yard, hardware store or Ace, maybe. First time I saw one
being used was a siding installation crew. Ought to work for you.

Joe

On Jun 16, 7:10*am, Frank wrote:
On Jun 16, 4:16*am, ben wrote:

I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. *The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. *So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. *The length will be about 27'.

How can I level this? *Or is there a better way to do this?

thx!

Don't know if this helps but kids bought me a laser Straightline.
Laser light puts out a straight line and the small unit has leveling
bubbles. *Don't think they are expensive.

Unless they've improved the Straightline product line recently, they
are not much help.

The bubble is so much smaller than the space between the 2 lines that
you have to eyeball it to choose your own center. Over 27' any
eyeballing of a crappy bubble level just isn't going to be accurate.

On Jun 16, 12:24*pm, Joe wrote:
On Jun 16, 3:16*am, ben wrote:

snip
*So I bought a chalkline but I now realize, I don't know how I can make sure
it's level. *The length will be about 27'.

How can I level this? *Or is there a better way to do this?

I have a small 'line level' that simply hooks into the center of the
chalk line. With one end firmly attached, the other end of the line
can be raised or lowered *incrementally until level. Only takes
minutes, seems perfectly accurate and IIRC it cost about $5 or so at
local lumber yard, hardware store or Ace, maybe. First time I saw one
being used was a siding installation crew. Ought to work for you.

Joe

The trick with a line level is to level the 2 end points over a long
distance, then remove the level and pull the chalkline taut between
the 2 points before snapping.

Over 27' feet, the level is going to bow the line downward
significantly, so the only 2 level points along the line will be at
the very ends.

On Jun 16, 9:14*am, harry k wrote:
On Jun 16, 1:38*am, "iwdplz" wrote:

you could take a bubble level and draw some short lines. *Make several of
these along the entire length (like a dashed line). *Then use any straight
edge to extend the dashes to the full 27' so the full line is parallel to
all of them. *You might be able to use the top edge of the panel as a
vertical guide..

For 27' feet? *You won't even be close at the end.

Harry K

It might work if you use a 6' level and 6" increments. g

On 6/16/2009 8:19 AM Doug Miller spake thus:

In article
,
harry k wrote:

Water levels are a great tool and is the only way I know of to
level around a corner but need some care.

1. The entire line must be in the same condition, i.e., all in sun
or all in shade.

Utter nonsense.

Amen. This ain't the Hubble Telescope.

2. There can be no air bubbles in the line.

If you fill it the way I described, there won't be.

Personally, I would use a laser for the OP's use. They are not
expensive and will be used many times if the OP does much carpentry
over the years.

Phooey. Even the "cheap" ones are an order of magnitude more
expensive than 35 feet of vinyl tubing, and they're MUCH less
accurate. With a steady hand and a sharp eye -- and a sharp pencil --
it's easy to get +/- 1/32" with a water level. Ever look at the
specs on the consumer-grade laser levels they sell at home centers?
Typical is +/- 1/4" at 25 or 30 feet; I saw one at Sears a few years
ago labelled as "accurate within 1/2%". That doesn't sound too bad
until you do the math: that's an error of an INCH AND A HALF at 25
feet.

Yep. I second that emotion.


--
Found--the gene that causes belief in genetic determinism

On 6/16/2009 10:12 AM DerbyDad03 spake thus:

On Jun 16, 12:24 pm, Joe wrote:

On Jun 16, 3:16 am, ben wrote:

So I bought a chalkline but I now realize, I don't know how I can
make sure it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?

I have a small 'line level' that simply hooks into the center of the
chalk line. With one end firmly attached, the other end of the line
can be raised or lowered incrementally until level. Only takes
minutes, seems perfectly accurate and IIRC it cost about $5 or so at
local lumber yard, hardware store or Ace, maybe. First time I saw one
being used was a siding installation crew. Ought to work for you.

The trick with a line level is to level the 2 end points over a long
distance, then remove the level and pull the chalkline taut between
the 2 points before snapping.

Yes.

Over 27' feet, the level is going to bow the line downward
significantly, so the only 2 level points along the line will be at
the very ends.

27 feet feet?

Sorry, couldn't resist. Always amuses me when I see constructs like "$27
million dollars".

Brought to you by your Department of Redundancy Department.


--
Found--the gene that causes belief in genetic determinism

On Jun 16, 1:30*pm, David Nebenzahl wrote:
On 6/16/2009 10:12 AM DerbyDad03 spake thus:







On Jun 16, 12:24 pm, Joe wrote:

On Jun 16, 3:16 am, ben wrote:

So I bought a chalkline but I now realize, I don't know how I can
*make sure it's level. The length will be about 27'.

How can I level this? *Or is there a better way to do this?

I have a small 'line level' that simply hooks into the center of the
chalk line. With one end firmly attached, the other end of the line
can be raised or lowered *incrementally until level. Only takes
minutes, seems perfectly accurate and IIRC it cost about $5 or so at
local lumber yard, hardware store or Ace, maybe. First time I saw one
being used was a siding installation crew. Ought to work for you.

The trick with a line level is to level the 2 end points over a long
distance, then remove the level and pull the chalkline taut between
the 2 points before snapping.

Yes.

Over 27' feet, the level is going to bow the line downward
significantly, so the only 2 level points along the line will be at
the very ends.

27 feet feet?

Sorry, couldn't resist. Always amuses me when I see constructs like "$27
million dollars".

Brought to you by your Department of Redundancy Department.

--
Found--the gene that causes belief in genetic determinism- Hide quoted text -

- Show quoted text -

It was a typo, not a "construct".

I'll try to live up to your standards next time.

On 6/16/2009 10:34 AM DerbyDad03 spake thus:

On Jun 16, 1:30 pm, David Nebenzahl wrote:

On 6/16/2009 10:12 AM DerbyDad03 spake thus:

Over 27' feet, the level is going to bow the line downward
significantly, so the only 2 level points along the line will be at
the very ends.

27 feet feet?

Sorry, couldn't resist. Always amuses me when I see constructs like "$27
million dollars".

Brought to you by your Department of Redundancy Department.

It was a typo, not a "construct".

OK.

I'll try to live up to your standards next time.

Then what will we do for amusement?


--
Found--the gene that causes belief in genetic determinism

I have a small 'line level' that simply hooks into the center of the
chalk line. With one end firmly attached, the other end of the line
can be raised or lowered incrementally until level. Only takes
minutes, seems perfectly accurate and IIRC it cost about $5 or so at
local lumber yard, hardware store or Ace, maybe. First time I saw one
being used was a siding installation crew. Ought to work for you.

Over any distance at all, the line level weighs enough to sag the line
substantially -- which means that it won't give an accurate reading unless you
have it in the *exact center* of the line.

On Jun 16, 1:48*pm, David Nebenzahl wrote:
On 6/16/2009 10:34 AM DerbyDad03 spake thus:







On Jun 16, 1:30 pm, David Nebenzahl wrote:

On 6/16/2009 10:12 AM DerbyDad03 spake thus:

Over 27' feet, the level is going to bow the line downward
significantly, so the only 2 level points along the line will be at
the very ends.

27 feet feet?

Sorry, couldn't resist. Always amuses me when I see constructs like "$27
million dollars".

Brought to you by your Department of Redundancy Department.

It was a typo, not a "construct".

OK.

I'll try to live up to your standards next time.

Then what will we do for amusement?

--
Found--the gene that causes belief in genetic determinism- Hide quoted text -

- Show quoted text -

Your posts? g

DerbyDad03 wrote:
On Jun 16, 7:10 am, Frank wrote:
On Jun 16, 4:16 am, ben wrote:

I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.
How can I level this? Or is there a better way to do this?
thx!
Don't know if this helps but kids bought me a laser Straightline.
Laser light puts out a straight line and the small unit has leveling
bubbles. Don't think they are expensive.

Unless they've improved the Straightline product line recently, they
are not much help.

The bubble is so much smaller than the space between the 2 lines that
you have to eyeball it to choose your own center. Over 27' any
eyeballing of a crappy bubble level just isn't going to be accurate.


You're probably right. I've never used it. The plastic tubing or hose
method would be the best to use.

On Jun 16, 3:04*pm, Frank wrote:
DerbyDad03 wrote:
On Jun 16, 7:10 am, Frank wrote:
On Jun 16, 4:16 am, ben wrote:

I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. *The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. *So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. *The length will be about 27'.
How can I level this? *Or is there a better way to do this?
thx!
Don't know if this helps but kids bought me a laser Straightline.
Laser light puts out a straight line and the small unit has leveling
bubbles. *Don't think they are expensive.

Unless they've improved the Straightline product line recently, they
are not much help.

The bubble is so much smaller than the space between the 2 lines that
you have to eyeball it to choose your own center. Over 27' any
eyeballing of a crappy bubble level just isn't going to be accurate.

You're probably right. *I've never used it. *The plastic tubing or hose
method would be the best to use.- Hide quoted text -

- Show quoted text -

That's what's always bothered me about the design of some laser
levels.

It's not that they aren't usable due to the small bubble that bothers
me the most (yes, that sucks) but it's more the fact that the
manufacturers actually produce them like that.

Who were the test users? Anybody who has actually used a level would
have picked up on the problem the first time they tried to use the
device. Sure, it shoots a nice straight line, but if the user has to
guess as to whether the unit itself is level or not, what good is it?

The few times I've used mine, other than to have fun with the cat,
I've laid it on top of a torpedo level with a decent sized bubble.

On Tue, 16 Jun 2009 15:19:31 GMT, (Doug Miller)
wrote:

With a steady hand and a
sharp eye -- and a sharp pencil -- it's easy to get +/- 1/32" with a water
level.

That's dang close! "Looks good from my house!" g

"harry k" wrote in message
For 27' feet? You won't even be close at the end.

If he uses the chalk line to make sure he's parallel with ALL of the dashed
lines, including lines near the end which are vertically aligned using the
top of the panel as a measuring reference, why wouldn't it be close at the
end?

what about a self-leveling laser level like the Stanley CL2 cross-
line? reviewers say it works ok outdoors as long as it's in shade.

In article , "iwdplz" wrote:
"harry k" wrote in message
For 27' feet? You won't even be close at the end.

If he uses the chalk line to make sure he's parallel with ALL of the dashed
lines, including lines near the end which are vertically aligned using the
top of the panel as a measuring reference, why wouldn't it be close at the
end?

Any small error in marking is magnified as the number of marks increases. So
is any small error in the level itself.

A water level is dirt cheap to make and dirt simple to use, and its accuracy
rivals that of professional surveying equipment. Why use anything else?

On Tue, 16 Jun 2009 01:16:58 -0700 (PDT), ben
wrote:

How can I level this?

Saw this the other day. Made with aviation materials.

Short video:

http://www.chhanson.com/layoutLevel.html

"Stop squinting at the bubble"

"ben" wrote in message
...
I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?



Get a 6 foot level and a pencil...It's not rocket science...Gesh....

On Jun 16, 6:08*pm, Oren wrote:
On Tue, 16 Jun 2009 01:16:58 -0700 (PDT), ben
wrote:

How can I level this?

Saw this the other day. Made with aviation materials.

Short video:

http://www.chhanson.com/layoutLevel.html

"Stop squinting at the bubble"

"Made with aviation materials."

Really? Where did you get that from?

On Tue, 16 Jun 2009 18:43:57 -0700 (PDT), DerbyDad03
wrote:

On Jun 16, 6:08*pm, Oren wrote:
On Tue, 16 Jun 2009 01:16:58 -0700 (PDT), ben
wrote:

How can I level this?

Saw this the other day. Made with aviation materials.

Short video:

http://www.chhanson.com/layoutLevel.html

"Stop squinting at the bubble"

"Made with aviation materials."

Really? Where did you get that from?

From the link. Aviation technology is mentioned.

Might be something from war planes and instruments panels

Maybe even NASA, but I looked. Take a gander.

Frank wrote:
DerbyDad03 wrote:
On Jun 16, 7:10 am, Frank wrote:
On Jun 16, 4:16 am, ben wrote:

I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.
How can I level this? Or is there a better way to do this?
thx!
Don't know if this helps but kids bought me a laser Straightline.
Laser light puts out a straight line and the small unit has leveling
bubbles. Don't think they are expensive.

Unless they've improved the Straightline product line recently, they
are not much help.

The bubble is so much smaller than the space between the 2 lines that
you have to eyeball it to choose your own center. Over 27' any
eyeballing of a crappy bubble level just isn't going to be accurate.


You're probably right. I've never used it. The plastic tubing or hose
method would be the best to use.

Recommending a product that you've never used? Genius.

On Jun 16, 9:57*pm, Oren wrote:
On Tue, 16 Jun 2009 18:43:57 -0700 (PDT), DerbyDad03



wrote:
On Jun 16, 6:08*pm, Oren wrote:
On Tue, 16 Jun 2009 01:16:58 -0700 (PDT), ben
wrote:

How can I level this?

Saw this the other day. Made with aviation materials.

Short video:

http://www.chhanson.com/layoutLevel.html

"Stop squinting at the bubble"

"Made with aviation materials."

Really? Where did you get that from?

From the link. Aviation technology is mentioned.

Might be something from war planes and instruments panels

Maybe even NASA, but I looked. Take a gander.

"Take a gander"

I did. That's why I asked "Where did you that from?"

Go back, take another gander yourself and then come back and tell us
what he *really* said.

I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make
sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?

Water level or laser. Laser is simple. Water level will get it close as a
gnat's whisker. Water level is cheaper, and you will use it on a lot of
more projects. Easy to master, simple in principle. A good laser is also
good, but you have to spend $$$ for a good one.

Steve

"benick" wrote in message
...

"ben" wrote in message
...
I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?



Get a 6 foot level and a pencil...It's not rocket science...Gesh....

Six foot level on a 20 foot run?

Gesh (sic)

ben wrote:
I'm cutting off the bottom 20" of my t1-11 panel siding to replace it
and want to cut it off straight. The bottom edges of the siding are
rotten, so I can't just measure up from those 20" as a guide. So I
bought a chalkline but I now realize, I don't know how I can make sure
it's level. The length will be about 27'.

How can I level this? Or is there a better way to do this?

As DanG mentioned, you could measure from a consistent height on
the building. A story pole is in order:

http://www.taunton.com/finehomebuild.../021197070.pdf

--Winston