Count or Not Count towards Wind Mit. Report

[Brian C. Hoagland]

Originally Posted by bgromicko

We just finished updating the Wind Mitigation course http://www.nachi.org/wind-mitigation...ion-course.htm.

Special thanks to John and Michelle Shishilla of Honor Construction Inspection Services, who worked night and day with me for the last week.

The recently updated course teaches the student how to perform wind mitigation inspections, including how to complete the new wind mitigation form.

All well and good, care to weigh in with your own opinion regarding the question at hand? Feel free to post your opinion regarding this. I promise not to bite the hand that feeds me, thanks to you, John and Michelle for the hard work.

[Eric C. Van De Ven]

Originally Posted by bhoagland

All well and good, care to weigh in with your own opinion regarding the question at hand? Feel free to post your opinion regarding this. I promise not to bite the hand that feeds me, thanks to you, John and Michelle for the hard work.

I posted the question on the course form as well.

To expand on this, my wife who is the lead dietitian at Health South, came up with this, "if you wanted to know what percent of an apple a person took with one bite, you wouldn't measure an orange".

[Brian C. Hoagland]

Originally Posted by evandeven

I posted the question on the course form as well.

To expand on this, my wife who is the lead dietitian at Health South, came up with this, "if you wanted to know what percent of an apple a person took with one bite, you wouldn't measure an orange".

Point taken, I would weigh the apple before and after the bite. And then juice the orange after zesting the top of my coconut wahoo fillet. But... I digress.

[Humberto Carvajal]

All this talk of food is making me hungry...stepping out to dinner. Be back later.....Bye Y'all!

[Ed Bancroft]

Wahoo!......... covered with blackberry chutney

[Brian C. Hoagland]

Originally Posted by ebancroft

Wahoo!......... covered with blackberry chutney

I digress for one post and... No matter, I think we covered the bases.

[Eric C. Van De Ven]

Originally Posted by ebancroft

Wahoo!......... covered with blackberry chutney

Carrabbas trio chicken.........................

[Richard Murphy]

Originally Posted by evandeven

Ms. Brewer,
I hope you are the right person to contact with regards to this question.
It pertains to the 1802 form and the measurements for determining the amount of roof area that is non-hip for the purposes of selecting either a hip or non-hip roof.
This is what it says on the form:

Hip roof with no other roof shapes greater than 10% of the total roof system perimeter.
Total length of non-hip features: ______ feet; Total roof system perimeter: _______ feet

So now here are the examples.
Example A: total roof perimeter. The roof for our purposes would be 40 feet across the front and 30 feet across the side, just to make it easy.
On the back of the house we have a flat roof which is 12 x 15.

Your perimeter measurements will be, starting at the front of the house: 40+30+5+12+15+12+20+30=164 total roof perimeter.
Your non-hip roof length will be 15.(see attached diagram)
15/164=.0914 * 100= 9.14% non-hip which makes the roof a hip roof.
That is what the form says.

Example B:
Same house
Your perimeter measurements will be, starting at the front of the house: (40+30+40+30)+(12+15+12+15)=194 total roof perimeter.

Your non-hip perimeter measurements will be 12+15+12+15 = 54
54/194=.2783 * 100=27.83% (see attache diagram)

Now, mathematically, example B is correct and it is how you would get the actual percentage. You are measuring the actual roof area, sort of, as opposed to Example A. To truly get the correct area, you would have to include the pitch in the main roof as well.
Total roof perimeter of main roof (A)+Total roof perimeter flat roof (B). You have to separate them in order to get the perimeter of each.

Or, you could have example C
Same house and measurements.
Main roof area 30*40=1200
Flat roof area 15 * 12 =180
180/1200=.15 *100 = 15%
--
It would be my interpretation, that according to the wording on the form, the method in Example A would be the correct formula to use.
There are others that say Example B should be used and others say Example C.
The issue I have is I want to get the form correct and to me, using the proper definitions of length and perimeter, Example A, would be the only answer, as per the form.

If possible, could you give some clarification on this?
Thank You!

A little confusing, but I don't think that you would measure the back of the flat roof in your second equation - It is not the perimeter of the dwelling, but attached to the main roof presumably - so the non-hip portion should be 39' (12+15+12) so 39/164 = 24% - Non-Hip

[John Shishilla]

I promised this to someone so here is it, this is an example from the wind mit class.





To measure the perimeter:



12+15+12= 39'




To measure the non-hip(flat, structurally attached patio)



45+24+10+12+15+12+20+24 = 162'


39' / 162' = 24%

[Eric C. Van De Ven]

Originally Posted by jshishilla

I promised this to someone so here is it, this is an example from the wind mit class.





To measure the perimeter:



12+15+12= 39'




To measure the non-hip(flat, structurally attached patio)



45+24+10+12+15+12+20+24 = 162'


39' / 162' = 24%

Sorry, but that is incorrect.
The correct formula would be (15 * 2)+(12 * 2)= (A)/(45 *2)+(24 * 2)= (B) = C * 100 = C%
That would give you the percentage of the flat roof as opposed to the main roof.
If you wanted the total of all roofs and the percent of flat, again, you would have to separate them, add the total, then dived the total into the flat.

I will now make this as simple as possible to understand.
If you want to know the percentage of something, you have to know the total of all of it and the part you want the percentage of.

Example:
You have an ice cube tray. For those that have never seen one, it is either metal or plastic and you pour water into it. Place it in the freezer and a few hours later, ice cubes.
If done properly, you will have, in this case, ten equally size cubes of ice.
Here is where the math comes in.

Take one cube out. What % of cubes have been removed?

You had 10, removed 1.
1/10th or 10% has been removed.
Now,You remove 2 more cubes.
3/10ths or 30% have been removed.
As you are on your third scotch now, you remove another cube and a half.
Quiz: How many cubes have been removed and what percent of cubes have been removed?

Pretend your ice cube is the flat roof. How many will fit in the main house?

To go even further, your main house is 10 ice cubes. Your flat roof is 2 cubes.
What % is the flat of the total roofs?

2 /12 =.1666 * 100 =16.66%

And to make it even easier,
You main house is 10 cubes.
Your flat roof is 10 cubes.
What is the percent of the flat roof as opposed to all of the roofs?
10/20=.5 * 100 =50%

The problem comes in because that isn't what the form says. Or did they just put length and perimeter on there to confuse everyone?

[John Shishilla]

another example


http://honorconstruction.com/blog1/

[John Shishilla]

Originally Posted by evandeven

Sorry, but that is incorrect.
The correct formula would be (15 * 2)+(12 * 2)= (A)/(45 *2)+(24 * 2)= (B) = C * 100 = C%
That would give you the percentage of the flat roof as opposed to the main roof.
If you wanted the total of all roofs and the percent of flat, again, you would have to separate them, add the total, then dived the total into the flat.

I will now make this as simple as possible to understand.
If you want to know the percentage of something, you have to know the total of all of it and the part you want the percentage of.

Example:
You have an ice cube tray. For those that have never seen one, it is either metal or plastic and you pour water into it. Place it in the freezer and a few hours later, ice cubes.
If done properly, you will have, in this case, ten equally size cubes of ice.
Here is where the math comes in.

Take one cube out. What % of cubes have been removed?

You had 10, removed 1.
1/10th or 10% has been removed.
Now,You remove 2 more cubes.
3/10ths or 30% have been removed.
As you are on your third scotch now, you remove another cube and a half.
Quiz: How many cubes have been removed and what percent of cubes have been removed?

Pretend your ice cube is the flat roof. How many will fit in the main house?

The problem comes in because that isn't what the form says. Or did they just put length and perimeter on there to confuse everyone?

You are using the 15' dimension twice and that would be incorrect. We are measuring only the perimeter and using only perimeter length measurements. We are calculating the % of a length(perimeter).

[Eric C. Van De Ven]

Originally Posted by jshishilla

You are using the 15' dimension twice and that would be incorrect. We are measuring only the perimeter and using only perimeter length measurements. We are calculating the % of a length(perimeter).

Again, look at my ice cube example.

Make both roofs flat roofs.

The formula used by the OiR is incorrect. So is yours.

We are talking about one percentage of one object as opposed to the total of two objects.
You need either the area of both, perimeter of both, or volume of both in order to get a proper result.

Taking a length and comparing it to a perimeter is apples and oranges.

[John Shishilla]

Originally Posted by evandeven

Again, look at my ice cube example.

Make both roofs flat roofs.

The formula used by the OiR is incorrect. So is yours.

We are talking about one percentage of one object as opposed to the total of two objects.
You need either the area of both, perimeter of both, or volume of both in order to get a proper result.

Taking a length and comparing it to a perimeter is apples and oranges.

No we are calculating a % of a length.

If the total length around a house is 100 and the non-hip length is 20 than it is 20% non-hip.

Look at some of the other examples such as a dutch hip. There is no area to measure on those.

We are getting the % of non-hip features compared to the the length of the perimeter.

[Eric C. Van De Ven]

Originally Posted by jshishilla

No we are calculating a % of a length.

If the total length around a house is 100 and the non-hip length is 20 than it is 20% non-hip.

Look at some of the other examples such as a dutch hip. There is no area to measure on those.

We are getting the % of non-hip features compared to the the length of the perimeter.

Which is why the formula is wrong.

Try this with your formula.
You have a three story structure and due to the code requirements of the city, it can only be 30 feet high.

To get the home built, on all four sides, there are hip roofs that meet up into a flat roof.
The total perimeter of the roof is 200 feet.
The flat roof is 10 x 10.
What percent of the roof is non-hip?

Think ice cubes!