## Question 17 Predesign NCARB 3.1

Site Zoning Vignette and Multiple Choice

### Question 17 Predesign NCARB 3.1

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'.
overseas

Posts: 185
Joined: Mon Dec 16, 2013 7:19 pm

### Re: Question 17 Predesign NCARB 3.1

Why are you messing with the 313? That's the area you use.

Coach

Posts: 13209
Joined: Wed May 23, 2012 2:08 am

### Re: Question 17 Predesign NCARB 3.1

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.
overseas

Posts: 185
Joined: Mon Dec 16, 2013 7:19 pm

### Re: Question 17 Predesign NCARB 3.1

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.
ghost

Posts: 50
Joined: Sun Dec 08, 2013 7:32 pm

### Re: Question 17 Predesign NCARB 3.1

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".
overseas

Posts: 185
Joined: Mon Dec 16, 2013 7:19 pm

### Re: Question 17 Predesign NCARB 3.1

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
jamesarch13

Posts: 30
Joined: Wed Oct 23, 2013 2:34 pm

### Re: Question 17 Predesign NCARB 3.1

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.

Coach

Posts: 13209
Joined: Wed May 23, 2012 2:08 am

### Re: Question 17 Predesign NCARB 3.1

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?

Posts: 14
Joined: Sat Jun 13, 2015 11:42 am

### Re: Question 17 Predesign NCARB 3.1

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.

Coach

Posts: 13209
Joined: Wed May 23, 2012 2:08 am

### Re: Question 17 Predesign NCARB 3.1

Coach 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?

Posts: 14
Joined: Sat Jun 13, 2015 11:42 am

### Re: Question 17 Predesign NCARB 3.1

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.

Coach