I would be careful of hiring a company to check the seal of your house. I worked for a home builder in Austin years ago. They would offer the new home owners a check of the seal of the houses then do all sorts of stuff to "seal" the house for them. They would install a device( which was actually a fan in the front door of the house. Turn it on and watch a gage that they had set up in the house to see if the pressure went up as the air was blown out of the house. No pressure change meant that the house had a leak and needed sealing. The home owners were charged for this "service".
I stood in a house one day after doing the sealing of a new house, as they ran the device in the front door.
The operator, checked the "pressure monitor" and declared the house to be all sealed up.
I walked over and looked up the chimney to see if they had sealed the flue, which of course they had not.
I ask the operator to explain how this worked to pressurize the house when the chimney was wide open.
He gave me a dirty look and told me to keep my mouth shut.
Since this pissed me off, I immediately pointed out the open chimney to the home owner
who ask the same question of the operator. He tried to give them a song and dance about how the thermos confection of the atmosphere dilated the.. well you can see how this went. By the way, I was fired the next day.
I considered going to the labor board, but decided that that would have me begging for a job that I didn't want.
When the enemy is in range, so are you.