Heritage Restoration, Inc.

History and Care of Porches

Porches and deck are an interesting footnote in the development of standardized building techniques.  There is nothing more tragic than preventable injuries or death.  Whenever I hear about porch and deck failure I wonder, was it poor construction, neglect, or both?

 

American building codes did not start until the early 1900’s, during the time where a rash of mechanized technological advances, a new “design” field, and lots of city fires caused a concern about the built environment.  Building traditions evolved very slowly for a thousand years until the 19th century.  Steel, modularized wood products(REAL 2” studs), elevators, and other advances changed the way we built.  Many material tolerances and system performances were essentially untested.

 

While building codes were developed to insure public safety, somehow porches (with a roof) and decks (without a roof) attachment systems were not clearly defined until 2009.  Until then, most porch and deck frames were attached by nailing a “ledger”, or 2x framing, to the sheathing of the house.  If someone was not paying attention, the attachment was only as good as the sheathing.  It was always best to be sure you hit framing, and perhaps a few bolts too.  Porch and deck framing rarely was integral with the house framing.

 

Up to about 1970’s or so, the outside edge of the porch or deck was set on a pier, typically stone or brick.  The cantilever method, where the piers were set in from the front edge, allowed less precise setting of the piers.   The ledger and pier system was fine as long as the ledger stayed dry and the piers did not drop.  Corroding or insufficient fasteners can cause the inside edge to collapse.  If the structure’s outside edge drops or rotates, the ledger can pull out and it collapses.

 

Then there is the quality of the wood used.  I have inspected and repaired, not replaced, hundreds of porch frames from the 19th century.  All the lap joints, notches, cut nails, and untreated wood are usually fine where water and neglect did not destroy them.  While I am not a huge fan of pressure treated wood, it does have its place.  In 2002, pressure treated wood formulation changed from chromated copper arsenate (CCA) by removing the arsenic and relying more on copper, using acid copper chromate, alkaline copper quat (ACQ), copper azole, and copper HDO.  A problem did occur where the greater concentration of copper rotted poorly galvanized steel parts very quickly, although now they sell double dipped galvanized hangers and fasteners.  Stainless steel is fine too.

 

But do not assume that all green-treated wood is equal. The type of preservative, its retention, and quality of treatment are critical to performance. With CCA alternatives, it will be more important to match the type of preservative and its retention with the intended application.  Because the new preservatives are more expensive, the wood is now treated to a lower retention for aboveground use. Wood treated for aboveground use should not be placed in contact with the ground.  Look carefully at the end tag of each piece of treated wood to determine its appropriate end use. It’s very easy for pieces treated for different end uses to be mixed in the same pile.

 

So now that you know the how’s and what’s of porch and deck construction, what do you look for?

 

Movement & Stability

A porch should always be straight and level, sort of.  You want about ¼ of an inch slope per 4 feet, but not an inch or more.  No bounce.  Sometimes I start with a bounce test and end with a jump test.  No rotations.  Movement means something is bad, be it rotting fasteners, failing piers or rotting wood.  Check framing against the house and at the rim.  Railings should not move at all, adding a tenth nail won’t always help.

 

Organic Growth

It’s like eating organic food; the more you have the more it will cost you.  Organic growth is part of the decay process.  All woods, even pressure treated, will rot eventually.  Stop the growth using cleaners, such as: store bought pre-mixed, or ½ bleach and ½ water, or use natural alternatives like strait up white vinegar.  A light pressure washer will not kill the growth, only make it look clean.

 

Water

Water destroys.  Insects, like carpenter ants, love moisture and wood.  Keep gutters clean and functional.  Gutters prevent water from splashing onto a building and direct water with intent.  Yet a non-functioning gutter makes things worse.  If I had to choose, I would say remove a bad gutter and don’t replace it before you let a bad one cause more problems.  Keep it dry, resolve water infiltration before it gets more expensive.

 

Finishes

Protect the wood.  If you cannot paint it, clean it, or are just lazy, then just apply some preservative, not a sealer.  It can’t hurt anything, just perhaps not be as effective as a full prep and finish job.

 

 

 

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