Many structures built in the 1980’s-1990’s used hardboard siding; not all of these buildings were maintained properly, and many may have severe siding problems due to neglect and lack of information about the issues that can arise from the presence of bad hardboard siding.

Hardboard siding naturally absorbs water and swells slightly. With proper sealant application, caulking and regular paint maintenance, this process can be controlled and kept at a safe level. However, improperly manufactured and installed hardboard siding can undergo serious deterioration, the effects of which can include:

• Buckling
• Rotting
• Softening
• Blistering
• Severe swelling

This can cause severe damage to homes and surfaces. Further damage can occur in the form of:

• Irremovable mildew
• Bowed wall studs
• Indoor leaks
• Buildup of toxic mold within the walls
• Cracked exterior stucco
• Cracked exterior paint
• Damaged nails

These effects can allow large amounts of rainwater to enter the walls and cause further deterioration.

Prior to the 1980’s, Masonite had manufactured high-quality hardboard siding (also known as "Georgia-Pacific siding"). However, due to cost-reducing changes in the production of their hardboard siding, the products manufactured during the 1980’s and 1990’s were of a low quality, loosely-pressed and susceptible to extreme swelling, buckling, etc.

During the 1980’s through the early 1990’s, many homes were constructed using hardboard siding products manufactured by the Masonite Corporation. Millions of structures were built using the defective hardboard siding, which then began to exhibit the signs of early deterioration, causing millions of dollars of damage to homes and businesses.

In 1994 a lawsuit was filed against Masonite contending that the product had failed to meet its warrantee; the result of the original lawsuit was a class action suit and a settlement which stated that the anyone who owned property that had been constructed using or fitted with Masonite hardboard siding between January 1, 1980 and January 15, 1998 was entitled to reimbursement for any damage caused as a result of the faulty siding.

Following the class action suit, Masonite ceased production of their hardboard siding. Millions of dollars were paid out to claimants who had taken part in the lawsuit, as well as other property owners who proved the presence damage from the use of Masonite hardboard siding.

Not all structures that used Masonite hardboard siding (or similar brands which also demonstrated the deficiencies of lax production measures) were repaired or had the siding replaced. It is possible that a property that you purchase could have unseen damage if it has been constructed using hardboard siding. It is important that you look for and be able to recognize Masonite hardboard siding and/or the signs of severe siding deterioration so that you can protect a building from further damage.

Masonite hardboard siding will usually have the name "Masonite" stamped on the siding itself, sometimes accompanied by the notation "X-90".

If the deterioration of any kind of hardboard siding is not severe, the process of deterioration can sometimes be slowed by the regular application of paint and/or caulk. Unfortunately this is not a permanent measure, and without replacement, defective hardboard siding will incur problems in the future. To ensure the minimum risk of deterioration, siding should be a sturdy variety such as vinyl siding. Some types of siding can be examined and replaced by a homeowner, but for absolute certainty that there is a minimal risk of siding deterioration or damage from incorrect installation, contact a licensed contractor.