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Question 17 Predesign NCARB 3.1

PostPosted: Thu Apr 03, 2014 7:53 pm
by overseas
Can anybody explain for me Question 17 Predesign NCARB 3.1 . How they calculate the width of the sliding door to be 5' ?
Here is the link to NCARB 3.1
http://www.ironwarrior.org/ARE/_NCARB_Software/3_1/multiplechoice_31.pdf

Here is how I calculated:
-Living room/Dining Area 313SF ( The rest of the floor area looks to me 1/3 of the Living room/Dining ) so Floor area should be 313/2=156.5 x 3= 469.5
-5% of 469.5 = 23.47
-ventilation area = W x H, So 23.47=6.6 x X. X=3.5' The NCARB answer is 5'.
- Ventilation area should be half of the bypassing sliding door so the sliding door should be 3.5 x 2 = 7. The NCARB answer is 5'.

Re: Question 17 Predesign NCARB 3.1

PostPosted: Thu Apr 03, 2014 11:51 pm
by Coach
Why are you messing with the 313? That's the area you use.

Re: Question 17 Predesign NCARB 3.1

PostPosted: Fri Apr 04, 2014 7:25 am
by overseas
Coach wrote:Why are you messing with the 313? That's the area you use.


Thank you Coach, I thought "Floor area" means the whole floor area, not the room area.

Re: Question 17 Predesign NCARB 3.1

PostPosted: Fri Apr 04, 2014 10:11 am
by ghost
I needed to review this question so I am glad it came up.

Code: Select all
ventilation area = W x H, So 23.47=6.6 x X. X=3.5' The NCARB answer is 5'.
- Ventilation area should be half of the bypassing sliding door so the sliding door should be 3.5 x 2 = 7. The NCARB answer is 5'.


From your formula using the proper SF I am getting X=2.37. Since 2.37 is the operable half of the sliding door we multiply it by 2 to get the full width, which is ~5'. I had to work through this one as I was typing my reply. Seems so simple now.

Re: Question 17 Predesign NCARB 3.1

PostPosted: Sat Apr 05, 2014 8:25 am
by overseas
ghost wrote:I needed to review this question so I am glad it came up.

Code: Select all
ventilation area = W x H, So 23.47=6.6 x X. X=3.5' The NCARB answer is 5'.
- Ventilation area should be half of the bypassing sliding door so the sliding door should be 3.5 x 2 = 7. The NCARB answer is 5'.


From your formula using the proper SF I am getting X=2.37. Since 2.37 is the operable half of the sliding door we multiply it by 2 to get the full width, which is ~5'. I had to work through this one as I was typing my reply. Seems so simple now.


It is simple... My only confusion was the term " Floor area".

Re: Question 17 Predesign NCARB 3.1

PostPosted: Tue Oct 07, 2014 4:49 pm
by jamesarch13
Hello All,
I am coming to the party a little late here, but I have two issues with understanding this question. I want to get it because this is a typical confusion inducing item for the ARE.

First, I can understand the "floor area" being the area to be ventilated or used so the 313 is the only number for that calc. That is however a leap I can't imagine taking in the test room. But I will learn to.

However, the second issue, and I think more critical and even more ARE aspect of this, is that the width of the door being twice the vent area width is LESS than the IBC code minimum for egress. The door opening needs to be 32" x 2= 64" making the answer 6' not the illegal life threatening 5'. This feels more ARE typical anyway where the numbers are extra info. Seriously.

I suppose this means I need only apply code when directed specifically by the individual question...I think I know the answer.
I feel better already, but I love being told how I am getting it wrong.
J13

Re: Question 17 Predesign NCARB 3.1

PostPosted: Tue Oct 07, 2014 11:38 pm
by Coach
jamesarch13 wrote:First, I can understand the "floor area" being the area to be ventilated or used so the 313 is the only number for that calc. That is however a leap I can't imagine taking in the test room. But I will learn to.

No leap required.

However, the second issue, and I think more critical and even more ARE aspect of this, is that the width of the door being twice the vent area width is LESS than the IBC code minimum for egress.

Not true. Read the entire code section.

Re: Question 17 Predesign NCARB 3.1

PostPosted: Sat Apr 07, 2018 9:02 pm
by MarciAdair
Coach wrote:Why are you messing with the 313? That's the area you use.


So since 5% of 313' is 15.65' and
15.65/ 6.66 = 2.34' door width
Not 5'.
What am I doing wrong?

Re: Question 17 Predesign NCARB 3.1

PostPosted: Sun Apr 08, 2018 1:08 am
by Coach
MarciAdair wrote:
Coach wrote:Why are you messing with the 313? That's the area you use.


So since 5% of 313' is 15.65' and
15.65/ 6.66 = 2.34' door width
Not 5'.
What am I doing wrong?

It's a bypassing sliding door.

Re: Question 17 Predesign NCARB 3.1

PostPosted: Sun Apr 08, 2018 8:54 pm
by MarciAdair
Coach wrote:
MarciAdair wrote:
Coach wrote:Why are you messing with the 313? That's the area you use.


So since 5% of 313' is 15.65' and
15.65/ 6.66 = 2.34' door width
Not 5'.
What am I doing wrong?

It's a bypassing sliding door.


Guess I was waiting to see something saying door *Leaf* size. Is it common to refer to each leaf as a full bypass sliding glass door?

Re: Question 17 Predesign NCARB 3.1

PostPosted: Mon Apr 09, 2018 2:46 am
by Coach
MarciAdair wrote:Guess I was waiting to see something saying door *Leaf* size. Is it common to refer to each leaf as a full bypass sliding glass door?

The question asks for the min width of the entire door.