Expectations when applies for non-conventional built dwelling or for a non- dwelling permitted structure to be made into a dwelling.
This is a notification of expected requirements to owner for building a non-conventional dwelling or converting any existing building into a dwelling. When the owner requests a dwelling permit to do this project they must provide a building plan that meets Wisconsin Uniform Dwelling Code If you agree to meet UDC and provide a design plan that meets the UDC your request for a building permit will be conditionally issued.
Building Inspector for the municipality.
Tom Smith Inspections LLC 2740 Otto Court Green Bay WI 54313
Background. As a code official for several municipalities ... I am getting an increasing number of questions concerning the building of a dwelling unit inside a metal siding and roof building or other existing non-dwelling buildings. The short answer is probably yes it can be done. But that does not mean that any building will work nor does it excuse you from not building to a level of health and safety that is defined for any other dwelling unit under the Uniform Dwelling Code in Wisconsin.
You also need to be reminded that not all code officials will precisely agree on requirements or even allow for practices that are new or might not have a track record in that community. For that reason, you always need to go to your local code enforcement officials early in your planning.
The following is provided to document issues I find as a code administrator for the municipalities where I issue permits and inspect those projects. It represents my view but does not mean that something may not need to change in the future as more research is published or as codes might change in future adoptions. The topics are presented in a sequence as is generally followed in the codes for traditional construction. You can read the full code for any of my comments by going to Wisconsin Uniform Dwelling Code on line.
https://dsps.wi.gov/Documents/Programs/UDC/CodeArchives/2011DSPSDecCh320to325UniformDwellingCodeAppendix.pdf
1. Most municipalities have a minimum size for the living area of the dwelling unit. Some are defined by the County and are uniform for all towns in that county. Check with your county to see if they require a Land Use / Zoning permit or if that is done at the town, village or city level for where you plan to build. It appears the average minimum size across the state of Wisconsin is 500 square feet but I find that to be more around 700 square feet in my municipalities. You will need a Land Use / Zoning permit when required by County.
2. Existing Slab Foundations: Generally, most of these structures are not on frost protected floating slabs. But often floating slabs can be made to meet code in dwelling by using sleepers and installing foam on top of slab. If soils did not allow for a floating slab, then a four foot frost wall may have been used for the existing building. In any case the slab needs to be frost protected. The term frost protected has a definite meaning in the building code. There are several ways to accomplish this standard especially as more of these foundations are built and new products for frost protection methods are appearing.
3. Dwelling Thermo Envelope SPS 322.30 If area above a slab is heated a vapor barrier is required. Ceilings and attic spaces require at least R-38. If no attic space the ceiling R-30 can apply but only to 500 square feet of ceiling. Any slab floor that has its bottom less than 12 inches under grade shall have perimeter insulation with value of at least R-10 foam. It is to extend for 48 inches. Be sure to cover slab edge.
The following are some links to articles on those items and best practices.
https://warmform.wpengine.com/code-compliance/
https://www.finehomebuilding.com/2014/10/15/prefabricated-foam-forms-for-slab-foundations
Remember that when you do a slab you need to know very precisely where drain and water supply lines need to be installed under and stubbed up through the slab.
Remember PEX used for floor heating is different than PEX water supply tubing. It has an oxygen barrier to protect the boiler.
4. Load calculations. SPS 321.01 These are usually not a difficult thing to accomplish. If in Shawano, Marinette or Oconto County roof snow load is 40 Pounds per square foot. If in Outagamie County is 30 pounds per square foot. Most metal buildings have load calculations provided by the manufacturer or installer. Wind is 20 pounds per square foot uplift acting over the surface. This section also has floor and ceiling load specifications if going two stories. If using an existing building check that roof trusses or rafters are secured to the top plate of the supporting wall.
Uniform Dwelling Code compliance required.
1. Exits SPS 321.03 A living area over 400 square feet needs to have two exits. At least one needs to exit to grade. There are requirements for second floor and balconies. A window must have a free clearance of 20 by 24 inches when open to be an exit.
See SPS 321.01 for details.
2. Interior air circulation: SPS 321.035 and natural light requirements: Door openings shall be at least a clear space of 30 x 80 inches or a 32 inch door. Hallways are at least 30 inches wide. Kitchens need 30 inch space between island and other cabinets. This section also covers stairs and their construction including need for hand and guard rails.
3. I have seen missed on a couple occasions, that the requirement for installing electrical supply wires to a kitchen island is missed when using an existing slab floor. Code requires at least one general receptacle in a kitchen. But if you have an appliance in there, such as a dishwasher, you probably need a second dedicated circuit. Sometimes a problem when building on an existing slab. To solve the problem the owner built an island on wheels thus it is not be fixed to floor but a piece of furniture. Thus it would not require electricity.
4. Natural Light SPS 321.05 : All habitable rooms shall be provided with natural light: from windows sized based on 8% of the floor space of that room.
5. Fire separation: SPS 321.08 This can be difficult if not planned properly. When you have an attached garage you need to have a fire barrier wall design between it and the living area of the dwelling. Any wall adjacent to the dwelling living area needs to be 5/8 Type X gypsum drywall on garage side. If the ceiling of the garage area is not covered in this manner then the wall section will need to be covered floor to roof as a fire barrier wall. This can be difficult when roof truses are used as no wood can be exposed to the garage space. Attic space over garage would need to be separated from attic space over the dwelling living area. If you create a room for the heating equipment it is usually easier to make that part of the dwelling area so you do not need to be concerned about penetrations of this fire barrier wall. See full code for details
6. Fire blocking SPS 321.085 I have found that this is often missed when doing a retro fit in an existing building. You need to provide fire blocking at each floor level or between wall and attic. Penetrations need to be sealed which can be difficult when doing flexible insulated heating ducts in attic.
7. Smoke & CO2 detectors SPS 321.09 Follow same rules as any new construction. Carbon Monoxide alarm needed on any floor with any fuel burning appliance.
8. Foam plastic SPS 321.11 Foam needs to be separated from the interior of the dwelling
½ inch wallboard, or ½ inch wood paneling.
¾ inch tongue in groove wood boards.
1 inch masonry concrete
A product tested for this use.
9. Protection of insulation: Wind wash SPS 322.21 All insulation installed in any position except horizontal shall be protected on the cold in winter side with a permanently attached material to maintain R-value of the insulation. Remember pony walls between any attic space and a heated space would need to be covered.
10. Methods for insulating steel clad walls and roofs. This is a difficult concept as manufacturers have installation requirements and the code has requirements as well. When you have cold and warm surfaces at some point you can have moisture control problems. Hot roof designs as they are called, offer some data. As an inspector I am concerned with getting the R value expressed in the code. Also need vapor control and air infiltration SPS 322.10 and subchapter III .
How to meet this code is the problem. Research on making homes highly energy efficient and new products have inspired contractors to think about alternative wall designs. Codes change is much slower than the innovative ideas are tried so do some research. We now have special sheathing that if applied as manufacturer requires eliminates the need for an additional water barrier and seals wall from air getting through the design. Another is to put ridged foam over the exterior wall sheathing so there is a reduction in thermo transfer through the wood framing studs.
Using spray foam is common today but remember many of the articles written on this subject coming from Minnesota indicate their experience is that sprayed closed cell foam needs to be at least 2 inches in our northern climate to insulate enough to keep water from creating condensation inside the wall on the warm side in winter
Occasionally I see a thin coat of foam sprayed on the interior side of the wall sheathing. Works good to seal against drafts but if any moisture is in that wall cavity in winter you might have long term moisture and maybe mold issues. If you put plastic on inside of this wall under the sheet rock, any moisture in that air will reach dew point on the thin foam. Result maybe mold... So be sure to carefully consider these possible issues.
SPS 322.32 (4) Insulation Requirements Steel frame and wall shall meet requirements of table 322.31-2
REQUIREMENTS for conditions usually found in steel siding and roof construction Ceiling R−49 minimum Wall R−20 minimum
The sheathing usually adds about R-5 to a wall assembly.
Foam and other insulated boards are usually around R5 to R7 per inch.
.Check the manufacturers data sheet for precise testing data.
Here are some links to new products and methods:
Product: Prodex Total Plus: https://www.insulation4less.com/metal-building-insulation-stop-condensation-heat-cold-and-air?gad_source=1&gclid=EAIaIQobChMIzqCl0vvBggMVxfPICh2FJAiLEAAYASAAEgJ99PD_BwE
Product: BlueTex Insulation: https://bluetexinsulation.com/pages/new-construction-metal-framed-buildings-installation
Building guide article: https://www.buildingsguide.com/build/metal-building-insulation/
General Steel Buildings: https://gensteel.com/building-faqs/building-customizations/insulation-options/
Spray Polyurethane Foam: https://www.metalconstructionnews.com/articles/spray-polyurethane-foam-insulation-in-metal-buildings/