Help wanted with first decking project

Hello @TonyMax

Welcome to the Bunnings Worskhop community. It's fabulous to have you join us, and thank you for sharing your questions about building a deck.

It's great that you've found some useful information about deck building in the community. To keep your deck safe from water accumulation underneath, I suggest installing at least two french drains running parallel and equally spaced to provide adequate drainage for the area. Should you encounter very strong rain the french drains you've installed will protect your deck from getting water trapped underneath.

There are no issues with your plan on the framing layout, however, I would recommend drawing your own plan so that you'll be very familiar with the distance of the footings. Please keep in mind that the timber framing you'll be using will determine the distance you can place your footing.

Having pipes running along the wall means that you'll have to modify your deck framing and possibly add extra footing to support this part of the deck. Extra noggins and an independent free-floating frame are some of the things you'll have to consider when going around your pipes.

The good news is that you can purchase stair stringers that are pre-made saving you from having to make them. You'll need to build a cement base at the bottom of the deck for the stringer to be anchored on. As to the mounting of the bearers, you can do either one, in order to level the posts, I suggest using a builders line to mark each post.

Bunnings also has a seven-part series on how to build a deck:

Here are some handy links:

If you have any other questions we can help with, please let us know.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/21721#Comment_21721

Thank you so much Eric for the detailed reply. As I thought it has generated more questions.

Should the French drains run across the slope, one about half way and one at the bottom? I do have a 2 cubic metre rubble drain nearby for stormwater from this building and a nearby shed.

Do decking boards come longer than 6m or will I have to have joins (staggered) on a deck section longer than 6m? Or would you recommend running the decking boards the other way to prevent butt joins?

No doubt there will be more questions along the way.

https://www.workshop.bunnings.com.au/discussion/comment/73584#Comment_73584

I suggest putting the french drain in parallel to the length of your deck pointed toward your rubble drain if possible. I'm afraid 5.7 meters is the longest length you can get in Merbau or composite decking.

As to decking panel orientation, it all depends on your preference regarding which way the boards face. If you wish to have a uniform look, I suggest using a picture frame layout with breaker boards. You can then calculate the lengths you'll need without having any butt joins.

If you need more advice or information, please let us know.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/100240#Comment_100240

Hi Eric,

I've found 6m decking boards:

https://www.bunnings.com.au/90-x-22mm-6-0m-decking-h3-treated-pine_p8032595

Now I'm thinking I'll run the stairs off the short edge of the deck so the deck space will end up 6m x 3m or so, plus stairs and I can run the 6m boards lengthwise.

I've put some pegs in which gives me a better idea of the fall under the deck. The deck finished height is roughly the underside surface of the board in the photos. The shortest peg is 370mm so I've got plenty of room for concrete footings, stirrups and varying length posts, with 120x45mm for bearers and 90x45mm for joists, plus 19mm decking.

With the height of the deck I can probably also do some minor earthworks so that ground falls away from the deck, which will be covered anyway so the ground under the deck won't receive any direct rainfall through the deck.

With the bearer and joist sizes mentioned how far apart should the joists be at a maximum (i.e. what's the minimum number of joists I could get away with)?

Also does anyone have a ballpark figure of the difference in price per square metre between treated pine and merbau decking? This deck is 18 square metres.

https://www.workshop.bunnings.com.au/discussion/comment/116980#Comment_116980

It's great that you've found some 6-meter length decking boards. I suggest having a look at the Hyne Span Table, it should give you a very good idea of how far the bearers and joists should be. I also suggest having a look at this discussion - Low-level composite deck over concrete slab by @Nat2. It's a very good example of a single-level deck frame with uneven mounting to the house.

Pine decking at 6-meters is currently priced at $23.88 and the per linear cost of Merbau is $6.60, when multiplied by 6-meters gives you a value of $39.60. Merbau decking is pre-oiled and should be something you should take into consideration. It is also classified as hardwood and technically will last longer than the pine decking panel.

Doing a bit of earthworks is always a plus and will prevent the bottom of your deck from getting water logged.

Please keep us updated with your progress, we look forward to seeing the start of your decking project.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/126610#Comment_126610

Is this the right sort of timber I'm looking for in bearers and joists?

120 x 45mm Framing MGP10 H2 Blue Pine

90 x 45mm Framing MGP10 H2 Blue Pine

https://www.workshop.bunnings.com.au/discussion/comment/133037#Comment_133037

I suggest using H3-treated timber instead. While H2 is treated, it is used for indoor framing. Whereas H3 is treated not only for insect attacks but against the weather as well.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/136998#Comment_136998

I have another question that's probably easily answered about fixings.

Fixing the posts to the anchors/stirrups and fixing the anchors/stirrups into concrete I know about, but if the bearers sit on top of the posts, and the joists on top of the bearers how are these all fixed together?

https://www.workshop.bunnings.com.au/discussion/comment/139727#Comment_139727

The parts you mentioned are actually fixed to one another, there are several methods on how to join them together. But before we go any further, I suggest looking at the rules and regulations of your local council on building a deck. There possibly will be preferred methods and fixings that they require.

However, I suggest having a look at parts four and five of the Bunnings building a deck series that shows how the bearer is attached to the post and the joist attached to the bearer.

Bunnings build a deck series parts four and five:

If you need further assistance, please let us know.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/141592#Comment_141592

Thanks for that Eric. I've now got stirrups to bolt to the concrete footings and will buy some bolts and gal nails.

My next question is regarding attaching posts for a roof and handrails in the corners and along the edges.

I'll attach a couple of photos, but in the corners (red dots) the posts will be supporting a laserlite roof covering, and the blue dots will just be handrail height posts.

Should I try to mount them inside the edges of the deck surface or just bolt them to the outside?

images (5).jpeg

images (6).jpeg

images (7).jpeg

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/142997#Comment_142997

It's up to you where you position the posts @TonyMax. Personally, I think handrail posts look neater on the inside of the frame, with the decking surrounding them. However, this is slightly more difficult to achieve.

You might like to make the roof a standalone structure. By this, I mean the posts for it go into the ground and do not connect solely to the deck. If it's a standalone structure, its posts support the roof and transfer the weight directly to the ground. If you only bolt the roof's posts to the deck structure, then the deck supports the roof's weight. If the deck supports the roof, you need to consider that additional weight when constructing the deck.

Mitchell

https://www.workshop.bunnings.com.au/discussion/comment/143975#Comment_143975

Thanks Mitchell for the advice.

Now I'm getting into a more detailed plan as I have to start building soon. The plan now is:

Five posts supporting the roof direct into stirrups bolted into concrete footings, with a sixth roof support point attached to the peak of the building (solid red support on the deck roof plan below). Rafters, beams and battens (not shown) attached to posts and roof sheeting, fascias and guttering also attached.

Picture frame two boards width (straddling the posts) around the outside then fill with decking running lengthways inside this.

Stairs using treated pine stringers and treads running off the east and north sides of the deck.

Treated pine handrail with preferably a few runs of stainless wire horizontally filling the gap between handrail and deck.

Questions as a result of my more detailed plan:

Can I have handrail support posts just attached to the deck? If so do I attach them to bearers or joists?

If I run the stainless wire can I drill holes through handrail posts to run the wire and just attach it at the ends?

What are some ways (preferably the easy way) to determine accurately corner/edge locations when the ground under the deck is not level (pictures attached earlier in this thread)?

What else do I need to consider that I haven't asked a dumb question about already?

Deck Floor Plan.jpg Deck Roof Plan.jpg Deck Elevation East.jpg Deck Elevation North.jpg

https://www.workshop.bunnings.com.au/discussion/comment/144736#Comment_144736