How to work out levels on low deck?

Hi!

I’m thinking of building a wooden deck over this sunken concrete area. But I’m confused with two issues - what ‘level’ to use and if/how I should adjust for the uneven shaped area. See pic below

Level

I’m confused because to make the deck horizontally level/flat, I would build it roughly along the solid yellow line in the picture. But this would mean the deck would get higher and higher compared to the slope of the concrete wall (by about 15cm by the end of the deck). Which I think would look weird. Alternatively see the dotted yellow line if I followed the slope of the concrete wall. Obviously the deck would not be flat if I followed the dotted line. But this may not be a problem as the deck would rarely be walked upon - this sunken area sits near the front door and hardly ever has anyone walking in it. I’m just hoping to clean it up to make it look nicer. Any thoughts on what to do?!

Size

The distance from the concrete wall to the house on one side (Distance A in the pic) is about 97cm, while distance B is about 93cm. So the area gets smaller by about 4cm. Would I just line up the decking board to the concrete wall at the front, and then cut the last decking board near house to size? Cut this final board like a wedge?

Any thoughts would be appreciated!

Find more posts tagged with

Tools and Materials

Decking and Paving

Building and Construction

Landscaping

Comments

MitchellMc

Welcome to the Bunnings Workshop community @johnc1. It's brilliant to have you join us, and many thanks for your question about building a deck.

I'd recommend building the deck flat. Although the deck will have a large gap at one end, it will be neatly covered by fascia boards on the face of the structure. You can use 90mm decking for the top and 140mm for the fascia board. Since it's a decent difference in height from one end to the other, the wider board will assist in covering it.

For the difference in width, 4cm is not an incredible amount. I would work that into constructing the structure and gaps between boards. Build your structure 5mm in from the wall and the concrete slab on the broader end. That's 1cm dealt with, and a 5mm gap is indiscernible. You can then gap your boards slightly wider on the larger end, so if you are using a 5mm spacing, space the boards 7mm on the larger end. Once again not really a noticeable difference. Make minor adjustments to how you build the deck to make up the 4cm. Alternatively, as you've mentioned, you can cut the rear board to suit, which would be a more straightforward approach.

I've put some renderings together for you to illustrate better how you could construct the deck. If you haven't already read through them check out: How to build a deck, How to build a low-level deck and How to build a decking boardwalk.

Please let me know if you have any questions.

Mitchell

Noyade

https://www.workshop.bunnings.com.au/discussion/comment/19640#Comment_19640

Afternoon John!"

"Alternatively see the dotted yellow line if I followed the slope of the concrete wall.

Visually I like the idea of the concrete and deck being at the same level.

Is it decking blasphemy to cut tapered lengths to fit? That's what I was thinking for the piece next to the concrete.

But that's just me - and I've never built a deck. 🤔

Cheers!

Noyade

https://www.workshop.bunnings.com.au/discussion/comment/72481#Comment_72481

By the way - what's to the right of your photo above John? The same gap between concrete and wall?

EricL

Hi @Noyade

Let me tag @johnc1 to make them aware of your question. I think at this point all possibilities are worth considering, it just depends on the final look you're going for. I was thinking along the lines of a terraced step but that would involve more work.

Eric

johnc1

https://www.workshop.bunnings.com.au/discussion/comment/99629#Comment_99629

@Noyade Hi, yes it’s roughly the same gap to the right. I’ve only done rough measurements at this stage

johnc1

https://www.workshop.bunnings.com.au/discussion/comment/72481#Comment_72481

Thanks for your thoughts and picture!

johnc1

https://www.workshop.bunnings.com.au/discussion/comment/19640#Comment_19640

@MitchellMc Thanks very much for your advice and very professional renderings! I didn’t think about using a fascia to cover the higher end but that’s a good idea. And good recommendation about trying to space the decking boards a bit more to make up the difference in width. That would make it look clean

johnc1

https://www.workshop.bunnings.com.au/discussion/comment/19644#Comment_19644

@EricL @Yes I wondered about doing some steps too. Will give it a bit more thought

dowd_hardware

You can always use adjustable deck supports to make the deck flat. Use a pad for suppports - Cruched gravel and a 40mm paver will be enough or you can pour a concrete pad.

johnc1

https://www.workshop.bunnings.com.au/discussion/comment/19648#Comment_19648

@dowd_hardware thanks for your reply. But I’m a bit unsure what you mean by pads? Do you use these for the bearers?

johnc1

https://www.workshop.bunnings.com.au/discussion/comment/19640#Comment_19640

@MitchellMc just thinking more about your idea of using fascia boards. Looking at the rendering, it looks like you run the fascia the on the front and another one on the end (right hand side of pic).

would you just attach the fascia with screws to the front of the treated pine frame? I was thinking of dynabolting the front of the frame into the concrete wall, but for the frame that sits above the concrete wall height I would have to attach to the ground some how. Unsure what would be best for this?

Are you suggesting the bearers would be 140x45 with joists 90x45? I was hoping I could get by with 90x45 for the bearers

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/19648#Comment_19648

Hi @johnc1,

@dowd_hardware is likely referencing something similar to these pedestal feet. They are completely adjustable and are fantastic when working on a sloping foundation. They require a solid base and a paver can be used for this. I've used this method in the article I linked below.

You'd typically run fascia boards on all sides of the deck, even on those abutting the walls; it gives the deck a neat framed finish.

On the front, the fascia is screwed into the timber structure. The pedestal feet @dowd_hardware referenced would be ideal for supporting the frame there.

You have no bearers in this structure as it is a single level. You have the joists and the frame that surround them. The whole frame structure can all be made from 90 x 45mm treated Pine. I recommend the 140mm decking for the fascia as at the higher end, 90mm fascia might not cover the gap at the front. The 140mm fascia can be screwed onto the 90 x 45mm timber. Have a look at this article I put together: How to build a deck. You'll see I have a raised 90 x 45mm structure on pedestal feet. Due to the additional height under the frame, I used 140 x 19mm decking for the fascia to cover the large gap.

Please let me know if you have further questions.

Mitchell

dowd_hardware

https://www.workshop.bunnings.com.au/discussion/comment/72488#Comment_72488

A pad is just what the deck supports (post) go on. Deck can be free standing so they can be on a pad. A pad is just a solid base - use can use timber, bricks, pavers etc

johnc1

https://www.workshop.bunnings.com.au/discussion/comment/72490#Comment_72490

Hi @MitchellMc thank you for your response. I’d never seen those pedestal feet before but they look very easy to use.

Unsure how many pedestal feet I’d need? The distance from left to right in the photo is roughly 3.8metres. Maybe two at either end and two in the middle?

johnc1

https://www.workshop.bunnings.com.au/discussion/comment/99636#Comment_99636

Thanks @dowd_hardware . I’m not familiar with all the building terms!

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/116636#Comment_116636

@johnc1,

You need to support 90 x 45 mm timber roughly every 1000mm. So, if you weren't connecting the frame to the house or the concrete slab at the front, you'd have four supports along the front and four at the back of the structure.

Mitchell

Child Item