Opinion: Energy Code

Subject: 

Relocated Homes, Prefabricated Homes, and Manufactured Homes

Code:

Part 7670.0100, Subpart 5, Part 7672.1200, and Part 7674.1100

Submitted By:

Rice County Planning & Inspections

Approved By:

Thomas R. Joachim, State Building Official

Issue Date: 

June 14, 2000

Question:  

What parts of the energy code apply to 1) relocated homes, 2) prefabricated homes, and 3) manufactured homes?

Answer:

1) Relocated homes -- Minn. Stat. § 16B.61 provides:

Relocated residential buildings. A residential building relocated within or into a political subdivision of the state need not comply with the State Energy Code or section 326.371 provided that, where available, an energy audit is conducted on the relocated building.

The Minnesota energy code would apply to the basement or other on-site construction.

2) Prefabricated homes -- Detached 1- and 2- family homes must comply with either Chapter 7670 (Category 1) as amended by Laws of Minn. Chapter 407, or Chapter 7672. Three or more attached single family and other prefabricated residential construction must comply with either Chapter 7670 (Category 2) or Chapter 7674.

3) Manufactured homes - HUD standards apply to the manufactured home. The Minnesota energy code would apply to a heated crawl space or basement.

Subject #1

Infiltration Contribution to Required Ventilation

Code::

Part 7670.0325, Subpart 28, and Part 7672.0500, Subpart 15

Submitted by:

E P Sales, Inc.

Issue Date:

June 15, 2000

Question:

Part 7670.0450 indicates that "Infiltration does not satisfy the requirement for ventilation in residential construction."

a) Can infiltration be relied on to provide the required ventilation? b) Would an exhaust only mechanical ventilation system be used to provide the required ventilation?

Answer:

The definition of infiltration in both Chapters 7670 and 7672 includes air leakage driven by natural forces, but not by mechanical means. Fan induced air leakage would not be considered infiltration by the definition of the term.

When Chapter 7670 is used for detached single family and two family construction, Category 1 requirements and the ventilation and depressurization requirements of Laws of Minn. Chapter 407 apply. When Chapter 7670 is used for multifamily construction, then only Category 2 requirements apply.

a) Ventilation in Category 1 homes must be provided by a mechanical ventilation system. Under Chapter 7670, ventilation for a multifamily building is provided by either mechanical ventilation or operable windows. Infiltration does not satisfy the requirement for ventilation in multifamily construction.

b) An exhaust only mechanical ventilation system could be used to provide the required ventilation. While Chapter 7670 provides no guidance for the design and installation of such a system, Part 7672.1000 could be consulted.

#2 Subject

Ventilation Requirements for Category 1 Houses

Code:

Part 7670.0325, Subpart 30, Part 7672.1000, Subpart 3, and Chapter 7672

Submitted by:

City of Inver Grove Heights Inspections

Issue date:

October 3, 2000

Question:

1) Can a ventilation system designed under the requirements of Chapter 7672 be used in a Category 1 house?
2) How should the calculation of minimum ventilation quantity for Category 1 or Chapter 7672 account for an unfinished basement area?
3) For the purpose of ventilation system designed would an unfinished space that may be used regularly by the occupant be considered "habitable space"? Would a basement area that might later be converted into a bedroom be considered a bedroom?

Answer:

Answer: 1) A ventilation system designed under the requirements of Chapter 7672 may be used in a Category 1 house as long as the Chapter 7672 requirements are at least as stringent as would be required under Category 1. While all of the equipment and installation requirements of Chapter 7672 are more stringent than in Category 1, the requirements for ventilation quantity should be checked.

2) Under Category 1 the ventilation quantity is the greater of that determined by the volume of habitable rooms or the number of bedrooms. If a basement contains either habitable rooms or bedrooms, then these must be included in the determination of ventilation quantity.

Under Chapter 7672 the total ventilation quantity is determined by the conditioned area of the house, which normally would include an unfinished basement. The people ventilation is determined by the number of bedrooms; an unfinished basement would not be considered as having a bedroom.

3) Under Chapter 7670, an unfinished basement space would not be considered habitable space for the purpose of ventilation system design. A basement area that might later be converted into a bedroom would also not be considered a bedroom for ventilation sizing requirements.

#3 Subject:

Vapor Retarder Requirement for Rim Joists

Code:

Part 7670.0450, Subdivision 6

Submitted by:

City of Prior Lake Inspections

Issue date:

October 3, 2000

Question:

For Category 1 construction, part 7670.0450 indicates that "a vapor retarder need not be installed on rim joist insulation not susceptible to condensation from moisture diffusion." Would an interior insulated rim joist without a vapor retarder be susceptible to condensation from moisture diffusion in either of these cases

a) in an unfinished and heated basement? b) in a finished and heated basement?

Answer:

An interior insulated rim joist without a vapor retarder could be susceptible to condensation from moisture diffusion in either case. The two conditions when such a rim joist would not be susceptible to condensation from moisture diffusion during the winter would be if the basement was extremely dry, or the temperature of the basement was close to the outdoor temperature. Conditions for condensation exist when a condensing surface is at a temperature below the dew point of the air present at that surface. The dew point for an assembly can be found on a psychometric chart given the conditions of temperature, air moisture content, and R-values in relation to the condensing surface. An example:

an R-19 batt with no air barrier / vapor retarder on the interior of a TGI or floor truss rim with 15/32 medium density fiberboard and wood siding, interior conditions of 68°F and 30 percent relative humidity, condensation will form on the interior side of the fiberboard whenever the outdoor temperature is below approximately 36°F. If sufficient insulation is installed on the outside of the rim joist, the rim would normally be warm enough to not be subjected to condensation.

#4 Subject:

Moisture Barrier for Interior Insulated Foundation Wall

Code:

Part 7670.0470, Subpart 9, item E

Submitted by:

BCB Construction, Inc

Issued date:

March 13, 2000

Question:

When foundation wall insulation is installed on the interior, the code requires a moisture barrier from floor to grade. Does the code prohibit extending this moisture barrier above the grade to the top of the wall?

Answer:

No.

Subject:

Ventilation Requirements for Category 1 Construction

Code:

Laws of Minn. 2000, Chapter 401 and Category 1 Construction

Submitted by:

City of Brooklyn Park Inspections 

Issued date:

May 12, 2000

Question:

What is meant by the terms "direct or indirect means" in the sentence:

"All new detached single one- and two-family R-3 occupancy buildings must have a mechanical ventilation system which replaces, by direct or indirect means, air from habitable rooms with outdoor air.

What are some examples of these systems?

Answer:

This question concerns the statute. The departments do not provide legal advice on statutory intent. This answer should not be construed as an interpretation, but rather the departments' analysis of one possible meaning of the language

Direct ventilation means ventilation air brought directly from outdoors into a habitable room, such as through individual room air inlets. Where outdoor air supplies are separated from exhaust points by doors, provisions should be made to ensure air flow by installation of distribution ducts, undercutting doors, installation of grilles, transoms, or similar means permitted by the building code

Indirect ventilation means outdoor air brought into one area of the home and distributed to habitable rooms by separate distribution ducts or the furnace ductwork.

#5 Subject:

Definition of Sealed Combustion Appliance

Code:

Laws of Minn. 2000, Chapter 407

Submitted by:

City of St. Paul Inspections

Issue date:

May 12, 2000

Question:

Does a sealed combustion furnace (installed to facilitate a single exhausting device of over 300 cfm) need to be capable of operating at 50 Pascal negative pressure?

Answer:

This question concerns the statute. The departments do not provide legal advice on statutory intent. This answer should not be construed as an interpretation, but rather the departments' analysis of one possible meaning of the language

Yes. The sealed combustion appliance cited in Chapter 7670 and Laws of Minn. 2000, Chapter 407 should meet the definition of a sealed combustion appliance in Chapter 7672, which requires it to be capable of operating at 50 Pascal negative pressure.

#6 Subject:

Make-up Air for Category 1 Construction

Code:

Laws of Minn. 2000, Chapter 407

Submitted by:

Rice County Planning & Inspections Issue

Issued by:

June 14, 2000

Question #1:

If a 100 cfm exhaust fan is to be installed as an exhaust only ventilation system in a Category 1 house

a) Can the fan be located in a bathroom b) Would make-up air be needed for this ventilation system c) If ventilation system make-up air is provided, is it required to be conditioned d) What would be needed to make this a balanced ventilation system?

Answer #1

This question concerns the statute. The departments do not provide legal advice on statutory intent. This answer should not be construed as an interpretation, but rather the departments' analysis of one possible meaning of the language

a) Yes, provided that the system meets the requirement of Chapter 407 that the ventilation system replace air from habitable rooms with outdoor air b) No c) No d) A powered intake of outdoor air equal to the ventilation exhaust flow. Subject: Make-up Air for Category 1 Construction Code: Laws of Minn. 2000, Chapter 407 Submitted By: City of Brooklyn Park Inspections Issue Date: May 18, 2000

Question #2:

What is meant by "alternate make-up air source" in the sentence:

If any single exhaust device over 300 cubic feet per minute is installed, sealed combustion space heating equipment or an alternative make-up air source must be used

What would be some examples of alternate make-up air sources? Would an adequately sized combustion air intake located in the area of the furnace satisfy this requirement?

Answer #2:

This question concerns the statute. The departments do not provide legal advice on statutory intent. This answer should not be construed as an interpretation, but rather the departments' analysis of one possible meaning of the language

An alternate make-up air source would mean a source of make-up air to provide not less than the flow rate of the single exhaust device. Examples would be a powered make-up air unit or a passive opening using the sizing chart in part 7672.0900, subpart 8, item C as a guide. A passive opening consisting of an oversized combustion air intake might be able to provide this make-up air.

#7 Subject

Make-up Air for Category 1

Code:

Laws of Minn. 2000, Chapter 407

Submitted by:

City of St. Paul Inspections

Issue date:

June 14, 2000
 

Question:

Can a ducted outside air opening into the return side of a system be used as a supply source for an exhaust only ventilation system in Category 1 construction? If so, does the blower need to operate continuously or can it run intermittently?
 

Answer:

This question concerns the statute. The departments do not provide legal advice on statutory intent. This answer should not be construed as an interpretation, but rather the departments' analysis of one possible meaning of the language.

An outside air duct to the return side of a system is permitted under either Category 1 or Chapter 7672. In Category 1 construction, if the ventilation system relies on the blower to distribute fresh air, then the blower would need to operate continuously to meet the requirement of Chapter 407 that the ventilation system replace air from habitable rooms with outdoor air. For Chapter 7672 construction, the blower may not need to run continuously when installed per the requirements of Part 7672.1000, subpart 5, item H.

#8 Subject:

Make-up Air for Category 1 Construction

Code:

Laws of Minn. 2000, Chapter 407

Submitted by:

City of St. Paul

Issue Date:

June 14, 2000

Question:

Can a Category 1 mechanical ventilation system rely on a single passive opening (ducted or unducted) into a mechanical room as an outdoor air source for an exhaust only system? If so, can the passive opening chart in Part 7672.0900 be used to determine the opening size?

Answer:

This question concerns the statute. The departments do not provide legal advice on statutory intent. This answer should not be construed as an interpretation, but rather the departments' analysis of one possible meaning of the language.

A ventilation air passive opening would not be required, but is permitted to be part of the ventilation system. Its location in the mechanical room is permitted, as long as the ventilation system replaces, by direct or indirect means, air from habitable rooms with outdoor air. Yes, the passive opening chart in Part 7672.0900 could be used as a guide.

Answer:

The Minnesota State Building Code which includes the amended 1997 Uniform Building Code specifies the following required inspections:

• Reinforcing steel and structural framework must be approved by the Building Official before covering.
• Foundation inspection.
• Concrete slab or under-floor inspection.
• Frame inspection.
• Insulation inspection.
• Lath and/or gypsum board inspection when part of a structure or fire-rated assembly.
• Manufactured home setup inspection .  (MSBC 1350.2100)
• Reroofing inspection at completion of work.  (UBC Appendix 1515.2.2)
• Final inspection.
• Special inspections as required by UBC Chapter 17 (special inspections specified by the engineer of record to be approved by the Building Official may include but are not limited to soils, concrete, welding, high-strength bolting, spray-applied fire-proofing and pilings.)
• Other inspections as required by the Building Official to verify compliance with the building code and other laws which are enforced by the code enforcement agency.

The Building Official is responsible to determine which inspections are necessary for all construction activity regulated by the code.  Other codes may have additional inspection requirements.