Marc D. Pevar
606 Ridge Ave.
Kennett Square, PA 19348
610-470-0093
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Dear ***********:
On **********I inspected the siding system on your home at your request to give my expert opinion regarding the siding system. This correspondence reports my findings and professional expert opinion.
OVERVIEW: Your home has an older and a newer section. The walls of both sections are built from untreated cypress planks that are nominally one inch thick and twelve inches wide, installed vertically. A gap that is one and one-half inches wide separates each plank. Vertical cypress batten strips that are approximately three inches wide cover the gaps between the vertical planks. The planks and battens are fastened to the substrate behind it using rust-resistant nails, which appear to be stainless steel.
NAILING: The batten strips are nailed near their edges, with the frequency of nails being random, varying from four inches to approximately one foot apart, sometimes alternating from one side to the other. The visible nails in the planks are set approximately one-half inch from the edge of the batten strips separated by random distances. There are some nails visible at the bottom of the planks. Additionally, the planks might be nailed along the edges where the batten strips conceal the nails, but the battens prevent inspection of that area.
SUBSTRATE: I did not investigate the substrate (which was not visible). I saw Tyvec vapor barrier behind the siding where it is visible through wide splits in the cypress planks on the new section of your home, and also at the wide gap at the front inside-corner where new section joins the old section. The plank and batten system covers the entire exterior of your home and appears to be firmly anchored to the substrate by the nails.
CAULK: No caulk was visible where the windows, doors and “picture-framing” cypress exterior trim abut the siding system, or at inside or outside corners. It is possible that caulk was used between the window nailing flanges and the structural substrate, as required by window manufacturers. However, caulk is also required at these other places for weather-tight installation of siding systems such as yours.
Caulk is needed at these places to prevent water from entering behind the siding, into the substrate, into the wall system and into the living space of your house. If water enters these areas it can attract wood-destroying insects, promote mold, fungus and other organic growth, and thereby cause structural damage to your home, as well as damaging your furnishings. I strongly recommend that you apply exterior quality silicone caulk to these areas per manufacturer’s recommendations. If you do not install caulk, you run a high risk of water-related damage to your house and furnishings. Based on my solely non-destructive inspection, I cannot rule out that the lack of caulk may have already caused some damage.
SPLIT PLANKS: The siding system on the older section of your house is not split, warped or bowed. The siding system on the new section of your house is visibly different. Although the batten strips are sound, many of the vertical planks themselves are not. On the front wall there are twenty-six planks. Twelve of these planks, or forty six percent of them, are split either at their ends or within the body of the plank. More planks are split on the other walls the new section.
The splits are located toward the center of the planks, following grain lines. Some splits are close to one-half inch wide, and many splits are at least three-eights of an inch wide. In some places, the full length of the plank is split. The splits typically go all the way through the full thickness of the planks from front to back. I could see the Tyvec house wrap through many splits. Most planks are eighteen feet long, others are cut shorter because of window and gable conditions.
The function of the siding system is to stop water. The splits in the planks defeat this function and allow water to get behind the siding, where only the Tyvec house-wrap keeps the water out of your house. Tyvec will deteriorate over time and let water into your walls and house. Additionally, the manufacturer only warrants Tyvec to keep water out if it is installed with special Tyvec tape at all seams, and with the Tyvec overlapping the window nailing flanges. I could not see whether any tape was installed. Tyvec is not designed to stand alone and function as an exterior water-tight wall system.
PROBABLE CAUSE OF SPLITTING: Cypress expands with moisture and contracts as it dries. If planks are neither seasoned nor kiln dried when they are installed, they start out wide at first, and then become narrower when they shrink by loosing water that is either free or bound. Areas exposed to the sun experience the most dramatic differences in moisture content and consequential change in size. Your planks are nailed vertically along their edges. When the planks dried and shrank, the fibers in the center of the planks were the most stressed. The stresses caused the fibers to separate in the center so the wood could shrink, thereby relieving the stress caused by the shrinking plank.
The splitting of these planks is consistent with wood that was installed with high moisture content, fastened securely at the edges, shrinking as it dried, with the resultant forces in the planks tearing the wood fibers apart toward the middle of the planks along grain lines where the forces were pulling away from the center toward each edge of the planks.
CORRECTIVE ACTION: It is not physically possible to close these splits, and filling the splits is both difficult and will be highly visible. I recommend removing and replacing what amounts to twenty-one planks, each eighteen feet long, on the new section of your house. First you must remove the associated batten strips and picture-framing around windows, doors, etc. Because the battens and picture-framing are well nailed, and aged cypress becomes brittle and inflexible, it is likely that most battens and picture-framing will break and need to be replaced. To make the battens and picture framing will require approximately twelve additional eighteen-foot long planks. The total material needed to replace the damaged siding system is 32 planks, each eighteen feet long.
RESPONSIBILITY: Whoever furnished and installed the siding system did not receive seasoned or kiln dried wood, either because of an error by the supplier, or because of an error by the installer in ordering. Either way, whoever furnished and installed the siding system installed a product which was bound to split when wood dried and shrank. The nailing pattern contributed to the splitting, by concentrating and focusing the forces within the planks to the center where the planks subsequently split. Additionally, the system was not installed in a water-tight fashion as recommended by window manufacturers and by the Southern Cypress Manufacturer’s Association, because caulk was not used were needed to keep water out.
Very truly yours,
Marc Pevar
Encl: CD with images I took when I inspected your home