How to Build a Pergola
A pergola is a feature which, basically, consists of a series of upright poles or lengths of wood which are linked together with a number of horizontal sections to form a pleasant pattern or design. Further variations can be achieved by the introduction of different types of materials such as brick or stone for the supporting pillars.
By itself, a well-designed and constructed pergola will add considerably to the appearance of the garden layout, and if it is clothed with suitable climbing or trailing plants, its appearance will be greatly enhanced.
When you contemplate making a pergola, it is important to consider its appearance in relation to the general layout or ‘atmosphere’ of the garden. The design, for example, could be a rustic affair or it could be ‘contemporary’. What is its function to be? Will it have to divide or partition off part of the garden or will it be used as a decorative screen to provide privacy? Depending on the answers to these questions, so will the design be formulated.
The choice of materials for the construction of a pergola is comparatively limited. Larch or pine poles are ideal and can be used dressed or with the bark left on. Dressed poles have had the bark stripped off and the wood treated or varnished. Squared deal, oak or cedarwood are other suitable timbers which make up into very attractive pergolas. Oak is an extremely durable timber but rather difficult to work as it is so hard. It quickly blunts saws and is not easy to cut with a chisel. Cedarwood, on the other hand is a soft, easy-to-use wood which has a natural resistance to rot and insect attack. It will, however, weather to a grey colour unless treated every year or so with a suitable preparation which helps to retain its original beautiful warm colour. It should be used in fairly generous thickness as it is relatively weak — especially in the thinner sections. It is fairly expensive, but well worth the investment as far as appearance and durability are concerned.
Brick or stone can be introduced in the design of a pergola and for the main uprights or supports, these materials provide considerable strength and durability. If care is taken in selection, the appearance of a pergola can be enhanced, especially if rough textured and coloured stone is used. It takes longer to build a pergola using these materials, but the result is well worth the time and effort expended.
There are several important points which must be observed during theof a pergola. Strength is of paramount importance. This is provided by the use of thick section timber and also by inserting the uprights or main pergola supports well into the ground.
The base of each upright should be thoroughly treated with a copper naphthenate wood preservative. Ideally, the bottom 2 ft. of the post should be immersed in a container of this solution for at least two to three hours. Ensure that the timber is treated for several inches above the soil level position.
Each upright or supporting post should be inserted at least 18 in. in the ground and for tall and large pergolas, this depth should be increased to 2 ft. Try to keep the excavation hole as narrow as possible as this ensures more compactness around the upright. When the upright is in position check with a spirit level that it is vertical and at the same time pack a few large pieces of stone or brick around to keep it in place as some cement is poured in Using a piece of wood, work the cement in place and make sure that there are no air pockets left. The top of the cement packing should finish an inch below the surface of the surrounding soil. When the concrete is dry, some soil can be pulled back over it to conceal it.
Ingenuity will play a large part in the design and construction of a pergola feature and anyone who has reasonable skill with saw and hammer will be able to erect some fascinating patterns.