Hardboard Siding - WARNING!
Hardboard siding has come under intense scrutiny over the last few years, due to manufacturing deficiencies by certain producers, and partly due to installation deficiencies. Many manufacturers are stopping production due to lawsuits.
This article will examine the common installation problems. If you want to research the manufacturing problems and lawsuits, go to the "Home Claim Services" website at Home Claim Services. You will also find information regarding all class action lawsuits against manufacturers in your state.
In my experience, hardboard siding is rarely installed according to the manufacturer's specifications, and this is obviously a contributing factor to siding failures. There are two primary aspects of siding installation - the physical installation itself (cutting and nailing) and the finishing (caulking and painting) of the product. Hardboard manufacturers have very clear specifications regarding both aspects, but many contractors disregard this vital information.
Most hardboard is warranted against product defect for 20-25 years. However, if you have siding that is not performing as expected and file a warranty claim with the manufacturer, you may find that the warranty is VOID, due to improper installation and/or finishing! Since problems don't usually manifest untill several (3-5) years after installation, the builder's one-year-warranty will have expired, and your only recourse may be to sue the builder for negligence (assuming the statute of limitations hasn't expired!).
The ideal situation is to monitor the installation and have deficiencies corrected as they occur. This is where your friendly home inspector can be of assistance. But what if you are buying a resale property with hardboard? Again, a qualified inspector can identify deficiencies and any related damage, and propose remedial action needed. I have seen many homes where the siding is beyond repair and the replacement cost would be around $10,000. The moral of the story is "Don't skimp on the cost of a quality inspection!"
Moisture is the enemy of hardboard siding. Almost all installation deficiencies allow exposure to moisture, resulting in absorption and subsequent degradation of the material. Here are some common defects:
Defect #1 - Overdriven nail heads. Nail heads should be driven to where they butt tight to the siding or are flush with the siding face. If the nail head is "sunk" beyond flush, the siding fibers are exposed which will allow moisture absorption. The siding then swells out beyond the nail, creating more access for moisture and the situation goes from bad to worse. If the nail head is sunk less than 1/8" it can be caulk filled and painted. More than 1/8" requires caulk fill and a new nail adjacent to the overdriven nail.
Defect #2 - Thin/missing paint. Most builders spray paint a house. Unfortunately this technique results in less paint applied than the specifications require. Even for pre-primed material, at least 2 spray coats are necessary to achieve proper coverage. When was the last time you saw a builder apply 2 coats? That is why builder homes tend to need to be repainted after 3-5 years, whereas a quality paint job should last 10 years! Also, the bottom edges of lap siding tend to receive little or no paint, especially on the lower courses since the painter is spraying downward at this point. To cover those bottom edges properly would require hand brushing, but again this is rarely done. Water tends to hang on these bottom edges and gets sucked into the siding through micro cracks in the material. The result - swollen and decomposing siding! Inspectors should walk along the lower rows with a mirror. You will be surprised how the bottom edges of the lower 3 or 4 rows is different in color than the higher rows!
Defect #3 - Unpainted cut edges. When siding boards are installed whole (uncut), the end edges are generally unpainted, but since most hardboard comes pre-primed there is some protection. Ideally these ends should be painted prior to installation. However, the bigger problem occurs when the boards are cut to fit. This leaves an un-primed edge that is thirsty! Caulking and/or joint clips help but don't eliminate the problem. Even worse is where a sloping section of roof frames into an upper wall. Here the slope-cut boards are almost never painted on the cut edge, and at a very wet location!
Defect #4 - Deficient Clearances. Compounding the slope cut problem at roof/wall junctions is the fact that most builders provide too little clearance from the bottom of the siding to the roofing material below. Most manufacturers require 1-1/2" clearance, but 0" to 1/2" is a typical deficient installation. The other common clearance deficiency occurs at the bottom row of siding adjacent to the ground. Building Codes and hardboard manufacturers require at least 6" clearance (8" in some areas), but this is frequently violated in the name of providing good drainage away from the house. The real problem is that the house was sited too low on the lot. This location is doubly sensitive since the bottom edge of this bottom row rarely gets painted, as previously mentioned.
Other Defects - There are many others but the preceding citations represent the major defects that typically result in moisture related damage to the siding and are therefore, in my opinion, the most important defects to be aware of.