Want to build a deck

[khusnil_deo]

Hi there,

I have an alfresco that I wish to deck out. The alfresco is concreted with the house if that makes sense. Now I have compiled a list as below to take on this projec.

1. a concrete sealer to prevent moisture coming out of the concrete slab.

2. H3 treated 90x45 pine for joists and bearers.

3. Merbau decking 19mm height in the 90mm width.

4. stainless steel decking screws.

5. joist hanger.

6. fixings to fix the joist to the concrete slab.

7. spacers 4mm

8. multitool counter sink drill bit

9. decking oil

now i am having some issues with my concrete slab. the alfresco is a permanent part of the house and is undercover, but having said that, when it rains, there is a slight gush of rain which wets a part of the alfresco (east facing). Now the problem is that my alfresco has a 70mm setdown, there's weep holes just above the very first course of bricks so I prefer not to cover it as it may void the builder's warranty. so now i have a total of just 70mm height to build my deck.

I have narrowed down that I will need to lay the joist flat side up meaning i will have a 45mm height of the joist instead of the 90mm height, then i will use the bracket (Carinya 50x50x40x3.5mm) and position the joist in such a way that there is a 5mm clerance between the concrete slab and the joist. in theory this will give me a 45mm height of joist and 5mm clearance and 19mm height of merbau decking, sufficient to work with a 70mm setdown.

Is there a better way of increasing this clearance? i don't like the idea of the joist sitting in direct contact with the concrete slab thereby shortening the life of my joist and bearers? i have considered the plastic window packers but i have reached a dead end. Can someone please help. I want to do the decking by this weekend and want to order the materials from the green shed.

thank you.

[EricL · Accepted solution]

Hi @khusnil_deo

I'm so sorry but I'm afraid that there is no timber frame that will be sufficient to work in that size of a gap. I don't wish to offer you alternatives that will not give you a good strong deck. If you've seen a deck built in this manner with the wide side of the timber frame facing up, it is because they've taken the risk of building it in this manner. I personally have not seen it built this way and have no idea how they mounted it. Hence, I don't recommend building it this way.

I understand that you are very keen on building this deck. However, I recommend not rushing into this project. Another option is to retile your concrete base with tiles that look like timber. You can increase the height of your concrete base so that it lines up with your deck.

If you need further assistance, please let us know.

Eric

[khusnil_deo]

Hi @EricL  this homeowner built his deck past the weep holes.

[khusnil_deo]

Dear @EricL ,

I was able to scour the internet and seacrh for people who has built their decks when working with a 70mm height.

If you look at the middle picture, the most dirtiest is from a builder who was building their display home. In all the three pictures they put the widest part of the joist facing up. So if i did that and put the joist much closer together, will that work. I believe the placement of the joist is 40cm apart isn't it? I'll put mine at the 30cm apart to prevent wobbling

[MitchellMc]

Hi @khusnil_deo,

I apologise for the delay in my reply.

You can place your joists in whatever orientation you choose. However, they are more structurally sound placed on the thinner edge, as @EricL has pointed out. Decreasing their spacing would be a good way to get around this issue.

Please let me know if you have further questions.

Mitchell

[khusnil_deo]

HI @MitchellMc,

Thats ok, thank you for your reply. I understand you might be away for the Xmas shutdown. I spoke to a few landscapers and carpenters. they said its not a good idea to put the joist widest edge facing up. they recommended to look into steel frame decking. So i sent out a enquiry with Stratco and I'll see how I go. Once I have exhausted my options, I will settle down with the timber look tile and be worry free for as as the adhesive on the tiles hold hahhahah.

[khusnil_deo]

Hi @MitchellMc @EricL @Jason 

I think its wise not to proceed with this decking project as the tolerances are too high to get my levels right. I am going towards the timber look tiles now. I think I will need screeding and how to finish of the edges and that will be my next project to ask questions.

Thank you for your help.

[EricL]

Hi @khusnil_deo

I'm glad you've chosen another type of covering for your cemented area. Increasing the height of your alfresco area will not be too difficult. The key is to prepare the materials before you begin your project. Once you've decided on the type and colour of your tile, the rest of the materials needed will fall into place. Please let us know when you're ready to ask your questions. We will be more than happy to provide you with advice and information.  

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

Eric