How to build a low-level deck between house and retaining wall?

[davidburns1]

I would like to attack a low level deck to my house and portion of a retaining wall close to the home. The  structures would act as  bearers for joist . Is this able to be done iaw correct practice? 

[JacobZ]

Hi @davidburns1,

Many thanks for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.

I've moved your question to a separate discussion so we can keep all the information about your deck in one place.

Is it possible to get some photos and dimensions of the area? This will help our members to offer advice specific to your circumstances. 

Let me know if you need a hand uploading images, I'm more than happy to help.

It is possible to use the external wall of your property as a support for your deck as long as it is in line with Part 3.10.6 Attachment of decks and balconies to external walls of buildings | NCC. Unfortunately, it would not be possible to support it with the retaining wall. 

As there are quite a few requirements for this to be compliant, you may need the assistance of a qualified carpenter if you'd like to go down this route.

It would be much simpler for the deck to remain separate from the house and the retaining wall. You would need to install posts, or joist supports, but there would be much less construction code to interpret.

When left separate from the other structures, your deck can be designed using Timber Span Tables such as those from Hyne Timber.

Allow me to tag some of our helpful members who may be able to offer further advice, @Dave-1, @Jewelleryrescue, @Nailbag.

I'm happy to offer more advice and design considerations once we get some more information and some photos.

Jacob

[Dave-1]

Afternoon @davidburns1 

Just followed your name back from @JacobZ's post to give some thoughts.

First up, do you have any pics of the area? An overall one form a few directsions and maybe a close up of the points you want to use?

As Jacob says you can have the wall attached to the side of the house but there are set rules to follow. I usually try not to attaching to a board as any movement of the house or deck will create that break/fracture point of failure. As to attaching it to a retaining wall, same line of thinking. Wall most likely to move pushing  the deck out of alignment 😕 

I know overall price is always a pain but using the existing sides is a bit of false economy, I made sure my deck wasnt attached to anything as I did not want to have a repair job down the track due to flexing or compression.

One thing to factor in when digging post holes is make sure you dig a little off from the wall of the house otherwise you will hit the foundation concrte Yes I have done so twice lol  The same goes for a foundation of the retaining wall, the concrete could come out further then you realise.

Dave

[Dave-1]

Afternoon @JacobZ 

Wooo I saw the link you had in the last post for span tables... Was thinking "Span tables? that sounds interesting.... Then followed it lol

Just Bookmarked it and am in heaven! That looks like a handy resource.

@davidburns1 just commented against your question.

Dave

[JacobZ]

Hi @Dave-1,

Yes, the span tables are the perfect resource for any aspiring deck builder. I have these saved on my desktop for quick reference whenever the questions come up.

Jacob

[Nailbag]

Hi @davidburns1 @JacobZ suggestion of a freestanding deck is an excellent one as one main concern for me when fixing to retaining walls is they can suffer from long-term movement from over-bearing weight and timbers aging.

Regards, Nailbag