How to check & clean exhaust pipe on roof. (sewer gas smell)?

First off that gas is deadly I hope you know. It could be a cracked pipe leading to your toilet which you might not even be able to see because the pipe isn't visible without tearing up the floor. Also to clean your stack you need to do two things.

First feed a plumber's snake down it to see if it is blocked and then use a high pressure hose or at least a garden hose into the pipe on the roof and run water into it. Leave the water running and check for leaks in your house. I do plumbing for a living so PLEASE listen to what i'm saying.

Like I said , sewer gas can kill. If you can't find out the reason by doing this call a plumber immediately.

Vent pipe clogs are almost always due to leaves and debris building up in the pipe or sometimes small animals building a nest. The easiest way to clean one is to find where your vent pipe exits through the roof and use a high pressure garden hose to force water down the pipe and hope that it will dislodge the clog. The vent is just an extension of your drain lines so the water and clog will just wash down into your sewer source, If this doesn't work a sewer snake gently worked from the roof top down will also work but if too agreesive you can run the risk of breaking your vent connections.

Good luck.

The toilet must sit firmly in place. If the toilet moves a little when it is sat upon... then it only takes a few days or a couple weeks for the wax seal to loose its seal. The way to test it is to sit on the toilet and get up... while a friend carefully watches the toilet and also watch the drain pipe under the floor to see if any movement occurs... such as the floor joist bending or flexing just a little.(Use a flashlight in basement to look at the pipe movement.) If movement of the toilet or pipes or the wood floor is seen when the friend gets up or sits on the toilet.... then that is the problem.

Floor joists might need re-inforcing (add more boards or support brackets to stop the movement. Re-inforce and replace the wax ring again. Another problem is some floors have a floor drain.

If the water is evaporated out of the P-trap in the floor drain... then sewer gases can come up. Just pour some water into the floor drain every few weeks to keep the floor trap full of water.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.