Why Do I Need Ventilation In My Mobile Home Skirting-What To Look For?

Air flow under mobile homes

Under Mobile Home Ventilation Issues Need To Be Addressed!

Today’s re-leveling job in Florida prompted me to write this article about skirting ventilation.

I look into the reasons for ventilation and why ignoring it will not only cost you money, it could damage your home and cause health problems.

This is just one example of thousands of mobile home all over the country.

We arrived at the home which had steel roofing panels being used for skirting. The skirting panels had the ribs oriented vertically and it generally looked like a good job had been done.

Everything looked great.


metal roofing used for skirting


Three things immediately came to mind:

  1. It was 82 degrees here at 9.30 am.
  2. Steel is a conductor of heat.
  3. There was no ventilation in the skirting.

So lets take a closer look….

What Was Going On Behind The Skirting?

On removing some of the panels to gain access to the foundation area I found:

  • Hot air.
  • Moisture.
  • Damp ground.
  • Rusty straps.
  • Water lines on the block

This rusty anchor strap is just hanging from the I beam. The stap is doing absolutely nothing to secure the home. Unfortunately 90% of the straps on this home were in the same condition.

These straps are part of the foundation system and should be able to take a 4000+ lbs load.


Rusty andchor straps

Does Mobile Home Skirting Need To Be Ventilated?

If the above pictures are enough to convince you that you need your skirting ventilated then depending on the material used it should be possible to add vents.

If you are using vinyl skirting it comes ready vented from the manufacturer.

Lap skirting can be vented by machine or have vents added.

Concrete block skirting can have block turned on their edge.

Split blocks can be spaced out to ventilate.

Big spaces in vents should have screen material glued to the back to prevent pests from gaining easy access.

Vents can be purchased from most DIY store and installed as needed.


Ventilation panels


I don’t recommend the use of metal roofing as a skirting material, but if you already have it installed on your home then please add a sufficient amount of ventilation to prevent costly damage.


How Many Vents Should  Mobile Home Skirting Have?

So how do you know how much ventilation is needed to stop these problems from happening?

The usual way is to allow so many square inches of vents per square foot of floor space. The figure used in Florida by the DHSMV is not less than one square foot of opening to the outside per 150 square foot of floor space.

(144 sq in/150 sq ft)

That is approximately one square inch of ventilation per square foot of floor area.

Why Is It Important To Ventilate The space Under My Mobile Home?

When there is insufficient air flow in a confined space:

  • Heat builds up
  • Moisture accumulates
  • Stale Air
  • Mold
  • Bacteria
  • Rust

This is a picture of the moisture lines on the concrete block.


Moisture lines on block

How Do I Get Rid of Moisture Under My Mobile Home?


If you decide to retrofit your home with ventilation panel, it is a good idea to dry out the space first. This may take a few days to complete but will pay dividends in the future.


To Air Out The Space

  • Remove most of the skirting on all sides of the home to allow air flow.
  • If there is no wind it will take a little longer, use electric fans if needed.
  • Finally add permanent ventilation to enhance air flow.


Do I Need Vapor Barrier Under My Mobile Home?


The jury is still out on whether a vapor barrier helps or not. Do they help or hinder?

Some mobile home manufacturers specify the need for a 6mm minimum polythene barrier to be installed at the time that the home is set.

All new homes set in Florida require a vapor barrier.

New or used mobile homes in a flood zone are required to install a vapor barrier according to HUD regulations. Fema 85 regulations usually specify a poly barrier 6mm minimum.

Vapor barriers can cause the unwanted accumulation of water under the home.

You will find an article about mobile home vapor barriers here.