Thread: 2009 Changes in Dryer Vents

I thought you guys may be interested in this.

Section Number: M1502 Section Title: Clothes dryer exhaust Change Type: Modification Change Summary: Dryer exhaust duct installation under the 2009 IRC focuses primarily on the dryer manufacturer’s installation instructions. The code clarifies the provisions for duct materials and installation to reflect current industry practices. Except where determined by the manufacturer’s installation instructions, the maximum prescribed length for dryer exhaust duct has increased from 25 feet to 35 feet. Equivalent lengths for fittings appear in a new table and are based on the radius and type of fitting. When a concealed exhaust system with a length greater than 35 feet is installed in accordance with the dryer manufacturer’s installation instructions, the developed length must be identified with a permanent marker. New provisions require protection of the dryer duct against penetration by drywall fasteners.

Change Significance: The modification to Section M1502.3 emphasizes that the manufacturer’s installation instructions are the first source for dryer exhaust termination requirements, which are related to the design and testing of the specific model of dryer. For example, the manufacturer may permit a clearance to openings less than 3 feet or may require a termination point greater than 3 feet from openings. The prescriptive requirement for the minimum 3-foot distance between dryer exhaust terminations and openings into buildings applies only when the clearance is not specified by the manufacturer or is not known. The dryer manufacturer’s installation instructions also govern the maximum developed length of the exhaust duct including provisions for fittings, but only if the model of dryer is known and the installation instructions are submitted to the building official. Modern dryers are increasingly efficient and are generally designed to exhaust greater distances than otherwise allowed by the code, with some models permitting duct lengths up to 90 feet and many models reaching 60 feet. When dryer exhaust duct is installed in accordance with the manufacturer’s specifications, exceeds the length prescribed in Section M1502.7 and is concealed, the code now requires a permanent sign, label or tag identifying the developed length of the exhaust duct. This new requirement intends to alert homeowners installing replacement dryers to match the specifications for the make and model to the existing exhaust duct installation. Often the dryer make and model is not known at the time of construction and
installation of the exhaust duct must meet the prescriptive requirements of the code. Recognizing that distances permitted by the manufacturers typically exceed the distances permitted by the code, the maximum length of dryer exhaust duct has been increased from 25 to 35 feet. By permitting the longer lengths, greater flexibility is achieved in laundry room placement within the building. Elbow fittings increase the resistance to air flow and reduce the allowable length of exhaust duct. Previously, the code required a reduction of 2 feet 6 inches for 45 degree elbows and 5 feet for 90 degree elbows. These deductions were based on 4-inch radius fittings. An exception referenced the ASHRAE Fundamentals Handbook for large radius fittings, but this required calculations based on air friction resistance. To consolidate the information in the code for ease of use, the 2009 IRC places the reductions for fittings in a new table that includes both 4-inch radius fittings and 10-inch radius long-sweep fittings. The equivalent lengths of 10-inch radius fittings are based on values published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and Sheet Metal and Air Conditioning Contractors’ National Association (SMACNA). Testing at Underwriters Laboratories (UL) verified that the 10-inch radius elbows perform significantly better than 4-inch radius elbows. Other changes to this section clarify the duct construction and gage criteria and correlate the fastening requirements to the SMACNA Duct Construction Manual. The SMACNA standard requires a minimum of three fasteners for ducts 14 inches and smaller and does not recognize tape as a means of joining duct. Accordingly, the new text permits sheet metal screws, pop rivets or other fasteners to penetrate the duct sufficiently to provide an adequate joint connection but requires that the penetration length be limited so as not to obstruct the flow of dryer exhaust and thereby causing lint build-up. The new Section M1502.8 duplicates the language in Section G2439.5.2 for gas dryers. Most dwellings have a space for a dryer installation and the intent of this language is to require installation of a clothes dryer exhaust system at the time of construction so it may be inspected for compliance with the code. Adding Section M1502.8 applies the requirement to electric dryers. The 2009 IRC also adds provisions for protecting dryer duct from penetration by fasteners. The new requirements are similar to protection requirements for piping and gas vents. In the case of dryer duct, the concern of fastener penetration is related to the buildup of lint catching on the penetrating fasteners over time and increasing the fire hazard.





Similar Threads:

• 3-wire dryer receptacle outlet
• dryer vent
• Dryer Vent Next To Condensing Coil
• Gas Dryer in Bathroom
• Vents

WC: I have seen this and it is ridiculous. How is one to know what the dryer's (which has not yet been purchased) manufacturer allows?

It will be a SWAG! I don't know how we (AHJ) are going to be able to determine at the rough-in or final.

I guess we'll go by the most restrictive code we can and hope for the best! That's about all we can do!

It will be up to you guys (HI's) to regulate after that!

Codes are very stupid sometimes! Not very well thought out!

Codes are very stupid sometimes! Not very well thought out!

WC: Amen!

That "Bold" print hurts my eyes! But thanks for the update.

Sorry, I tried to get rid of the "bold" and make the print smaller but even when I edited it, it came out the way it is....

Sorry!

I'll try to do better next time.

I tried to change it.............it keeps coming back the this way..........

Try to find a dryer that is rated for less than 35 feet and you will see why the code changed. 35 feet and up has been allowed for a long time when it is shown on the plans with the model number of the dryer.

Originally Posted by Wayne Carlisle

It will be a SWAG! I don't know how we (AHJ) are going to be able to determine at the rough-in or final.

I guess we'll go by the most restrictive code we can and hope for the best! That's about all we can do!

That's basically what was done in South Florida (at least in Broward County) - if the builder wanted to exceed the code stated maximum dryer length, the builder HAD TO SUPPLY the clothes dryer, and provide documentation of the clothes dryer upon permitting, AND the clothes dryer had to be installed and match the model number stated during permitting.

That put the onus on the builders to either not exceed the code length or to follow all the way through by specifying the dryer and providing it. Some cities even required the builder to affix a permanent label stating the dryer duct's effective length to the wall above the dryer duct connection point - another very good idea.

Originally Posted by Wayne Carlisle

I thought you guys may be interested in this.

Section Number: M1502 Section Title: Clothes dryer exhaust Change Type: Modification Change Summary: Dryer exhaust duct installation under the 2009 IRC focuses primarily on the dryer manufacturer’s installation instructions. The code clarifies the provisions for duct materials and installation to reflect current industry practices. Except where determined by the manufacturer’s installation instructions, the maximum prescribed length for dryer exhaust duct has increased from 25 feet to 35 feet. Equivalent lengths for fittings appear in a new table and are based on the radius and type of fitting. When a concealed exhaust system with a length greater than 35 feet is installed in accordance with the dryer manufacturer’s installation instructions, the developed length must be identified with a permanent marker. New provisions require protection of the dryer duct against penetration by drywall fasteners.

Change Significance: The modification to Section M1502.3 emphasizes that the manufacturer’s installation instructions are the first source for dryer exhaust termination requirements, which are related to the design and testing of the specific model of dryer. For example, the manufacturer may permit a clearance to openings less than 3 feet or may require a termination point greater than 3 feet from openings. The prescriptive requirement for the minimum 3-foot distance between dryer exhaust terminations and openings into buildings applies only when the clearance is not specified by the manufacturer or is not known. The dryer manufacturer’s installation instructions also govern the maximum developed length of the exhaust duct including provisions for fittings, but only if the model of dryer is known and the installation instructions are submitted to the building official. Modern dryers are increasingly efficient and are generally designed to exhaust greater distances than otherwise allowed by the code, with some models permitting duct lengths up to 90 feet and many models reaching 60 feet. When dryer exhaust duct is installed in accordance with the manufacturer’s specifications, exceeds the length prescribed in Section M1502.7 and is concealed, the code now requires a permanent sign, label or tag identifying the developed length of the exhaust duct. This new requirement intends to alert homeowners installing replacement dryers to match the specifications for the make and model to the existing exhaust duct installation. Often the dryer make and model is not known at the time of construction and
installation of the exhaust duct must meet the prescriptive requirements of the code. Recognizing that distances permitted by the manufacturers typically exceed the distances permitted by the code, the maximum length of dryer exhaust duct has been increased from 25 to 35 feet. By permitting the longer lengths, greater flexibility is achieved in laundry room placement within the building. Elbow fittings increase the resistance to air flow and reduce the allowable length of exhaust duct. Previously, the code required a reduction of 2 feet 6 inches for 45 degree elbows and 5 feet for 90 degree elbows. These deductions were based on 4-inch radius fittings. An exception referenced the ASHRAE Fundamentals Handbook for large radius fittings, but this required calculations based on air friction resistance. To consolidate the information in the code for ease of use, the 2009 IRC places the reductions for fittings in a new table that includes both 4-inch radius fittings and 10-inch radius long-sweep fittings. The equivalent lengths of 10-inch radius fittings are based on values published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and Sheet Metal and Air Conditioning Contractors’ National Association (SMACNA). Testing at Underwriters Laboratories (UL) verified that the 10-inch radius elbows perform significantly better than 4-inch radius elbows. Other changes to this section clarify the duct construction and gage criteria and correlate the fastening requirements to the SMACNA Duct Construction Manual. The SMACNA standard requires a minimum of three fasteners for ducts 14 inches and smaller and does not recognize tape as a means of joining duct. Accordingly, the new text permits sheet metal screws, pop rivets or other fasteners to penetrate the duct sufficiently to provide an adequate joint connection but requires that the penetration length be limited so as not to obstruct the flow of dryer exhaust and thereby causing lint build-up. The new Section M1502.8 duplicates the language in Section G2439.5.2 for gas dryers. Most dwellings have a space for a dryer installation and the intent of this language is to require installation of a clothes dryer exhaust system at the time of construction so it may be inspected for compliance with the code. Adding Section M1502.8 applies the requirement to electric dryers. The 2009 IRC also adds provisions for protecting dryer duct from penetration by fasteners. The new requirements are similar to protection requirements for piping and gas vents. In the case of dryer duct, the concern of fastener penetration is related to the buildup of lint catching on the penetrating fasteners over time and increasing the fire hazard.

I thought you guys may be interested in this.

Section Number: M1502 Section Title: Clothes dryer exhaust Change Type: Modification Change Summary: Dryer exhaust duct installation under the 2009 IRC focuses primarily on the dryer manufacturer’s installation instructions. The code clarifies the provisions for duct materials and installation to reflect current industry practices. Except where determined by the manufacturer’s installation instructions, the maximum prescribed length for dryer exhaust duct has increased from 25 feet to 35 feet. Equivalent lengths for fittings appear in a new table and are based on the radius and type of fitting. When a concealed exhaust system with a length greater than 35 feet is installed in accordance with the dryer manufacturer’s installation instructions, the developed length must be identified with a permanent marker. New provisions require protection of the dryer duct against penetration by drywall fasteners.

Change Significance: The modification to Section M1502.3 emphasizes that the manufacturer’s installation instructions are the first source for dryer exhaust termination requirements, which are related to the design and testing of the specific model of dryer. For example, the manufacturer may permit a clearance to openings less than 3 feet or may require a termination point greater than 3 feet from openings. The prescriptive requirement for the minimum 3-foot distance between dryer exhaust terminations and openings into buildings applies only when the clearance is not specified by the manufacturer or is not known. The dryer manufacturer’s installation instructions also govern the maximum developed length of the exhaust duct including provisions for fittings, but only if the model of dryer is known and the installation instructions are submitted to the building official. Modern dryers are increasingly efficient and are generally designed to exhaust greater distances than otherwise allowed by the code, with some models permitting duct lengths up to 90 feet and many models reaching 60 feet. When dryer exhaust duct is installed in accordance with the manufacturer’s specifications, exceeds the length prescribed in Section M1502.7 and is concealed, the code now requires a permanent sign, label or tag identifying the developed length of the exhaust duct. This new requirement intends to alert homeowners installing replacement dryers to match the specifications for the make and model to the existing exhaust duct installation. Often the dryer make and model is not known at the time of construction and
installation of the exhaust duct must meet the prescriptive requirements of the code. Recognizing that distances permitted by the manufacturers typically exceed the distances permitted by the code, the maximum length of dryer exhaust duct has been increased from 25 to 35 feet. By permitting the longer lengths, greater flexibility is achieved in laundry room placement within the building. Elbow fittings increase the resistance to air flow and reduce the allowable length of exhaust duct. Previously, the code required a reduction of 2 feet 6 inches for 45 degree elbows and 5 feet for 90 degree elbows. These deductions were based on 4-inch radius fittings. An exception referenced the ASHRAE Fundamentals Handbook for large radius fittings, but this required calculations based on air friction resistance. To consolidate the information in the code for ease of use, the 2009 IRC places the reductions for fittings in a new table that includes both 4-inch radius fittings and 10-inch radius long-sweep fittings. The equivalent lengths of 10-inch radius fittings are based on values published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and Sheet Metal and Air Conditioning Contractors’ National Association (SMACNA). Testing at Underwriters Laboratories (UL) verified that the 10-inch radius elbows perform significantly better than 4-inch radius elbows. Other changes to this section clarify the duct construction and gage criteria and correlate the fastening requirements to the SMACNA Duct Construction Manual. The SMACNA standard requires a minimum of three fasteners for ducts 14 inches and smaller and does not recognize tape as a means of joining duct. Accordingly, the new text permits sheet metal screws, pop rivets or other fasteners to penetrate the duct sufficiently to provide an adequate joint connection but requires that the penetration length be limited so as not to obstruct the flow of dryer exhaust and thereby causing lint build-up. The new Section M1502.8 duplicates the language in Section G2439.5.2 for gas dryers. Most dwellings have a space for a dryer installation and the intent of this language is to require installation of a clothes dryer exhaust system at the time of construction so it may be inspected for compliance with the code. Adding Section M1502.8 applies the requirement to electric dryers. The 2009 IRC also adds provisions for protecting dryer duct from penetration by fasteners. The new requirements are similar to protection requirements for piping and gas vents. In the case of dryer duct, the concern of fastener penetration is related to the buildup of lint catching on the penetrating fasteners over time and increasing the fire hazard.

Okay....now that pisses me off! I tried yesterday three different ways to change it and you come in here and walla.....done!

Thanks Ted!

Originally Posted by Wayne Carlisle

Okay....now that pisses me off! I tried yesterday three different ways to change it and you come in here and walla.....done!

Thanks Ted!

The quick way. Highlight it, copy it, open a new email, paste it, highlight it, get rid of the bold and turn it to a 10 instead of a 14, done.

Originally Posted by Ted Menelly

The quick way. Highlight it, copy it, open a new email, paste it, highlight it, get rid of the bold and turn it to a 10 instead of a 14, done.

The really quick way is to copy it, paste it to Notepad where it loses ALL FORMATTING , then copy it and paste it to the board for posting.

One thing about this board is you may not learn a lot about inspecting but you'll learn computer tricks!