Low-level deck

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

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Comments

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

https://www.workshop.bunnings.com.au/discussion/comment/17349#Comment_17349

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.

Joists from what I have read are fixed to the frame using joist hangers. In the design I have proposed I am strengthening by
Screwing/nailing the joist(s) to the external frame.
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)?

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?
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

https://www.workshop.bunnings.com.au/discussion/comment/17349#Comment_17349

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

https://www.workshop.bunnings.com.au/discussion/comment/71301#Comment_71301

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

https://www.workshop.bunnings.com.au/discussion/comment/98884#Comment_98884

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

https://www.workshop.bunnings.com.au/discussion/comment/116235#Comment_116235

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

https://www.workshop.bunnings.com.au/discussion/comment/126131#Comment_126131

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

https://www.workshop.bunnings.com.au/discussion/comment/132766#Comment_132766

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

https://www.workshop.bunnings.com.au/discussion/comment/136829#Comment_136829

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.

https://www.workshop.bunnings.com.au/discussion/comment/139606#Comment_139606

It is important to level the area first if you're planning on using the DEKO 250 x 150 x 150mm Instant Concrete Foundation Block.

I recommend using joist hangers as it provides better overall support for the joist. When choosing your timber, please remember that it has to be rated for framing/outdoor use. A rating of H3.2 is sufficient for your needs.

If we measure the DEKO foundation block you'll see that it is 150mm tall. But when the timber sits inside the gap the actual height is only 110mm. So if we add the actual height of the DEKO and the 90x45 you will get an overall height of 200mm. But the actual gap from the bottom of the timber to the soil is only 110mm. If you are using standard 90 x 19mm L/M Decking Merbau SpecRite Pre Oiled KD Select the overall height of your deck will be 219mm. Anything you add under the DEKO Foundation Block will make the deck go higher.

Here is the link to the DEKO block: Deko Instant Foundation Block

If you need further assistance, please let us know.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/141503#Comment_141503

Hi Eric

Thanks for the reply. I don't intend to use Deko, i had rather stick to the posts (and digging) which i am a bit familiar with. Levelling the area itself would be a bigger task for me. Thanks for the info on rating of timber. With the design that Mitchell has proposed, there is no place for me to put the joist hangers (assuming that I will have to screw/nail the posts to the joists ) . That's what it appears to me. Would you be able to give me an idea of how I could use joist under these circumstances?

Regards

Ravi Jinugu

https://www.workshop.bunnings.com.au/discussion/comment/142920#Comment_142920

I've placed a picture of a joist hanger below and how it is attached to the frame.

If you need further assistance, please let me know.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/143910#Comment_143910

Hi Eric Sorry for the barrage of questions. Pls have a look at the the image I had attached. With the joists screwed to posts, where and how do i put the joist hangers. Thanks

https://www.workshop.bunnings.com.au/discussion/comment/144684#Comment_144684

Your right, there is no space for the joist hangers. From my understanding the footing can be moved back a bit so that you will have space for the joist hangers. Let me just double check this with @MitchellMc when he comes back. As soon as I have more information, I'll get back to you.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/144684#Comment_144684

As @EricL mentioned, you can set the post back slightly from the frame to allow the installation of joist hangers.

Mitchell

https://www.workshop.bunnings.com.au/discussion/comment/145247#Comment_145247

Thanks Mitchell. Appreciate your help. I am sure I will have more questions. Thanks once again.

https://www.workshop.bunnings.com.au/discussion/comment/145247#Comment_145247

Hi Mitchel/Eric

I must say you guys are very patient. One more question. When you say 'back slightly from the frame", would it be

1. where the green square is shown i.e a little bit to the right of the joist hanger and so will still support the frame? or partly on top of the joist hanger?

2. or is it where the purple arrow is shown in the image below ( i am sure it won't be this option since in this case the post will not be supporting the frame at all)

A small pic will really help me. many thanks for your help.

p.s in any case the joists will be supported by the posts in the middle (i.e other than the ones attached to the frame) as shown in the image below

https://www.workshop.bunnings.com.au/discussion/comment/145696#Comment_145696

It is on the purple arrow and not on the green square. Support must be given to the joist as it carries all the weight. Depending on the type of post you are using, the example I've drawn up is with a 90 x 90 post. Have a look at the sketch and if you have any other questions, don't hesitate to post them.

If you need further assistance, please let us know.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/146031#Comment_146031

Thanks Eric. From the image I can see that the post is cut to let the joist sit on it. Will it work if I just attach them together without the cut - still nailed to the joust though.

https://www.workshop.bunnings.com.au/discussion/comment/146323#Comment_146323

The frame is connected to the joists via the hangers, so it doesn't need its own post. You can screw through the frame directly into the ends of the joists with bugle screws instead of using the hangers.

You can connect the joists to the posts without the cut if you use a couple of bolts. I wouldn't suggest using nails, though.

Mitchell

https://www.workshop.bunnings.com.au/discussion/comment/146556#Comment_146556

Thanks Mitchell.

I am just reconfirming. I can get away with not using the joist hangers, instead screw the through the frame directly into the ends of the joists?

I almost have my plan of action ready, time to execute. Lastly which decking board would you recommend?

Ravi

https://www.workshop.bunnings.com.au/discussion/comment/146757#Comment_146757

That's correct, @jinugu. You don't need to use joist hangers. The frame can be fixed into position with screws instead.

For the decking board, check out this helpful guide: How to select decking timber. I'd recommend Treated Pine if you're on a strict budget. Merbau/Stringybark/Blackbutt/Ironbark/Tallowwood for beautiful, long-lasting hardwood options. Or, for a no-maintenance solution, you should consider composite decking.

Personally, I can't go past a good hardwood and am currently building my deck out of Merbau.

Please let me know if you have any questions.

Mitchell

https://www.workshop.bunnings.com.au/discussion/comment/146912#Comment_146912

Hi Mitchell

I have started working on my project. I got some one to dig holes for me. Since, I am working alone I am doing it a bit different to what normally people would do. I am just aligning all the posts before I pour concrete. I didn't want to do a lot of timber cutting, hence bought precut posts. 600 mm in length - circa 400mm in ground and 200 above. The problem i now have is, i don't have enough space to use the batten screws to fix the joists to the frame. can i use angle brackets instead? (i know the work i have done so far looks shabby at its best but this is only my 2nd project - the first one was a shade sail). I will wait for your reply.

https://www.workshop.bunnings.com.au/discussion/comment/147046#Comment_147046

Thank you so much for posting an update on your low-level deck project. If you're going to use angle brackets for the "joist" or that outside piece of framing timber, I suggest levelling and aligning everything in place first, then pour the concrete into the footings. You can then attach that piece of timber after everything is in place.

I'm sure @MitchellMc will add more information in case I've missed anything.

If you need further assistance, please let us know.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/147151#Comment_147151

Thanks Eric.

Hi Mitchell

Do you have anything else to add?

Also, could you post a link to the ones (angle brackets) you would recommend. Thanks

https://www.workshop.bunnings.com.au/discussion/comment/147249#Comment_147249

Given your method, I highly suggest you get yourself a 1200mm level and make sure those joists are perfectly positioned before concreting them in.

Something like this Carinya 100 x 100 x 40 x 6mm Galvanised Heavy Duty Angle Bracket - single should suffice.

Mitchell

https://www.workshop.bunnings.com.au/discussion/comment/147333#Comment_147333

Many thanks Mitchell. I have bought a level.

Some of the joists themselves are not straight (a little curved). How do I fix it? chisel doesn't look like an option for me. Some time ago I looked up the website there was something better available (don't remember the name) Any suggestions. Thanks

Usually, the posts are placed into the ground first and are lined up using a builders line and concreted in place. Then the timber framing is attached to the posts which force them to straighten out using the nut and bolt assembly. In this instance, we can't do that anymore as you have already drilled into the timber frame and posts.

Your current option is to try and level the frame as best you can before fixing them in place. If you need to trim a bit of the top of the frame, I suggest using a Planer to flatten the top of the timber. Please note that over planing the timber frame will compromise its strength.

I recommend using Dunnings 40 x 40 x 40 x 5mm M12 Galvanised Angle Bracket to attach the outside timber piece.

If you need further assistance, please let us know.

Eric

https://www.workshop.bunnings.com.au/discussion/comment/18157#Comment_18157

Many thanks Eric

I was aware of the usual practice i.e posts placed in ground first ... and i understand that's the best way to do it.

I would have struggled to get the posts correct i.e in line and all at the same height (i am working alone - no help what so ever until this stage except for digging holes for which i used the services of a handyman - and may not have help going forward as well). I thought the process I have used will give me the best chance to get all the posts at the equal height. I will concrete in the first row (joist) to the desired height i.e 200 mm from the ground and take that as a reference point for the other rows. Thanks for suggesting the planer; i had that in mind and your advice just reaffirmed my thoughts. I will use the planer only sparingly, as i can see that the joists are not very crooked. I have some spare joists just in case I need to replace the crooked ones.

Thanks for suggesting the angle bracket. I will keep updating the project with pics for your thoughts and suggestions. I will take a wee while but intend to complete latest by the end of this month.

Thanks for all your help.

Best regards

Ravi Jinugu

https://www.workshop.bunnings.com.au/discussion/comment/71736#Comment_71736

Hi Eric long time. I couldn't finish within the time frame I set for myself. But finally I managed to. I had to take the help of a handy man. Could have been better (in terms of finish), but still happy with the end result. Costed me atleast 25% less than what the cheapest builder quoted. Some quoted 4900$ + gst. Thank you so much. Your comments based on the attached picture pls. What could have been done better. Do you recommend applying paint? If yes, your recommendations. Budget ones.

Thanks Ravi

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