Anyone here ever design windows into an existing masonry party wall? Or is that just a bad idea in general?
At least here in California, we need to also have a 3' setback. Wondering whether having the windows protruding into the inside is something that would look really weird. Then the trouble of the additional fire protection, shutters (if needed) etc. Reason we are looking at this is because there is space were trying to get air and light to which are far from the glazing which is only in the front and back of the building.
I'm assuming you mean in a party wall that is only built on your property and that the adjacent property has nothing, or at least where you are trying to put the window.
We did this exact thing in California. We had an existing CMU wall with ~0' setback, and no adjacent building. We had to submit a request for modification to the building ordinance to do it. I believe the proposed and accepted solution was to provide windows that were less than 15% of the area of the wall (which would normally require 3-5' setback) and then provide a water curtain, which I think we may have overdesigned as well. There was also some narrative around the logic of it. The AHJ accepted it.
As it was a modification, it was completely up to the AHJ, so there is no guarantee you'd be allowed to do it. This project had 4 different modifications. I would argue one was actually because the AHJ didn't properly interpret the code though.
Can't share any real information as the project was a hard NDA.
thx for sharing. Yes party wall is built on the property line and the adjacent building is only 1 story high. Possibility that next door gets redeveloped but pretty unlikely on one side and the other side is almost zero. Owner is willing to take risk that one of the sides might get filled in someday
Jul 23, 24 4:21 pm ·
·
greenlander1
yeh thats roughly the similar idea we have. less than 15% of wall + some fire protection
Jul 23, 24 4:24 pm ·
·
natematt
So I was actually trying to find this modification but couldn’t. Upon further thinking, I seem to recall the overdesign argument going something like this… there are two options for improving your allowable opening percentage, provide a protected opening, or provide an unprotected opening but have a fully sprinklered building. Since we are both fully sprinklered and providing protection (via a water curtain) we are explicitly over-designing it and requested to reduce the code allowable separation distance as a result. Since the minimum allowable was 3’ with either of these options at the percentage we had, we thought it was a fair argument, and the AHJ agreed. In my experience LA has a bit of a thing for water curtains though.
hmm Im wondering whether its easier and cheaper to have the building fully sprinklered. The current building has sprinklers but maybe the city (San Diego) will ask for more.
In a la la land where i’m practicing, you need a consent from your neighbour to build a wall on boundary , zero setback. ( assumed it was a typo when the OP referred to a boundary wall as a party wall ?) No idea though whether in my area that you could do an opening to a zero setback boundary wall.
It can be done under the IBC - it's difficult and expensive though. As others have pointed out, there may be additional local requirements that you must follow.
I remember digging into the protection requirements thinking that maybe you could do a 3hr rated window assembly of some kind and not classify it as a protected opening since it's the same as the wall or something... bla bla bla.... I'm recall the code has an explicit requirement for party walls that says you cannot have glazed openings at all.
You can do it without hideously expensive fire-rated window assembies ... IF you get a minimum 5 foot no-build easement from your neighbor on their property adjacent to the window. That's enough to satisfy the IBC requirements.
Wouldn't that still be a protected opening limiting you to min 3' setback?
Jul 23, 24 1:50 am ·
·
greenlander1
so in addition to the 3' setback you need the fire shutter (which Im assuming is activated by fire alarm?)
Jul 23, 24 4:36 pm ·
·
natematt
Correct, or you could just have a fully sprinklered building with the 3’ separation.
As I noted in my comment above, when we did this with a modification, I think the argument was that we opted to both provide fully sprinklered building AND protection, which is overdesigning for the minimum allowable separation of 3’, and thus we should be allowed to reduce the separation distance. Again, that is not actually per code though. If you don’t want to do a modification, I think you’re stuck at 3’.
In NYC some years ago - Fire rated windows. Opening protectives are (were?) limited by percentage of wall area and if I remember correctly also by distance to property line. The term "party wall" to me means there is a building on each side so not sure exactly what you are asking. I've also done major additions to existing buildings that were classified as new buildings - not additions. As such, fire areas need to be maintained. Opening between buildings were solved most often using magnetic hold opens (doors and passthru's) and tied into fire alarm system
OP has described every classic brownstone / row house layout in NYC: shared masonry party wall with air / light shaft w/ windows for both units built roughly at the wall midpoint.
You need to understand that the term “opening” in the building code is very specific. There are protected and unprotected openings. Look at table 705.8 A 2hr-rated transparent portion of wall in a 2 hour rated wall is not considered an opening provided it is detailed and tested in a way that achieves continuity. Does that make sense?
forgot to mention, an operable 2hr rated transparent piece of wall is considered an opening and this is subject to the limitations in table 705.8 regardless of whether or not it is protected or unprotected. Protected usually means that there is a very specific type of sprinkler head above the window that provides a deluge along the surface of the opening so to reduce the surface temperature along the surface or the opening and thus prevent the passage of fire and smoke.
Lastly, you need to make sure of a few things when punching openings in party walls:
1. A party wall is owned by two separate owners. Be sure you have a licensing agreement or restrictive declaration (in nyc) to do so as the neighbor might either require you to close up the openings in the future and/or need to give you restricted access to his property for the actual construction/installation of the opening. You may need to have the owner consult an attorney to draft up that agreement between the two property owners.
2. Prior to doing anything, if the party wall is covered by a wall finish, either make some probes or scan the wall with construction scanning equipment to see if there aren’t any existing structural members (columns, cross braces, etc)
3. If you make an opening into a brick party wall, and adding more load on top, consult a structural engineer who might order some prism tests (structural compression tests of brick sections cut-out in from the wall and transported in whole to a lab) to test the compressive capabilities of the brick. Older masonry walls have slightly softer mortar and the brick’s moisture content might be higher due to less controlled moisture absorption rates.
Examples of windows installed into party walls
Anyone here ever design windows into an existing masonry party wall? Or is that just a bad idea in general?
At least here in California, we need to also have a 3' setback. Wondering whether having the windows protruding into the inside is something that would look really weird. Then the trouble of the additional fire protection, shutters (if needed) etc. Reason we are looking at this is because there is space were trying to get air and light to which are far from the glazing which is only in the front and back of the building.
Can you do skylights instead?
unfortunately not bc roof is occupied w cell antenna and we are looking to get windows into 4 levels
I'm assuming you mean in a party wall that is only built on your property and that the adjacent property has nothing, or at least where you are trying to put the window.
We did this exact thing in California. We had an existing CMU wall with ~0' setback, and no adjacent building. We had to submit a request for modification to the building ordinance to do it. I believe the proposed and accepted solution was to provide windows that were less than 15% of the area of the wall (which would normally require 3-5' setback) and then provide a water curtain, which I think we may have overdesigned as well. There was also some narrative around the logic of it. The AHJ accepted it.
As it was a modification, it was completely up to the AHJ, so there is no guarantee you'd be allowed to do it. This project had 4 different modifications. I would argue one was actually because the AHJ didn't properly interpret the code though.
Can't share any real information as the project was a hard NDA.
thx for sharing. Yes party wall is built on the property line and the adjacent building is only 1 story high. Possibility that next door gets redeveloped but pretty unlikely on one side and the other side is almost zero. Owner is willing to take risk that one of the sides might get filled in someday
yeh thats roughly the similar idea we have. less than 15% of wall + some fire protection
So I was actually trying to find this modification but couldn’t. Upon further thinking, I seem to recall the overdesign argument going something like this… there are two options for improving your allowable opening percentage, provide a protected opening, or provide an unprotected opening but have a fully sprinklered building. Since we are both fully sprinklered and providing protection (via a water curtain) we are explicitly over-designing it and requested to reduce the code allowable separation distance as a result. Since the minimum allowable was 3’ with either of these options at the percentage we had, we thought it was a fair argument, and the AHJ agreed. In my experience LA has a bit of a thing for water curtains though.
hmm Im wondering whether its easier and cheaper to have the building fully sprinklered. The current building has sprinklers but maybe the city (San Diego) will ask for more.
In a la la land where i’m practicing, you need a consent from your neighbour to build a wall on boundary , zero setback. ( assumed it was a typo when the OP referred to a boundary wall as a party wall ?) No idea though whether in my area that you could do an opening to a zero setback boundary wall.
a wall on boundary that form part of building envelope for habitable space… to be perfectly clear
@luvu, see my comment above. That was in LA.
@Nate , didn’t see you post when I responded. Your comment was spot on.
yes the party wall is an existing exterior wall of a building which sits right on the property line.
Interesting question!
It can be done under the IBC - it's difficult and expensive though. As others have pointed out, there may be additional local requirements that you must follow.
Let us know what solution you decide to go with.
Good luck!
I remember digging into the protection requirements thinking that maybe you could do a 3hr rated window assembly of some kind and not classify it as a protected opening since it's the same as the wall or something... bla bla bla.... I'm recall the code has an explicit requirement for party walls that says you cannot have glazed openings at all.
You can do it without hideously expensive fire-rated window assembies ... IF you get a minimum 5 foot no-build easement from your neighbor on their property adjacent to the window. That's enough to satisfy the IBC requirements.
With a 1-3 hour rated fire wall. The fire wall is the really expensive part. ;)
Sure install a Fire shutter
Wouldn't that still be a protected opening limiting you to min 3' setback?
so in addition to the 3' setback you need the fire shutter (which Im assuming is activated by fire alarm?)
Correct, or you could just have a fully sprinklered building with the 3’ separation.
As I noted in my comment above, when we did this with a modification, I think the argument was that we opted to both provide fully sprinklered building AND protection, which is overdesigning for the minimum allowable separation of 3’, and thus we should be allowed to reduce the separation distance. Again, that is not actually per code though. If you don’t want to do a modification, I think you’re stuck at 3’.
In NYC some years ago - Fire rated windows. Opening protectives are (were?) limited by percentage of wall area and if I remember correctly also by distance to property line. The term "party wall" to me means there is a building on each side so not sure exactly what you are asking. I've also done major additions to existing buildings that were classified as new buildings - not additions. As such, fire areas need to be maintained. Opening between buildings were solved most often using magnetic hold opens (doors and passthru's) and tied into fire alarm system
OP has described every classic brownstone / row house layout in NYC: shared masonry party wall with air / light shaft w/ windows for both units built roughly at the wall midpoint.
You need to understand that the term “opening” in the building code is very specific. There are protected and unprotected openings. Look at table 705.8 A 2hr-rated transparent portion of wall in a 2 hour rated wall is not considered an opening provided it is detailed and tested in a way that achieves continuity. Does that make sense?
forgot to mention, an operable 2hr rated transparent piece of wall is considered an opening and this is subject to the limitations in table 705.8 regardless of whether or not it is protected or unprotected. Protected usually means that there is a very specific type of sprinkler head above the window that provides a deluge along the surface of the opening so to reduce the surface temperature along the surface or the opening and thus prevent the passage of fire and smoke.
Lastly, you need to make sure of a few things when punching openings in party walls:
1. A party wall is owned by two separate owners. Be sure you have a licensing agreement or restrictive declaration (in nyc) to do so as the neighbor might either require you to close up the openings in the future and/or need to give you restricted access to his property for the actual construction/installation of the opening. You may need to have the owner consult an attorney to draft up that agreement between the two property owners.
2. Prior to doing anything, if the party wall is covered by a wall finish, either make some probes or scan the wall with construction scanning equipment to see if there aren’t any existing structural members (columns, cross braces, etc)
3. If you make an opening into a brick party wall, and adding more load on top, consult a structural engineer who might order some prism tests (structural compression tests of brick sections cut-out in from the wall and transported in whole to a lab) to test the compressive capabilities of the brick. Older masonry walls have slightly softer mortar and the brick’s moisture content might be higher due to less controlled moisture absorption rates.
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