Masonite and Hardboard Siding: Problems, Repair and Replacement
By Bay Area Siding Company
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Masonite siding is a brand of hardboard: wood fibers pressed under heat into dense boards that look like painted wood but swell and break down when water gets into them. Hardboard from several manufacturers was installed on many homes in the 1980s and 1990s, and in a national class action an Alabama jury found Masonite's siding "unreasonably prone to failure." That settlement's claims program has closed. Today the practical question is whether your boards can be repaired and kept painted, or whether the walls need re-siding with a more water-tolerant material.
What hardboard siding is
Hardboard is made from wood broken down into fibers, then pressed in a hot press until it is very dense. The industry standard for the product, ANSI A135.6, defines it as made mainly of interfelted wood fibers consolidated under heat and pressure. It was sold as lap boards with a printed or embossed wood grain, and as 4-by-8 panels, usually primed for paint.
"Masonite" was the best-known brand name, so many people use it for all hardboard siding. Other companies made similar products. The material is still made: in 2010 the industry renamed hardboard siding "engineered wood siding," and the ANSI standard now uses that name. That is a different product from strand-based engineered wood such as LP SmartSide, which is made from wood strands rather than fibers and treated against decay.
How to tell if you have hardboard siding
Hardboard is easy to confuse with wood, fiber cement and engineered wood. A few checks help:
- The grain pattern repeats. Embossed hardboard has a stamped wood grain that repeats from board to board. Real wood grain does not.
- The edges look like dense cardboard. At a damaged or cut edge, hardboard shows compressed fibers rather than wood grain, cement or visible wood strands.
- It swells where it is wet. Wood checks and splits; fiber cement stays flat. Hardboard puffs up at the bottom edges and around nails.
- Look at the back. Where the back of a board is visible, such as in an unfinished garage, you may find a manufacturer's name or mark.
The age of the house helps too. A home built or re-sided in the 1980s or early 1990s with painted lap boards is a likely candidate. When in doubt, a siding contractor can usually identify it in a few minutes on site.
The Masonite class action: the basic facts
- Filed: December 1994, in Alabama, against Masonite Corporation and its parent company, International Paper (the Naef case).
- Verdict: In September 1996 a jury, deciding liability only, found that the siding failed to meet an ordinary customer's reasonable expectations and was "unreasonably prone to failure."
- Settlement: The trial court approved a settlement in January 1998. It covered Masonite hardboard siding installed in the United States from January 1, 1980, through January 15, 1998.
- Claims: The claims program, which inspected homes and paid for damaged siding, ran through 2008 and is closed.
- Other makers: Other hardboard siding manufacturers, including Georgia-Pacific, Jefferson Smurfit and ABTco, also settled class actions over their siding by 2000.
If you are buying a house with hardboard siding, assume any manufacturer claim is long closed. The siding's condition, not its history, is what matters now.
How hardboard fails
Hardboard performs reasonably while its paint film is intact and water can't reach the raw fibers. Once water gets in, the fibers swell and do not shrink back. The usual pattern:
- Bottom edges swell first. The lower drip edge of each lap board takes the most water. It thickens, softens and "bloats," and paint flakes off.
- Nail holes become entry points. Overdriven nails break the surface. Water gets in around them, and the board bulges or cracks around the nail head.
- Soft spots. A screwdriver pushed into a damaged area sinks in easily. Firm, sound hardboard resists it.
- Buckling and waviness as boards absorb water and expand against each other.
- Fungus or mushrooms growing from wet boards in shaded spots, a sign of advanced decay.
- Fuzzy, exposed fibers where the embossed face has worn or broken away.
Look hardest at the walls that get the most water: those below roof edges without gutters, near sprinklers, at the base of walls close to soil or concrete, and on the shaded, foggy sides of the house. Damage to the siding often means the sheathing and framing behind it have been wet too. Our guide to moisture behind siding explains what to look for inside the wall.
Repair or replace?
| Condition | Reasonable approach |
|---|---|
| Paint failing, boards still firm and flat | Repaint, sealing all edges and nail heads; fix sprinklers, gutters and clearances |
| A few swollen or soft boards in one area | Replace those boards and find out why that spot got wet |
| Swollen bottom edges along most of a wall | Re-side that wall; patches will keep failing beside the old boards |
| Soft spots, fungus or buckling on several walls | Re-side the house and inspect the sheathing |
| Water stains inside, below windows or at the base of walls | Open the wall; repair sheathing and framing before new siding |
Spot repairs have two limits. First, the profile and embossed texture of 30-year-old hardboard are hard to match; our article on discontinued siding covers the options when the original is no longer made. Second, a new board sitting next to old, water-damaged boards is still part of a wall that lets water in. Repairs make sense when the problem is local and the cause is fixed.
If you are keeping it for now
- Keep it painted. Hardboard depends on its finish more than almost any other siding.
- Seal cut ends and bottom edges when repainting, and set any popped nails.
- Keep the bottom of the siding clear of soil, mulch and concrete, and point sprinklers away from the wall.
- Make sure gutters and kick-out flashing at roof-wall corners are directing water away.
Our guide to preventing dry rot covers the same habits for wood siding and trim.
Replacement options
Fiber cement
Fiber cement lap siding, such as James Hardie's HardiePlank, gives the same painted lap look without the swelling problem. It doesn't rot, it is noncombustible when tested to ASTM E136, and it is available with a factory finish. It is heavier and needs fiber cement cutting tools. Our Hardie board siding guide explains the product.
Strand-based engineered wood
LP SmartSide is the most common modern engineered wood siding. It is lighter than fiber cement, comes in long lengths and cuts like wood. It is treated against fungal decay and termites and carries a 5/50-year limited warranty, but it is still a wood product, so edge sealing, clearances and paint upkeep matter, and it is combustible.
Vinyl
Vinyl is the lowest-cost replacement and never needs paint. It is combustible and can distort under concentrated heat, so it is a weaker choice in fire hazard zones or close to neighbors' windows.
What re-siding a hardboard house involves
The hardboard comes off, the sheathing and weather barrier are inspected, damaged sheathing is replaced, a new barrier and flashing go on, and the new siding is installed with proper clearances. On homes built before 1978, removal follows lead-safe work practices. Our siding replacement page explains how we estimate, and we give a free written estimate after a walkthrough.
Frequently asked questions
What is Masonite siding?
Masonite is a brand of hardboard siding: wood fibers pressed under heat into dense lap boards or panels with an embossed wood-grain face. The name is often used for any hardboard siding.
Can I still file a claim under the Masonite siding settlement?
No. The settlement was approved in 1998 for siding installed from 1980 through January 15, 1998, and its claims program ran through 2008. Repairs or replacement now are the owner's cost.
How can I tell if my hardboard siding is failing?
Look for swollen or bloated bottom edges, bulges around nail heads, soft spots a screwdriver sinks into, buckling and fungus. Check the walls that get the most water first.
Can you repair Masonite siding?
Yes, if the damage is limited to a few boards and the cause of the water is fixed. Matching an old profile can be difficult, and widespread swelling usually means re-siding the wall.
What is the best replacement for Masonite siding?
Fiber cement lap siding is the most common replacement because it gives a similar painted look and doesn't swell or rot. LP SmartSide and vinyl are lower-cost options with their own trade-offs, including combustibility.
Sources
- Supreme Court of Alabama: opinion in the Masonite hardboard siding class action
- Lieff Cabraser: Masonite hardboard siding settlement
- Composite Panel Association: ANSI A135.6 engineered wood (hardboard) siding standard (PDF)
- Seattle Times: Weyerhaeuser poised to settle massive suit over bad siding (2000)
The information provided here is intended for general reference and should not be considered professional advice. Before starting any project, consult a licensed contractor. Product features, specifications, and warranties may have been updated since this was published. Any mention of brands or products reflects personal opinion and does not constitute an endorsement or warranty.
