How to build a courtyard deck?

[SparkyStu]

Hi, I'm looking at designing/building an outdoor deck in my courtyard. Can you please help me design it correctly with the correct materials?

It is to go level with the left window sill to have it as high as possible for access from the house sliding door

I have attached what I have considered so far...

Cheers,

Stuart

 

 

[JacobZ]

Hi @SparkyStu,

Thank you for your post and welcome to the Bunnings Workshop community, it is great to have you with us. It's very exciting to see you're getting ready for a decking project; they are one of my personal favourites so I'm more than happy to offer guidance. 

It is common that decks over 10 square meters require approval prior to construction. I would start by enquiring with your local council as to whether you need building approval for this deck.

Unfortunately, according to the National Construction Code, fixing of a waling plate (ledger board) to a brick wall is not permitted as they are not designed to withstand the dead and live loads associated with a deck or balcony. For this reason, I propose this deck will require more posts to support it and align with the NCC. 

H3 treated pine is a good material to use as a frame for your deck but following the bearer and joist tables provided by Hyne Timber, your chosen timbers would not be adequate without an excessive number of posts to support the bearers. I propose you use 240x45 H3 Pine as bearers, supported by three 90x90 posts to each bearer, then use 140x45 H3 Pine as your joists. 

Have a look at the render below for my proposed design. This will allow you to run the boards perpendicular to the door and allow for the picture frame you've drawn in your sketch. I have not included the decking boards as they are not the main structural concern.

 

The proposed design is in line with the NCC requirement to not fix waling plates into brick but should not be used without the approval of a consulting engineer.

I would suggest that an engineer would also require suitable fixings including joist hangers be used to connect the joists to the bearers

Allow me to tag some of our knowledgeable members for their thoughts and if they have anything they can add @Dave-1, @Nailbag, @TedBear. 

Let me know if you have any questions, I'm more than happy to assist further.

Jacob

[Dave-1]

Afternoon @SparkyStu 

I really liked your drawing and idea, Not keen about attaching it to the walls but thought that was just me. Listening to @JacobZ  makes a bunch of sense. So the idea of a freestanding deck not attached to the walls in any way sound like a better move.

The only thing id do different is to use stiffups for the posts to sit into, and make sure the posts dont "sit" resting on the base of the stirrup so they cant rot. One thing to note when digging holes for the posts/stirrups is the foundation of the house will prob extend a little past the brickwork so have the posts along the wall set back by say 300mm so they dont hit concrete.

Looking forward to seeing your new plans

Dave

[SparkyStu]

Hi Jacob, thankyou for your detailed reply and your expert advice. If I went an additional bearer, would I still require 240mm wide h3 pine?

Being that the posts likely can't sit next to the house due to foundation, I will still need to fix to the brickwork because of the overhang (i.e. 300mm gap potentially) wouldn't I? Ideas on this?

Many thanks 🙏 

[JacobZ]

Hi @SparkyStu,

The third bearer is necessary due to the orientation of your decking boards. For the decking to run perpendicular to the door, the joists have to run parallel to the side walls. There is not an advisable way to run joists over a span of 4.8m without engineered lumber or steel.

This is why my design proposes the third bearer, as the joist spans of around 2.4m are far more manageable and achievable with cheaper materials.

I have however noticed that I've made a mistake on the required size of the bearers. As they are supported by 3 posts in my design, it is possible to use either a 190x45 or 190x35 for your bearers.

There is some ability for framing to be cantilevered off of a post and I don't believe 300mm would be excessive for this overhang and size of timber. It may be worth asking an engineer to confirm this before committing to a design.

Let me know if you require further clarification or if you have any other questions.

Jacob

[SparkyStu]

Also, would you suggest checking in the bearers to the posts or sitting on top with some kind of a brace?

[Dave-1]

@SparkyStu 

I generally like checking into the posts, that way they are trully supported. I never go deeper into the post then 1/3rd tho

Dave

[JacobZ]

Hi @SparkyStu,

My preference is to cut a half lap so the bearer can be screwed horizontally into the post and is still supported from underneath by the post. 

Jacob

[SparkyStu]

Dave, why do you suggest stirrups over the posts in the ground?

So I'm only confused about how to fix the posts and bearers at the door end where my posts will sit 300mm out from corners. I get the overhang will be fine on the sides, but what about the end near the door? How do I set that up to be structurally strong. Fix that part to the brickwork? Or do you have a better idea?

[Dave-1]

Afternoon @SparkyStu 

I like stirups as it seperates the timber from the ground, I built my deck freestanding and not attached to the wall as I wanted  it solid and not putting strain on the surrounding brickwork/bessa blocks as the previous people had. Here is the link to stage 1 of my deck from 2011 and its still going strong. I did use recyled hardwood for the timber and new timber for the deck itself.

Pool deck stage 1  There is overhang but the way the beams and then the joists are layed create a solid base with no spring to it. With the three posts  width wise that @JacobZ  has suggested think of it as a jungle gym, the more posts the less likely there will be sway.

With the steps in particular, you could run an extra joist so there will be three at the step, how deep are the stairs themselves? If its too deep you may need some sort of support on the steps/attached or resting but allowing water to drain. If you look at my pool deck you can see how I managed the edge of the concrete to the pool, it is an overhang by 20cm Ish I think, Think layers that will create a base for the boards (the way you want to run them) and work backwards,

Dave