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What are the Pipes & Vents Used for on Your Roof?

The pipes and vents visible from your sidewalk, while perhaps an eyesore to some, are very important to making sure different systems function properly. The following is a guide to the vents and pipes you might find on the roof of your home, and what they do.

What are all of those pipes and vents?

Photo by Paul VanDerWerf from Flickr

The purpose of almost everything sticking out of your roof is to provide ventilation inside your house. Everyone knows that a chimney gives the smoke and soot from a fireplace somewhere to go. What about those PVC pipes and metal vents?

Plumbing vent pipes

Indoor plumbing is a complex system that moves water, waste, and air. Making sure that everything moves in the right direction requires regulation of air pressure in your pipes.

As a general rule, you want liquids and solids to move down through your drainage pipes, not up through sinks or drains. Wastewater produces gas that needs to go somewhere. Plumbing air vents allow waste gases and odors to exit the house through the roof, where they won’t bother anyone.

HVAC vent stacks

Photo by PPD on Pixnio

The HVAC appliances inside your home, such as A/C evaporators, furnaces, or water heaters, generate a great deal of heat. These vent stacks channel the heated air outside through your roof.

Attic fans

Attics are a great place for hot and humid air to build up in the summer months. This isn’t ideal for your house. As heat builds up in the attic, it makes your air conditioner have to work harder. Attic fans help take pressure off HVAC systems by circulating hot and humid air and pushing it outside.

Box vents

These vents can come in several sizes, depending on their purpose. Small box vents are often connected to appliances or other fixtures that circulate air, including dryers and bathroom vents. Large box vents are often used in connection with attic fans to help circulate hot air and moisture out of attic spaces.

Commercial roof vents

Photo from pxfuel

You’re not likely to see these kinds of vents on an average home. Commercial roof vents come in many shapes and sizes, from small ducts to enormous stacks. They also serve a variety of functions – most of which are related to venting hot air out of commercial buildings.

What happens if they leak or get obstructed?

A leak in a vent pipe can cause serious problems over time if it is located inside the house. A leaky plumbing vent pipe can allow bad odors to escape into the home. Leaks in an HVAC vent can affect air conditioning performance by letting heated air circulate.

Obstructions in a vent or stack can cause even more problems. Blockage in plumbing vent pipes can destabilize your entire plumbing system. In the worst-case scenario, this could cause things to flow in directions you don’t want them to flow. If your dryer uses a box vent located in the roof, be sure to check the vent screen for lint and other materials.

Can I paint the vents on my roof?

You can paint vents and stacks however you want, although you should make sure they are installed properly and free from damage first. RoofCrafters can check the seals and flashing on your roof vents and paint them for you.

Learn more

The experienced professionals at RoofCrafters provide unmatched workmanship and service to greater Austin. Contact us today to schedule a free roof and ventilation inspection!

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