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Guide to Porch & Deck Construction InspectAPedia®  -     Construction details of how to build a deck or porch Deck & Porch construction details & procedures Deck & Porch Construction Materials Choices Deck & Porch Construction & Structural Fasteners Deck & Porch Safety Deck & Porch Railings, Code Requirements, Safety Finishes for Exterior Decks Poor Construction Details and Improper Connections Can Lead to Dangerous Collapse of Decks and Porches

Here we discuss critical safe-construction details for decks and porches, including avoiding deck or porch collapse and unsafe deck stairs and railings. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons. Also see our review of that book.

© Copyright 2009 Daniel Friedman, Steve Bliss, Wiley & Sons, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Photos & Construction Details of Unsafe Compared with Safe Deck Piers & Posts

Our photo at above left shows reinforcement details at a poured concrete pier installed at our New York forensic lab entry deck. The contractor excavated to bedrock (we could not get below the frost line) where he then drilled into the rock to insert wired re-bar to pin the pier to the rock surface. We took this photograph to provide to the building code inspector who could not be present at the time the piers were poured.

Our photo at above right shows an above-grade masonry piers. Structural connectors were used to connect post to pier, post to girder, and joists to a ledger board that was bolted to the building's rim joist.

According to Best Practices Guide to Residential Construction:

In frost-susceptible soils, all deck or porch posts should sit on concrete piers that extend below the frost depth. The tops of the concrete piers should extend slightly above grade to keep the post ends out of standing water.

It is also a good idea to use steel post bases to keep the wood out of direct contact with concrete.

Where uplift from wind is an issue, use structural post bases that are rated for the necessary uplift loads and connected to the concrete with anchor bolts.

Many of these are adjustable laterally so the footing and anchor bolt do not need to be precisely placed. Use pressure-treated posts rated for ground contact with a minimum preservative level of .40 pounds/cubic feet. Treat any cut post ends and do not place cut ends in contact with soil or concrete.

While 4x4 posts can be used up to about 10 feet in height, depending on loads, tall pressure-treated 4x4s are prone to warping and twisting when they dry. Some local codes limit the use of 4x4s to 8 feet. Diagonal sway bracing can help stiffen tall posts and provide resistance against racking. The easiest approach is to run short 2x4 or 4x4 sway braces from posts to beams.

Also see STAIRS, RAILINGS, LANDINGS, RAMPS - INSPECTIONS, CODES and see Building Safety Hazards Guide for a list of other building safety topics for home owners and home inspectors.

Collapsing Deck Piers & Posts

Above are some photographs of short cuts taken to "get the deck up" when proper lengths of post were not available or where piers were re-cast on top of older poured concrete piers that were tipping or collapsing. It is surprising how often we see an extra block or scrap installed to make up for a deck post that is too short. This is an un-stable structure at risk of dangerous collapse (above left).

At above right the original concrete piers were probably not dug deeply enough nor properly constructed and were tipping and sliding down hill. A repair contractor placed a new pier on top of the tipping, sliding, collapsing pier - a dangerous repair. The cross bracing may slow the fall of this deck when it collapses.

Also see Manual for the Inspection of Residential Wood Decks and Balconies for an excellent guide to deck construction inspection and deck safety.

Deck Building Building Permit and Deck Building Code Inspection Warnings

Our photo, left, shows a tall deck that became a porch, constructed by the website editor, Daniel Friedman, in 1983. One of the project conditions requested by the owner was that this high deck should not be wobbly or bouncy (nor unsafe).

We inspected a free-standing deck built nearly eight feet above ground level, and without any railings. The owner wanted the view to remain unobstructed. Our opinion was that this was a dangerous structure and that guard railings were needed. A local inspector examined the deck and opined that because the deck was a free standing structure, "building codes did not apply" and so no guardrail was "required".

In most jurisdictions, home inspectors, building consultants, and builders are not permitted to declare that a structure does or does not comply with local, state, national, or modern building codes. That authority is reserved for the local building code compliance officer.

But in most jurisdictions a building permit and final building code compliance inspections are required to build a deck, regardless of whether or not the deck is attached to the principal structure.

And regardless of what any inspector claims about the "legal requirement" for guard rails on decks, we recommend that for safety, guard rails and stair railings (if stairs are installed) should be provided; if the deck is more than 3 ft. above ground level the requirement for guard railings and stair rails is required by model and most local building codes.

See Codes for Stairs for details about stair building codes and specifications.

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Technical Reviewers & References

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• Daniel Friedman - principal author/editor of the InspectAPedia^® Website
• Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

EXTERIORS of BUILDINGS
STRUCTURAL INSPECTIONS & DEFECTS
ADVANCED INSPECTION METHODS
AGE of a BUILDING - how to determine
BEST CONSTRUCTION PRACTICES GUIDE
CHIMNEY INSPECTION DIAGNOSIS REPAIR
Cracks, Checking or Splitting Beams & Log Homes
CRAWL SPACES
DECK & PORCH CONSTRUCTION
  Deck Piers & Posts
  Deck & Porch Connections to Building
  Deck Flashing at Building
  Deck & Porch Structural Fasteners
  Deck & Porch Steps or Stairs
  Deck & Porch Railings
DECK COLLAPSE Case Study
DECK FLASHING LEAKS, ROT Case Study
DEFINITIONS of Mobile Home, Doublewide, Modular, Panelized
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE
DISASTER BUILDING INSPECTION & REPAIR SAFEY
EARTHQUAKE DAMAGED FOUNDATIONS
ENERGY SAVINGS in BUILDINGS
FLOODS IN BUILDINGS-priorities
FOUNDATION BULGE or LEAN MEASUREMENTS
FOUNDATION CRACKS & DAMAGE GUIDE
FOUNDATION WATERPROOFING
FRAMING DAMAGE, INSPECTION, REPAIR
FRAMING DETAILS for BETTER INSULATION
FRAMING DETAILS for DOUBLE WALL HOUSES
FRT PLYWOOD
LOG HOME GUIDE
PANELIZED CONSTRUCTION & KIT HOMES
MODULAR HOME CONSTRUCTION
MOBILE HOMES, DOUBLEWIDES, TRAILERS
MOISTURE CONTROL in BUILDINGS
ROOFING INSPECTION & REPAIR
ROT, FUNGUS, TERMITES
  TERMITE SHIELDS vs TERMITICIDE
ROT, TIMBER FRAME
SINK HOLES

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Wiley.com and also at Amazon.com. See our book review of this publication.
• Manual for the Inspection of Residential Wood Decks and Balconies, by Cheryl Anderson, Frank Woeste (Forest Products Society), & Joseph Loferski, October 2003, ISBN-13: 978-1892529343, $39.00 at Amazon.com or at the InspectAPediaBookstore
• ...

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