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'How to Decking' - 'How to build Decking'
Building your own timber deck isn't that difficult, but like any DIY job it requires the right material and tools. Before starting a garden decking project it is important to have a clear plan - this step by step guide explains all the stages involved in creating the perfect timber deck.
1. Preparation & Groundwork.
Check for any drainage problems in the area where you plan to build your deck so that you can sort this out before starting. Deck design must maximise airflow through and around the construction to ensure good ventilation.
Carefully mark out the site with builders lines and ensure that it is square. To help create a square deck and determine its overall size, mark out the proposed area using batter boards, pegs and string line. The easiest way of obtaining a right angle is to make a 3'-4'-5' triangle which will give a 90' angle at the corner. Simply measure off a piece of string into 3', 4' and 5' 'unit' lengths with a felt tipped pen. The units can be in feet or metres which ever you prefer.
2 Prepare the Site.
Do not lay the deck directly onto grass. Remove all turf, cover the ground with a permeable membrane or black polythene and then gravel, to prevent weeds from growing. If Polythene is used, pierce a series of holes in it to allow drainage of any surface water. The finished deck must be at least 2 brick courses below the damp course level if attached to the house. If this is not practical, a gap must be left between the house and deck to aid drainage.
3 Ground Level Deck.
This deck is simply a platform on the ground, laid onto a level surface. If you are laying your deck on an existing level concrete area, the framing can be placed directly onto this surface. If you are laying your deck on a non-concrete surface, e.g. grass or clay, lay the framing on patio slabs for additional stability. It is important that this is either well compacted ground or virgin soil. The frame is constructed using 150 x 47mm joist timbers. These should be fixed using galvanised nails. Joists should be fixed at 400mm centres for maximum support. These can be fixed with joist hangers or galvanised nails.
4 Raised/Elevated Deck.
Elevated decks can be free standing or attached to a wall or side of a house. For projects over 600mm - a qualified decking professional should be contacted. Structural posts 100x100x1200mm should be used for raised/elevated decks.
At least half the length of the post should be sunk into the ground and then fixed with concrete, or alternatively concrete feet and dry cement can be used.
Joists should be spaced at 400mm centres. Structural posts should be positioned no more than 1800mm apart.
Use a joist and spirit level to mark the ledger height at the wall.
Joists are attached to the ledger or double beam with galvanised joist hangers. Place a scrap piece of joist material in the joist hanger to set the width of the joist hanger and then nail or screw the joist hanger on the inside of each double beam every 400mm.
Place the joist inside the hanger, and nail or screw through the hanger into the joist.
Noggins are used to keep the joists from twisting or buckling. Measure and square cut noggins to fit snugly between the joists. Attach these in a staggered manner as shown below at 1200 centres.
5 Fixing Deck Boards.
Deck boards should be pre-drilled before screwing to avoid splitting.
Boards should be spaced leaving a minimum of 6mm - 9mm to ensure that there is adequate ventilation.
Deckboards should be fixed at right angles to the joists.They can overhang the edge of the joists at the end or can be trimmed flush with the joints.
A fascia board can be added for a more decorative neat finish.
All cut ends, notches and drill holes must be brushed with a End Coat preservative to maintain the integrity of the pressure treatment and to seal the deck again.
6 Fitting Balustrading.
Balustrading should be assembled and fixed to joists before installing deck boards. Balustrading can finish off ground level decks and must be used on elevated decks for safety. Building regulations state that balustrading must be 1.1 metres high or above. The maximum recommended length of rails between posts is 1.8m. Additional newel posts must be used for longer railing.
The colonial system uses one rail which is used as a handrail, base rail and concealing handrail. It is easiest to assemble the spindles to the hand rails before fixing.
For the colonial system decide where you want the top handrail to be in relation to the Newel post. Draw around the handrail profile onto the face of the newel. Draw two rails, one for the top, one for the base rail.
For the colonial rails, drill the end section of the handrail using an 8mm diameter wood bit, to a depth of 60mm at a distance of 10mm up from the groove in the rail.
Turn the rail over, in the groove of the colonial rail at a distance of 60mm from the end of the handrail drill a 35mm diameter hole to a depth of 18mm using a hinge drill/forstner bit or similar to create an access hole for fitting the balustrading bolt. If you chisel a rebate in the smallest groove of this rail, it can make drilling easier.
The American rail is drilled in the centre of the rail using an 8mm wood bit to a depth of 60mm and a 35mm access hole is drilled on the side face of the rail.
Drill the other end of the handrail in exactly the same way. For the colonial rail on the face of the previously marked newel post, measure up from the groove of the lower pencil drawn handrail section a distance of 10mm.
For the American rail measure up 60mm.
Drill the newel post at this point using a 9.5mm diameter drill bit to a depth of 25mm. Screw the threaded insert of the balustrading bolt into the newel post using a 6mm allen key. Mark and drill the remaining newel posts in exactly the same way and fix inserts into position. Measure a distance of 900mm down the face of the newel, from the top of the handrail and draw a line, which will represent the finished deck board level.
From this line, measure up 75mm and draw the profile of the rail to be level with the line at 75mm above deck board.
Mark and drill all newel posts and rails as previously described.
Screw the threaded bolts into the inserts in the newel posts and position rails onto threaded bolts.
Tighten all rails to newel posts with the combined pressure place and nuts of the balustrading bolt.
For the American rail, use a Cover cap to hide the access hole.
Ensure that all access holes are treated with a End Seal.
7 Fixing Newel Posts.
These are fixed to joists using 100mm landscape screws. If possible fix newels so that two faces can be secured through two joists at 90' to each other.
8 Fixing Colonial Spindles.
When using colonial rails as a baserail - ensure groove faces downwards.
Fix spindles to rails using 40mm galvanised screws, screwing down (top) and up (base).
Spindles should be spaced at approximately 120mm centres - (the gap should be at most 100mm).
Offer up the whole unit including the posts, make sure that the base rail is approximately 75mm above the deck level.
To hide the screws on the top rail, place an additional rail on top and fix by screwing through the underside of the lower rail using a 40mm galvanised screw.
9 Fixing American Spindles.
These Spindles can be cut square, or left at an angle. If you cut them ensure that the exposed surface is treated with End Seal. Space the spindles at 125mm centres, drill, countersink and fix to the side of the top and bottom rails using 40mm galvanised screws.
10 Fitting Steps.
The stair strings should be positioned at right angles to the deck.
The base of the string may need to be cut at an appropriate angle to allow it to sit firmly on the ground, preferably on a solid area.
The strings should be set at a maximum distance of 400mm centres.
Fix these using galvanised brackets or joist hangers.
The treads should then be fixed through the top face of the deckboard using 63mm screws.
Treads are made by cutting deckboards to length.
Allow 30mm to overhang each string.
Any cut ends should be treated with End Seal.
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