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Siding and Wood Rot

Protect your largest investment: your home, from costly water damage

Masonite is man-made home siding composed entirely of wood chips, which are pressed together to form boards. It is one of many kinds of similar man-made products that are called “fiber board” or “hardboard,” as a group.

Problems occurred with Masonite for several reasons. Improper manufacturing of the product actually generated a class action law suit. To be fair, hardboard manufacturers have complained that home builders have not always followed their instructions on usage and have not installed the product properly when constructing homes.  

Although its popularity has faded, Masonite or fiber board siding in general has been very widely used throughout the united States for many purposes like home siding, roofing underlayment, sub floors, and wall sheathing. Invented by William Mason in 1924, it was first manufactured in 1929. Although the original Masonite is no longer made, similar hardboard siding is still being put onto homes in many places today.

Today’s manufacturing methods differ from Mason’s, and materials like resin and wax have been added to the product mixture. However, all fiber board sidings have several things in common. Wood chips are the basic material of composition, and the resulting board has one smooth, paintable side, and one unfinished interior side. These products are similar to what you see at home improvement store under names like press board or chip board. Other names include composite siding or man-made siding or manufactured siding.

Why Masonite and hardboard are so vulnerable

If hardboard is not kept seamlessly caulked and well painted at all times, it will absorb rain water and deteriorate, even if it has been properly manufactured and properly installed, and this is what is affecting most of us in Wake County and the Triangle.

Simply put, “hardboard” is not hard; it is softer than plywood or solid wood. In addition, hardboard is not very water resistant either. Masonite and all hardboards for exterior use have one smooth, paintable side, but this thin surface is only about as deep as a sheet of paper. Therefore, it does not take much to scratch or to puncture or to otherwise compromise the integrity of this very thin surface. Once breached, the surface provides a pathway for rain water to enter the unprotected interior of the product. As it absorbs water (or just accumulates high levels of moisture in the presence of dampness), Masonite swells up and distorts.

Rot due to water damage is always suspected when the factory-smooth surface looks buckled, wavy, corrugated, puffy, or bumpy. To confirm suspected rot, you need only press your finger against the damaged area. If damaged, that area will be soft to the touch. How soft is “soft?” Moderate finger pressure will bend or dimple the surface inward. In bad cases, you can simply poke your finger right through the board.

Because the smooth exterior surface is all that keeps rain water out and because that surface is as thin as a sheet of paper, it is absolutely crucial to keep the product well painted at all times and to keep the seams at the end of each board filled completely with quality caulking. Thin or worn paint and gaps in the caulking lead to the product just falling apart over time, in which case it will have to be pulled off of the home and replaced. This can be expensive. How expensive is “expensive?” Individual hardboards or substitute materials like Hardiplank boards are not so pricey when you only need to buy 1 or 2 to replace a couple of rotted Masonite boards. However, if the whole exterior or large parts of it have to be replaced on an entire 2,500 square foot house, the bill for labor and materials can range from $10,000 to $20,000. (Most of that cost is the labor to remove the bad stuff and dispose of it, and install something else in its place.)

Masonite must have lots of maintenance, continuously

Home owners with Masonite who try to stretch even a good paint job out for 6 or more years before repainting are taking a huge chance that a lot of their siding will have to be replaced, at considerable cost, as the protective coat of paint gets thinner and thinner year by year. Think of the paint on your home as its “skin.” Just as with your own skin, you don’t want scratches or punctures in it because germs can then invade, hardboard siding without lots of good caulk and good paint seamlessly applied will begin to let invading rain water in over time.

Homes in the Triangle with trees on the property, or nearby, are especially vulnerable because the resulting shade thrown onto the house means that the Masonite or hardboard does not dry out quickly after rainfall. It simply stands to reason that the longer the time period is that fiber board is exposed to high level of moisture (sitting on the shingles or anywhere else for that matter), the greater the chances are that the hardboard will absorb some of that moisture over time.

Also, homes where the lowest course of Masonite is close to the ground or where shrubs shade this part of the siding will also see that the high moisture content of the ground and the moisture retained by the under sides of plant leaves will speed up the deterioration of this sensitive product. Shrubs should be kept a few feet away from Masonite. Further, many caulks shrink over time when exposed to UV, and the powerful southern sun can make budget caulking material between Masonite boards retreat or shrivel by just a fraction of an inch over time, leaving open seams which look like dark vertical cracks at the ends of these boards. Each of these cracks or open seams is an entry point for rain water and for moisture in the air that inevitably shortens the life of the product. Many homes in Wake County have literally dozens and dozens of such open seams on each of the sides of the house. Open seams are an invitation to costly trouble, and if enough rain gets in over a long enough period of time it may damage the wall sheathing, the load bearing studs and so forth. NC Gutter Guys been hired many times just to caulk and paint over all of the open seams on a house in between repainting.

Hardboard is nearly always improperly installed next to the garage roof

Even when all conditions are right for maintaining Masonite in good condition, yet another problem can rear its ugly head. Masonite homes with an attached garage naturally have the siding boards cut at an angle where the roof of the garage meets the house. Several issues can cause trouble. One is that all too often the hardboard siding is cut in such a way that it almost touches the shingles Often, just a thin like of aluminum step lashing can be seen between the boards and the shingles. It is recommended that even with tougher siding material such as Hardiplank that the boards be cut so that there are 2 full inches of space between their lower edge and the roof. What happen too often is that leaves get caught between the under edge and the shingles. This is just like putting a wet towel in there. The leaves retain moisture, and this moisture is wicked up into the siding. 

Also, what a home owner cannot see is that the under edge of the Masonite or fiber board is almost always unpainted. Why is that? Because of the way that homes are built, the painters are not called in until the shell of the home is finished, so they are not on site when those boards are being installed. When replacing rotted boards today, even many experienced handymen and carpenters do not paint this vulnerable lower edge and just leave it raw when installing a new piece of siding. NC Gutter Guys is the company we know of that, when replacing Masonite, paints the under edge of the new boards so that there is some protection there against moisture being wicked up from below.

Finally, the James Hardie Company recommends that builders - band also repairmen - install kick outs on the last piece of siding. Kick outs are frequently used in the North, but are extremely rare in the South. A kick out is a piece of metal that protects the last edge of the last piece of siding over a garage roof and also kicks rain water flowing down the roof outwards and away from this piece of siding. NC Gutter Guys is the only company we know that routinely installs kick outs when replacing siding next to a garage.

The many other kinds of damage that Masonite is subject to

In the law suit against the manufacturers of Masonite, the court’s definition of “damage” describes a variety of problems that still plague homes. My comments are in parentheses in red below:

“Damage”

“To be entitled to payment under the Settlement, an Eligible Claimant must be determined to have compensable Damage as defined by the Settlement Agreement. In summary terms, the Settlement Agreement defines Damage as follows:

(1) thickness swell exceeding .520"; (that is, the width of a Masonite board will expand, indicating moisture absorption)

(2) edge checking wherein a gauge can be inserted one half inch into the board; (that is, the vulnerable lower edges of Masonite or hardboards becomes soft enough over time that you can push a probe ½ inch into it)

(3) fungal degradation which results in soft board in which thumb pressure exhibits sponginess in the board deforming or producing significant indentation; (on the left is a photo of significant rot with the resulting buckled or wavy surface, which is most pronounced in the third board from the top of the photo, to the left on the vertical electrical wire; on the right is Masonite the way it is supposed to be with a smooth surface, heavy painted and tightly caulked)

(4) buckling exceeding of 1/4" between studs placed not more than 18" on center; (this means that the boards will buckle or bend if they san an area greater than 18 inches wide)

(5) wax bleed; (“wax bleed” means that the wax in the product can flow out and over the finished surface)

(6) delaminated or cracked primer or primer peel or peeling, or blistering; (primer and paint can get pushed off of the board as moisture tries to escape)

(7) surface welting, or swelling around nailheads; (nails driven too deeply into Masonite leave a dimple in the product and sometimes expose a little bit of the unprotected interior of the board. Rain water can run in to these little depressions and sit there for long periods before evaporating.)

(8) moisture content exceeding 20%; or (a high level of moisture like this weakens the structure of the product, but also provides a seed bed for mold, fungus and mildew)

(9) raised or popped wafers visible on more than 25% of the surface of a board.” (formed by being pressed, the product is composed of intermingled layers, which can spring loose from their surroundings and pop up)

How to test for the presence of rot

How can a home owner tell if rot is present in their siding? Usually, but not always, some parts of the siding will look puffy, swollen, wavy or buckled – anything but smooth. (Sometimes the brownish interior of the Masonite can even show through.) The real test however is whether the area is soft. Simply press the area with your finger or with something like a screw driver to see if it is soft or if it bends or moves in any way. Siding in good shape and sound wood do not bend; they are either firm or hard, but you cannot put a dimple into material that is OK. If it’s soft, it’s been damaged by water.

Sometimes the situation is more complicated though. Corner boards - and siding too - may occasionally look smooth and well coated with paint, but when pressed, turns out to be soft. In these two photos, the corner boards looked OK. However, the lowest sections in each case (which are the last ones that rain drips off of) were soft to the touch. The interior corner board shown runs all the way down to the cement driveway, so therefore rain water will sit for months underneath the very bottom of boards like this before it eventually evaporates. All that time though the moisture there will wick upwards into the vulnerable end grain of the wood. In addition, the problem of moisture remaining under the end grain of such wooden boards is vastly compounded by the fact that builders almost never paint the ends of these boards, thus leaving the raw wood end grain constantly exposed to pooled rain water. Perhaps because of our roots as a painting company, we are the only people we know of who always paint the ends of boards like this, if the home owner insists that new wood be used to replace the old damaged section. We will do what the home owner tells us to do; however, we always strongly recommend that water-proof PVC be substituted wherever a vertical board has to terminate on top of cement or asphalt or any other surface where it is highly probable that rain water will collect underneath it.

Even where a board has a smooth and flat-looking surface, any softness indicates that it has been damaged. If it’s soft but smooth and well painted, then water has probably been seeping behind the material for a long period of time, sapping its strength. The two things needed to rot a piece of wood or siding are: water (or lots of moisture) and a sufficiently long period of time. Of course there are other important factors as well, when it comes to building materials, such as whether the area has an adequate coating of good paint and caulked edges. The type of wood plays a big role too - almost all wooden window frames and sills for instance have been made out of softer woods like pine for decades now, and soft pine, particularly if the paint is cracked, or flaked or thin, does not stand up to water much better than Masonite.

These parts of a hardboard home are the hardest hit by rain
Water damage may be found almost anywhere, but is most frequent in these areas: dormers, the lowest course of boards where the siding meets the foundation, and the lowest edge of siding boards that are located too close to shingles. Also, window sills, and thin wooden drip caps above the tops of windows. Siding that is cut too close to the shingles on a garage roof for example are often water damaged. First, the under edge which was cut to shape the siding board is nearly never painted by home builders and unfortunately also by handymen as well. Second, these vulnerable unpainted under edges, if too close to the shingles, will occasionally trap leaves and debris which should have slid down the roof and into the gutter. Trapping wet debris under the edge of the board is like placing a wet towel there that never quite dries out. Over time, the trapped moisture will be wicked up into the siding board.

The single most vulnerable part of a hardboard home, however, is the chimney chase. The chase is the siding clad surround through which the metal gas pipe exits out of the house and up to the level of the roof. This structure sticks out from the house and as a result every bit of weather hits it. In addition, the bottom of the chase often terminates close to the ground with its high levels of moisture. Finally, the upper half of the chase, and especially the back of the chase (which faces the front of the house), is particularly difficult to see from way down on the ground. When problems start, they fester up there for a long time before it becomes apparent to the naked eye that something is wrong.

Is there any alternative to Masonite and hardboard?

The least expensive way to replace a rotten Masonite board is with another piece of fiber board that is properly painted and properly installed. You may ask, ‘why replace one problem with the same kind of thing?’ If you feel you can keep boards of this type well caulked and well painted over time, you save money on the price of the material. Or if you are moving soon, and you simply want the problem board fixed in the least expensive manner, consider new fiber board.

The most popular alternative is Hardiplank

You may have heard of Hardiplank because it is being widely used for siding instead of fiber board.

Hardiplank is somewhat more expensive than hardboard but has a number of genuine advantages. Hardiplank is made out of a mixture that contains mostly cement, not wood chips. As a result of its high cement content, Hardiplank is never bothered by insects, and it’s also resistant to fire and also to damage from high winds. Then too, it also resists water better than Masonite, although it is not “water proof” as is commonly supposed. The manufacturer, the James Hardie Company, recommends that the product be kept caulked and painted at all times and also that it not be used where it will be submerged frequently or continuously in water. For constant immersion in water, pressure treated or Wolmanized wood is the preferred product. Both Hardiplank and hardboard should be nailed in place with water resistant fasteners, i.e., the galvanized nails you can buy at any hardware store. The James Hardie Company recommends “hot-dipped” galvanized (as opposed to “electroplated” galvanized) 2-inch nails. Fortunately, it doesn’t take any more time to install Hardiplank than it does to install hardboard. So the labor cost for one will not be more expensive than for the other. The price of the material is the only significant difference. Hardiplank looks identical to hardboard after it’s been painted, and it comes in the same sizes and styles, too.

Rain also damages many window sills and frames

Wooden windows are damaged by rain a lot more often than you might think. Window sill and frame rot can usually be identified by blackish holes or blackish cracks in the wood, but again the real test is whether the material is soft when you press against it.

We can replace wood window elements with new wood of course and keep the area caulked and well painted for years of useful life. However, many people are asking us to install a new material: PVC. PVC window replacement materials have grown in popularity every year since they were first introduced. PVC is a plastic and as a result is impervious to water and also to insects. PVC comes in white and when installed and painted looks like wood. It comes only in white from the factory, but it can be painted any color you wish. Although it’s plastic, the same kinds of nails and screws for wooden windows can be used with PVC.

When painting either new wood or PVC, please remember that when a part of a window gets fresh paint, it may look brighter or shinier than the older, more weathered parts of the window. If you want the whole window painted to match the newly installed piece, please tell us in advance so that we can price the additional painting time into the Estimate for the job. When painting new material, we feather it off to help blend it into the surrounding wood, but painting the entire window frame is not included in the usual and customary Estimate price.

The only drawback to PVC is its higher price compared to wood. A window sill and nosing (the rounded, leading edge of the sill, which also has to be replaced if the sill behind it is damaged) made of PVC costs us $43, including the tax on these materials.

PVC replacement parts are also available for garage door stops and jambs and for some kinds of trim elements as well. A piece of garage door stop and jamb to replace just one side costs us $30, including tax. Unfortunately, PVC does not come in every size and style of trim and molding, but every year more types and styles become available. It must be said too that since PVC will never rot, over the long haul it will be less costly than having to replace a piece of wood several times over if the wood is in a water-stressed location.

Thin wooden drip caps cause trouble

The health and life span of windows is also affected if thin wooden drip caps (see photographs) are present. These are thin strips of wood installed right above the top of the window frame, ostensibly to keep rain from penetrating the window frame. The big problem with these drip caps is that they are almost always flat on the top or upper surface. Sometimes they are even tilted so that rain water runs towards the house and pools against the siding! All drip caps should be sloped away from the house to shed rain.

When the caps are flat, rain water just sits and sits and sits on the top surfaces for extended periods of time. Home owners often don’t notice the damage that is being done because the upper surface of drip caps on first floor windows is usually high enough that the average person cannot see the water puddles there. Eventually the thin wood strip will crack from the water, and the water may begin to drip through and damage the top of the window frame and the siding board above it, too. Often, by the time the water damage becomes visible from the ground, it has become quite extensive. You can however easily check the tops of your first floor windows by opening your second story windows and looking down. Thankfully, on most homes the roof overhangs far enough outward that the tops of the second story windows are usually protected from this type of damage.

Metal drip caps are so much better than thin wood

It is always advisable to install a metal strip over thin wooden drip caps for its greater resistance to water, but thousands and thousands of homes in the Triangle were built without this piece of metal. In addition, these wooden caps are made of soft wood and are so thin (about 3/8ths of an inch in diameter) that the sun in North Carolina sucks all of the moisture out of the wood fibers, desiccating them. The result is that these wood strips shrink away from the paint on their surfaces, and the paints then blisters, cracks and eventually blows away, leaving raw wood exposed to all of the elements. Most of the time too much water is a problem for wood; in this case, it is too little moisture in the wood that is the culprit.

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