The Content Of The Article:
- The right wood
- Native wood species
- The right dimensions
- Screws and fittings for wooden terraces
- The height of the wooden terrace
- Distance to the house wall
- The substructure of the wooden terrace
- Set foundations and base stones
- Apply gravel and place the beams
- Lay floor boards of the wooden terrace
- Straight edge
- Large wooden terraces: laying floorboards on joint
- remaining work
Take your time and prepare an exact drawing of your project before the start of construction - it's worth it! Measure exactly the surface intended for the wooden terrace and draw a scale top view with pencil and ruler, taking into account each individual plank, the substructure and the distances between the boards. So you can then calculate exactly how many wooden planks, beams and screws you need. You may even save some money by doing so.
Important: Plan the size of your wooden terrace so that you do not have to cut through any boards lengthwise. If this is unavoidable, you should definitely saw through this floorboard with a circular table saw with a guide rail or have it sawn in at the hardware store.
The right wood
The most popular wood for wooden terraces is Bangkirai, a tropical wood from Southeast Asia. It is very heavy, weather resistant and has a reddish brown color. In addition, there are a number of other tropical wood species with similar properties, but other shades, such as Massaranduba, Garapa or teak. A fundamental problem with tropical wood is - with all constructive advantages - the overexploitation of tropical rainforests. If you choose tropical wood, then you should definitely buy FSC certified wood. FSC stands for Forest Stewartship Council - an international organization committed to sustainable forestry around the world. However, this seal does not offer 100% certainty because it is often forged, especially in the case of highly demanded wood species such as Bangkirai.
Home gardeners appreciate decking boards from Bangkirai. The tropical wood has an attractive color and is very durable. Buy the wood only if it carries an FSC seal
Native wood species
Who wants to play it safe, buys wood from local forestry. For example, decking made of Douglas fir or larch is relatively durable and about 40 percent cheaper than Bangkirai. Robinia wood is even more durable, but also more expensive and harder to obtain. For some years, so-called thermo wood is also offered. A special temperature treatment gives beech or pine wood the same durability as teak. The so-called Wood Plastic Composites (WPC) go one step further. It is a composite material made of wood and plastic, which is also very resistant to weathering and decay.
The right dimensions
Decking boards are usually offered in 14.5 centimeters wide and 2.5 centimeters thick. The length varies depending on the provider between 245 and 397 centimeters. Tip: If your patio is wider and you need to lay two planks on each lane anyway, it's best to buy shorter planks. They are easier to transport and process, also the impact is then not too close to the outer edge of the terrace, which always looks a bit "patched".
The support beams for the wooden floorboards should have a minimum thickness of 4.5 x 9.0 centimeters. The distance between the beams should not exceed 60 centimeters and the projection from the beam to the edge of the terrace should not be more than 2.5 times the beam thickness - in this case 22.5 centimeters. This formula also applies to the plank projection. He should not significantly exceed 2.5 centimeters thick planks 6 centimeters.
Screws and fittings for wooden terraces
All visible screws and metal parts that you use when building your wooden terrace must be made of stainless steel. Reason: Normal wood screws corrode by the moisture and the wood gets ugly black-brown spots on the screw connections. A screw size of 4.5 x 50 millimeters is optimal for the mentioned plank size. Longer screws require more effort and do not make the design much more stable. Best buy countersunk stainless steel screws with partial thread. Specialist retailers have developed screws specially developed for wooden terraces. They have a drill bit that penetrates easily into the wood, and are screwed in with a multi-tooth Allen key. Such screws are also known under the trade name Torx. Torx screws are designed to withstand greater torque than regular Phillips head screws, so when screwed in, they are not as likely to produce sharp-edged burrs that could injure you.
If the wooden terrace is to be completed at ground level with a stone edge, you must pit the underground deep enough
The height of the wooden terrace
Measure your wooden terrace very carefully, especially at height. Especially with wooden terraces on the house you have usually given heights such as the threshold of the patio door. It should be at the level of the decking, so that no dangerous stumbling blocks arise. Rule of thumb: either an exact height connection or a clearly visible step.Also, light wells for basements should not be overbuilt with the wooden terrace of course. In the case of ground-level wooden terraces in the garden, the subsoil must be laid out correspondingly lower than in the case of wooden terraces that protrude above the earth's surface and complete with a plinth panel.
If the wooden decking is not covered, you should install a slight incline of about one percent (one centimeter per meter) along the wooden floorboards so that the rainwater can drain well along the longitudinal grooves. This is especially important in shaded areas, where the terrace does not dry so quickly. The longer the moisture can hold on the wood, the lower the lifetime of the decking. In addition, algae can settle over time and make the surface very slippery.
Distance to the house wall
In many building instructions it is recommended to screw the first support beam directly to the house wall. We advise against this for two reasons: On the one hand, dirt and rainwater collect in the groove between the wall and the wood - an ideal breeding ground for wood-destroying fungi. On the other hand, the wood works and expands in moisture. A firm connection with the house wall can cause tensions in the wood, leading to cracks or bulging. The same applies to the wooden floorboards: they should therefore be laid at least five millimeters away from the house wall - especially if they are parallel to the wall.
The substructure of the wooden terrace
The most difficult step in building a wooden deck is the support structure. There are different types of construction, from simple concrete block substructure to point foundations with beam girders. We recommend a substructure with concrete blocks on small foundations. It is inexpensive and not so rigid, because the beams are on the stone without further attachment, so that the wood can work. Before you start, you should stake out the intended area for the wooden terrace at the corners with metal bars and mark the height of the upper edge of the support bar with a circulating string, taking into account the required slope. The height corresponds to the final height of the terrace minus the thickness of the decking. Then bag the entire surface and replace the topsoil with about 10 to 15 centimeters of filler sand. The ground level after the preparation of the subsoil depends on the desired terrace height: If, as in our example, the terrace covering should be above the ground level, including the side screen, the prepared ground must be about ten centimeters lower than the ground surface.
Example of a wooden terrace: 1 foundation (about 20x20x40 centimeters), 2 filling sand (about 10 to 15 centimeters), 3 plastic fleece, 4 gravel layer (about five centimeters), 5 concrete block (gutter stone, 14x14x15 centimeters), 6 pond liner, 7 wooden beams ( 4.5x9 centimeters), 8 wooden boards (12.5x2.5 centimeters), 9 wooden blocks as spacers, fixed on both sides with metal brackets, 10 wooden planks as a screen
Set foundations and base stones
Now, according to your design drawing, lift 20 x 20 centimeter and 40 centimeter deep foundation holes at a distance of no more than one meter from the center of the hole to the center of the hole along the upper end edge. If you want to make things easier, you can also use a bur. The devices can be borrowed at the hardware store. Fill the foundation holes row by row with earth-moist concrete and compact it thoroughly. Then place a plastic fleece over the finished foundations as protection against weed growth and place one concrete foundation stone per foundation. Square gutter stones in the format 16 x 16 x 14 centimeters are best suited for this purpose. They are also known as basement stones and they are used in road construction for paving the side gutters next to the Bürgerstelg. Tighten a second string, which is at the lower edge of the later support beam, and align the basement stones exactly to this height in rows. To do this, you must either feed them with additional concrete or knock them down with a rubber mallet. In addition, check with a water balance whether every base stone is flat. According to this principle, with a maximum distance of sixty centimeters, you can also lay the foundation rows for the other support beams.
Apply gravel and place the beams
When the concrete has set, you should cover the entire surface with a layer of gravel about five centimeters high. This so-called cleanliness layer ensures that the rainwater quickly seeps into the soil and the humidity is not too high, which increases the life of the patio flooring. Then place the support beams at the exact distance after you have brought them to the right length with a saw. Between the beams and the base stone you should place a 16 x 16 cm piece of pond liner with a smooth surface. It ensures that no moisture enters the stone. If necessary, you can also compensate for slight height tolerances with several layers of pond liner. Tip: If you have to lay two beams on the joint because their length is not sufficient, you should join them together.It is best to use stainless steel perforated plates, which you screw on both sides. The connection should rest on a base stone for static reasons.
Important: Only drill the deck board and not the support beam, otherwise the screw will not have enough hold at the end
Lay floor boards of the wooden terrace
Start at one end and choose a floorboard that is as straight as possible. Place these on the support structure and align them exactly at right angles and, if necessary, at the recommended distance from the house wall. If the planks in the sawmill have not been cut to length at right angles, you should cut one end with a chop saw before installation. Then fasten the board to each support beam at the front and rear with one screw each so that the wood can not bulge when damp.
Care must be taken when screwing to the support beams: For visual reasons, all screws should be exactly in line. As a guide, a taut brickwork string is very helpful. You should pre-drill the screw holes of each plank, at least on hard tropical wood. The drill must be one millimeter larger than the screw, so that the wooden planks can work and are not too much under tension.
Fix a special countersink on the drill with a clamping screw. So the recess for the screw head is milled out in one operation. Some screw manufacturers provide the screw package with a matching drill bit with countersink. To screw in the screws, it is best to use a powerful cordless screwdriver with a matching Torx attachment and replaceable battery, because experience has shown that the current accumulator is quickly depleted, especially in the case of tropical timber. Incidentally, the screws are easier to screw in if you dip them briefly into vegetable oil.
In order to maintain an exact plank spacing of five millimeters everywhere, you should work with spacers made of hardwood or plastic. They are inserted into the joint at the front, in the middle and at the back before screwing the board into place. If the distance varies because a decking board is not quite straight, use a lever clamp or a strap. This allows you to easily press the board into the right position. The spacers get you after screwing, however, usually only with a pair of pliers back out.
For reasons of constructive wood preservation, experts recommend inserting a three-millimeter thick polyamide plastic disc for each screw connection between the plank and the support beam. This has the advantage that planks and support beams have no contact surfaces and dry faster after rainfall. However, this technique is nowadays hardly practiced by professionals even for reasons of time.
In order to get a straight finishing edge, it has proven useful to let the planks at one end first survive a bit and then bring them to a uniform length with a circular saw. Fix a guide rail before sawing with the aid of screw clamps so that the edge becomes exactly straight. Of course, you must calibrate the guide rail in such a way that the floorboards protrude beyond the support beams in the desired length.
Top view on a wooden terrace with professionally attached decking
Large wooden terraces: laying floorboards on joint
For large wooden decks, the construction becomes a bit trickier because the planks are not long enough to cover the entire terrace. In order to achieve a pleasing overall picture, you must take this into account when designing the substructure: Place two support beams side by side on the base stone at points where a new board is to be attached, about three to four centimeters apart. Now start each new row alternately with a longer and a shorter board, so that two mutually offset rows of joints arise. Make sure that the joints are at least five millimeters wide and that the screws are exactly in line. For visual and constructional reasons, you should also screw the respective continuous planks with both side-by-side support beams.
Depending on the construction, you can either enclose the wooden terrace with a plastered edge or - with slightly raised seats - attach a plinth panel so that you do not see the substructure. The plinth panel must be below the decking to avoid water drainage. Also use decking for the panel and cut it to the correct length. They are then fixed laterally to the support beam with stainless steel screws. Ideally, the panel should be flush with the terrace edge without offset. If the distance from the longitudinal beam to the edge of the terrace is too great, for example, you can insert suitable wooden blocks as spacers and fix them with stainless steel angles.
Finally, check all the screws on the wooden terrace and, if necessary, tighten them slightly so that the screw heads do not protrude.Then sand down all corners and edges with emery paper and sanding block or orbital sander so that you can walk barefoot on the terrace without getting injured by wood splinters. At the end you only have to clear the surface with a broom of wood and metal shavings - and you can plan the housewarming party for your new wooden terrace.