Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
EXTERIORS of BUILDINGS
ADHESIVES, EXTERIOR CONSTRUCTION
AGE of a BUILDING - how to determine
ALGAE, FUNGUS, LICHENS, MOSS
ANIMAL ENTRY POINTS in BUILDINGS
ARCHITECTURE & BUILDING COMPONENT ID
BASEMENT WALKOUTS & COVERS
BRICK VENEER WALL Loose, Bulged
BRICK WALL DRAINAGE WEEP HOLES
BOOKSTORE - EXTERIORS
CAULKS & SEALANTS, EXTERIOR
CHIMNEY INSPECTION DIAGNOSIS REPAIR
DECK & PORCH CONSTRUCTION
DECK FINISHES COATINGS PRESERVATIVES
DRYWELLS, FRENCH DRAINS for FLAT SITES
EIFS & STUCCO EXTERIORS
EXTERIOR WALL SIDING TRIM & FINISHES
EXTRACTIVE BLEEDING STAINS
FLASHING on BUILDINGS
GALVANIC SCALE & METAL CORROSION
GLUES ADHESIVES, EXTERIOR CONSTRUCTION
GRADING, DRAINAGE & SITE WORK
GUTTERS & DOWNSPOUTS
HOUSE PARTS, DEFINITIONS
HOUSEWRAP / SHEATHING WRAP
ROOF ICE DAM LEAKS
INSECT INFESTATION / DAMAGE
LEAD POISONING HAZARDS GUIDE
LOG HOME GUIDE
PAINT & STAIN GUIDE, EXTERIOR
PAINT FALURE, DIAGNOSIS, CURE, PREVENTION
PORCHES & Sunrooms
PORCH CONSTRUCTION & SCREENING
RAILINGS, DECK & PORCH
RETAINING WALL DESIGNS, TYPES, DAMAGE
ROOF CLEANING RECOMMENDATIONS
ROT RESISTANT LUMBER
SHEATHING, GYPSUM BOARD
FIBERBOARD SHEATHING, Celotex Homasote & Other
SHEATHING, FOIL FACED - VENTS
SIDING TYPES, INSTALLATION, DEFECTS
SINKHOLES, WARNING SIGNS
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIRS, RAILINGS, LANDINGS, RAMPS
STONE SURFACE CLEANING METHODS
STONE VENEER WALLS
STUCCO WALL METHODS & INSTALLATION
SURFACE GRADING, SITE DRAINAGE
THERMAL EXPANSION CRACKS in BRICK
TREES & SHRUBS, TRIM OFF BUILDING
TRIM, EXTERIOR CHOICES, INSTALLATION
VINYL SIDING or WINDOW PLASTIC ODORS
WATER BARRIERS, EXTERIOR BUILDING
WATER ENTRY in BUILDINGS
WINDOWS & DOORS
Fiber cement board lap siding repair guide.
This article describes repair procedures for cosmetic or functional siding issues that may arise such as loose siding, wind-damaged siding, siding paint or coating failures, and siding gaps, especially gaps at fiber cement siding butt joints where lap siding is installed.
Our page top photo shows loose and improperly installed fiber cement siding on a New York home. We quote from the siding manufacturer's installation guides, contractor guides, and appropriate codes & standards and we debate the pros and cons of caulking vs. flashing for certain siding repairs. We include sources for building siding back flashing & H-flashing products.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
Here we tackle steps to stop ongoing leaks, damage, or to un-do damage from either a sloppy siding installation job or from more normal wear and tear as a building's exterior siding is exposed to weather, kick balls, peeing dogs, squirrels and raccoons, or to my grandsons and granddaughters, all six of whom (Chase, Tanner, Quinn, Sophie, Zoe, Chloe) could be hired as a home wear and tear test gang.
Our close-up photo of a butt joint gap in this fiber cement lap siding (above left) shows the width of the shrinkage gap.
The installers failed to install the recommended backer flashing / weatherproofing at any of the butt joints that we examined and we think the siding was installed wet and possibly not properly end-butted.
Here as well as at page top are photos of loose fiber cement siding.
Considering that in our photo at left the siding should have been lapped (by the board above, typically 1 1/4"), for this end butt joint to be completely out of alignment with its neighbor we figure that the board above was also not properly nailed, possibly bulged as well.
Also notice that the boards are misaligned vertically as well. All of these clues suggest a super high-speed, sloppy siding installation by un-trained and un-supervised installers.
For more diagnosis we ask about the fiber cement siding's original installation & nailing: was the siding installed according to the product specifications for type of nail, nail spacing, overlap, back priming, butt joint and trim joint end priming & caulking? See the product's caulking, nailing, flashing, installation details provided by James Hardie and excerpted in our notes below.
Pin-Back Nailing repairs for loose fiber cement siding
In James Hardie's technical bulletin No. 17, the company provides a description of PinBack nailing for use at loose planks that were "high nailed" at original installation) or where there are problems with gaps, loose planks, or rattling noises.
At left we show a different loose siding problem: where the diagonal end-cut siding was installed against the home's sloping gable-end trim, the installer perhaps couldn't catch a stud, or perhaps s/he simply didn't want to move the ladder to nail the end of the siding board.
Now just a few years later the siding ends are curled away from the building. How can we fix this other than by a complete removal and replacement of this wall covering?
Cures for Buckled Fiber Cement Lap Siding
Buckled fiber cement siding is most likely to occur because the installer failed to give the recommended gap between the ends of the fiber cement boards and abutting vertical trim at corners, windows, doors, etc.
Buckling fiber cement siding may also occur if the product was not properly nailed.
It may be possible to cut an end gap clearance in place between the siding end and vertical trim, wearing proper protective gear to avoid silica dust hazards etc.
Also see Pin Back Nailing discussed above.
At JAMES HARDIE HardiePlank Siding we discuss the failure of this factory-coated fiber cement siding installation.
How to Decide on a Remedy for Paint Failure on Siding
Cosmetic issues: Building owners should also be made aware of possible future cosmetic issues, depending on the repair method used and workmanship;
For cosmetic concerns, if building condition permits a slower approach, consider trying more than one product and method for gap sealing, examining the durability and appearance of the repair after 12 months or longer of weather exposure on the most-challenged building sides.
Details about repair approaches to open butt joints in fiber cement lap siding are give at SIDING, FIBER CEMENT GAP CURES.
There we also discuss adding back flashing to seal open lap siding butt joints against leaks into the wall system.
Cures for Algae, Fungus, Moss, Lichens on Building Siding
Algae, fungus, moss or lichens on siding are usually due to a combination of moisture and shade on the building wall. Plants too close to the building wall, repeated wetting by sprinkler systems, or unnecessarily dense close shade tree growth are conditions that can usually be remedied.
For more about algae, lichens, moss growth on buildings see ALGAE, FUNGUS, LICHENS, MOSS.
Adapted, expanded & excerpted from CertainTeed Corporation's "CertainTeed WeatherBoards™ Fiber Cement Siding Installation Manual" [5a], from "Fiber Cement Siding Best Practices for Effective Job Site Management"[5b] and from JamesHardie Corporation installation instructions and bulletins for JamesHardie HardiePlank lap siding. [12b] and finally also from applicable building codes & standards.
Reader Question: how do I remove individual or bottom fiber cement siding boards?
20 January 2015 Tony said:
Great Question, Tony. I have had to deal with this problem on FC shingle siding, lap siding and also on slate roofs.
If the FC siding has been painted such that the lower edge of the upper board is sealed tightly to the one below, cut the paint seal with a utility knife.
Then use one of the following methods to cut the nails holding the lower board:
If the lower edge of the upper board above the one to be removed is face-nailed through the lower edge of the upper board, reaching between the two boards, cut the nails with a hacksaw blade or slating tool as I describe next:
For slate roofs there is a hammer-tool that can be used for some siding removal - the tool slips up under the upper slate, a sharp flat hook slides over the nail, an outside handle of the tool is hammered down to cut the nail - but you may have trouble finding this tool.
But you can see it - the bright blue tool illustrated near the top of the article - at SLATE ROOF SOURCES & TOOLS and shown at left.
Alternatively, working carefully so as not to break the Hardie Lap boards above the ones to be removed, you can use a hacksaw blade to slip up between the boards, slide it horizontally to find the next nail, then saw through the nail. Buy a few metal-cutting hacksaw blades and a simple handle that attaches to one end of the blade leaving about 6" of free hacksaw blade.
If the FC lap siding boards are nailed very tightly you may be able to reach up under the board you are going to remove, using a flat bar, to pry GENTLY at the top of the board, beneath thus the board to be removed and the lower edge of the board course above it, prying thus between the back of the lower board and the wall sheathing, just enough to open the boards enough to go back to the hacksaw. Don't pry too much or you'l break the board above.
If the lower board was blind-nailed, that is nailed to the wall through its upper edge such that the second course lapped over the nails holding the first course board in place, you'll need to ....
Gently pry up the lower board using a flat bar beneath its lower edge just enough to be able to slide the flat bar up to the upper edge of the board to find where it is nailed.
From that position you probably can't use the hacksaw trick I describe above, but you can use either the slating tool I describe to cut the nails OR you can use a thin flat bar to drive up, cutting each nail in position.
Take care not to pry too much or you'll break the boards above.
More details about removing fragile or brittle siding materials are at ASBESTOS CEMENT SHINGLE REMOVAL
Continue reading at SIDING, FIBER CEMENT MAINTENANCE or select a topic from the More Reading links shown below.
Suggested citation for this web page
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
No FAQs have been posted for this page. Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Questions & answers or comments about the cause & cure of butt joint gaps in fiber-cement siding.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
HTML Comment Box is loading comments...
Technical Reviewers & References