Specific Code Questions

Jeff Ruppert is a registered Professional Engineer in the State of Colorado. He has over 15 years of experience in the construction trades from laborer to general contractor to engineer, and he prefers to work on projects that will offer some aspect of reduced impact or consumption of our natural resources. From early 1996 to late 1999 Jeff worked as part founder and owner of a straw bale construction company in Boulder, Colorado, called StrawCrafters. During that time he oversaw and participated in the design and construction of 11 custom straw bale homes and provided professional assistance on well over 50 additional straw bale and natural building projects. To date, Jeff has consulted on well over 400 straw bale and natural building projects around the country. He has given many presentations to groups, such as the local AIA chapters and he sat on the Structural Panel at the 1999 International Straw Bale Conference in Marin, California. He is regarded as one of the leading structural engineers in the field of straw bale construction, and continues to participate and expand the breadth of knowledge and understanding at the national level.

Questions and Answers

Q: In New Mexico what is the code for handrails on stairs. Is there a specific number of stairs before a handrail is required?

A: Not being from New Mexico, I am not sure what the CID (Construction Industries Division) has adopted as their code (whether it is the Uniform Building Code or another one), but I can tell you that they are very similar with regards to stairs. Typically, 30" or more above grade will require a handrail. This means that if a deck or porch is above grade it will require a handrail. As for steps, if there are more than 2 risers, a handrail is required on one side of the steps only. A handrail in a residential structure is required on one side only for all stairs, interior or exterior.

Q: We recently completed our first strawbale office building. We live in a county (Johnson) in Missouri with NO zoning codes. Our contractor installed an "instant on" water heater. It is vented into the open air "attic". We have 14 inches of insulation on the ceiling and the roof is metal with a full length ridge vent with open air soffets on both sides of the building. The heater exhaust vent enters the attic area and proceeds upward to the ridge vent.Our local propane dealer/supplier installed the supply tank and then returned a few days later and disconnected it. He says that we do not meet venting "regulations" and insists that we must cut a hole in our perfectly good roof and have the pipe extend above the roof line. Our contractor has built 8 homes/buildings like this with no problems and thinks the guy is nuts. Unfortunately, he is not supplying us with the tank and propane! I have searched for any codes or regulations referring to this with no luck. Any ideas? Thanks in advance for your help.... hotwaterless in Missouri

A: The codes used to allow for venting of appliances into attic spaces, but has halted that practice due to condensation and other problems. This is probably what your gas supplier is referring to. He/she probably has to deal with codes in other areas near you and doesn't like to turn on the supply to appliances that do not comply with acceptable codes they are used to dealing with. The most important question is, is it safe? In my opinion, as a builder and engineer, everything that needs to be vented should be vented to the outdoors. The reason anyone would vent it into the attic would be to save money in materials and labor to take it the next 5 to 10 feet out the roof. Ventilation from a water heater has carbon monoxide and water vapor in it. These both have very potential risks if not treated properly. Why not just get them out in the first place?

I am not sure what your agreement is with your contractor, but if he is building your house on a bid, it costs him less money to vent into the attic. If he is doing the work on a time and materials basis, he should not really have any incentive either way. And in either case, is he familiar with any of the building codes? Even though they are not enforced in your area doesn't mean they should not be referred to on occasion. Good luck.

Q: Our neighbor has obtained a use and occupancy permit on a home that does not appear to be finished. There are wooden steps in the front leading up to a porch which is approximately 30" above grade. There are 4 risers and no handrails. The width is approximately 36". The rear of the house has 3 doors leading to a cement slab which is about 2' below floor level. The wood trim on the house is unpainted and the exterior deck and porch have no protective water proof coating on them. I have no idea what the status is of the interior. Our concern is that there is no incentive for the owner to complete the project since it has been signed off. Is this unusual for an inspector to have signed off on a project at this stage?

A: Without knowing what code is used in your jurisdiction, I can't comment in great detail about the clearances and handrails, but I can comment in general about the Certificate of Occupancy. Typically the building department is not concerned with finishes, so the concern of finishing the house, such as painting will not be on their list. Of course, each building department also enforces their regulations differently. For example, rural areas tend to be more forgiving than urban areas. If any of these issues is a violation of the local code, and was known at the time of approval, the building department is at fault and should have not issued the C.O. I have seen the installation of temporary sinks and plywood counter tops approved. This is not a violation of code. The building official is not in the business of checking plans to make sure finishes are correct, only that the safety issues are addressed with any installation or assembly.

Q: I'm considering building a steel arch home using a purchased steel arch (American Duro Span) probably 30'X 60' on a concrete slab in rural Colleton County, SC. Do you know if basic building codes restrict such a use?

A: American Duro Span should have on-staff engineers to design the structure, meaning this would ensure the compliance of the structure with local codes. Other stuff, such as egress requirements and other life safety issues will be enforced by the local building department. The basic building codes should not restrict your use of such a structure.

Q: I was wondering if you had any advice/instruction for getting a rubble trench passed by the building department here in Boulder County (Colorado). I know this county is renowned for being sticklers with alternative approaches, but since we're in this concrete shortage and the suppliers charge an arm and a leg and $6,000 to get concrete up to us in the mountains, I would like to get approval on this more earth/time/pocketbook friendly approach. I'm guessing that the building department will want an engineer to approve the plans. Do you have any recommendations (i.e. yourself or someone in Boulder)? I'm also guessing that the inspectors probably won't approve the plans by themselves.

My more technical question is about the width of the trench. I have already dug the trench 4' wide by 3' deep. Even though it's not as friendly now to fill it with trucked in rock, I'm thinking it's the only way to finish this foundation before the frost sets in this winter. So my question is whether a 4' trench is "too wide" compared to the 16" ones recommended in the books? I've heard wider is better but maybe I'm pushing the structural limits. Any advice on this technical issue would be appreciated too.

A: The wider trench is ok. We can help you gain approval for a rubble trench. Boulder County is actually not that bad in terms of approving things. At least not with us. In fact, when they see my stamp on things I think they feel good, especially if it is a bale home. Call us at the office number in Boulder and I should be able to help.

Q: Would I use a normal soffit or a vented soffit for an overhanging second floor ?

A: You would use an un-vented soffit in this case. There is no cold roof over the cavity, so there is little need to vent. Moisture will travel up, so making sure there is a good moisture barrier at the ceiling will reduce infiltration into that cavity from the first floor. You will need to block at the beginning of the overhang, so this will help isolate that cavity somewhat. Sealing with caulk or adhesive around the blocking will also help keep that space dryer.

Q: Is there a regulation/code for the height a closet must be in order to be considered a closet? I have additional space in my bedrooms I would like to turn into closets (not storage space), but I only want to do so if when I sell the house they will still be considered closets.

A: I do not believe there is a definition for the height of a closet. The safest bet is to use common sense and determine what a realtor selling the house would think. If what you are planning seems unusable to a realtor, chances are they will seem unusable to others.

Q: I am planning to build a post and beam solar cabin at 9000' elevation in Colorado. I plan to trench for a monolithic pour but want to place sona tube at the points of my posts. First I plan on placing a bed of gravel and then drain line. After placing the sona tube, I will pour my concrete and then plan on backfilling the trench with rubble stone. On top of the rubble stone I will place a concrete bond beam. All of this is due to the expense of hauling concrete up to the top of the mountain. I have large quantities of stone available.
Do you have any concerns over permitting or of my theory of constructing this foundation?

A: I constructed a bale cabin back in 1998 at 9000' elevation above Masonville and had a similar obstacle. We chose to pour piers on top of pads and raise the whole floor off the ground. We insulated the floor system and sealed it with plywood. This technique saved a bunch of concrete, only requiring one concrete truck.

I usually do not like to design foundations on the internet because each one is unique to the site. However, you may need to put the piers on pads to spread the load, based on your soil bearing capacity. I would also suggest tying the grade beams to the piers with rebar sticking out the sides of the piers, otherwise you will get differential movement, or settling of the grade beams, resulting in cracking.

As for permitting, the building department will require you to have an engineer stamp your foundation plan, unless of course, there is no building department in your location.

Q: What is the code/rule of thumb for building stairs; I thought it was 7" figured into the total length. Example: I have 89 inches that drops into the basement, 89 divided 7 = 12 riser's, and how wide (the depth) should the step be?

A: The tread depth will be determined by the local code. 10" to 11" is usually standard.

Q: I live in Michigan and want to run a water pipe from my house to my barn to have running water for our horses. To prevent freezing, how deep do I have to dig the trench leading from the house to the barn? Is there any a code restricting what type of pipe to use in the trench?

A: (Kelly) The depth of burial of water pipes depends on what the deepest frost level of your soil might be, which varies from region to region. In the mountains of Colorado it was at least 5 feet, but in many places in Mexico the water lines are not even buried. It gets pretty cold in Michigan, so I would imagine that your pipes would need to be buried perhaps a yard, but you might check this with other locals. The type of water pipe used for domestic water also varies from one place to another. People use galvanized metal, copper, PVC, black plastic hose, PEX, and probably others for this purpose, and this is often controlled by the local authorities. However, for an agricultural outbuilding, there are rarely such requirements. I would probably use either the black plastic or the PVC because it is easy and cheap.

Q: I'm doing a repair for a contractor that has been lathing with foam around an exterior fire place box in Pheonix, AZ. I've requested that they start lathing with a fireproof/ black board, for the future chance of a possible fire; does it matter or not?

A: Most foam installations need to be protected for fume generation. The stucco probably fulfills this role, so I would think that their way is ok. Is the firebox connected to an existing structure? If so, code will apply, which will require separation, but not necessarily more cover for the foam.

Q: Are 2'8X4'4 windows acceptable to use in a new home? The windows are upstairs. Do we have to use 2'8X5'0, which will pass egress code?

A: Egress applies to bedrooms. You cannot install a window smaller than egress requirements in a bedroom because a bedroom must have two forms of egress in case a fire starts at night while the occupants are in bed. You can use those windows in other locations, either upstairs or downstairs.

Q: I'm trying to put a concrete slab on commercial land where there is a septic clean out, tank and leech field underground. Is there any code that doesn't allow me to do that? If there isn't where can I find the documents that state where is possible. I live in Arizona, Maricopa county.

A: The building codes do not address such specific circumstances. The building official should have some concerns if this issue is brought to his/her attention. In short, it is not good practice to build over anything but solid compacted fill or undisturbed natural soil that meets the bearing requirements of your particular situation. That said, it is possible to design a structural slab that is capable of spanning soft areas. This should be done with the help of an engineer.

Q: I'm curious if there is some building code or other reason as to why plumbing is always placed under the house? Is there a safety issue or maybe a physics one for this? Can't it be run along, but not inside, a wall?

A: There is no restrictions to running plumbing along a wall. It is placed under the house and inside walls to conceal it because it can limit the use of the space, and some people find it ugly to look at. There is also a minor noise issue while water is running.

Q: We are building a small cabin in Cuchara, CO. The problem is stairs to a loft that will rarely be used. We understand that there is a 36" width requirement. We want a steeper, ladder type effect. What is the incline (slope, etc) required?

A: This can be tricky with the building department. I have seen this issue interpreted in many ways. If the loft will be used as storage, installing a half wall or railing across the opening and stating it will only be used for storage will allow you to access it with any regular ladder. Some people install their permanent ladder after they receive a Certificate of Occupancy, but there are obvious issue associated with that approach. If the space is to be used as regular living space, the building department will likely want to see a stair that conforms with code. It might be worth an anonymous phone call to the building department for some clarification.

Q: Is it absolutely necessary, according to the new IBC, to use a monolithic slab when building with compressed earth blocks or can I use a poured footing / stem wall?

A: The building code does not limit the type of foundation under adobe walls. Adobe falls under the masonry category, Section 21, and technically you can build a masonry foundation (CMU block) to support the adobe (masonry wall). There are other considerations depending on your location though. If you live in the west were earthquakes are an issue, lateral design will dictate much of your design.

Q: I am an Iranian architect. I want know if there is there any code about construction of adobe buildings in seismic areas (like Iran)?

A: I am not aware of any seismic considerations in any codes that address adobe construction.  Doing a quick search on the internet shows that in Costa Rica, adobe is actually banned due to the seismic nature of the area.  I understand the importance of your inquiry, given the large number of earth buildings in a seismic area like Iran.  I wish I could offer you some guidance other than maybe considering different materials, such as straw, which is very good is seismic zones.  Earth construction is impossible to reinforce against the tremendous forces generated in an earthquake.  The fact that earth (adobe) buildings are so heavy make them even more susceptible to damage when the earth shakes.  Keeping buildings low (one story), light (not heavy) and stiff are your first lines of defense.

Q: Where a load bearing wall sits on the outside edge of a slab or concrete wall, what code would control any tolerance for the sill plate to overhang the edge. The diagrams pictured in both the IRC & IBC show none yet make no reference as a yes or no. Even the residential & light commercial construction standards picture it very well yet does not address the issue.

A: Though your question is a good one because an overhanging sill plate is used in many details, it is not specifically addressed.  Your question implies that there must be a minimum capacity of that detail and I would lead you to Table 2308.9.1 of the 2003 IBC.  This table provides the minimum stud size and spacing of exterior, load-bearing walls.  You will notice that 2x4 studs spaced at 16 inches are only able to support one floor, roof and ceiling.  Whereas 2x6 studs spaced at 16" will support an additional floor.  What this tells me is that a 2x4 wall can be used up to two stories.  If I am framing my walls on a two story house with 2x6 walls, I can overhang my sill plate 2" and still retain the same bearing as if it were a 2x4 stud wall. 

The detail you describe is used by some of us, but not many all over the country.  It is not worthy to address it specifically.  You must look at the limits of the system in question and pair it with your insulating needs and see what you are left with.  For those of us in cold country, all of our exterior walls will be framed with 2x6's at a minimum for insulation purposes.  The overhanging sill detail is usually also installed in cold climates to bring the finish proud of any exterior foundation insulation.  Structurally speaking, a 2x4 wall will suffice so we are able to use the extra 2" of a 2x6 sill plate to overhang up to 2" of rigid insulation.  This is limited to two-story buildings!  If the building is taller you will need an engineer to sign off on the design.

Q: Is there anything in the IBC that indicates where water for indoor use must come from? Can we use a ferrocement rainwater cistern and a graywater system for plumbing a small house/cabin?

A: The codes do not address the water source for a structure.  That requirement is usually set by ordinance at the local level or by law at the state level.  In Colorado we have a department of water resources which requires each house to either drill a well or hook up to a municipal system.  No other options are available.  The building departments are required to verify one or the other before issuing a permit.  Some people have used cisterns in Colorado but the building departments only allow them in unique circumstances.  So, this is an example of how the state sets the law and it is enforced at the local level.  It will be different for each state.  Most states allow rainwater catchment.  Colorado is one of three that do not.  If you do not live in Colorado, chances are you can use a cistern.  But to answer your question, the code itself does not address the water source.

Q: I've been teaching English in Vietnam for some time but eventually will come back to the US to retire and I'll need a place to live. It's likely I'd be doing a lot of the labor myself, so lifting timbers to frame a strawbale or cordwood house would be difficult. Is it possible to build rammed earth corners and posts and infill with straw or some other material? I'm sure it's possible - I guess what I'm asking is whether it would be likely to be structurally up to code.

A: (Kelly) I doubt that code officials would accept rammed earth corners or posts as sufficiently structural to rely on for post and beam building design. Maybe reinforced concrete would work in this way. My suggestion would be to arrange for a bit of help erecting your post and beam structure, and then do the infill by yourself.

Q: I have been told that the current International Building Code will allow any construction that is less than 120 sq. ft. Is this true?

A: To get it permitted as a residence under the IBC or IRC you need to have basic services such as water, power, waste disposal, etc.  Without these things there is no building dept that will issue a permit for this as a residence.  This specific provision is to allow non-occupied structures to be built that are very small.  Obviously the the intent of the provision is to make it easy for folks to build a shed or unoccupied structure.  Also, it would make little sense to hook up to utilities or put in a septic for something so small.  The minimum costs of those services would lead you to a different conclusion. 

Once you add services, it will require a permit.  That is my opinion, not what I am reading in the code.  Again, there is no building dept that will let you slide without a permit if services are intended to be hooked up.

Some places require you to file for a permit for something like this, they just won't do any inspections.  Boulder, CO would strike me as one such place, or most places in the Bay Area, etc.  It would fall under planning ordinances even though a building permit would not be required.  They would still want to know about it even though they would not inspect it.

As far as the word "accessory" goes, it applies to any zoned property that allows such, no matter if another primary structure is in existence or not.  The word "accessory" is not exclusive of any use, such as living or non-living uses.  It is simply an accessory use to what is intended to be the primary use.  For example, if a property is zoned residential, sure you can build a shed as an accessory structure without a house there first.  However, many zoning/planning dept will not let you build a granny unit as the only structure, acting like it is the primary structure and use.  They would require a development plan showing your total build-out ideas.  The question here is about uses, not about whether you can put up ten 120 sf sheds and call them all residential.  If you are working in a place where there is a weak planning dept you will have an easier time getting away with stuff folks in cities are unable to do.  You can't offer anything like this as a solution that would work anywhere due to a supposed hole in the code.  It is not a building code issue as much as it is a zoning and planning ordinance issue. 

A: (David Eisenberg): the 120 sf exemption is for accessory structures, in other words, non-habitable buildings - ones not intended to serve as dwellings. And, if there are utilities in these structures, such as electrical or plumbing, they need permits for those things. That's the quick and dirty answer. When you are going to use a building as a residence or dwelling unit, much more scrutiny and regulatory control is applied.

Q: I hope to eventually build my own outpatient clinic in Arizona. Do you think I would be allowed to build my clinic out of cob with an earthen floor?

A: There are very clear health regulations that apply to clinics. The finishes are everything. You need to either hire an architect who specializes in these things, or become very familiar with health safety codes. It doesn't matter what the structure is, as long as it is structurally sound and proven. The finishes your patients will be in-contact with will determine what you can do.

Q: Is pex plumbing under building code in Michigan?

A: If PEX plumbing pipe meets ICBO/ICC standards it should be acceptable. Most brands of PEX pipe meet the requirements of the International Plumbing Code and should be acceptable. All brands that meet code have undergone an evaluation based on code standards. The manufacturer should be able to provide documentation of compliance which would make them acceptable to any code official.

Q: I am trying to build a cob home in NC, the county recognizes the standard building code and has no problem letting me build my dream if I can prove one thing: cob is suitable in a 110mph wind zone. Even though you can put a friggin trailer anywhere you want, "big sigh", this must be proven, or at least convincing. I am in touch with a structural engineer here who is willing to put his seal on my plans; this is all I need and I can't find any info regarding this particular subject. Any help you may be able to give me would be absolutely wonderful. Even the word of a fellow engineer would be something, compared to what I have now, which is nothing

A: Since hurricanes Andrew and Katrina requirements have changed quite a bit. Proving that any given wall system will withstand 100 mph winds is not a simple tasks, although not impossible. Somehow you must show a continuous load path from the roof to the foundation. Cob is a heavy wall system, like adobe or straw bale. It has some inherent characteristics that make it better in wind than wood and light-gage steel framing. However, you still must show how it will work with the numbers. The best thing you can do is find folks, such as Ianto Evans or Leslie Jackson who can helps with detailing such a wall system to resist high winds. Once the details are in-place, the numbers will work.

However, there is one item to consider. 110 mph winds don't just happen in a vacuum. The scouring effect of winds at that speed is much greater than wind at 80 mph. The debris caught in the wind is actually what is dangerous, not just the wind itself. They found with Hurricanes Andrew and Katrina that the scouring effect literally wiped the earth clean of any vegetation and structures. Nothing survived, but those winds were higher than 110 mph. You need help from professionals who can help you put together a concept and then have your engineer work his/her magic.

Q: We have an old barn where the walls have partly fallen down. The old walls are built out of wood. We want to enclose the barn with straw bales, and are wondering if Taos county requires a building permit.

A: (Kelly) New Mexico is unique in that there are state building codes that are administered by local authorities, so yes, there are likely codes to deal with. You would find out through a county office.

Q: I have a question about dry stacked stone foundation on top of a rubble foundation. In my county building codes go by 2006 IRC and IBC codes. But in the codes there is no standard or mention of these types of foundations. How would I go about getting this permitted in my county or would I have to go with concrete?

A: The model building codes (such as the IBC, IRC, etc.) are generally prescriptive in nature, meaning that if you build something to the letter of the code you will not need an engineer to assist you, and the building official is capable of determining compliance, also without any assistance. Once you step outside those prescriptive methods and materials (wood, concrete, steel) you must prove that your chosen method will meet minimum performance standards. This must be shown in a way that satisfies the building official. The best thing to do is talk to the building official and see what they will require. Not knowing your location I cannot comment on specific strength and durability requirements. If you are in an area that has earthquakes, this method is not recommended.

Typically, foundations are made of reinforced concrete because of durability and strength. Dry-stacked masonry does not possess any tensile strength. We know that masonry foundations work when built by skilled masons because we see them still in fine shape after hundreds of years. The key word here is "skilled." Again, talking to your building official will help answer your questions and is a good first step.

Q: We live in Longmont, CO, and have a finished basement. Due to a second pipe rupture, the carpet has to be changed. I believe we have a concrete floor. The basement is always cold. I would like to insulate the slab. Due to cost, we are shying away from a radiant floor plan. Any ideas? The house was built in 1998. Any idea was the concrete slab insulation code was at that time.

A: Chances are the basement was not insulated. I do not have a copy of the code that far back, but generally things were a lot more lax back then. Even if it is insulated it may not have been done right or the wrong materials were used. Anyway, one option is to frame a floor on top of the slab using 2x4, or even 2x2, “sleepers" and place rigid insulation between the sleepers. You could then put wood flooring down. This option will reduce the last stair step by the depth of the floor system.

There are a couple caveats to doing anything along these lines. First, a vapor barrier must be installed on top of the slab and sealed very well. The slab is probably not well sealed from beneath. You do not want dampness rising up into your new floor system. The barrier material needs to be durable - not simple 6-mil plastic. Second, install ventilation in the basement. Basement floors can become cold and even drop below the dew point of humid air. We live in a dry climate, but removing moisture on a regular basis is important for the longevity of the floor system. You might consider a heat recovery ventilator for this task. I would recommend talking to a reputable contractor who has experience doing these types of things. They will recommend the best way to do it based on your specific circumstances.

Q: I was wondering what the minimum sq.ft for building a small home in Ontario Canada would be?. The smallest you could build.

A: (Kelly) I am not aware of the building regulations in Canada. In the US these regulations differ depending on where you are, with city, county, and state jurisdictions. Often you can avoid these regulations if you build small enough, say below 100 square feet or 10 square meters, but this is also established by the local authorities. Another parameter is if it is on wheels like a trailer or an RV which places the structure in a different category. I suggest that you find out who controls this where you live and ask them.

Q: I am hoping to buy property outside the city limits of Bolder, CO I was wondering if current code in that area would allow for the building of a earthbag home or would I need to jump through hoops to allow for that?

A: I am not aware of any special building code adoptions related to natural building in Boulder County, CO.  The City of Boulder has been progressive in the past by adopting a very early version of a straw bale code many years ago, but the County has not adopted anything special. Boulder County does have an energy audit requirement called BuildSmart.  You will need to comply with that, which will probably require you to apply insulation to your earthbag structure.  Maybe you are already planning to do so, but this requirement will determine how much. Other than that, you will need an engineer to design the structure and stamp the plans because earthbags are not part of the prescriptive requirements in the building code.

Comment: I just found that New Mexico state has building code for tiny homes. I’m told that these rules apply to counties that do not have their own building or zoning codes.

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