Building a Decking Area

Which Materials?

Decking can be obtained in hardwood and softwood. In the Uk pressure treated softwood which prevents rotting is the most popular choice. Standard materials are available from builders and timber merchants and are usually bought with a guarantee of 20-25 years.

Decking boards range in width from 75mm to 150mm and most come with a choice of groove formation. The grooves on the one side vary to those on the other. The grooves aid in grip, especially when wet.

Step by Step

The principle of creating a decking area is to attach decking boards to horizontal joists which comprise the frame. Depending on whether the decking is to be raised or to lie flat on the floor, the frame is attached to vertical posts or laid at each corner on a concrete base. It is always advisable to consult a professional when undertaking a large project and what follows is a general outline on how to construct a small decking area.

On the floor

1. When working out where the decking is to go and its dimensions, keep in mind that it should be sloping in one direction to improve drainage. When the boards are to be laid, the grooves should run in the same direction as the slope. Also the grooves should run perpendicular to any doorways as to aid gripping the decking when steeping onto it.
2. Decking boards come in standard lengths . When planning the size of the decking area it is always helpful to keep these lengths in mind as to minimize wastage and increase the efficiency of the project.
3. Once the dimensions for the area have been found, the area should be prepared. The area should be fairly level and it is recommended that a membrane is lain to ensure that there is no growth under the decking.
4. A frame consisting of 2x4 should now be built making up the perimeter of the decking. Joists should be attached every 500mm along its length.. This can be achieved by using joist hangers and galvanized screws.
5. To prevent twisting of the joists and to improve in the overall stability, shorter lengths of wood, noggins, should be added every 1-2m, perpendicular to the inside joists. Staggering the noggins makes attaching them to the joists easier.
6. Now that the frame has been built, it can be packed up and leveled into place using concrete blocks concreted into place. The base should be supported at least every 1.5m around its perimeter. It should then be left overnight to dry.
7. You can now place the decking boards into place. These are laid perpendicular or at a 45 degree angle to the inside joists and should be 6 to 10mm apart to aid drainage. If the length of the decking area is greater than the length of a decking strip and two have to be joined, make sure that the line joining the strips are staggered from board to board.
8. Once the decking boards are laid, using a string line cut off the excess of the decking and paint the ends with a sealant.
9. The whole decking area can then be painted for colour if required and a coated with a clear water repellent

Raised

1. Follow points 1 and 2 from above
2. With raised decking, the frame is attached to vertical posts. When the area of the decking has been decided, it should be worked out where the posts will go. The decking should be supported at all four corners and there should be posts every 1.5m around the perimeter. They should be closer, however if the decking will be supporting a heavy load.
3. Holes should be dug 400mm in depth and 300mm wide. A concrete block or a stone should be placed in the bottom of the holes and the posts placed on top. A spirit level is then used to ensure the posts are upright and then concreted into place. The concrete should now be left to harden for 24 hours.
4. Joists should now be attached horizontally to the outside of the posts and at the desired height using bolts. Remember to leave the joists high enough for the railing or banister which is to be attached later.
5. The inside joists can now be attached using joist hangers or galvanized screws/nails. These should be placed every 500mm along the inside of the frame.
6. (As point 5 above) To prevent twisting of the joists and to improve in the overall stability, shorter lengths of wood, noggins, should be added every 1-2m, perpendicular to the inside joists. Staggering the noggins makes attaching them to the joists easier.
7. Follow points 7 to 9 above

Laying a Lawn

• The existing turf should be cut off and turned over or removed
• Depending on the condition of the soil, sand or a sand/soil mix can be laid to condition the area.
• The area should then be leveled
• When laying the turf try to avoid walking on it. If this is not possible use a wide plank of wood, laid down as a walk way
• The turfs should be bonded. This means that the joints are staggered, so that there are no two joints next to each other.
• After the lawn has been laid, take a wide plank, lay it on the lawn and walk over it. Work from one edge of the garden to the other, repeating the process.
• After the lawn has settled (after a good watering) it is not a problem to fine tune any lumps and bumps. The turf will take approximately two weeks to ‘knit in’ and should be kept moist for at least this period.
• Turf comes in varying lengths and widths but all is sold by the square meter (m2).
  To find out how many square meters you require, multiply the length of your garden by the width.

Area (m2) = Length (m) x Width (m)

Landscapers Tips

When laying from one side of a garden to the other, often you will be left with an area narrower than the roll of turf. ‘Cutting in’ is made easier if the roll is placed up against the border/wall etc. and lay overlapping the last roll laid. Then you are able to cut through the overlapping roll and the edge of the overlapped role ensuring a perfect fit.

Laying a Patio

It should be emphasized that every patio laying project comes with many implications and the instructions to follow are merely general guidelines.

• Consideration One
  First and foremost, if patio is to be laid adjacent to your house or garage you must ensure that the finished level is at least 150mm below your damp course (DPC). If existing ground does not allow this you must excavate the ground allowing 50mm (2”) for a sub-base approximately 25mm (1”) for concrete mix and the thickness of the slab. Slabs vary in thickness but are usually between 32 and 50mm.
  
• Consideration Two
  The patio should slope away from the house and excavation should allow for this and consideration should be given to where the surface water will drain.
  
• Consideration Three
  You always need to have your cuts at the least visible edge. Try to have your start point where there will be whole slabs closest to the door or the path commonly used.

How to Lay the Patio

There are two ways to lay a patio but the initial steps remain the same, and this only applies if the base is virgin soil e.g. if the patio is laid on an existing concreted area, sub-base is unnecessary. Unless the ground has been made substantially stable you will need to take the following steps.

Lay 2” of ¾ to dust as a sub-base, raking out to get as close to desired level as possible. Hire a compactor plate and run this over the entire area, ensuring that every part is compacted. This ensures that years of the weight of the slabs plus people walking on it will not compact it further resulting in slab movement. There are many examples of patios laid incorrectly, “if you job is worth doing, its worth doing well”

Once the sub-base has been laid there are two standard ways in which you can proceed. A small area lends itself to using a wet sand cement mix of seven sand to one of cement with a plasticizer additive. Spread the mortar and lay the slab checking its level and desired fall.

A large area is best laid by placing screeding bars on top of your sub-base and leveling. Set a second bar and level using the first as your reference. Mix a semi dry, sharp sand and cement mix (again seven sand to one cement but with no plasticizer additive) and fill in between the screeding bars. Use a straight edge and place on top of the screeding bars then slide over the bars, thus screeding the area. Remove the bars and carefully fill in the remaining gaps where the bars were.

At this point it is merely a case of laying your slabs down with the required gaps in between and using a mallet, tap the slabs down which compresses the screed beneath and ensures a nice stable slab.

Landscapers Tip

The fall away from the house is indicated when the bubble of your spirit level is touching one line of the centre mark.

Grouting

Grouting is a very time consuming part of laying a patio unless a specialized grouting compound is used, which consists of an air cured epoxy compound that you simply brush into the joints and it cures.
The only one that our contracting teams have found to not have any flaws is Romex Easy and comes in grey and neutral.