Pergola Design Techniques

Pergola is an advisable open cover to compliment any deck or patio area outside your home and it will attract more visitors to enjoy the outdoors. If you will add planting and lattice to the sides, it will give your pergola much privacy and protection from the sun. Climbing plants and the addition of lattice to the roof will give you more shade.

Preparing your Pergola Building Plan 

You need to ensure the dimensions and location of your proposed pergola building are acceptable to your local building office, therefore, this construction will be an advantage to your home. You need to determine if you need to build a traditional four post pergola construction with a particular distance from your home or if your pergola building plan is approved. Your local building office will give you advice on acceptable procedures to secure your pergola posts in your area. 

To speed up any necessary planning permissions for your pergola building plan, you can use your home design software or use a pencil and paper to help you to create the draft of your intended project. Once you get the approval, you need to know where all the underground utilities are running to and from your home. Although building an attached Pergola usually only requires digging footings for two pergola posts, it could be costly if you burst a pipe. 

Measuring for Square

It’s time to measure out the area to ensure that your pergola will be square. The easiest and best way to get it right is placing stakes or boards into the ground and extending mason string raised off the ground and along the extremes. 

(In this diagram we have used red to denote mason's string.)

Length 1 - runs along the wall of the house the full length of the proposed construction.It should be exactly the same length as side 2

Length 2 - represents the outer beam of a parallel beam attached construction, and should be the same as length 1

Length 3 - is the distance the pergola will extend out from your home and should match length 4.

Length 4 - is the distance the pergola will extend out from your home and should match length 3.

At this point we can measure the diagonals to make sure that our pergola building plan is square. When constructing the pergola, it’s also important for you to make sure the fitting beams and rafters are equal length. 

*Note the alphabetical letters is each corner of the diagram:

Measure diagonally from corner a to corner d

Measure diagonally from corner b to corner c

If both diagonal measurements are the same, you can be confident that your plan is square.

This is the same measuring method used for any like construction - including building a deck.

Preparing Pergola pass

To secure the posts for your pergola, its important the procedure is up to your local code and will give the best possible solid foundation. You need to prepare a solid concrete foundation into the ground which reaches below the frost level in your area

Figure 1: The concrete foundation rises to a couple of inches off the ground and the top is rounded off for good drainage.

A galvanized steel metal post anchor is pushed down into the cement and placed into the exact center of the footing before it dries.

These tall two-sided metal post anchors provide more strength than the shorter versions used for anchoring posts of low level decks.

It is important that they are placed square and facing the right direction for the posts to be placed square to the build once the cement is dry.

Leave a small gap between the post and cement footing to allow for good drainage then the posts are secured with 4" machine bolts or as otherwise directed.

Concrete footing will take about three days to fully set unless you are going to use pre-prepared and bagged - quick drying cement which can take mere hours to dry - as per instructions given on the product used.

Concrete footings for a pergola to be built over a deck or patio will mean that the pergola will extend just beyond the surface deck or patio - to where you can dig post holes.

Figure 2: The post is embedded into the cement. It’s advisable to use cedar for this method to ensure that the construction would be reliably long lasting.

Once the hole is dug, small stones are placed on the bottom before pouring in the cement - the stones mean better drainage out of the bottom of the hole. Once the post is in place, it will need to be braced until the cement has completely set.

Figure 3:  This is a method used to secure pergola posts directly onto decking. The post anchors are later covered with wood post trim to hide them.

Although the post anchor is placed directly onto a decking board - the board must rest securely on top of a under-supporting joist and with additional blocking between surrounding joists to provide a strong base.

Figure 4: This is a more secure way to anchor posts to the strongest part of your under-deck construction. Here the posts extend below the level of the deck and are bolted directly into main joists.

We would then still use trim and molding around the base of the post at the deck surface for a neater finish.

You must contact the pergola designers in your area for the better designs