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Room addition remodel - new windows framing


zaydo's Avatar
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10-07-16, 04:07 PM   #1  
Room addition remodel - new windows framing

Hi,
I have a 25'x11' room addition that was added to the exterior walls in 1978. The foundation is concrete slab. The room has a flat roof with ceiling joists 16" o.c. running north to south. There are eaves on the south side.

I'm thinking of re-framing the south and south-west angled wall for new windows and a patio door and partitioning the room to add a bedroom. The finished room is to look like this:
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Here is a sketchup of how I think the new framing on the south and south-west angled wall will look:

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Each window header spans 59" to allow for 2 mullioned 28"x64" double hung windows with a 3" mullion. (Can I use only one 2x4 for a 1.5" mullion?) The patio door R.O. is 60" wide. Each header is 3"x11.25".

I'm in a D[SUB]2[/SUB] seismic zone so the west end of the south wall is to framed as continuously sheathed portal frame (CS-PF) with braced wall panel length 18". If I were to use CS-WSP for this end, the code requires 27" instead. The east end of the south wall will be a 45" long CS-WSP braced wall panel. The total length of bracing is 18+45 = 63" which almost just meets the total bracing required by code for CS-WSP.

I have individual headers for each opening for two reasons:
1. It's easier for me working semi-alone.
2. I can build a small temporarily wall to only support ceiling/roof for one header only.
3. As far as I can interpret, this satisfies Table 602.7.5 to have 3 full-height studs on the east end of the south wall. The west end of the south wall has a CS-PF and should be exempt, right?

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The other option was to have a long header spanning both window and the door openings (16'3") but:
1. This would be much harder to install.
2. It seems, that I would not be able to meet Table R602.7.5 as there isn't space for 6 full height studs on the east end of the south wall. I would then need need a CS-PF on the east end as well, right?

The CS-PF needs two 1/2" anchor bolts through the sill plate 7" into the concrete foundation.
1. I'm thinking I shouldn't use wedge anchors so close (1.75") to the edge of the foundation. My options are Titen HD or epoxy anchors, right?
2. I don't have a return panel on the south-west angled wall so I need a hold-down device from the CS-PF's corner stud to the foundation to meet end-condition 2 of fig. R602.10.7. Can I share one of the anchors from the CS-PF's sill plate anchors to bolt the hold-down device also?
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The west wall will be CS-WSP and more than 48" long so I only need one braced wall panel on this wall. The south-west angled wall is less than 8' so is projected onto the west wall for BW purposes.

However, do I meet Table 602.7.5 to have 3 full-height studs on each end of the header in this angled wall? It doesn't look like I do.. Is there a workaround for this?

I know this is very long and there are lots of questions. Thanks for reading. Any input is appreciated.


Last edited by zaydo; 10-07-16 at 04:23 PM.
 
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XSleeper's Avatar
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10-07-16, 04:20 PM   #2  
Won't comment on your framing questions but im sure you know that you will need windows that meet egress for fire escape. Escape exits must have a “net clear opening” of 5.7 square feet. On a double hung, that is the size of the opening when you fully open one half of the window.

 
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10-07-16, 04:41 PM   #3  
Are you getting a permit? I'm not a framing expert but have submitted plans and built additions.

Your shear wall hold downs and anchor bolts should be expoxied in. It sounds like you've done your homework on that.

My concern is if the City or State will let you build this room. I believe your glazing area far surpasses what California allows. I don't know the % off hand, it's under Title 24 requirements.


Brian
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10-07-16, 06:32 PM   #4  
Some thoughts. Any window below 18" AFF must be tempered. Have you considered casement windows as opposed to double hung? Much more ventilation and a smaller window will suffice for egress as long as it meets the 5.7 sf requirement. By raising the sill of the window to above 18" AFF, you save a ton of money.

 
zaydo's Avatar
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10-08-16, 02:17 PM   #5  
Thanks everyone. I guess I need a lot more planning before drawing framing plans.

XSleeper, I knew about the egress requirements but didn't really calculate the open area of the double hung window. You're right and they won't work.

Handyone, I definitely plan on getting all permits. Like you say, I'm just trying to do all my homework first. I didn't even know about Title 24. Skimming through it, it seems that the total fenestration (glazing + frame) area must be less than 20% of total conditioned floor area for the entire house, with a maximum of 5% west facing. I measured all windows today and see that with my original plan I'll go just over 20%.

Chandler, I had thought of the glazing being at least 18" AFF. I think in general I should be ok because even if the window frame is 18" AFF, the glazing will be a couple of inches higher. I'm not sure about casement windows because the area right outside is the patio and open windows might be hazardous. Also, I think they get complicated with screens.

So, given all the new information, I've changed the windows to single 5050 (60"x60") glider windows for the south wall. (Originally I had liked two double hung windows because the smaller window frame would warp less over time. With 5050 windows, the window frame will need to be quite strong for durability.) The southwest angled wall has a 48"x60" glider window.

Here are the new pics:
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What do you think?

Thanks


Last edited by zaydo; 10-08-16 at 02:49 PM.
 
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10-08-16, 03:37 PM   #6  
The total fenestration is still a concern to me.
Since this is an addition the % might apply to the addition only, not the entire house.

In a typical addition this size, I would only expect to see one patio slider and one large or two smaller windows.

This is one of the first questions I would ask the plan reviewers.


Brian
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zaydo's Avatar
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10-09-16, 12:35 PM   #7  
Thanks Handyone. I will ask my city's planning/plan checkers.

I wonder if the room is still considered an addition even if it was built decades ago.

 
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10-09-16, 01:27 PM   #8  
Calling it a sunroom may help. Codes are funny that way, and while I'm not at all familiar with California codes, there are sometimes small exeptions written into codes like that.

 
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10-09-16, 01:47 PM   #9  
As X said, the room might need to be designated an enclosed patio or sunroom, preferably not.
A sunroom is generally a lightweight structure in California, so you don't want that.

The codes for an enclosed patio are pretty strict, the room will be strong and not much different from what you want.
You might be happy with that option and have a room just as functional.


Brian
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10-09-16, 02:04 PM   #10  
I would think the total fenestration calculation would apply to the house as a whole anyway, but its a valid question to get answers to.

 
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