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Don_P
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# Posted: 26 Jan 2016 18:43 - Edited by: Don_P
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On bedrooms and windows.
Whenever you can put an egress window in a room, do so! Nobody wants to make it harder for you to get out or for firefighters to get in. Some of the first building codes were about fire, light and ventilation due to windowless tenements.
"2012 IRC R303.1 Habitable rooms.
All 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, 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 minimum openable area to the outdoors shall be 4 percent of the floor area being ventilated."
"R310.1 Emergency escape and rescue required.
Basements, habitable attics, and every sleeping room designated on the construction documents shall have at least one operable emergency escape and rescue opening. Where basements contain one or more sleeping rooms, emergency egress and rescue openings shall be required in each sleeping room. Where emergency escape and rescue openings are provided, they shall have a sill height of not more than 44 inches (1118 mm) measured from the finished floor to the bottom of the clear opening. Where a door opening having a threshold below the adjacent ground elevation serves as an emergency escape and rescue opening and is provided with a bulkhead enclosure, the bulkhead enclosure shall comply with Section R310.3. The net clear opening dimensions required by this section shall be obtained by the normal operation of the emergency escape and rescue opening from the inside, except that tilt-out or removable sash designed windows shall be permitted to be used. Emergency escape and rescue openings with a finished height below the adjacent ground elevation shall be provided with a window well in accordance with Section R310.2. Emergency escape and rescue openings shall open directly into a public way, or to a yard or court that opens to a public way.
R310.1.1 Minimum opening area.
All emergency escape and rescue openings shall have a minimum net clear opening of 5.7 square feet (0.530 m2), including the tilting or removal of the sash as the normal operation to comply with Sections R310.1.2 and R310.1.3.
Exception: Grade floor openings shall have a minimum net clear opening of 5 square feet (0.465 m2).
R310.1.2 Minimum opening height.
The minimum net clear opening height shall be 24 inches (610 mm).
R310.1.3 Minimum opening width.
The minimum net clear opening width shall be 20 inches (508 mm). "
What determines whether a room is a bedroom or not is whether the construction documents call it a bedroom. If challenged point to that citation, you're welcome.
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creeky
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# Posted: 26 Jan 2016 18:44
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Quoting: Jabberwocky EXACTLY what my wife loves about tin roofs
it is lovely when the rain is light. but wait'll she hears the thunder of a big storm. of course I built mine under trees with wild grape growing through them. the scratch skreek scunch of the grape vines ... the girlfriend had me up on the roof the next day, clippers in hand. 
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Julie2Oregon
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# Posted: 26 Jan 2016 19:12
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WOW, LOTS of good info and discussion!!! Thanks so much, guys! This isn't muddying the waters at all -- it's clarifying some things for me, actually!
I'm roof-wary from living in Texas. I currently live out in the country and in 8 years, I'm about to embark on my second reroof from wind and hail. There is nothing wrong with the roofing materials or the work, it's just the crazy weather. Oregon isn't as bad but stuff happens.
So, I'm leery of doing external insulation. In my mind, it would add cost and complexity if any of the roofing sections needed to be replaced for some reason. Am I being silly?
Steve_S I'm interested in the rock wool. Over the weekend, I spent some time at a shed sellers place studying the gambrel "cabins." I think I'd want 2 X 6s up there for "snow load" anyway and filling those spaces with rock wool wouldn't be horribly difficult.
I've mulled this -- do you know what would be cool? Installing a tin ceiling over that insulation at the top. The tin would be more flexible and could be attached to the framing, if that would work. Beadboard over the more vertical side sections.
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Julie2Oregon
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# Posted: 26 Jan 2016 19:26 - Edited by: Julie2Oregon
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Quoting: Don_P R310.1.2 Minimum opening height. The minimum net clear opening height shall be 24 inches (610 mm). R310.1.3 Minimum opening width. The minimum net clear opening width shall be 20 inches (508 mm). "
Crap! Seriously? So the 3X2 insulated sliding windows I planned to use in my kitchen and loft won't meet code even though I can easily fit through them. I'm off by 2 inches. That sux.
All right, I just measured my widest body area at 16 inches so this is about the point where we offer the inspector $50 for his tape measure to slip.
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upndown
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# Posted: 26 Jan 2016 19:44
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My kinda thinking!! Hahaha. 
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Julie2Oregon
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# Posted: 26 Jan 2016 19:52
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razmichael
This is great! Thanks for posting the link to your blog -- I'm going to read and follow it!
There isn't nearly as much info available online for doing proper gambrel small cabins as there is for gable so this is much appreciated!
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Julie2Oregon
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# Posted: 26 Jan 2016 19:54
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Quoting: upndown My kinda thinking!! Hahaha.
LOL, upndown! You gotta do what you gotta do. To a point, lol.
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Don_P
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# Posted: 26 Jan 2016 20:05
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Kitchen isn't a sleeping room, is the loft? Think before you answer if you need to.
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Julie2Oregon
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# Posted: 26 Jan 2016 20:34
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Yes, the loft is my bedroom. Just lumped in the kitchen because I don't want to fiddle around with a bunch of different window sizes/types and planned to install the same windows in the kitchen and upstairs.
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MtnDon
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# Posted: 26 Jan 2016 20:46
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Egress windows also can act in reverse... for fire fighters coming in to rescue someone.
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Julie2Oregon
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# Posted: 26 Jan 2016 22:08
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My little place is going to have 3 doors (in case I want to add a room onto the side in the future) and big windows in the living room. It should be adequate for evac in case of fire. If the downstairs is burning, I WILL be jumping out that loft window long before the volunteer FD shows up! If the loft is alight, downstairs I run!
No joke, on my visit with the neighbors, they told me the local volunteer FD is quite slow to mobilize and emergency response actually comes faster from a town about 15 miles away. By which time, my cabin would be ash unless I and some neighbors could save it!
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Jabberwocky
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# Posted: 26 Jan 2016 22:36
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Quoting: Julie2Oregon So, I'm leery of doing external insulation. In my mind, it would add cost and complexity if any of the roofing sections needed to be replaced for some reason. Am I being silly?
No, not silly, but perhaps not envisioning the layers properly. The insulation is still underneath OSB (or plywood) sheathing. Here is a list of the layers from the top (outermost) down:
Metal roofing
Purlins (or sleepers as some call them)
OSB decking
Rigid Insulation
Vapor & air barrier
OSB decking
Rafters
Conditioned space
Moisture dries to the outside of the building and doesn't infiltrate the conditioned space through the roof. As you can see, the additional materials is the second layer of decking, and the purlins for the metal roof.
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Julie2Oregon
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# Posted: 26 Jan 2016 22:56
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Ah, so there's 2 layers of decking and the insulation is closest to the vapor barrier. I see now.
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Julie2Oregon
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# Posted: 26 Jan 2016 23:03
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Incidentally, all of this talk about ceilings, insulation, the loft, and then going down the fire rabbit hole actually came together inexplicably as I began to read about drop tin ceilings tonight. I think it might actually work jolly well for a gambrel! But I'll start a new thread on that, in case anyone is interested in it.
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silverwaterlady
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# Posted: 26 Jan 2016 23:46
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We sleep in our loft. Have two windows up there on opposite ends for good cross ventilation. We also have two fire escape ladders. If you are going to sleep in a two story house I would suggest purchasing one.
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Julie2Oregon
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# Posted: 27 Jan 2016 00:03
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silverwaterlady
Where can you buy those ladders at a good price?
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silverwaterlady
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# Posted: 27 Jan 2016 00:23
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I bought mine on clearance at Walmart.
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Julie2Oregon
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# Posted: 27 Jan 2016 01:06
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Wow, I never thought Wally would sell something like that! I'll have to check it out. Thanks!
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Steve_S
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# Posted: 27 Jan 2016 06:06
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Here are some worthwhile articles for you to catch up on Julie.
BSC: 2x6 Advanced Frame Wall Construction with Mineral Fiber Insulation Board
BSC: 2x6 Advanced Frame Wall Construction
Creeky, Myself, Jabberwocky and a few others are using variations on what is called "The Perfect Wall" which is a building/insulating method to maximize energy efficiency and keep our heating & cooling costs minimal. Here's some reference info related to "Perfect Wall" building.
BSI-090: Joseph Haydn Does The Perfect Wall (2015)
BSI-001: The Perfect Wall (2010)
A note about Vapour & Moisture! There are Vapour Barriers, Moisture Barriers, Air Barriers. These are all unique and different and each has a specific task and rules for installation which varies according to the "target climate". This is one spot where a lot of folks get confused because these terms often get mixed up or used "interchangeably" which they are not.
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Jabberwocky
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# Posted: 27 Jan 2016 08:52 - Edited by: Jabberwocky
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Quoting: Steve_S A note about Vapour & Moisture! There are Vapour Barriers, Moisture Barriers, Air Barriers. These are all unique and different and each has a specific task and rules for installation which varies according to the "target climate". This is one spot where a lot of folks get confused because these terms often get mixed up or used "interchangeably" which they are not.
This is true. However, should you use a membrane such as Grace Ice & Water Shield as your barrier, you are effectively covering all the bases. https://www.airbarrier.org/resistive/difference_between_air_barriers_vapor_barriers_a nd_water_resistive_barriers.php
Also, someone may correct me on this, but it was my understanding that the Huber Zip walls used with their tape also covers all the bases.
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creeky
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# Posted: 27 Jan 2016 09:44
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Jabberwocky, your "cool roof" uses two layers of OSB. This is unnecessary. The second layer of OSB on the outside adds nothing but cost. Your purlins can be attached directly to the roof with longer screws. I did mine into the roof joists with 8" screws (6" of ISO).
If you want to get fussy you could tape the outside edges of the ISO boards. I didn't. In my region nothing (bugs/critters) goes into the ISO. I have done multiple tests. I can't get critters to invade either ISO or XPS. Even if I put it on the ground on top of a nest (ants). The white EPS however... the bugs love it.
My second "cool roof" used only 1" ISO boards and purlins. Works well. Of course the building is only 4 winters old. So. We'll see what's what in another 10 years.
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Jabberwocky
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# Posted: 27 Jan 2016 10:47
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creeky
I guess it depends Creeky. I see your point, however I think it might depend on a case-by-case application and how paranoid the owner/builder is. The reason I personally would prefer a top layer of OSB is because I've read about long-term issues with rigid foam shrinking and pulling apart at the joints. I think this applies to certain kinds of foam over others, but off the top of my head I can't remember which. Should the roofing material be compromised, I would also be concerned about potential water damage. Not to the foam so much as just making it that much easier for water to work its way down through the various materials. Thirdly, it would allow someone to lay asphalt shingles if they so desire rather than a metal roof by eliminating the purlins. I wasn't certain which Julie wanted, so figured I'd describe the overkill method. One thing is for sure, either way takes some stinkin' long hardware for fastening!
If I were to build my own version, I would have the second OSB layer on the roof, whereas I wouldn't on the walls. Since the walls are a vertical plane, there's plenty of gravity to sufficiently expel water without 'overkilling' it. I would do as you say - screw the battens through the foam into the 2x framing. The nice thing about building small however, is that additional preventative measures don't usually break the bank.
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Don_P
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# Posted: 27 Jan 2016 18:57
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Well, I do it differently than you guys. Someone said they had a link to a cool roof design on the building science site... let's start there. I can't recall any of Lstiburek's details with the metal in the vent space, I'm curious how he is dealing with it.
Most roof metal manufacturers call for at least 5/8 sheathing, on some patterns you do need a solid deck under the metal, which is what I do for all. Zip is in 7/16 only last time I used it. It didn't seem to be cheaper or faster when it was all done. On a wall it doesn't provide for lapping of a weather resistive layer, there isn't one. I wouldn't consider it an improvement over the existing methods for those reasons.
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Jabberwocky
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# Posted: 28 Jan 2016 11:43
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Quoting: Don_P Most roof metal manufacturers call for at least 5/8 sheathing, on some patterns you do need a solid deck under the metal, which is what I do for all. Zip is in 7/16 only last time I used it. It didn't seem to be cheaper or faster when it was all done. On a wall it doesn't provide for lapping of a weather resistive layer, there isn't one. I wouldn't consider it an improvement over the existing methods for those reasons.
F.Y.I. Zip is available in 1/2." I have no experience with them mind, you, I'm only commenting on the concept. Whether it's cheaper or faster probably depends on what sort of wall one is trying to achieve. If someone were trying to build a 'perfect wall' a.k.a. PERSIST system, it IS cheaper - I know because I've priced it both ways. Probably faster too, since a 3" wide roll of tape around the joints seems to be an easier install than large rolls of sticky-backed membrane over regular OSB.
On the other hand, if someone is simply trying to build a "pretty good wall" and have no intention of deviating from standard building practices (as in NOT taping joints and/or worrying about air leakage) then yeah, they are definitely not worth it since the sheets come at a higher premium than regular OSB.
At any rate, they seem to have become pretty popular around my area; I see new houses going up all the time with Zip walls. I shake my head in derision every time I pass by a certain project however. They have used Zip wall OSB but haven't taped a single joint. They paid twice the cost of regular OSB and are not getting a single additional benefit for their money. Wow. Dunno who thought that was a good idea LOL. 
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creeky
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# Posted: 28 Jan 2016 13:11
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Quoting: Jabberwocky additional preventative measures don't usually break the bank.
Cost issues aside. The roof would be better served with a water/ice barrier in place of that second layer of OSB. Dead trees up on the roof that only increase the weight, cost and construction time. Meh.
I have not seen any pull out or dimension change in my ISO. The mfct does warn about it tho. I left my ISO exposed for 3 years just so I could watch it. Much tougher than I expected.
File under, mentioned previously: There was some really interesting research done on foam based building failures. The researchers concluded. Either do it perfectly with the latest techniques, or build it with "breathing room." As I know my buildings are small and using salvaged/repurposed materials with wood of often odd dimensions ... I've opted for the latter technique.
Quoting: Don_P I can't recall any of Lstiburek's details with the metal in the vent space, I'm curious how he is dealing with it.
I haven't seen him deal with this either. The latest article that Steve posted suggests they treat the roof the same way as the walls, but I don't seem to be able to find the research or actual finishing details (which are well documented for the walls).
I've been waiting for Lstiburek to look at the issue. So if anyone sees a post by him about the "cool roof," let me know.
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Julie2Oregon
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# Posted: 28 Jan 2016 19:00
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How different are the "smart walls" from SIPs? I was reading about SIPs early on when I was looking at cabin builders who used them in construction. Some of the purported "Amish" companies do.
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beachman
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# Posted: 28 Jan 2016 20:46
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FWIW We built a place with a standard peak roof, 8/12 pitch as I recall. We put in a dormer with a nice window for ventilation - could get out if I had to. We have a steel roof that is a "cool roof". The rain does not make that much noise with the vents built in and 7.5 insulation - pink batting. No leaks even through a hurricane. We have a fairly central wood stove with a pipe up through the peak of the roof. All works great and we love it. Build what suits you best but with the proper technique, any system should work well. We are in eastern Canada and can get heavy snow, but only use it three seasons. It would work in winter but water use would pose a problem.
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Jabberwocky
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# Posted: 29 Jan 2016 10:43
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Quoting: Julie2Oregon How different are the "smart walls" from SIPs? I was reading about SIPs early on when I was looking at cabin builders who used them in construction. Some of the purported "Amish" companies do.
I've looked into SIPs as well for my own project. They are neat! They seem to accomplish the same energy performance of a "perfect wall" with more simplicity and greater speed. One thing I found and maybe you have as well, is that for every single form of construction or method of doing something, you will find ten different contrary opinions.
The arguments against SIPs is that they are expensive, hard for electrician's and plumbers to work with, and some poorly manufactured ones have deterioration problems and they rot out at the bottom and your whole house collapses and everybody dies! 
My personal feelings are these: You WILL find horror stories of 'someone doing it wrong' with EVERY form of construction ever devised by man. So read up, weigh your options, decide what's important to you personally, and be willing to live with your decision.
Anyways, on to the comparision: SiPS are more expensive than regular construction = true. When I devised a 1000 sq ft. house plan and priced it using SIPs, the premium was somewhere around $5000. It depends on how much of an energy nerd you are as to whether the premium is worth it. When you are talking about a 30 mortgage, an extra $5k isn't much. I would do it in a heartbeat. If you are trying to live mortgage free however, a $5k upcharge can be prohibitive, and is why I eventually scrapped the plan.
Another thing to consider is that you really need to have your houseplan locked up before beginning with this method. While many of the SIP panels will simply be a standard size, when it comes to windows and such, the manufacturer may make some of the SIPs based on your specifications, So last minute changes would probably either be impossible or cumbersome. Again, the simpler/smaller the plan to begin with, the less troublesome these issues become.
I've watched videos on electricans working with SIPs, and in reality it doesn't look anymore complicated than working around conventional materials, however that's with electricians who HAVE worked with them before. I would imagine that if you are using, or have to use contractors who have no prior experience with SIPs, they are going to be hesitant, or else bid up the job to make it worth their while.
Until SIPs become a commonplace practice, (which may be never) these limitations will always be present. So if I were to seriously consider it, I would start checking around first to see whether or not I could find contractors who weren't scared of them.
I see their potential very much so in the tiny home market, especially the ones on trailers. Seems like a quick, simple way to frame up a tiny house, while the cost premium is negligible because of such small sizes to begin with.
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creeky
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# Posted: 30 Jan 2016 12:10
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Beachman. Rain noise is an issue with my build because I used polyiso only. Roxul and pink dampen sound better. Good point.
Julie. Sips are the expensive, hard way to build a wall. Build a perfect wall with exterior cladding of polyiso. Imho. Easier to fit windows and other openings is just the start. Ease of electrical and plumbing. Etc etc.
Jabberwocky. Green building calls your osb-foam-osb "home built sips." Interestink, but not very funny. Smile.
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Julie2Oregon
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# Posted: 1 Feb 2016 16:44
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I found SIPs interesting because, early in my process, I saw them on the websites of some cabin builders I looked at. And they were mentioned in the building code. But, in reality, I'll discuss some of these concepts with my builder and we'll see what he can do that I can afford. 
There are some non-negotiables with me, such as good insulation, a metal cloth rodent barrier and insulation in the floor, sturdy and well-insulated metal roof. (I, too, love the sound of rain on metal roof, lol, but with wind, snow, and ice, metal is the best bet.) I'll leave the walls to the builder, with some suggestions.
Incidentally, besides the gambrel roof providing more usable space in the loft, I've also read that the gambrel puts the load on the exterior walls, so there will be solid support for the cabin from walls straight down to my perimeter foundation and footings. That's a good thing in a seismic zone.
One other thought: With perfect walls, lots of insulation, and very tight construction, is it ever possible for a structure to be TOO airtight? I guess what I'm curious about is whether having just a bit of outside air coming in wouldn't actually be healthy?
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