How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

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

Friday, June 29, 2018

Florida homeowners tend to have a definite opinion about what is the best wall construction material, and it is often the same type as the home they grew up in. Concrete block has more boosters in South Florida, while wood frame is ahead in Central and North Florida. If you buy a newer two-story home anywhere in Florida you will likely get the equivalent of a chocolate-vanilla swirl cone: concrete block first floor and wood frame second floor.

    We both grew up in concrete block homes in South Florida, so that probably skews our opinion a bit, but here’s our list of the pros and cons of each construction type:

WOOD FRAME

     Pros

  • Better wall insulation - The cavity between wood studs in the wall provides plenty of room for insulation.
  • Faster and less expensive - Wood frame walls go up faster and, while only slightly less expensive for a simple rectangular home, they are much cheaper for homes with complicated exterior wall and window configurations. Running plumbing and electrical through the wall is also easier.
  • Easier to remodel - it is simpler and less expensive to add a window or door to a wood frame wall.

    Cons

  • Perceived as less hurricane-resistant than concrete block - Both wood frame and concrete block homes have to meet the same building code standards for storm resistance, and wood frame homes have been required for about the past 40 years to use extensive metal connectors at top and bottom of the wall, along with “shear wall” reinforcement at corners, to make the walls stronger. But concrete block homes have a long-standing reputation as a better home in a hurricane, even if it is no longer accurate. The Florida Building Code’s enforcement of a “continuous load path” from the ground to the roof of a home has improved the storm resistance of both types of construction.
  • Less termite resistant - Wood frame homes have more wood closer to the ground, so they are more likely to have termite problem. Advances in termite prevention, like bait traps, make both types of construction safer from termites nowadays. 
  • Less resistant to moisture intrusion problems - The exterior sheathing of wood frame homes is wrapped with a moisture-resistant sheet which is carefully taped around all openings. But when water finds its way into a wood wall it does much more damage than at a masonry wall.

CONCRETE BLOCK

     Pros

  • More termite resistant - Termites don’t eat concrete, so the block wall itself is immune to damage, but the wood furring strips running up the interior of the wall as nailers for drywall and the wood baseboard at the floor are fair game for termites to start working their way up the wall. The foundation type of older concrete block homes actually makes them more vulnerable to termites than wood frame.  
  • More forgiving of moisture intrusion - Block walls have the ability to absorb small amounts of water that get through the stucco, and dissipate it through evaporation over time without causing any damage to the interior.
  • Impact resistant - Many of the types of siding that are applied to a wood frame wall, including EIFS, are impact resistant but will be pock-marked at the impacted area. Stucco over block does not have that problem.

     Cons

  • Slower and more expensive - A block wall is more labor-intensive to build.
  • Not as energy efficient - It is difficult to provide a level of insulation in a block wall comparable to a wood frame wall. But block offers a secondary advantage, because of its thermal mass, which absorbs heat during the day and releases it at night. This buffer can smooth out heat transmission through the wall between day and night.

    Many homebuyers automatically assume that a home with stucco exterior walls is concrete block, but they will be wrong about half of the time. Both block and wood frame homes can have a stucco wall finish and, to find out how to tell which type of wall is under the stucco, see our blog post “Do stucco walls mean a house is concrete block? 

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

What are different types of exterior wall construction for a house?

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? 

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?

What are the common problems of different types of house foundations? 

• What are the warning signs of a dangerous deck?

How can I tell whether my house foundation problems are caused by a sinkhole or expansive clay soil?

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