DIY Deck Build - Advisable?

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#2635961 15-Jan-2021 11:56

chevrolux:

I just got the green bags of readymix from Bunnings. Bag at a time in the wheelbarrow kept it manageable. Ended up being a 2 bags a hole (more or less, some holes I got a bit carried away on width wise!)

This stuff?

nickb800

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#2635967 15-Jan-2021 12:02

I'd get a quote for your concrete delivered in a mini mixer. You'll need at least half a cube by my estimation, so you may find the cost of ready-mix to be comparable to buying bags of cement, trailer loads of builders mix, and hiring/buying a mixer

Paul1977

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#2635977 15-Jan-2021 12:10

nickb800: I'd get a quote for your concrete delivered in a mini mixer. You'll need at least half a cube by my estimation, so you may find the cost of ready-mix to be comparable to buying bags of cement, trailer loads of builders mix, and hiring/buying a mixer

Yeah, I'd worked out it would be a good half cube as well. I thought you could only get it delivered in the big trucks, do most concrete places have these mini-mixers?

The benefit of ready-mix bags or mixing my own I guess is can do it at my own pace, and don't need to have every single post pegged exactly in place at once.

Blurtie

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#2635979 15-Jan-2021 12:13

Paul1977:

I borrowed a petrol borer from a work mate. 200mm diameter, then squared the holes with a spade.

A day might have been enough for someone fitter, or more experienced - but it wouldn't have nearly been long enough for me. I'm not overly fit, and it was bloody hard going because of the number of large stones that would stop it in it's tracks (and try to dislocate my shoulder in the process). There was a lot of pulling it out of the hole, dislodging stones and trying again (rinse and repeat). By the time I got to the end I had developed a much better technique - but it was still much harder work than I though it would be.

If there hadn't been all the stones it would have been pretty easy though.

Good on you for giving it a crack.

Speaking from personal experience, I find the highlighted part to be the case with most of my DIY jobs, especially ones where I'm doing a task/job for the first time. Put it down to the learning experience, then bank the knowledge for next time!

nickb800

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#2635988 15-Jan-2021 12:28

Paul1977:

nickb800: I'd get a quote for your concrete delivered in a mini mixer. You'll need at least half a cube by my estimation, so you may find the cost of ready-mix to be comparable to buying bags of cement, trailer loads of builders mix, and hiring/buying a mixer

Yeah, I'd worked out it would be a good half cube as well. I thought you could only get it delivered in the big trucks, do most concrete places have these mini-mixers?

The benefit of ready-mix bags or mixing my own I guess is can do it at my own pace, and don't need to have every single post pegged exactly in place at once.

The big players (Firth, Allied, etc) probably won't do a half cube without a surcharge, but there are intendent mini mixer firms around - just google mini mixer and your area. Could be worth calling the big players and seeing what the cost would be with a small delivery surcharge anyway.

Can see the benefit of doing it hole by hole, but personally I'd take any opportunity to avoid mixing concrete I can!

Paul1977

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#2636160 15-Jan-2021 16:48

nickb800:

The big players (Firth, Allied, etc) probably won't do a half cube without a surcharge, but there are intendent mini mixer firms around - just google mini mixer and your area. Could be worth calling the big players and seeing what the cost would be with a small delivery surcharge anyway.

Can see the benefit of doing it hole by hole, but personally I'd take any opportunity to avoid mixing concrete I can!

@nickb800 Local place quoted $280/m3 inc GST delivered (and even provide the wheel barrow), they don't do half cubes but even getting a full cube still works out a lot cheaper than the bags (as long the they take the left over with them). Worth serious consideration, so thanks for the suggestion.

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duckDecoy

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#2636165 15-Jan-2021 17:05

BlinkyBill:

Thanks for the powerplanter link, it looks good - is it though?

I've found it really good.

WinNZ90

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#2636191 15-Jan-2021 18:44

What about NO concrete/cement?

These here are being used a lot overseas right now, I would probably be more inclined to dig the holes and concrete but I thought I would offer the idea.

https://www.bunnings.com.au/tuffblock-300-x-300-x-90mm-instant-foundation-system-deck-support_p2410345

mdubsnz

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#2636237 15-Jan-2021 19:00

BlinkyBill:
Thanks for the powerplanter link, it looks good - is it though?

YMMV but we found it useless in Auckland clay with an AEG 18V battery drill. Resorted to digging by hand in the end.

Grunta47

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#2636238 15-Jan-2021 19:01

duckDecoy:

My mates dad used this method and it didn't work well at all, didn't stay level. I assume the bracing slowly sagged under the weight or something.

Haha😀. Yep haven’t been over to their house for a while (separation and not a friend of the new guy). Not sure if there are any issues but haven’t heard any complaints/comments. Perhaps your mates dads eye wasn’t quite what it used to be🤔

neb

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#2636239 15-Jan-2021 19:05

WinNZ90:
What about NO concrete/cement?

These here are being used a lot overseas right now, I would probably be more inclined to dig the holes and concrete but I thought I would offer the idea.

Another option I've seen used overseas is expanding foam, not sure if that's allowed here.

A general thought about using quicker/cheaper options though is the standard one about what will it cost in the future. If you need to tear out half your deck and rebuild in a few years time because it's developed a noticeable list to port then that will destroy any small cost saving you can make from cutting corners now.

Another thing, for the OP, let us know when and where you're building and we can turn up with beer and offer ongoing commentary, conflicting advice, and criticism as you're doing it, all at no cost to you. Need to do something now that the Trump circus is almost over :-).

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Grunta47

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#2636255 15-Jan-2021 19:21

Paul1977:

Yep, Mitre 10 document says all holes should be at least 450mm. But the other NZ guides I've looked at (one was Placemakers), and the NZS3604:2011 all say minimum 200mm (for non-bracing/non-anchor piles).

200mm does sound shallow side though, and I want them deeper than that.

Perhaps the Mitre 10 guides says 450mm because it's just better practice?

How high is your deck off the ground? As a minimum you should go for a deck height and have 1/3rd below ground for the piles as a minimum, up to a maximum of course.
If your only 500mm above ground then 300mm depth is enough......but it also depends on the type of ground.

Rock or clay - 300mm is good

Soil or something else soft - 300mm not enough

Since you’ve dug 450mm already and think it’s a bit too deep I would go with what someone else said and just chuck in some old concrete, bricks or rocks to fill up the hole to minimise the amount of concrete required. You could also just refill the hole with what was taken out and compact it with a piece of timber.

And yep, bagged concrete is an expensive way to go if you have lots of posts to do. As you’ve said you’d like to do this in your own time so easiest is builders mix and cement. If you go premix from a concrete company every post hole has to be ready to go as they just turn up and drop off.

Good luck and good to see someone getting into it.

WinNZ90

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#2636261 15-Jan-2021 19:28

And about the grooves on decking timber, I have worked as a builder before and done decking and I asked the some question.

Couple of useful answers from the question tho:

If you live in a really wet place, you place the grooves down to allow the air flow better under the deck between the decking and the joists, this reduces the time in which wet sits between the boards, giving a longer life spanned to the timber. However, if you put the grooves down you have to remember to clean the top of with mould cleaner about once a year or so depending on how wet it does actually get otherwise it will be a great slip and slide. Grooves up in wet places and cold more often than hot, the water tends to pool in the grooves also.

When your in a warmer place thought, where it get quite wet but still quite hot and its going to counter act the wet ie by the beach in the more tropical areas of nz, then it is totally up to you whether or not you have the grooves down or up.

Personally I hate the grooves up but when you have kids, its a matter of having to, to reduce them slipping to much.

And Very true Neb

WinNZ90

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#2636266 15-Jan-2021 19:47

Also going off stuff that Mitre10 and Bunnings says in their tutorials, I have found them to be very biased.

I read and watch their stuff but never just do it how they say, otherwise you spend more money than the professionals would

I find placemakers do better all around informationals and they don't force their stuff down your throats like the others do.

NO I DON'T WORK FOR PLACEMAKERS, NEVER HAVE NEVER WILL, I find them to be far to over priced

WinNZ90

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#2636268 15-Jan-2021 19:55

On the note of hole depth actually, doing a little research here now.

Placemakers says the feet 'concrete at the base' need to be 200 by 200 square and if you post is 300 in the ground, your hole needs to be 400 deep to allow 100mm of concrete underneath the post to do a proper footing.

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