IS YOUR DRYER VENT UP TO CODE?

International Residential Code (IRC)

IRC Chapter 15 Exhaust Systems

M1501.1 OUTDOOR DISCHARGE 

All systems which exhaust air from home must discharge to the outdoors (not attic, soffit, ridge vent or crawl space)

M1502.3 DUCT TERMINATION 

1. Terminates outside of the building 

2. Exhaust terminates at least 3’ from openings (in any direction) into building 

3. Equipped with a backdraft damper 4. Screens shall not be installed at termination 

M1502.4.2 Duct Installation 

1. Supported at 12’ intervals and secured 

2. Duct fittings lapped in direction of air flow (shingle effect) 

3. Joints sealed in accordance with M1601.4.1 (See below) 

4. Joints mechanically fastened w/screws or similar (i.e. rivets) *** (Screws protrude less than 1/8” into duct!) 

[2018 – NEW] – Ducts shall not be deformed by wall or ceiling cavities (Example: 4” round duct cannot be installed in a 2”x4” wall cavity) 

M1502.4.5 Duct Length 

[2012 – NEW] Maximum length of dryer exhaust is 35’

Table M1502.4.5.1 Dryer Exhaust Duct Fitting Equivalent Length 

(The 35’ allowable length is reduced for each bend or elbow installed) 

Example: 4” duct- Reduction for 90° elbow=5’; Reduction for 45° elbow=2’6” 

M1502.4.5.3 Dryer Exhaust Duct Power Ventilators [2015 - NEW] – DEDPVs, (i.e. “booster fans”), are now allowed by code to increase the equivalent length of dryer duct, beyond 35’. (Adhere to manufacturer’s instructions).

M1504.3 EXHAUST OPENINGS (Labeled M1506.2 in the 2015IRC) 

[2012 – NEW] – 1. Minimum of 3’ from property lines 

2. Minimum of 3’ from operable and non-operable openings [2018 – NEW] (deleted the words: “non-operable”) 

3. Minimum of 10’ from mech. air intakes (unless 3’ above air intake)