How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manufactured and modular homes

What is the average life expectancy of plywood siding?

Friday, July 27, 2018

How long does plywood siding last? 

You can expect plywood siding to last  20 to 50 years, with an average of 35 years. It’s difficult to assign a lifespan estimate to any wood product with an exterior exposure to rainy weather and humidity, because a protective paint coating that seals out moisture must be vigilantly maintained. If not, wood-rot fungal growth begins on the surface within weeks in the humid and rainy weather of Florida, and relentlessly eats through the wood over just a few years. Also, because plywood is manufactured by stacking thin sheets of wood with a laminating glue between them, the life of the adhesive is also a factor. 

    Here’s our list of other factors that will shorten or extend how long plywood siding lasts:

1) The shortest lifespan we have seen recently was 15 years, and it appeared to be due to the wood not being adequately primed and painted initially, then not repainted as the original finish deteriorated at 8 to 10 years out. So a good coat of paint and regular repainting is important.

2) It’s also important to keep a good paint finish on the bottom of siding panels for two reasons: the bottom has end-grain wood, which is more absorbent of any water if not sealed, and the bottom of most panels is close the ground, where splash-back from rainwater falling off the roof onto the ground hits it.

3) Plywood siding lasts longer on houses with a gutter system that eliminates the rainwater splash-back against the base of the siding. Keep a maintenance alley between the wall and shrubs planted near the house. Dense bushes growing up against a home, like in in the photo below, keep the wall surface wet longer and promotes mildew, which will deteriorate the paint finish.

4) Many people replace just the bottom one to two feet of their plywood siding  when it shows signs of rot and de-lamination at the base of the panel. This is fine as long as you install a “Z” flashing at the horizontal seam that is created in the wall. Otherwise, it becomes an opening for rain to get into and start a new wood-rot cycle. Just caulking is not sufficient. To read more about it, go to our blog post What is Z flashing? 

5) Secondary areas where premature failure of plywood siding is also likely to occur are at corners and around window and door openings, usually caused by inadequate or deteriorated caulking letting rain water get behind the plywood. A professional painter knows that repainting a house means re-caulking too, but many homeowners skip that step. Be sure to caulk carefully when you repaint, check the caulk beads every few years to see how they are holding up, and touchup as necessary. 

    And here’s a bar graph that compares the life expectancy of plywood to other types of residential siding.
    Go to our blog post What is the average lifespan of the parts of a house? for rating of other house components. To understand the basis, potential use, and limitations of lifespan ratings, see our blog post How accurate are the average life expectancy ratings of home components? Are they actually useful? 

• • • • • • • • • • • • • • • • • • • • • 
Field Guide for Home Inspectors, a quick reference for finding the age of 154 brands of HVAC systems, water heaters, and electrical panels, plus 210 code standards for site-built and manufactured homes, and the life expectancy rating of 195 home components. Available at for $19.95.
• • • • • • • • • • • • • • • • • • • • • • 

To learn more about exterior walls and structures, see these other blog posts:

What is the average lifespan of a house foundation?

What causes vertical cracks in fiber cement siding planks?

What causes raised white lines of residue on a block wall that are crusty and crumbling? 

What is the difference between soil subsidence, heave, creep, and settlement? 

How much ventilation is required for the under-floor crawl space of a home? 

 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?

What causes the surface of old bricks to erode away into sandy powder? 

What are the pros and cons of concrete block versus wood frame construction?

Should I buy a house with a crawl space? 

Why is my stucco cracking?

There's cracks running along the home's concrete tie beam. What's wrong? 

What would cause long horizontal lines of brick mortar to fall out?

How do I recognize serious structural problems in a house?

What is engineered wood siding?

Should I buy a house that has had foundation repair? 

What is a "continuous load path”?

Should I buy a house with asbestos siding?   

How can I tell if cracks in the garage floor are a problem or not? 

What do you look for when inspecting vinyl siding?

Why is housewrap installed on exterior walls under the siding? 

How do I recognize serious structural problems in a house?

Why did so many concrete block homes collapse in Mexico Beach during Hurricane Michael? 

How can I tell if the concrete block walls of my house have vertical steel and concrete reinforcement?

Should I buy a house with structural problems? 

What are those powdery white areas on my brick walls?

What causes cracks in the walls and floors of a house?

How can I tell if the exterior walls of a house are concrete block (CBS) or wood or brick?

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

NOTE: These life expectancies are based on data provided by InterNACHI, NAHB, FannieMae, and our own professional experience. Because of the numerous variables that can affect a lifespan, they should be used as rough guidelines only, and not relied upon as a warranty or guarantee of future performance.

Water Heaters

Water Heater Age

"What Are The

Signs Of..."

Septic Tank Systems

Structure and Rooms

Plumbing Pipes

Termites, Wood Rot

& Pests



When It First

Became Code

"Should I Buy A..."

Park Model Homes


Shingle Roofs




Wind Mitigation

Roof and Attic

"Does A Home


Pool and Spa

"What Is The Difference Between..."




Concrete and

Concrete Block

Metal Roofs


Modular Homes

Rain Gutters

Mold, Lead & Other Contaminants


Older and

Historic Houses

Crawl Spaces

Mobile-Manufactured Homes

Building Permits

Life Expectancy

Clay Soil





Exterior Walls

& Structures


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



Doors and Windows



Electrical Wiring

Click Below  

for Links

to Collections

of Blog Posts

by Subject

Plumbing Drains

and Traps


Smoke & CO Alarms

Aging in Place

Top 5 results given instantly.

Click on magnifying glass

for all search results.






Air Conditioner & Furnace Age/Size


Electrical Switches





Water Intrusion

Electrical - Old

and Obsolete


Foundation Certifications

Tiny Houses

About McGarry and Madsen



Buying a home in North/Central Florida? Check our price for a  team inspection by two FL-licensed contractors and inspectors. Over 8,500 inspections completed in 20+ years. In a hurry? We will get it done for you.

Moisture Problems

Crawl Spaces