Low-level deck

[jinugu]

Help required experts.

I am attaching herewith a drawing (very crude) with what I was proposing (Drawing is not to scale & none of the timber will touch the floor except the posts). I want a low level deck (to avoid steps/avoid stumbling). I haven't provided the ground clearance etc because it's is flexible. I have seen else where in this workgroup that the deck will be classified as low level if its within 400 mm from the ground.

Some additional information :

1. External frame : 150 X 55 Treated timber. Fixed to the posts p1-p10. The external frame would not be touching he ground i.e will be screwed /nailed accordingly to the post. 

2. Bearer 1 will be fixed to the post at p1,p5 & p6, bearer 3 to post at p2, p12 & p7 and so forth.

3. Bearer 2 will be fixed to the post p11 (also intend to use angle bracket for additional strength) and the ends to the external frames on joist hangers j1 & j2. Bearer 4 to post 13 and the ends to external frame j3 & j4. 

4. May use noggins for support between the bearers for eg B1 & B2 and so on and so forth.

Any help will be very much appreciated.

Regards

Ravi

[MitchellMc]

Welcome to the Bunnings Workshop community Ravi (@jinugu). It's great to have you join us, and many thanks for your question about constructing decks.

If you haven't already read through it, this guide on How to build a low-level deck will be useful.

You appear to have a reasonably unique layout going on there, and I can only imagine the design is due to some external factors. Typically your joists would be evenly spaced at 450mm intervals across the deck. That's more like 11 joists instead of the seven in your current design. You'd also really be pushing 90 x 45 to span 1670mm. You'd likely be better off with two supports over the 3340mm width.

I'll be keen to offer more assistance. Please let me know what questions you have.

Mitchell

[jinugu]

Hi Mitchell

Many thanks for your reply. I had read through the guide that you have mentioned before I wrote.

I wanted a low level deck as I want the height of the deck more or less aligned (as much as I could) to height of the pavement. 

Pic of my place where I want the deck on is outlined in yellow

I have a few questions. I am a novice so pls pardon my ignorance. The only other DIY I have done is the sail you can see in the picture. I am sure your sharp eyes would have noted all that I have to state below. However, I just wanted to reiterate.

1. Joists from what I have read are fixed to the frame using joist hangers. In the design I have proposed I am strengthening by 
2. Screwing/nailing the joist(s) to the external frame.
3. The joists wont sit on the top of the post. Instead, they will be nailed/screwed to the posts and also intend to use angle brackets to further strengthen. In addition, I also propose to use noggins to provide that additional support.

    Does the above in any way help me avoid additional joists (and posts)?

1. Does increasing the no of joists (and additional support over the 3340mm width as you say) mean increase in the no of posts as well? If yes, how many more. If i am not asking for too much, could you pls scribble a rough drawing for me?
2. What depth and width do you recommend for the post holes in the above scenario.

My drawing/design was derived from the below image  

Thank you very much.

Shall wait to hear from you.

Regards

Ravi Jinugu

[jinugu]

Hi

You might already know - i wanted to fix my joists to the posts in this fashion. In addition a angular bracket. The external frame attaches to the posts in the same fashion. I got this pic from another thread of discussion.

Regards

Ravi Jinugu

[MitchellMc]

Hi Ravi (@jinugu),

There are some minimal building requirements when it comes to a basic deck. Your joists are spaced 450mm apart, and each joist must be supported at regular intervals. Anything over 1.5m supports for the joists is pushing the limits. I'll include a basic diagram of what would be considered a fairly minimal design for your deck.

Mitchell

[jinugu]

Thank you very much. One last question - what should be the ideal post dimensions I. E depth and width of the hole?

Much appreciated.

Thanks Mitchell

Regards

Ravi

[MitchellMc]

Here's our available H4 treated Pine posts for in-ground use Ravi (@jinugu). The soil type determines footer sizes (depth and width of the hole) in your area. Your local council might have these details, or a survey might need to be completed to determine this. In stiff soil, the footer might need to be 450mm wide, but it could be 600mm in soft ground. The National Construction Code of Australia outlines the different types of soils and the performance requirements for each soil condition.

Please let me know if you have any questions.

Mitchell

[jinugu]

Hi Mitchell

Thanks for for your message.

Before I start the project, I have a few questions(and am sure will have few more):

1. As can be seen in the pic (of my backyard), there are a few pavers all along in the area
of decking(proposed). Would you recommend using the paver as a support i.e the post will
rest on the paver (instead of under the ground). That way I will have 2 supports over the 3340 mm width as you have recommended, though not evenly distributed.
2. Would you recommend the use of noggins for more support.
3. for the joists (90 X 45 ) - do you recommend H3.2 timber. For the framing 150 X 45 mm what type would you recommend.
4. What height would you recommend (from the ground - its a low level deck) and how to ensure that air flows under the deck to prevent rotting.
5. Frame : I was to use 150 X 45 mm - from the basic diagram it looks like the frame is also 90 X 45. Is that what you meant?
6. Based on your comments on the footings, looks like i will have to do a trench. 450 mm X 11 = 4950 mm, the size of the
lengthier side of the deck is 4880 mm. 

Thanks for your help. I will wait to hear from you.

Ravi

[EricL]

Hi @jinugu

Have you thought about using Pedestal Feet or TuffBlock 300 x 300 x 90mm Instant Foundation System Deck Support? There is even a concrete footing called DEKO 250 x 150 x 150mm Instant Concrete Foundation Block. These are excellent footing alternatives and It will save you a lot of digging. 

Let me try and answer some of your questions:

• You can use your paver as a base, however, you'll need to use either Pedestal Feet or TuffBlock 300 x 300 x 90mm Instant Foundation System Deck Support. I propose putting at least 4 support posts per joist.

• Using noggins will stiffen the deck structure and is highly recommended.

• Both timber sizes will work for your proposed build. Using a single-sized timber piece would be more economical.

• It is important that drainage under the deck be addressed. Water must flow away from the area. Water must not pool under the deck. Using weed mat and gravel will help facilitate drainage. The area must be slightly sloped or have adequate drain pipes laid out so that water will flow away from the deck. The deck frame must be high enough that you will get good airflow and allow moisture to escape.

• Can you please rephrase your last question?   

I recommend looking at the other low-level deck builds our members have shared. 

Here is a link for ideas and inspiration: Inspiring low-level deck builds

If you need further assistance, please let us know.

Eric

[jinugu]

Hi Eric

Yes, I had seen the reviews for Deko (Which somehow appeals the most bcoz of the weight and the stability it will bring) and unfortunately the size (where the joist is to sit) it appears form the reviews is erratic.

Thanks for your advice on joggins

As regards the size of the timber. Noted your advice. Based on the basic diagram from Mitchell, seems like no joist hangers are required? As I see it, the joists are to be screwed/nailed to the posts. Am I correct? (that’s what I proposed in my first post as well) 

For the joists , size proposed by me is 90 X 45, do you recommend H3.2 timber?

As for the height from the ground, I thought 270 - 300 mm will be good. What's your advice.

Ignore my last question.

Thanks. Will wait to hear.