Deck Building

On this page. A simple decking plan. | Fixing decking boards | Fixing the boards straight over a long run. | A recent Example of a high set deck. | A deck with Modwood Boards and Steel Joists |

Deck - A plan layout of timber joists and boards with steel supports beams .

A simple decking plan.

• I have not used timber bearers for years, The fixings and the surface between the joist and the timber bearer seems to hold moisture and promote rot.   Partly because of this, but also the rising cost of timber has made steel bearers more cost effective.
• Yet I must admit, that I have not gone on to steel for the joists yet, even though a lot of builders use "C" purlin sections.  The advantages of low cost, straight, long lengths can't be ignored, and I would probably use steel joists if I had another deck to build.
• So I have always used timber, hardwood floor joists, and usually hardwood decking.
• I ALWAYS put timber preservative on the joists before fixing them, then more on the tops of the joists before fixing the decking.
• The same applies to the decking boards.  You can never have too much preservative.  Many times I have supplied the timber to the job, along with decking oil and saw stools, and the owner in his spare time has managed to get three or four coats on before we fix.
• I also dab plenty oil onto the end grain of the boards.  Again as much as possible.  It soaks in easily at first so do as much as you can.
• This is all good sound common sense, because the underside of the boards and tops of joists will never get oiled again.

Fixing Decking Boards

I always hand nail the decking boards with 2" bullet head nails.  The thickness is 2.8mm (sorry not got the US equivalent).

The reason I hand nail is that the nails are hot dipped galvanised.  I have not seen a nail gun nail with a good enough coating to last as long as standard galv. nails.  Once a nail starts to rust, it expands (rust takes up something like 7 times as much space as the metal it comes from) and tends to split the joist, which lets in more moisture, and so and so on.

I don't pre drill for the nails much, except for the joints and near cutouts.  Using a 2.5mm drill.  Of course this all depends on the timber that is being used.  Typically I have used new full packs of imported timber that takes the nails well, but that same timber if it has been laying around in opened packs in a timber yard for a year of so could be as hard as the hobs of hell and ever nail will have to be pre-drilled then.

I have never seen the need for twist grip nails, because all the joist timbers I have used have been F17 or stronger hardwood, and they grip the ordinary galv nails to the point of breaking.  In softwood of course it will be different.

Here are some other options for fixing decking boards:

• Another nail that is popular is a full galv, with a spiral grip to the side, Titadeck is a trade name.  Although I have not used them myself  I have heard good reports from guys that have used them.  50mm into hardwood and 65mm into softwood.
• Stainless steel screws.  I have only used screws, when screwing into steel supports.  
  • They are becoming very popular though with amateur deck builders into hardwood, because not everyone can spend hours at a time bumping a nailed floor down.  
  • Use 50 x 10 g square drive. into hardwood, longer into softwood.  You will be doing a lot of screwing so the square drive will be so much more positive in the gun.
  • Pre drill with a good quality tungsten tipped combination drill and countersink bit.  Self embedding heads leave a ragged look and don't work well in tough hardwood.
  • I am not alone in favouring an impact driver for this sort of work.  Gavan in Sydney who runs Dialadeck and has done heaps more decks than I have, recommends one also.  They have to be used to appreciate how good they are.
• Mick in Kunundra, North Queensland has done heaps of decks, and a couple using  secret fixing clips.  
  • He says you have to fix the first and last boards in the normal way, and the rest are fixed with the clips they are called Decktights or something like that.  
  • They allow the board to sit up off the joist a touch which provide an air gap, which has got to be a good thing.
  • Mick says he is not keen on using them on jobs, because they take 2 to 3 times as long to fix, BUT, he says he would use them on a job for himself.

In a perfect world we would be using dead straight timber with no twists.  We very rarely get it.  I have used mostly Selangan Batu, which is a cheap Malaysian hardwood, and out of the pack, it still has many bends in it.  Below is my method of fixing bent decking boards.  This method allows me to fix a few boards at a time without a lot of effort.

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Fixing the boards straight over a long run.

Deck - A system of fixing boards to keep them straight and even over long runs

• I start from a couple of fully nailed off  boards that are fixed straight. 
• Then I measure off a distance for say six or eight boards.  I clamp down to the joists one (or more if necessary) aluminium planks. You could use any straight piece of stiff timber or steel, whatever.  This is one of many jobs where my big Bessy clamps have paid or themselves.
• I lay the boards in position, cut at the joists.  The offcut from the far end piece usually starts the next row at the other end.
• Sometimes the last board in a set has to be forced into position because of the bends in it and the others.  This is acceptable, because I know that I am forcing them straight.
• Working by eye only, I tap in my wedges so that all the gaps look even.
• Usually I put the wedges in at about every 4th joist or so.
• When it is all looking OK to start nailing I go to the ends and tap the joints up tight.  The wedges hold the boards firm.
• I nail up a few selected boards here and there to keep them in position and I nail the last one solid for the next lot to push to.
• This method keeps the boards not only straight, but also parallel.  
• When I am getting close to finishing off I start measuring to the finish edge and if there is a difference in parallel it is easy to set the plank wider at one end than the other to creep a bit at a time to get back to parallel.  A difference of say 20mm over the last 16 boards just can't be seen by eye.
• If I have to rip a board to width at the edge, I use it one board back, with a full size board finishing off.

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A Recent high level Deck

Here are a few photos of a deck that I built a couple of years ago, at the age of 63 with a bad back, arthritis and just plain old age setting in.  It would have been so much easier with a nail gun eh? :-)

Deck - Part of the main area.  The ceiling has a lowered panel with a gap around the edges to allow the hot air to escape through a rotary roof vent.

There are a couple of other photos of this deck, on my steel stairs page and my  roofs page.

Thanks to Chris and Peter for letting me use these photos.  ( Peter has an old Drew Carey video clip that he delights on passing on to anyone who remarks on the size of this deck).

The decking boards here are a hardwood timber called Selangan Batu, which originates in Indonesia, probably Borneo.

As you can see we make use of steel a huge amount.   It is situated on top of a hill, overlooking the sea, so it had to be built as strong as possible.   (Cyclone ctegory 2.5)

Deck - Corridor from the existing house.

The handrails were all steel out of 50 x 25 RHS.

We have a requirement in our building code that we don't have gaps greater than 125mm between any parts of the handrailing or balustrades.

We used a very popular method of filling the gap, Stainless steel wire strained between uprights.  

Just to make a change we also used 12mm compressed cement sheets in a few places.

We cut the sheets with my small Makita wet saw.

Deck - I try to keep the gaps consistent, and do the same gap around any handrail supports.

Deck - Here's a shot looking up at the exposed ends of the floor joists in one section, and the different roofs.  You can see a half round gutter fixed directly to the rafter ends.

Deck - Here's a general view of the deck.  It has access from the old house verandah/deck and also it's own flight of stairs.

All the steelwork was grit blasted class 2.5 and a coat of inorganic zinc silicate primer.
This is the absolute best way to go for steel primer.  It is so tough, it bonds to the steel and can't be shifted.  All site welds were power wire brushed and primed with cold galv.  Then a coat of oil based primer an a coat of full gloss enamel.

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A deck with Modwood Boards and Steel Joists

Deck - A "timber" deck at our local University.  Virtually all hot dipped galvanised steel.  The joists are RHS section and the the decking and step treads are screw fixed to the steel with self embedding wing teks.

Deck - Modwood extrusions.

I originally thought that this material was MDF, but on of my readers, Paul in Brisbane told me that it is a product called "Modwood". (Thanks Paul).

Modwood is according to their website:
"Made from recycled wood and plastic, our products are wood composites. They look and feel like natural timber, but require none of the maintenance of traditional woods. You will not need to paint or stain our products since they already come in three contemporary colours (Redwood, Tallowwood and Grey) and will maintain their beauty for years to come".

I flicked off a couple of the plastic end caps to the boards, to reveal that they are hollow extrusions.  It will be interesting to see how long it hold up in our climate. I can't see it being as durable as solid hardwood, but I do hope it lasts, as the more of this type of material we use, the less we are encouraging the Indonesians etc. in their illegal logging activities.

Deck - The same series of decks, showing built in seating and tables.  The frames for the tables and seats are out of steel, which on a job like this with metalworkers involved is usually cheaper and more durable in our harsh climate that all timber.   Solid timber used for the seats, backs and table tops of course.

Deck - The roofs to the decks were lined on the ceilings in an interesting way that I have not seen done before.  They have used cheap MDF floating flooring.  I looks good and matches the rest of the job.

This shot shows the underside of a 300 dia. roof ventilator, a common addition to roofs in the tropics, to remove the hot air.  They are seldom totally still, even the slightest breeze gets them turning.

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