How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manfuactured and modular homes

Is Hardie fiber-cement siding waterproof?

Sunday, January 2, 2022

The answer to this question depends on whether you want to know if the fiber-cement siding material itself is waterproof, or if the wall is waterproof after installation of the siding.

MATERIAL - Hardie and other brands of fiber-cement siding receive a factory coat of primer, or primer and paint, that waterproofs the surface. But some water can be absorbed into the cut ends over time if they are not sealed with paint before installation or caulked. Because fiber-cement is inorganic, it will not rot. But dust accumulation on the satura areas may allow minor mold growth or staining. This is most likely to happen when an unsealed cut end is at the intersection of the side wall of a roof dormer and the roof slope, and too close to the roof surface. 

WALL - No horizontal lapped siding wall is waterproof, whether it is wood, engineered wood, vinyl, or fiber-cement. Lapped siding is very water resistant, but it depends on gravity to create a downward flow of water over the unsealed lap joints after it hits the wall. The driving rain and wind in a severe thunderstorm or hurricane will push some water up into the laps between boards. Because a waterproof housewrap is normally installed under the siding, the water will run down the house wrap and exit harmlessly at the bottom of the wall without damaging the structure. 

    Also, see our articles What causes vertical cracks in fiber cement siding planks? and What are the vertical butt joint requirements for fiber-cement (Hardiplank) lap siding? and What is the average life expectancy of fiber-cement siding? 

• • • • • • • • • • • • • • • • • • • • • • • • • • • •

Here’s links to some of our other articles about EXTERIOR WALLS AND SIDING:

• What are the pros and cons of vinyl siding?

How long does exterior siding last? 

• Can termites eat through siding? 

Do stucco walls mean a house is concrete block?

• What is board and batten siding?

 What causes stair-step cracks in a block or brick wall?

• What causes a horizontal crack in a block or brick wall? 

• How can I tell if a diagonal crack in drywall at the corner of a window or door indicates a structural problem?

• Why is my stucco cracking?

• Can vinyl siding be painted? 

• What does freeze damaged brick look like?

• What causes paint to peel prematurely on the exterior of a house? 

• What are the pros and cons of aluminum siding?

• What is engineered wood siding?

• Should I buy a house with asbestos siding?   

• What are those powdery white areas on my brick walls?

• What is the difference between "composite" and regular wood siding? 

• What causes a vertical crack in an exterior concrete block or brick wall? 

• Can vinyl lap siding be installed diagonally?  

Does stucco need expansion joints? 

• What is a vinyl siding zipper tool? 

     Visit our EXTERIOR WALLS AND STRUCTURE page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

Water Heaters

Water Heater Age

Wells

Septic Tank Systems

Structure and Rooms

Plumbing Pipes

Termites, Wood Rot

& Pests

Sinkholes

Stairs

When It First

Became Code

"Should I Buy A..."

Park Model Homes

Site

Shingle Roofs

Safety

Stucco

Remodeling

Wind Mitigation

Roof and Attic

"Does A Home

Inspector...?"

Pool and Spa

"What Is The Difference Between..."

Radon

Brick

Plumbing

Concrete and

Concrete Block

Metal Roofs

Foundations

Modular Homes

Rain Gutters

Mold, Lead & Other Contaminants

Condominiums

Older and

Historic Houses

Crawl Spaces

Mobile-Manufactured Homes

Building Permits

Life Expectancy

Clay Soil

Insurance

Floors

Insulation

Toilets

Exterior Walls

& Structures

Generators

Common Problems

HUD-Code for

Mobile Homes

Garages and Carports

Flat (Low Slope) Roofs

Electrical Panels

Sprinkler Systems

Electrical Receptacle Outlets

4-Point Inspections

Hurricane Resistance

Frequently Asked Questions (FAQ)

Home Inspection

Heating and Air Conditioning

Building Codes

Fireplaces and Chimneys

Inspector Licensing

& Standards

Energy Efficiency

Washers and Dryers

Electrical

Kitchens

Doors and Windows

(placeholder)

Cracks

Electrical Wiring

Click Below  

for Links

to Collections

of Blog Posts

by Subject

Plumbing Drains

and Traps

Appliances

Smoke & CO Alarms

Aging in Place

Top 5 results given instantly.

Click on magnifying glass

for all search results.

Bathrooms

Lighting

AFCI, CAFCI,

DFCI, & GFCI

Sinks

Air Conditioner & Furnace Age/Size

Attics

Electrical Switches

Siding

Search

This

Site

Water Intrusion

Electrical - Old

and Obsolete

(placeholder)

Foundation Certifications

Tiny Houses

About Us

(placeholder)