A mobile home is set on pier footings made of concrete. This means the home is elevated off the ground. Unless you install skirting, the underside of the home is exposed and open to animals and children. A permanent solution to this problem is to install a concrete cinder-block foundation. This is a DIY project for someone with masonry skills. It will take at least a week to complete.
Lay 1 inch of gravel directly under the mobile home where you plan to install the foundation. Tamp the gravel down with a tamping tool and let it settle overnight.
Mix up mortar and water in a wheelbarrow, using the proper mixing ratio specified on your cinder-block mortar. Use a trowel to mix the mortar until it is the consistency of a milkshake.
Trowel about 1 inch of mortar onto the gravel directly under the home in one corner. Place a cinder block into the mortar so the solid, flat side is facing toward you. Check to ensure the block is level, using a carpenter's level.
Spread mortar on the gravel next to the cinder block and apply some mortar to the side of the first block. Place the next block beside it about 1/2 inch away. Trowel additional mortar between the blocks if needed. Repeat Steps 3 and 4 until the entire first row of the foundation is complete.
Trowel 1/2 inch of mortar on top of the first cinder block and over half of the second block in the first row. Lay one half cinder block on top of the first block, flush with the end of the wall. Spread mortar on the side of this new block, then place the next block right beside it. Continue to apply mortar and cinder blocks to build the foundation up to your mobile home frame.