Decks Pergola Arbor and Trellis

Pergola
Pergola from the latin 'pergula' a projecting roof, the Italian word 'pergola' refers to a grapevine left on it's trellis for the winter. In the modern sense a pergola is a structure with an open rafter and lattice framework on columns. The pergola trellis-work is laid out horizontally above head height to provide a partial 'roof' and in some gardens were used to grow vines for additional shade hence the Italian reference from the ancient Roman and Egyptian courtyards.

Arbor
Arbor and pergola are sometimes interchanged but a pergola is more similar to a freestanding gazebo where an arbor is typically a smaller stucture and can have it's trellis work vertical as well as horizontal. A true arbor usually includes a bench sheltered underneath for seating which distinguishes it from a trellis but can also be a recessed or somewhat enclosed shaded area. The term arbor, an English word, is believed to be derived from the Anglo-French 'herbe', meaning herb or grass.


Trellis
A trellis has a framework of crossbars that is used to support, train, and display climbing plants, arched trellises are often used in the garden as a gateway feature. A trellis can also be a flat structure that is attached to a wall similar to the image when used over windows and doorways.

Redwood Grades
There are over 30 grades of redwood, the "architectural" Clear heart and Heart B grades are the finest grades but the cost limits our ability to use those for decking. These are used in trim and cabinetry work and come kiln dried which has the moisture content reduced for interior use or on siding for dimensional stability. Being kiln dried doesn't mean it's a higher grade though, decking for example is usually aired in place to conform to it's exterior use.

Construction Heart - Deck Heart
Left is an image of our prefered grade construction heart, it contains knots of varying sizes and other slight imperfections and is cost effective. Being one of the durable heartwood grades it can used on or near soil. The reddish-brown color of heartwood is an indication that it comes from the inner part of the tree which makes it more insect and decay resistant.


Construction Common - Deck Common
Same general characteristics as Construction Heart, but contains sapwood. This grade is commonly found in box stores, the cream colored sapwood from the outer part of the tree doesn't have the heartwood resistance to decay. It can be used in above ground applications but in my opinion it is a must to seal it with a deck stain. For the amount of savings initially we generally stay with con-heart but we can use it when that look is wanted like the image on the right.