Garden Decking Designs – Jetty Deck
The thought of sitting on a deck with a drink or enjoying a quiet dinner overlooking a tranquil lake or pond is very appealing. It is also relatively easy to construct for anyone who has the garden to accommodate the structure.
Decking overhanging water may sound like a recipe for disaster but with the correct guidance it should pose no problems at all. The idea here was to create a peaceful dining area away from the house in which to relax and enjoy the view of the pond. The basics of a cantilever deck are quite easy to understand and work out. No more than 25% or a quarter of the length of the deck must overhang the beam, to a maximum of 1m, as the 75% acts as a counterbalance. If the deck joists are 3.6m, the overhang should be no more than 90cm. Heavier grade joists should be used, no less than 150mm by 47mm. A beam is necessary to spread the load from all the joists to the foundations.
In order to keep the deck profile low a larger beam than necessary was used on its side to support the deck. With the basic design undertaken, the deck could be started. If the pond is a man-made one with a liner, be careful not to damage it when digging the foundations out or by dropping tools in the water.
The use of mains-powered electrical tools near water is highly dangerous, so always keep tools well away from the water. Only use cordless tools when working on the deck itself. Safety is of paramount importance.
1. Start the deck by building the frame on the ground. Check each timber for defects as the extra load of the jetty could cause a failure. Screw each joist together with threefor added security.
2. Level the frame off and use blocks to hold it in place. Now square the frame by measuring from corner to corner across the longest diagonal – if the deck is square the measurements should be the same.
3. On a cantilever deck, the overhang should not exceed more than 25% or 1m of the deck’s width, whichever is the smaller figure. Measure back 25% and mark the sites from the piers.
4. Dig out a hole for the piers and concrete in place. Check to make sure the piers are level and parallel with the frame otherwise the frame will be out of position.
5. Lay the beam across the piers and check the level. Make the distance between the front of the frame and the centre of the beam 25% or less of the deck’s total length.
6. To hold the beam in place constructioncan be used to it to the piers. The frame can then be fixed to the beams by screwing it in at an angle.
7. With the frame in place, fix all the supporting joists at 40cm centres across the frame. The overhang into the pond means that the loading pressure on this deck will be greater than on a ground deck – because of this, it is recommended that 150 x 47mm joists are used.
8. With each end of the joist secured in place,each one to the beam, ensuring that the 40cm centres between joists are maintained.
9. At the back edge of the deck dig foundations and install posts at the two corners opposite the beam. Mark off the correct height using a level on the frame and cut off the excess.
10. With a wood drill, make a hole for the coach bolt to go through and bolt the joist to the post. Repeat further down for security. Make sure you fix the post to the joist that runs out over the pond.
11. Concrete the post in and pack the soil back into the hole with a piece of timber for added weight. Paint all surfaces with preservative before fixing theboards down.
12. Cover the soil underneath the deck with weed block and fix down. Install somein the overhanging part of the support to stop any movement in the joists; with the beam in place there should be no need for any other noggins. As the deck is square the first decking board can be cut at 45° across one end and fixed down to one side of the centre of the corner Leave the other end overhanging the deck and secure as before. Use cordless screwdrivers when working near the water to prevent any accidents.
13. With the use of a 5mm spacer between each board, fix down the next boards and work to the edge. Secure the boards all the way along as you go. This gives a safe position to work from.
14. Screw a straight edge down as a guide and run a circular saw along to finish the deck surface, using eye goggles for protection. Treat all cut surfaces with preservative. Be careful not to drop anything in the pond.