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Minimum window size - NOT egress issue, but based on "room size" - is this an IRC requirement?

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KarlaE

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Joined
Aug 25, 2021
Messages
16
Location
Pahrump, Nevada
My plans are in plan review; several items were just redlined including the size of the windows in two rooms - note from plan review states "window shall be 8% of total room size" - is this actually in the code? Both windows are 34" x 48"; the one in the bedroom is casement style and meets egress requirements. One room is 11' 9" x 17' 5" and the other is 13' 4" x 17' 5".

I am building a 50' x 60' metal building with living quarters inside (meets local zoning); the living quarters run the entire 50' length and are 17' 5" wide. All windows are on the north side of the building, as the south wall is common to the shop area.

Local jurisdiction uses IRC as the standard for plan review - I'm trying to determine if this "8% rule" is legitimate. My steel building is in production with the window openings given above; the draftsman who drew my plans was very knowledgeable and mentioned window size for egress purposes, but said nothing about this? Can anyone provide feedback regarding this? Thanks!
 
Welcome

Not my area, give it a few days

You can go directly to the plan reviewer,,,, and ask nicely for the code sections,,, so you can review them,,,

And post here

Wonder if it has to do with ventilation??? First I heard that one.,

Any state or local amendments to the code???
 
There are exceptions but....

R303.1 Habitable rooms. Habitable rooms shall have an
aggregate glazing area of not less than 8 percent of the floor
area of such rooms. Natural ventilation shall be through windows,
skylights, doors, louvers or other approved openings to
the outdoor air. Such openings shall be provided with ready
access or shall otherwise be readily controllable by the building
occupants. The openable area to the outdoors shall be not
less than 4 percent of the floor area being ventilated.
Exceptions:
1. The glazed areas need not be openable where the
opening is not required by Section R310 and a
whole-house mechanical ventilation system is
installed in accordance with Section M1507.
2. The glazed areas need not be installed in rooms
where Exception 1 is satisfied and artificial light is
provided that is capable of producing an average
 
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Reactions: cda
8% of separation rule!!!!

Sounds like increase window size???

See more of the great state of Nevada
 
steveray said:
There are exceptions but....

R303.1 Habitable rooms. Habitable rooms shall have an
aggregate glazing area of not less than 8 percent of the floor
area of such rooms. Natural ventilation shall be through windows,
skylights, doors, louvers or other approved openings to
the outdoor air. Such openings shall be provided with ready
access or shall otherwise be readily controllable by the building
occupants. The openable area to the outdoors shall be not
less than 4 percent of the floor area being ventilated.
Exceptions:
1. The glazed areas need not be openable where the
opening is not required by Section R310 and a
whole-house mechanical ventilation system is
installed in accordance with Section M1507.
2. The glazed areas need not be installed in rooms
where Exception 1 is satisfied and artificial light is
provided that is capable of producing an average
Click to expand...
THANK YOU! I am installing a 3 ton HVAC system and there are ceiling fans in each room - not to mention the LIGHTING - your post seems cut off at the end - "capable of producing an average...." I will review Section R310 but it seems that my build meets the parameters of Exception 1...

In one of the rooms I have a closet that runs the entire width (17') of the room - is that floorspace excluded from this requirement? If so, that may be an option in the other room - add a long closet!
 
cda said:
Welcome

Not my area, give it a few days

You can go directly to the plan reviewer,,,, and ask nicely for the code sections,,, so you can review them,,,

And post here

Wonder if it has to do with ventilation??? First I heard that one.,

Any state or local amendments to the code???
Click to expand...
Thank you for the warm welcome - I certainly will be spending much time here. The fellow in charge of the local building department does NOT like owner/builders - so he finds ways to antagonize them. I have a friend that did a similar build two years ago - I called him to ask if there were such requirements for his build and he said "no".
 
KarlaE said:
THANK YOU! I am installing a 3 ton HVAC system and there are ceiling fans in each room - not to mention the LIGHTING - your post seems cut off at the end - "capable of producing an average...." I will review Section R310 but it seems that my build meets the parameters of Exception 1...

In one of the rooms I have a closet that runs the entire width (17') of the room - is that floorspace excluded from this requirement? If so, that may be an option in the other room - add a long closet!
Click to expand...
CLOSETS!!! (can't have too many) The IRC defines a Habitable Space as “A space in a building for living, sleeping, eating or cooking. Bathrooms, toilet rooms, closets, halls, storage or utility spaces and similar areas are not considered habitable spaces.”
 
KarlaE said:
Thank you for the warm welcome - I certainly will be spending much time here. The fellow in charge of the local building department does NOT like owner/builders - so he finds ways to antagonize them. I have a friend that did a similar build two years ago - I called him to ask if there were such requirements for his build and he said "no".
Click to expand...
Check agsinst your adopted code book::;



R303.1 Habitable Rooms

Habitable rooms shall have an aggregate glazing area of not less than 8 percent of the floor area of such rooms. Natural ventilation shall be through windows, skylights, doors, louvers or other approved openings to the outdoor air. Such openings shall be provided with ready access or shall otherwise be readily controllable by the building occupants. The openable area to the outdoors shall be not less than 4 percent of the floor area being ventilated.

Exceptions:
  1. The glazed areas need not be openable where the opening is not required by Section R310 and a whole-house mechanical ventilation system is installed in accordance with Section M1507.
  2. The glazed areas need not be installed in rooms where Exception 1 is satisfied and artificial light is provided that is capable of producing an average illumination of 6 footcandles (65 lux) over the area of the room at a height of 30 inches (762 mm) above the floor level.
  3. Use of sunroom and patio covers, as defined in Section R202, shall be permitted for natural ventilation if in excess of 40 percent of the exterior sunroom walls are open, or are enclosed only by insect screening.
 
cda said:
Check agsinst your adopted code book::;



R303.1 Habitable Rooms

Habitable rooms shall have an aggregate glazing area of not less than 8 percent of the floor area of such rooms. Natural ventilation shall be through windows, skylights, doors, louvers or other approved openings to the outdoor air. Such openings shall be provided with ready access or shall otherwise be readily controllable by the building occupants. The openable area to the outdoors shall be not less than 4 percent of the floor area being ventilated.

Exceptions:
  1. The glazed areas need not be openable where the opening is not required by Section R310 and a whole-house mechanical ventilation system is installed in accordance with Section M1507.
  2. The glazed areas need not be installed in rooms where Exception 1 is satisfied and artificial light is provided that is capable of producing an average illumination of 6 footcandles (65 lux) over the area of the room at a height of 30 inches (762 mm) above the floor level.
  3. Use of sunroom and patio covers, as defined in Section R202, shall be permitted for natural ventilation if in excess of 40 percent of the exterior sunroom walls are open, or are enclosed only by insect screening.
Click to expand...
I'm reading that right now... next will be to contact the HVAC contractor to see if I do/can meet Exception 1; then to call Electrical contractor to add lighting to meet Exception 2 - and all closets if all else fails!
 
I agree with Sifu. By referencing the exceptions you can eliminate the need for windows. And if the dwelling is sprinkled even egress windows may be open for debate.
 
e hilton said:
I think the purpose of exception 1 is that the windows do not have to open. Doesnt say anything about an exception frommthe 8% requirement.
Click to expand...
I think that it does, as it goes on to say that "if you meet the mechanical requirements for ventilation AND the lumens output" (lighting) - then the 8% does not apply
 
cda said:
You may just not want to do the exception, especially in Nevada:::



You will be sucking Death Valley in!!!!


Up size the windows!!!
Click to expand...
The framed openings in my STEEL building are under construction; I have also RECEIVED my windows - very expensive to make changes now. I can swap the location of the "bedroom" to the "exercise room" (which is exempt from the rule) - that will meet the glazing requirements for one room. The "kitchen" is a point to ponder......
 
Min&Max said:
I agree with Sifu. By referencing the exceptions you can eliminate the need for windows. And if the dwelling is sprinkled even egress windows may be open for debate.
Click to expand...

Ye but

Doesn’t call for “”” Whole House””.

Isn’t that a little different than normal air conditioning system??????
 
KarlaE said:
The framed openings in my STEEL building are under construction; I have also RECEIVED my windows - very expensive to make changes now. I can swap the location of the "bedroom" to the "exercise room" (which is exempt from the rule) - that will meet the glazing requirements for one room. The "kitchen" is a point to ponder......
Click to expand...
possibly remove 50% of the wall to open it to the other room with all the light....have an "open floorplan"
 
Min&Max said:
I agree with Sifu. By referencing the exceptions you can eliminate the need for windows. And if the dwelling is sprinkled even egress windows may be open for debate.
Click to expand...
No sprinklers.... going for ventilation & artificial lighting.... though I might reduce the size of the partition wall by 50% to go the "shared lighting" avenue - I like an open floorplan
 
As long as egress window is present in the bedroom, then the rest can be satisfied with artificial light and mech. ventilation. Easiest way to do whole house mech vent is to have one of the bath exhausts run 24/7 or a specific ratio - to provide the minimum required air volume per unit of time.
 
Getting off track a little but I wonder what the code says about existing houses where the basement or garage was turned to habitable space with no or less then 8% window openings with no other ventilation, just baseboard heaters installed, but the rest of the house does have a whole -house ventilation system? Does the code require windows or ventilation to be added?
 
KarlaE said:
I think that it does, as it goes on to say that "if you meet the mechanical requirements for ventilation AND the lumens output" (lighting) - then the 8% does not apply
Click to expand...
Ok, looks like you are right, with the caveat that you have to meet exception 1 before exception 2 is available.
 
Rick18071 said:
Getting off track a little but I wonder what the code says about existing houses where the basement or garage was turned to habitable space with no or less then 8% window openings with no other ventilation, just baseboard heaters installed, but the rest of the house does have a whole -house ventilation system? Does the code require windows or ventilation to be added?
Click to expand...
We verify that when they pull a permit to finish it....With typ basement windows and a door/ hatch, it usually works....But the door is key
 
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