Deck with Trellis and Lattice

Are you confused about deck construction terms?  Is your contractor talking to you in a foreign language?  He’s not using complex 12-letter words, no, just 7-letter words you never heard before.  It could be worse – he could be using “job talk” – some English sprinkled among all those 4-letter words.  If he is, then dump that 4-letter contractor and find one with a larger vocabulary. They do exist. Really, they do.

I am here to help you speak like a contractor.  Oh, cross that out.  Make it:  “Speak to a contractor.”  I’ll start with a quick story.

Willard and Millicent were first-time homeowners, young and ambitious but inexperienced with home improvement.  They wanted a backyard deck for their growing family  (yes, they will be three in about four months).  They found Ralph of “Ralph’s Home Improvement” on the internet and invited him to their home.

Ralph arrived at 20 minutes past 10 on Saturday morning.  He greeted them in his loud voice and listened to Willard explain what they wanted for about fifteen seconds.  Then Ralph took over, and the conversation turned muddy.

“What you want is a ledger from here to about there, with 24” joists.  We’ll build it four-square with footings all around.  No cantilevers, no sir.  And double bands, we never use no singles.  Flashing on top of the ledger.  Three stringers and a big ole pad over there.  A course we’ll add a hand rail on the edges for the Mrs. and junior, when he comes.  You want lattice?”

 Ralph paused to take a breath, and Willard jumped in:  “What kind of wood do you propose for the frame?”

Ralph glared at him and spoke slowly:  “W e   u s e   # 1   K D   S P F .   Only the best.”

Willard looked a little puzzled.

“You’re worried about it being solid.  Don’t you worry, Willie.  We’ll nail the **** out of it.  And we’ll add some doubles for you.  You want hangers, we’ll throw some hangers in.  And lags.  Some fat ole lags.”

 Millicent and Willard just stared at him.

“I’ll line up those splices and notch the posts.”  He leaned forward and dropped his tone.  “You know those posts run all the way to the ground.  And the sonotubes run d-e-e-p.  You like deep don’t you?  ‘Course you do.  We got a special on cap stock this week.”

Ralph took out a pad of printed forms marked “Contract” and began writing.

Millicent glanced at Willard and quickly said “We need to think about this, Mr. Howe.”

He just stood there with the pen in his hand and his mouth open.

As they walked back into their house, Willard wondered aloud “What was that?”

That was contractorspeak, used to confuse and overwhelm you.  Let me explain those terms so you can slow down the Ralphs of the world and tell them what you really want.  I will start at the top of a deck and work down.

BASIC DECK TERMS, from the top

Trellis or Pergola

         A Trellis is an overhead canopy comprised of widely spaced rafters and purlins, supported by a beam and posts and sometimes to your house.  It offers neither shade nor protection from rain, but it does create a sense of enclosure.  Hang your flowering plants there.  Call it a pergola to sound sophisticated – or to distinguish it phonetically from the much different “lattice”.  To see some intriguing pergolas and an explanation of their components, check out this article dedicated to pergolas.

Guard Rail

Guard Rails, often just called “rails”, prevent people from falling off a deck.  Building Code requires 36″ tall rails on decks 30” or higher.  Rail posts are normally 4×4 members bolted firmly to the deck framing;  they provide the primary support for rail systems.  Rail caps are the horizontal pieces that run along the tops of rails and support your beer or wine glass.  They will also support your child’s milk glass until he knocks it off.  The vertical pieces that fill the space below the rail cap and between the rail posts are called balusters or spindles (if they are round), or pickets (if you live down south).  Put a gate at the top of the stairs and you create a safe outdoor playpen for small children and dogs. (Cats just laugh at such a contrivance.)

Decking refers to the deck flooring.  Decking is often made of weather-resistant wood, like PT (on basic decks) or mahogany or cedar or (if you’re feeling rich) ipe.  A wide variety of manufactured, synthetic decking has also become popular because it promises low maintenance.  (For a discussion of just how low that maintenance is, see Low Maintenance Decks.)  Within the category of synthetic are several types:  Composite decking is composed of wood and plastic fibers.  PVC decking is made entirely of poly vinyl chloride plastic.  “Cap stock” refers to composite flooring that is covered on the top and sides with plastic.

Deck Ledger and Joists

A Ledger is the horizontal frame member that connects a deck to the house.  It must be carefully fastened through the house sheathing to solid framing within.  Galvanized lag bolts were used for many years to fasten ledgers until newer ledger screws arrived to accomplish the task with greater strength and easier installation.  Flashing between the deck ledger and your house is critical to prevent water from penetrating and rotting your house.  Several types are available (including copper and bituthene, a flexible rubber with a very sticky backing).  They are best used in combination.

Joists are the workhorses of a deck frame.  They are often 2×8 or 2×10 members that extend out from the ledger to the deck edge.  Joists lie directly under the flooring and provide primary support.  A joist hanger is a galvanized, U-shaped bracket designed exclusively to attach each joist to the deck ledger.

Supporting the joists is a beam.  Now, all those joists transfer considerable weight onto the beam below, so it must have some beef.  A beam may occasionally be a double 2×8, but more often it is a double 2×10 or larger.  Strictly speaking, a girder is a beam that lies not below the joists, but in the same plane as the joists.  You earn a gold star if you realized that joists attached to a girder need joist hangers to accomplish that connection.

Deck Cantilever

Deck Cantilever

If the deck joists extend past the beam, they create a cantilever  — an overhanging section of deck.  Cantilevers can be very efficient structurally and have other aesthetic and cost advantages, but they must be designed and constructed properly.  For a full explanation of deck cantilevers, see my blog article “What is a Cantilever and Why would Your Deck want one?”.

Beam & Columns

Columns are the large posts (usually 4×6 or 6×6) that carry weight from the beam to the footings below.  Columns are sometimes just called “posts”, as long as the context distinguishes them from rail posts, which support deck rails.

Stairs are just what you think they are.  They are composed of treads you walk on, vertical risers that enclose the space between treads, and stringers underneath that support the entire stair assembly.  Stringers on stairs are like the joists on a deck.  Stairs normally have three or four stringers.  A concrete stair pad forms a platform at the base of stairs to support the stringers and sometimes extends out to become the final step on uneven ground.  Hand Rails are banisters or “grab rails” attached to stair rails to help people keep their balance.

Square Green Lattice

Lattice is skirting made of thin wood strips (or plastic) layered in a diagonal or square pattern and used to enclose the vertical space between a deck and the ground.  Lattice performs no structural purpose and is entirely aesthetic.

Footing Brackets anchor deck columns to their footings.  They should be galvanized steel that firmly fastens the column to its footing and prevents lateral and vertical movement.  Footings are the bases in the ground that support the deck.  They are usually concrete poured into cylindrical forms called sonotubes.  These footings range from 10” to 18” in diameter and extend into the ground down to the frost line prescribed by your state.  As you probably guessed, the depth of frost varies with climate.  In Massachusetts the official frost line is 48” deep; in Connecticut it’s 42”, in southern New Jersey it’s 30”.  In Georgia, contractors just kick the grass away and start framing.

Helical Footings are fairly new to deck construction, although larger helicals have been used in commercial construction for decades.  They consist of a galvanized pipe, about 2” in diameter, with (usually) a single helix welded to at the bottom.  Think “large screw.”  A machine with a hydraulic head twists the helical footing into the ground.  As the steel footing descends, a gauge measures the soil resistance and tells the operator when the footing has achieved the desired bearing capacity.

Hey, we’ve reached the ground!  And we’re nearly finished.  Here are a few other useful deck terms.

A deck’s Frame refers to the system of structural members that support the deck.  The deck ledger, joists, beams, columns, stringers and their related fasteners and braces are all part of a deck’s frame.

Pressure treated wood, aka “PT”, is typically southern yellow pine (in eastern US) that is infused with chemicals which permanently bond with the wood and protect it against rot and termites.  The entire frame of your deck should be PT.  The decking and rails may be another outdoor wood or synthetic.  Ralph boasted about using “SPF” – that’s construction talk for spruce or pine or fir (any of them);  they offer no weather resistance and should not be used outdoors.

A freestanding deck refers to a deck that is self-supporting and imposes no load on an adjacent house, if there is one.  For a full explanation, see “What is a Freestanding Deck.”

Ten o’clock:  Ralph, this means the small hand points to 10 and the large hand points to twelve.  Got it?  Don’t be late again.

Now you have some verbal tools to converse intelligently with a deck contractor and keep him honest.

One final note:  You will be happy to know all ended well for Willie and Millie.  They dumped Ralph and hired a specialized deck building company.  The deck team spent the time to understand what Willie and Millie really wanted, drew detailed 3D drawings, explained the written specifications and all the construction terms.  They offered Willie and Millie a fixed price contract that included a written warranty.  Their stress melted away.  The deck company finished their new composite deck two months before Matilda joined the family. And, hey, the deck has a trellis overhead and is enclosed on all sides by a safety guard rail with a gate at the top of the stairs.  It even has lattice skirting all around the base.  Millie proudly explains all these features (using the best deck construction terms) when the local Mothers’ Club meets on her new deck.

We at Advantage Design & Construction offer professional design and build services for clients west and north of Boston.  Over the past 23 years we have designed and built over 800 projects.  We have enhanced the depth of our expertise by limiting our work to decks, porches, sunrooms, and patios.  To view some of these projects, visit our website.  To learn how we treat our clients, check our ratings on Angie’s List or read about us in an article in Remodeling magazine.  For a free design consultation and a relaxed and rewarding experience, contact us via e-mail, or by phone, 781-273-3500.

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