Home inspection findings by Frank Schulte-Ladbeck, Professional Real Estate Inspector TREC# 9073

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How to Repair Your Plumbing Vents

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Part of your plumbing system penetrates the roof. These are the vents, and they could be a source of leaks in the home.



plumbing vent
Did you realize that part of inspecting the roof is examining part of the plumbing system? There are homes where I find problems with the plumbing, and the problem is on the roof. Homes change; circumstances change; and you may find yourself with low water pressure. There can be various reasons for this situation, but it may be on the roof. Do you have a mysterious leak? The roof looks good. It may be new. Yet you have water stains on your ceiling or on your walls. This may be coming from the vent. You could be resolving some issues around your home by examining your vents.
    First, let us understand this part of the plumbing system. I use the comparison of children playing with straws. They suck liquid into the straw, then hold their finger over the top end. They are so amazed that they can hold the liquid in place, until they remove their finger. To allow the water to flow freely through your pipes, we need air in the system to prevent vacuums, which will hod the water in place. The vents going through your roof help with this flow. These vents can be different diameters, and they will be located near the major plumbing fixtures of your home. Look at the roof above your kitchen, utility room, and bathrooms, and you will see pipes sticking up above the surface.
    Why would these vents need to be repaired? Homes experience movement, making the pipes go up and down relative to the roof surface. New roofs could damage the vent. Falling branches or other objects during a storm can damage the vent. Birds make their nests on them. Small animals may decide to explore what is in the vent. The pipe coming out through the roof is attached to the plumbing below. When this pipe comes through the roof, a piece of flashing is placed around the pipe to prevent rain from entering the home. There are flashing pieces made from lead (more expensive), metal with seals, or plastic with seals. I prefer lead. Plastic flashing does not last as long as the roof covering. The seals on metal and plastic flashing will deteriorate faster than the roof covering as well. When the seal fails, rain water will run down the sides of the pipe. Lead flashing does not break down, but movement may cause it to have openings which let the rain into the home. Lead also can be bent over to seal the pipe’s opening.
   I buy one piece of lead flashing to make repairs to my vents. If the pipe and lead flashing has a gap, I place a piece of lead over the opening, and I bend it into place. I use my metal shears to cut the lead. A hammer and pliers is all that is needed to form the lead. These tools along with a screwdriver will work to open up the vent, if the lead has been closed over the opening. This is lead, so I wash my hands well afterwards. If my vents had a seal that has worn down, I use roofing caulk. A nice bead around the gap. This should last for five years, but I have seen caulk break away after a year. Birds nests are easy to remove, but check that the birds have not come back to rebuild. I do not see birds building their nests on vents often, but this does happen. As for animals crawling into the vents, you need to be careful. A live animal is not happy. Dead animals are not much fun either. They also may be stuck in a hard to reach spot, so it may be better to have a professional deal with them. Not as common, but I have seen leaves and branches fill in a vent. This happens when a tree is over the vent, and the situation is right for the leaves to pile into the pipe. A plumber’s snake can clean the leaves out. You want to be careful that you are not pushing the clog further into the pipe.
    What happens if the vents are hard to reach? Homes with a steep pitch for the roof can be problematic for the homeowner. A roofer will be able to repair these vents. I wear gloves when going up on a roof. You can burn your hands on a hot roof surface. Home improvement centers also sell kits for equipment needed when working on a roof. I have not used these kits, but this investment can be worth it for the safety issues. I also use long ladders that can be laid onto the roof from the ground.  Never place yourself in a situation where you do not feel safe. I always plan out how I can go up and come down from a roof.

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6 Responses to “How to Repair Your Plumbing Vents”

  1. Last month had to replace a roof vent after the home owner attached his TV aerial to it. Worked fine until the wind blew.


  2. That was good. I have seen owners attach them to chimneys. It really does not take too much more time to do the job right.


  3. Remmik Says:

    Went on my buddy’s roof and found all the lead on the roof vents were worn almost cut. This was at the very top of the pipe along the rim. All had major wear to the point of having holes and one had worn out all the way around. The rest of the lead flashing that tucks inside the pipe was gone, exposing the vent pipe to leaks. We had hurricanes here in Orlando and I guess branches did this as the lead looked very gouged but only on that top rim. With out having to rip up shingles is there a method or product to repair this. I don’t want to use caulking of any type. I was thinking to use anther lead flashing tube to slip over the original one (pipe and all), tucking the top into the pipe like normal and then using a hose clamp further down the pipe to secure it. What do you think? Any other ideas?


  4. I have done just that with success. If there is no problem with the flashing part around the base of the pipe and the section under the shingles, then placing a lead flashing cap over the current flashing is possible. One word of advice: plan out your cap to slip over the existing vent, so that you are not creating another hole when installing the new cap. Here is what happened to me when trying to save some money: I had one last vent to do, and I only had scrap pieces of lead left. I took hammer to form the pieces over the vent pipe, but I hit them a bit hard, creating a new hole.

    aulking with a roof caulk is fine, but for anyone reading this, you have to remember that the caulk will eventually need to be redone; whereas the lead flashing will last.


  5. Dave Nagy Says:

    When the wind is extreme for several hours, all of the water is siphoned out of all three toilet bowls in the house. The only cause I can think of is vacuum created in the vent stacks drawing water out of the traps. Is there any product that can be added to the top of the vent to prevent this from happening?


  6. I have not seen any product in my own area. What you are describing seems quite probable, but in most parts of Texas where I have been inspecting homes, this has not been an issue. I am wondering if installing a vent with a cap such as the ones that were used for furnaces many years ago, and are still used for mechanical exhaust vents will help you. My idea is that such a vent could go over the plumbing vent. You would still obtain air for the plumbing vent stack, yet the wind would not be blowing as strong over the top of the pipe.


© Frank Schulte-Ladbeck Professional Home Inspector Houston, Texas
Frank Theodor Schulte-Ladbeck
home inspector, TREC# 9073
Houston , Texas , 77063 United States
713.781.6090

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