I know there are allot of questions on this topic but we still don't know what is going on.
My plumber is right now for the 3rd time trying to locate where the pipes are etc. The traps on the roof are fine, there is no leak or broken seal at the toilets, the smell is intermittent and we smell the odor in the shower drains and the kitchen sink. It permeates the house. In the basement there is no smell, we have a sump pump and it is working correctly and no smell from there.
My plumber is at a loss and we all are frustrated.
Please help and thank you for your time

There are no traps on your roof but maybe you meant vent stack. Has the plumber rodder the vent stack? If he hasn't I'd look for a smarter plumber because this is the most obvious place to start assuming you gave us all your facts.

The first thing he did was to go on the roof, maybe I am using the wrong word for what could be see on the roof. He located where the stacks are today but still without going into the wall we don't know where a crack or damaged pipe would be.
Thanks, Kathie

It is far more common for them to get clogged than cracked. A trap is that loopy thing under your sinks, looks like a J

If one drain is clogged would it affect upstair sinks and showers and washing machine?
We are in Iowa and live in a two story house with a basement. I will check on the clogged issue,
Thanks for your time
Kathie

A clogged drain line on the first floor can affect the second floor. In most situations the drains all come together as they head for the basement and the main drain leaving the house. The same can be said about a clogged vent. If the vent is clogged a trap can be siphoned by water draining in the house. The vent would siphon the closest trap to itself and then you will have sewer gas up the ying yang.

My take on your problem is as follows:

1. Vents are not under pressure. Therefore, even if you drill a hole in your vent pipe, the sewer gas will select the easiest way to get out : it is up, and through the roof.

2. Vents usually don't clog up. They carry air, not sewage.

3. Vent, that has highest possibility to get clogged, is your toilet vent. That happens only if your toilet backs up, sewage backs up into your vent. Once the cloggage is cleaned, solids will remain in the vent. But, that doesn't happen too often. Actually, it happens very seldom.

4. Most of the vents are combined and connected. Even if one is "clogged" than the drain will suck air from another plumbing fixture in line to compensate for air displacement in your drain line. In other words, it utilizes "neighbors" vent to do the job (... provided every plumbing fixture has its dedicated vent )

Look for source of sewer smell in different direction, like: Septic left open ? Septic cover not sealed ? Does the smell happens when it is raining? Or around rainy days ? ( during low atmospheric pressure ). Bacteria in your shower drain ? Rotting food inside garbage disposer ?

Go to your "Mom 'n' Pop's" hardware store and talk to the old fella dressed in overalls. I bet you, he will solve your problem in a second ! :-D

Thank you both for your answers. I will go to the hardware store tomorrow and ask the guy about this issue. I also have a plumber to get a second opinion and see what he sees that maybe the first did not. I will print out your responses and show it to him as well.
I appreciate your responses

Vents can and do clog up from other issues than a backed up toilet. Vents in my area are frequently open pipes anywhere from 2" to 4" on the roof. Birds like to sit on them in the winter and can fall inside as does leaves and twigs. I have pulled all of these out of vents. For the sack of curb appeal we bring several vents together and revent so there are less pipes coming through the roof surface. Birds, twigs, leaves above the revnt can cause the entire home to have problems.

Thank you for your response and I am printing these suggestions and will have the second plumber come in on Monday. With all of the answers I feel like I am more educated and will be able to ask more intelligent questions. Like have you check this or that.
Thanks,
Kathie