Basements require complete dryness before insulation can be added to the interior. The requirement is the same for vapor barriers. Persistent problems with moisture or water leakage will only serve to destroy even the best quality work.

Dampness

There are many types of damage caused by minor dampness: stains, mold, peeling and blistering paint, stale smells and whitish deposits or efflorescence. Correct these problems by cleaning the mold from the interior before applying damp-proofing onto the foundation wall. More serious problems are usually corrected from the exterior. 

Major Cracks

Cracks in the foundation wall are never a good sign for your house. Growing cracks require professional help before home improvement work can be performed. You may need to consider structural repairs as well.

What Are My Choices?

Insulating the basement from the inside is not only the easiest method but also the least costly for a dry basement, whereas outside insulation is technically preferable. Weigh the pros and cons listed below before deciding on which to do.

Insulating Inside

Insulating from inside normally requires an extra wood-framed wall and some insulation material, as with a standard wall. 

Some advantages to inside insulation are:

• The insulation work can be conducted at any time of year.
• The value of your house when the insulation work is complete will increase.
• There will be more usable indoor space.
• This is the cheapest method for basement insulation, as well as for a vapor barrier.
• Outside landscaping and other features are not disturbed during the insulation work.

Some disadvantages are:

• Not suitable for basements that are constantly damp or wet.
• Interior obstructions such as furnaces, vent pipes, electrical panels, and plumbing equipment will be difficult for DIY framings.

Insulating Outside

Insulating outside requires more expensive excavation as the task is more complex. However, it allows homeowners to correct any foundation defects.

There are several advantages to insulating outside:  

• Simpler insulation on a straight wall outside when excavation is completed.
• You can correct both moisture and water leakage issues at the same time.
• You can also check for other damage, such as foundation cracking, and repair it at the same time.
• No space is lost inside even if the wall thickness is increased.
• The foundation mass or weight lies on the warm side which absorbs heat and cold to balance temperature differences.

Some disadvantages of outside insulation are:

• More costly excavation work which can also be more difficult with the presence of porches, decks or walkways adjoining the foundation wall.
• Lawns may be damaged by excavated dirt, mud and sand
• No work can be done in winter

Once you have decided which style suits your requirements, you will need to determine the work steps.