Standard is one square foot of venting for every 100 sq ft of floor space.
I saw a study on line many years ago that showed Venting was not necessary assuming a vapour barrier was placed on the ground under the home.
My homes have the vapour barrier, full skirting insulation as well as the one sq ft per 100 square feet ventilation.
Insulating the skirting in a cold climate area is in my opinion a nust have addition to reduce heating bills and protect water lines. With the insulated skirting the ground never freezes under my homes.
I own in Wisconsin. My installer also likes to only use vented panels. I questioned this also, but come to find out the vented panels are not as “open” as you might think. They do allow for fresh air in/out, but it’s not as if large volumes of arctic air are going circulate rapidly and be the main cause for freeze ups. Big items for freeze prevention are what you already mentioned…heat tape and a good belly. If needed, instruct your residents to pile up snow around the perimeter of skirting. It acts surprising well as an insulator. Just my $0.02
Yes…you always want venting. While heat tape and insulation are needed in our environments, the benefits of insulation behind the skirting not on helps the water/sewer, but it also helps keep the whole home energy costs down. With a ground set you do need the vapor barrier and on any type of set, there needs to be ventilation to dry out and prevent mold.
I have always gone with the standard of vented at the 4 corners and solid everywhere else. I believe this is code in Ohio last I knew and would be a good way to " use caution" and better prevent other issues.
I’m in northern Indiana and only use solid skirting.
I’ve never had any issues. Being in a climate that gets cold like WI and Ind. , having holes in the skirting is going to let cold air under the home 24/7 all winter, every winter. That hurts the heating cost.
I could see in the southern states using vented to help with mold and moisture, but northern states are fine with solid skirting. Been using it for over 20 years and would never think to go to vented.
I do have a few tenants who are “particular” who will open up a couple of panels to make a cross breeze under the home in the summer months. Or if the idea of just having a few vented pieces on the corners makes you feel better, you could do that.
The county offered “weatherization” to mobile home owners who were low income. Their crew installed vents in the solid skirting, one vent in the front corner on one side, another vent in a back corner on the opposite side. (Creates a cross breeze).
They simply cut a hole in the solid skirting, inserted the vent, and screwed it in place. These vents open and close. You close the vent for the winter; open it for the summer so ground under your trailer can dry out.