Thread: Ladder

07062006, 12:53 AM #1
 Join Date
 Dec 2005
 Posts
 4
Ladder
How tall is a 35 foot ext. ladder when up all the way at the propar climbing angle..Is there a formula for figuring this out?

07062006, 12:13 PM #2
 Join Date
 Oct 2005
 Posts
 735
Yes, there is a formula. Its called the Pythagorean Theorem.
C = square root of (A squared plus B squared)
C is your 35ft ladder
A is your height of ladder from ground to tip
B is your footing distance
This works perfectly for a ladder placed for rescue, not so perfectly for a ladder placed for roof access. A 35' ladder fully extended placed for rescue would give you a 34' working height.
For roof access you must subtract the length of the ladder from its resting point on the roof from its fully extended length thus changing your hyptenuse, the ladder length, to around 31'
Knowing a ladder placed for roof access should have 35 rungs above the roof line will reduce your working height to about 30'.
Its really quite simpleJust another one of the 99%ers looking up.

07112006, 02:51 PM #3
 Join Date
 Jan 2003
 Location
 Orlando Florida
 Posts
 7
Easy rough rule for ladder
Easier one to remember.
Take the working distance of the ladder that is extended and reduce it by 1/4. for proper climbing angle. So if you are using a 24 foot ladder you should have 6 feet from the building and this reduces the height to 18 feet. A 35 foot ladder in reality should give you a working length of 26 feet. Rough rule 35 foot ladder round off to 36 feet 1/4 of 36 feet is 9 feet and that gives you roughly 26 to 27 feet.
Plus or minus if your leaving tip over the top of the roof or window entry etc.
Dave Williams
City of Orlando Fire Department
Engine 101 station 1 " The Big House"

07112006, 05:43 PM #4
 Join Date
 Oct 2002
 Location
 The North East
 Posts
 489
Originally Posted by doughboy758
Using the Pythagorean Theorem, a 35 rounded to 36 ft. gives you 34 ft. of height. Basically using (B sq.)9 ft (1/4 the overall length as you distance from the wall) and 36 ft. as the ladder length (C sq.) so the formula looks like this:
A squared X 81 (9 squared) = 1225 (35 squared)
A squared = 122581 (1144)
A = 33.8
Basically the distance from the wall can not be completely subtracted from the height. By your formula the difference is nearly 10 ft.

08252006, 09:50 PM #5
 Join Date
 Dec 2005
 Posts
 81
Originally Posted by RFDACM

08252006, 11:22 PM #6
 Join Date
 Dec 2005
 Posts
 105
About 34 ft.
Last edited by MEDIC0372; 08272006 at 11:26 AM.

08262006, 05:06 PM #7
It would still be 35'. I dont think they shrink when you raise them.
Ill take what is the REACH of a 35' extension ladder for a $100 Alex.
Last edited by Dave1983; 08262006 at 05:09 PM.
Fire Marshal/Safety Officer
IAAINFPAIAFC/VCOSRetired IAFF
"No his mind is not for rent, to any god or government"
RUSHTom Sawyer
Success is when skill meets opportunity
Failure is when fantasy meets reality

08272006, 11:27 AM #8
 Join Date
 Dec 2005
 Posts
 105
Rule of thumb...Ladders 35' and less reach 1' less than the designated length.
Ladders over 35' reach 2' less than the designated length.Last edited by MEDIC0372; 08292006 at 08:05 AM.

08282006, 08:33 AM #9
 Join Date
 Jul 1999
 Location
 Upstate NY
 Posts
 72
Take the working distance of the ladder that is extended and reduce it by 1/4. for proper climbing angle. So if you are using a 24 foot ladder you should have 6 feet from the building and this reduces the height to 18 feet. A 35 foot ladder in reality should give you a working length of 26 feet. Rough rule 35 foot ladder round off to 36 feet 1/4 of 36 feet is 9 feet and that gives you roughly 26 to 27 feet.
This is not accurate at all.
The tip of the ladder, when against the building is a pivot point and will only come down inches. An example would be if you raise a ladder straight up against the wall to a window sill and then pull the base out the tip only drops an inch or two.
Your best formula would be to do it and measure it and remember it. When you need the ladder is not the time to do the math.IACOJ

08282006, 01:57 PM #10
 Join Date
 Oct 2002
 Location
 The North East
 Posts
 489
Originally Posted by masterFF
AxA (hgt of ladder @ wall) + BxB(dist. from Bldg) = CxC (ladder length)
rewritten as:
AxA= (CxC)  (BxB)
AxA= (35x35)  (1/4 of 35: 8.75x8.75 )
AxA= 1225  76.5
AxA=1148.5
Height up wall = square root of 1148.5 or 33.8 ft.
Same number as rounding within one tenth of a foot.

08292006, 11:56 PM #11
 Join Date
 May 2000
 Location
 Wheaton IL
 Posts
 1,765
I'm usually big on numbers and preplanning what goes where but in this case get out and throw the ladder. I'm finding out, fast, that guys aren't very good at judging distances by eye.
The only way you will know for sure is to throw the ladder, a lot. Use different buildings, houses under construction, vacant buildings etc. After a while you will get a feel for what goes where. These kind of drills are a must for the progressive ladder company, know what your stuff can do, know your district and know your guys.
Stay safe
Thread Information
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
Similar Threads

911 Remembered Painting,God Bless Us All
By devonc in forum Meet and GreetReplies: 4Last Post: 04252007, 11:08 PM 
saying from 91101 and the year 2001
By mtnfyre21 in forum Firefighters ForumReplies: 14Last Post: 08262005, 08:51 AM 
World Of Fire Report: 012305
By PaulBrown in forum World of Fire Daily ReportReplies: 0Last Post: 01242005, 08:28 AM 
World Of Fire Report: 022602
By PaulBrown in forum World of Fire Daily ReportReplies: 0Last Post: 02272002, 07:25 PM 
We have to look into our darkest day
By harlemBrother in forum Firefighters ForumReplies: 3Last Post: 02022002, 06:41 PM