What is Hardboard Siding and Why Does It Fail?

When it comes to choices for siding for home construction, builders have quite a few to work with. The quality, workability and costs vary greatly, and the final choice is often determined by both the structural and weather-resistance needs of the project, and the builder’s budget.

When it comes to choices for siding for home construction, builders have quite a few to work with. The quality, workability and costs vary greatly, and the final choice is often determined by both the structural and weather-resistance needs of the project, and the builder’s budget.

On the high end of siding options, there is faux stone, brick and stone veneer, wood, fiber cement and engineered wood. At the least expensive end of the siding product spectrum is vinyl, stucco, aluminum and steel, and T1-11 and composite board, which fall roughly in the middle of the cost range.

The product we typically consider to be “traditional” hardboard siding is a relatively inexpensive material that is easy to install. Hardboard siding material is harder than wood siding, which makes a more durable, and it’s more flexible. In addition, it can cost between 25 percent to 50 percent more than vinyl but less costly than wood.

What’s Good About Hardboard Siding

Hardboard siding is a vastly improved product from the original hardboard siding product known popularly as Masonite. In fact, Masonite ceased production of their siding products almost 20 years ago although contractors and vendors still use the name in a generic fashion when referring to modern hardboard siding products.

Hardboard Siding

Despite the poor reputation that still lingers with hardboard, it has some good qualities. It can be painted in almost any color and the composite and surfaced plank board varieties resist the cracks and other surface issues typical with traditional wood.

Hardboard lap siding is also the easiest to install on homes that still have older style Masonite or clapboard siding that need small repairs.

The Problems with Hardboard Siding

First, we should go back and look at what happened to the “original” hardboard siding, Masonite. This product was invented in 1924 by William H. Mason. It was quite popular in the 1930s and 1940s and was used doors, roofing, and walls. After the Second World War, it was being used for residential siding.

Real problems for Masonite began in the 1970s and 1980s when some lines were not properly manufactured or sealed. This made the hardboard susceptible to mildew and rot, which caused expansion and contraction of the boards. In addition, poor and improper installation aggravated these issues.

In some cases, the boards rotted away where they were nailed to the house and the hardboard would fall off! As a result, in 1994, a nation-wide class-action suit was settled against some of the major hardboard siding products manufacturers. Masonite, which is a trademarked name, was not part of the suit.

The homeowners won the suit, which stipulated that specific owners of houses constructed using hardboard could be reimbursed for any damages caused by the product. As a result of the lawsuit, nearly all manufacturers stopped producing Masonite siding and, in March 2001, the Masonite Corporation announced its decision to phase out production of all hardboard siding products.

Today, similar “tempered hardboard” is now a generic product made by many forest product companies and is often, erroneously, referred to as Masonite.

Hardboard Siding

Modern hardboard siding products are far superior to the traditional materials. However, there are still some disadvantages to using a wood-based siding product. Panels that have been Improperly stained and sealed, for example, will allow moisture to make its way underneath the siding and cause mildew. In addition to product quality, improper installation can lead to moisture problems that can degrade the effectiveness and expose a house to mildew and moisture-related problems.

Even with the minor improvements made to hardboard siding, the most common problem we see with this siding type is installation error. Replacing hardboard siding represents nearly 50% of our siding sales and during our inspections we notice several common errors that builders made in the late 1980s and early 1990s.  Builders would only install 1-2 “shear walls” with plywood under the siding and install the rest of the hardboard directly over the studs. The only siding that won’t warp or perform poorly when installed over studs is vertical siding that is 5/8” thick.

The biggest cause of dry rot in hardboard siding is inadequate water diversion flashing around gutter to siding transitions and installation of trim over the siding which does not allow for proper z-bar flashing over the head trim around windows. Furthermore, builders did not use joint connectors at the seams and would improperly nail the siding which would not allow the product to expand and contract and ultimately lead to bows in the siding. Lastly, homeowners failed to maintain this siding enough.  

Those homeowners who painted their siding every 5-8 years and caulked around the trim would find their siding still standing today – those who did not have already installed new siding or need to right now. The most misleading aspect to the class-action lawsuit and general disdain for hardboard siding is that home builders should share the responsibility of the product failure. It is safe to say that builders who used this product were happy when the lawsuit was accepted.

Alternatives to Hardboard Siding

Two great alternative siding products to consider LP® SmartSide® engineered wood siding and James Hardie fiber cement siding.

LP® SmartSide® is a siding product composed of chipped Aspen wood combined with a specialized resin formula used as a binding agent along with zinc borate for a treating element along with a phenolic acid overlay. The result is a product that offers superior moisture protection and strength. It comes in longer lengths than Hardie Board, weighs less, and is less expensive to install since there are no special cutting tools required.

Hardie Board, by the way, is not the same product as “hardboard,” which is a dense and thin pressed particleboard typically made from wood. Hardie Board is a fiber cement product known available as a horizontal lap siding called HardiePlank®, and a vertical siding called HardiePanel®. These fiber cement siding products are created from a proprietary formula of Portland cement mixed with ground sand, cellulose fiber, and other additives. Because of its popularity it has become a veritable generic product and referred to as concrete siding, cement fiber siding, and even fiber cement cladding.

8 thoughts on “What is Hardboard Siding and Why Does It Fail?”

  1. I do home inspections in N.E. Pennsylvania. I called out the siding as Hardie Board in one of my reports and now the buyer is claiming its masonite and is furious with my misinterpretation of the material.
    Is there a way to distinguish between the two without ripping a piece off of the house?

    • Joel – Probably the easiest way would be to look at the woodgrain as each manufacturer has a distict look (google James Hardie woodgrain) and all fiber cement products will feel like tile to the tap/touch while masonite and hardboards products will feel more like wood. Good luck with that one.

  2. We recently had a contractor install Masonite siding on about half of our home. We wanted to replace damaged sections and match the existing siding as closely as possible. I was responsible for the painting and caulking. I caulked all vertical joints , trim and any other significant gaps. The siding is now warping and buckling after only 3 months. The contractor claims that because I did not caulk the horizontal seams where the laps meet, moisture has entered and it’s entirely my fault. Is it truly necessary to caulk every inch where the laps meet? I’ve found several sources that say no, but I can’t seem to find a definitive answer. What would you recommend my next step to be with my contractor?

    • Mike – Sorry that you are going through that. Masonite and hardboard siding are very fickle, they will buckle and warp quickly if not nailed or spaced correctly. In my opionion, this would have nothing to do with water penetration and have everything to do with the contractor not installing the siding with enough spacing (to allow for expansion and contraction) or not nailing the siding in the correct locations. If you can find the brand/type of siding that was installed and find the installation instructions, this would help determine the cause. Try communicating with the contractor that you are just trying to find out the facts and get the problem solved and not blaming him (even if you find the problem to be 100% on them). Hopefully, the contractor will step up to the plate and do the right thing and make the repairs needed. In many cases, you can repair the panels without replacing them by cutting back some siding or re-nailing where needed. Good luck!

  3. Most Hardboard siding failures occurred because most painters would never paint the bottom edge of the starter piece or either the nails were driven too deep and water penetrated the nail holes which started it to spidering/cracking outwards from each nail hole

  4. After reading this, I am 100% sure our home has the hardboard siding. We bought this home 2 years ago and there are a few pieces that need to be fixed on the home and on our building. They are the 12″ wide size and smooth texture. What is your recommendation on trying to match what we have now to repair the places that need it? I really do not want to redo a 2-story 2300 sq ft home with new siding!!!!!

    • I would recommend completing entire walls with new, more advanced, warranty protected siding such as LP SmartSide or James Hardie fiber cement. You can start with your most damaged walls first (probably your south side) and if you can do two sides at a time that would be helpful from a cost standpoint. Repairing your siding with the same type will bring you similar results and you will get zero back in terms of ROI. Even if you cannot do this right away, better to save your money for something you can be proud of rather than complete multiple “dry rot repairs,” and get nothing in return. Good luck!


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