I am having my house tented for drywood termites today.

If you are not familiar with this procedure it involves putting a series of tarp over your house and sandbags water tubes to seal off the house then poisonous gas is pumped into the house to kill the termites living in the wood.

For the gas to do its work you need the tarp to be up 2-3 days, then the tarp removed and you can move back in after the reading of gas goes to zero.

As the crew tarped over my roof I said to the crew chief ...

"Wait, you are not taping over the plumbing vents?"

He said no. The vents are water tight below.

I said I don't think so. These pipes connect to the city sewers and there is no water tight seals.

He said "trust me, I have been doing this for 25 years, these pipes have a water seal below, just like your toilets have water in the bowl."

I said I know for a fact that all these pipes have no water seal or traps under them because I plumbed every single one of them, and there is no house trap either. If you cover these pipes with tarp your gas will go into these pipes and into the sewers it will kill off a few roaches and rats but the house will not have the needed pressure to kill the termites.

I made them uncovered the tarps while I duct taped each vent myself or I wasn't writing a check.

25 years tenting without taping vents!

So in your entire house there is not one sink trap or tub trap?

Individual fixtures have traps.

The vents sticking out the roof are not trapped.

I am not trying to prevent gas from entering the interior of the house. Fixture traps would prevent that. The gas is on the inside of house anyways.

I am trying to prevent gas from inside the tarped house from getting into the vents from the top, reaching down into the vents and entering the city sewer.

The gas are precisely calculated based on house volume. If they can't get positive pressure it will not be able to kill off the termites.

The tarp is applied over the entire roof, over the open vents.

There is no way for that to happen. And if your roof flashings are good, it wouldn't escape around the pipe. I guess I don't follow your logic.

If you cover your entire house with a giant balloon, all the vents are inside the ballon. Then you pump poison gas into the balloon, you don't see gas entering the vents?

Sum,

You are 100% correct

You will never hold the + pressure if the vents are open to the sewer - as they would normally and rightfully be.


For your 'questioner':

A vent is on the sewer side of the trap.

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

It has nothing to do with them. The roof vents are open to the area UNDER the tarp, and since the sewer does NOT have a house trap the sewer system is contiguous to the ENTIRE city system.

YOU are not following what the process is or HOW it is done.

My he was used to NYC where they do have house traps, but even then anything over a few inches water column would have "blown" the trap seal, but that would also happen inside the house at the fixture traps.

You got it right, sum. The gas would have rolled out the vents of your neighhors houses on either side of you.



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If one of my neighbors is doing some DIY plumbing and has his sink trap removed, he would be breathing this deadly poison gas!



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Looks like Barnum is in town!

Yes or a giant bounce house for kids.







Another reason for plumbers in Florida to be on alert if there are houses being tented nearby there may be deadly gas coming up the lines!

And would get rid of a lot of sewer roaches in the process. send part of the bill to the city.

The lizards in the house would be dead too.

I just can't imagine they have been doing this for 25 years and never taped up the vents. Either the gas is so strong it doesn't need to maintain the concentration or positive pressure to do its work, or they don't kill off all the termites but just a percentage of it.

Crazy that to cut down a rotted tree or to move my mailbox post I need a permit, while this whole poisonous gas administration doesn't. Even more surprised sealing roof vents is not a standard operating procedure! May be the gas is not as "deadly" as they claim.



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Sum, I don't think the house isn't getting pressurized like a balloon and with weight of the roof tarps laying on top of the vents, they're somewhat sealed.

steve:

I don't think it's super "air tight" but they claimed the gas will work it's way into the wall cavities, into the wood studs into framing in the attic etc etc etc and the only way they said this happens is the gas it distributed everywhere with no escape. They put water tubes and wet sand bags on the bottom of the tarp, and they taped up every little tiny holes.

As for the tarp sealing the vent this may work on some properties, but I think many properties won't work. For example, in my house I have a chimney on one side, and a roof ridge on the other side. They are higher then the vents. So in my case the tarp runs from the chimney to the ridge, and the three vents in between are thus not sealed.

Pressure differential between inside of the tent and outside atmosphere can be easily measured / verified using a Manometer. There are many types available from the simple U-Tube type to a Digital type.

If you ever have this kind of work done again --- and "IF" any claims are made by the contractor that the tent is actually "pressurized" during the process --- You may if you like, have included in the contract requiring use of a manometer to PROVE the tent is actually pressurized --- AND maintained.

From your description "I don't think it's super "air tight" the tent inside may not actually be under pressure (above atmospheric). I just wonder if the contractor claims that it is.

Well, generally you can't do such "cleaning" by your own, right? I read that some achieve positive results, while others are forced to fight for professional services. I tried to call termite inspection, but it took a very long time, and we couldn't stay in the house for several days. Now the termites have reappeared. I don't know where they come from, but I will try to expel them with my own methods. I read that there is an effective orange oil termite treatment [www.bugszapper.com]. You just need to pour into all the holes, pour all wood parts. Even flies and mosquitoes should kill.



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