Hardboard Siding & Pressboard Siding

Pressboard siding naturally absorbs water and swells slightly, but with proper installation and ongoing maintenance that absorption rate can be kept to a safe level. The real trouble occurs from improper installation. Improperly installed hardboard siding can undergo serious deterioration including buckling, rotting, softening, blistering, severe swelling, mildew, and insect infestation. Water passes through improperly caulked joints, sunken nail holes and the cut edges that are located near the ground. Water logged sidings will eventually form bulges, swellings, mildew and finally rot. Direct application of the pressboard siding onto masonry materials also allows water to seep in easily.

The best way to tell what type of siding is on your home, is to go to an unfinished area like the attic or garage, and pull back the tar paper from the back of the siding and look for markings. See if you can locate either the manufacturer's name or AHA code (The American Hardboard Association). You search the Internet for the AHA code to determine the manufacturer of the product, the type of siding it is, and where it was made. If you do not see any words or numbers, use the photos above to help you find specific markings for two of the largest selling brands of pressboard siding, IP's Masonite Omniwood and LP's Inner-Seal. Other pressboard siding brand manufacturers include Georgia Pacific (GP), ABTiCO or ABITIBI-PRICE, Weyerhaeuser, and Boise Cascade.

If your hardboard siding is not showing any signs of damage, then consider yourself lucky, but please make sure that you do the care and maintenance steps listed below to keep that luck going strong, as it is possible to have unseen damage with these types of pressboard siding products.

If your pressboard siding is not showing severe signs of problems, but does have a few indications of water penetration (slight discoloration, rusted nails, etc.), the process of deterioration can sometimes be slowed by the regular application of paint and/or caulk. Unfortunately once hardboard siding has absorbed water, the damage has already been done, so this is not a permanent solution. Without replacement, the damaged hardboard siding will cause problems in the future.