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  1. #1
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    Default Decking Posts - What's the best method?

    Hi guys,
    Forgive me if this has already bee asked somewhere. And this may be to hard a question to answer as every situation is different but is there an industry standard method for doing your posts/stumps for supporting your subfloor.
    It seems to me everyone has a different way.
    1. Post straight into hole, hole has gravel to allow for drainage, fill with concrete
    2. Same as above except people put some sort of protective paint/stain on the part of post which sits in the ground
    3. Some use concrete stumps
    4. Some use post stirrups embedded in the concrete in order to keep post from water damage

    What's everyones thoughts?

    Side note: Whats the general amount of concrete to use in post holes, 2 bags? 3 bags?

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    4K Club Member Marc's Avatar
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    Depends what you are building. Stumps in dirt wouldn't be allowed in termite area but may be in Tassie (?) Stirrups in concrete for a deck but not for a house. timber post in concrete unless under cover is a bad idea ...Concrete and steel post can be used for most things. Brick veneer use mainly brick peers. You will have to be more specific.
    Pre-mixed concrete in a hole ... mm ... for fencing I use 1.5 usually or 2 if a deep hole. For a stirrup I don't use bags since I own a mixer, for post in dirt I use a thick paver under it and gravel ...
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    Hey Marc,
    Thanks for replying. I guess I just mean the standard deck most people get here in Victoria. For instance, say you had a 3m x 5m deck at the back entrance of a house. Regular soil conditions. I reckon if you had 3 different builders build the same deck theres a good chance each would pick a different method. One would use concrete stumps, the other timber posts straight into concrete and the other stirrups in concrete. I suppose I'm asking which would be the best method or industry standard?

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    Concrete stumps.. set and forget!

    If it's real low to the ground, stirrups

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    Ok, so you are talking a deck ... that narrows it down.

    If you get a builder that wants to put timber post in concrete, run away fast.

    Concrete post for a deck? Probably not cost effective and bad for your back, but in theory, nothing wrong with it.

    Considering decks are built by carpenters, and carpenters like to use wood, a deck is made with timber post in stirrups and concrete. Sure you could use steel post, concrete post, brick peers, hardwood post in dirt, large rocks ...

    You could even use steel bearers and joist, metal decking material ... mm ... may be not that last one
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    Quote Originally Posted by Optimus View Post
    Concrete stumps.. set and forget!

    If it's real low to the ground, stirrups
    +1

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    4K Club Member Marc's Avatar
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    Concrete stumps life is probably 100 years and counting, a deck life is 20 years (?). Not much sense using concrete sumps and then treated pine bearers and joist.
    But you can use them, sure.
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    my personal preference is to hang the stirrups from the bearers (low deck) and then concrete around the stirrups. Level the bearer exactly where you need it with props, and then concrete in the stirrups. Nice and easy.
    For a higher deck timber posts on stirrups can be cut once you figure out your bearer heights. Nice and easy.

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    is it a post or a stump?

    in my part of the world a stump holds up a bearer
    a post holds up a roof and/or a balustrade

    different lateral forces at play.

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    Quote Originally Posted by Marc View Post
    Concrete stumps life is probably 100 years and counting, a deck life is 20 years (?). Not much sense using concrete sumps and then treated pine bearers and joist.
    But you can use them, sure.
    Bought from the right places in VIC, 100x100 concrete stumps are cheaper than stirrups. What's wrong with building foundations which last longer than the subfloor? Better than the other way around, I reckon.

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    4K Club Member Marc's Avatar
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    Ha ha, nothing wrong. I think what is wrong is the original question. "What is best or what is industry standard"
    Considering the run of the mill deck is between one to two meters high, I wouldn't even consider concrete post, not to mention that I fix post to bearers first and concrete later, not sure if anyone has ever done that with concrete post. May be with very short ones, but it would be a form of punishment.

    As for making footings for eternity and deck for 20 years there is nothing wrong with it but it is incongruent. It's like having a kitchen sink with golden taps in a tent.

    Usually building materials are used for a purpose and buildings built to a price and not for eternity.
    A DIY builder can do a sub frame for a deck using SHS 100x100x6 every meter and I beam 250x150x10mm for bearer and Iron bark joist 300x100 and there wouldn't be nothing wrong with it, but one would expect the decking boards to be made of African Ivory and not reeded treated pine with the reeds up ...
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    Quote Originally Posted by Marc View Post
    ...not to mention that I fix post to bearers first and concrete later, not sure if anyone has ever done that with concrete post. May be with very short ones, but it would be a form of punishment.

    ...
    That's what Re-stumpers do every day in VIC, and yes, I consider it a form of punishment I would never inflict on myself

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    Marc, every post in this thread you have said something that is false/stupid

    Maybe stick to answering the threads you are familiar with. Makes it hard for people who look on this forum for advice/knowledge.

    You don't need to post for the sake of posting

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    Quote Originally Posted by davegol View Post
    my personal preference is to hang the stirrups from the bearers (low deck) and then concrete around the stirrups. Level the bearer exactly where you need it with props, and then concrete in the stirrups. Nice and easy.
    For a higher deck timber posts on stirrups can be cut once you figure out your bearer heights. Nice and easy.
    Nice method, I like it

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    Quote Originally Posted by r3nov8or View Post
    Bought from the right places in VIC, 100x100 concrete stumps are cheaper than stirrups. What's wrong with building foundations which last longer than the subfloor? Better than the other way around, I reckon.
    I agree

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    So majority vote seems to be post straight into concrete is a no go.
    Stirrups best job

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    Quote Originally Posted by Optimus View Post
    Marc, every post in this thread you have said something that is false/stupid

    Maybe stick to answering the threads you are familiar with. Makes it hard for people who look on this forum for advice/knowledge.

    You don't need to post for the sake of posting
    Opt ... from memory you do restumping right? How many decks have you built? Do you use concrete stumps for 2 meter high decks? Come on man, I know you don't like me but since I have nothing against you, why don't you lay off a tad?
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    Quote Originally Posted by Builderboy View Post
    Hi guys,
    Forgive me if this has already bee asked somewhere. And this may be to hard a question to answer as every situation is different but is there an industry standard method for doing your posts/stumps for supporting your subfloor.
    It seems to me everyone has a different way.
    1. Post straight into hole, hole has gravel to allow for drainage, fill with concrete
    2. Same as above except people put some sort of protective paint/stain on the part of post which sits in the ground
    3. Some use concrete stumps
    4. Some use post stirrups embedded in the concrete in order to keep post from water damage

    What's everyones thoughts?

    Side note: Whats the general amount of concrete to use in post holes, 2 bags? 3 bags?
    All above methods are acceptable, some are better than others.
    Concrete stumps are a VIC thing, NSW don't get them off the shelf like VIC, so we either go for timber or steel posts for decks, brick piers or steel for houses.

    Sort of like most houses in WA are double brick, used to be that way in NSW but now it's all brick veneer.

    The easiest method is to use posts on stirrups ( set the stirrup so the timber is at least 75mm above ground level).

    Few ways of doing them.

    Either set the stirrups in concrete first, or set them in concrete last, depends on the height of the deck.

    If it's a low deck, then build the sub frame, prop it up at the height you want with bricks etc so it's level, then bolt the stirrups on, make sure the foot is in a decent amount in the hole, then pour concrete around it, this is the easiest way to get a strong, level deck.

    If it's a higher deck, set the stirrups in concrete first ensuring they are all in line (very important) heights of stirrups doesn't matter, once concrete dried cut posts to required height using laser level to get all the heights, then build from there.

    As a general rule a footing of 400x400x400 is acceptable but can change depending on site conditions.
    Mieux vaut prévenir que guérir

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    Quote Originally Posted by METRIX View Post
    All above methods are acceptable, some are better than others.
    Concrete stumps are a VIC thing, NSW don't get them off the shelf like VIC, so we either go for timber or steel posts for decks, brick piers or steel for houses.

    Sort of like most houses in WA are double brick, used to be that way in NSW but now it's all brick veneer.

    The easiest method is to use posts on stirrups ( set the stirrup so the timber is at least 75mm above ground level).

    Few ways of doing them, can be set the stirrups up first, or set them in concrete last, depends on the height of the deck, if it's low, then build the sub frame, prop it up so it's level with bricks etc, then bolt the stirrups on, make sure they are a decent amount in the hole, pour concrete around it, this is the easiest to get a strong, level deck.

    If it's a higher deck, set the stirrups in concrete up first, cut posts to required height using laser level, then build from there.

    As a general rule a footing of 400x400x400 is acceptable but can change depending on site conditions.
    Great advice thanks mate

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    Just to ad a little if it's for you and you are thinking design life of many decades, not a couple. Ensure timber can dry by keeping it well clear of the ground, also no horizontal timber to steel contact (or at least minimal), and you can use an plastic spacer to keep the steel off the concrete (minimise rust chances) - so here is one I prepared earlier.

    (Sorry about light, sun has gone down)

    Attached Thumbnails Attached Thumbnails img_0174.jpg  

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    I recently put in plans to a building surveyor for an above ground pool and deck (Victoria). He wouldn't approve posts on stirrups. Said all holes had to be 400 x 600 with a 150mm concrete pad then post straight in on top. Not happy about it, but what else do I do?

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    Change surveyor.
    Science is never settled,
    it advances one funeral at the time.
    Max Planck

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    Default Decking Posts - What's the best method?

    Quote Originally Posted by Marc View Post
    Change surveyor.
    Very difficult to change surveyors mid way.

    x

  24. #24
    4K Club Member Marc's Avatar
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    Sure. But that is not a technical issue. There are many ways to build a deck, as it is clear from this thread. All perfectly legal and acceptable.
    So if you struck a dude that is so narrow minded that states his way is the only way and the rest will not be approved, would you give him your business?
    If you do, you will have to do it his way. If that is a problem, you must get someone who listens to you.
    Science is never settled,
    it advances one funeral at the time.
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    I once (15 years ago) had a council certifier insist I use roof batten straps rather than batten screws. Reason was that he wanted to be able to inspect from the ground! Was my first major extension, so I did it, but the hardware guy just shook his head when I explained...

    Anyway, maybe the type stirrups specified would help, i.e. discuss high wind post anchors with him?

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    4K Club Member Marc's Avatar
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    May be go with the crowd and use concrete post if they are so prevalent over there. The local trade would be used to them. Sometimes it may be wiser just for peace of mind.
    Science is never settled,
    it advances one funeral at the time.
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    I did concrete stumps and they are pretty miserable to work with at best. I was keen on using them due to having an uneven deck height and being in an area with lots of moisture.

    Great part is that your average larger bunnings sell them for cheap and they last a long time, however it takes some knowhow on how to set them in concrete right. They're also quite heavy to deal with - esp the 1.2m varieties.

    I spent many hours trying to work out a good way to get them to stay in position while the concrete set and also getting the right mix of concrete for them. Originally I tried to set them against a string line and later decided to do it by attaching them to the bearer, and then lifting that bearer with car jacks and supporting it all with bricks until the concrete went hard.

    With the first batch of concrete posts (not attached to bearer) in my experience it was really hard to pull them in and out of the hole if you need to realign their height, esp if the concrete mix was either too hard or too wet. Generally I first put the post in the hole, then put some concrete, pulled up the post, backfilled concrete underneath and kept putting more concrete in until the bearer was at height and didn't sink no more, and then back fill with concrete for strength. Long winded process. Make the mix too wet and you'll fight it from sinking, too hard and you're twisting and wacking the damn thing to go lower.

    I think if I did it again, I'd probably use stirrups instead.

    And as above, no surveyer or builder recommeded putting timber into concrete. Big no no.

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    Default Decking Posts - What's the best method?

    With concrete stumps it's generally a 2 person job, put a pad of concrete in the bottom of each hole then one person holds the stump to a string line set 20 mm high while the other person backfills the hole with soil to hold the stump in place. Once you've done a row of stumps you then go along and tap the stump down to final height using a sledge hammer and block of timber. We used to do a house of around 150 stumps in a couple of hours with 4 people.

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    Posts concreted in concrete are ok if the hole is prepped with gravel at bottom, post sits on gravel, and water drains from the side of the post. You get far better stability than stirrups that way.

    its like anything, it can be done properly or done poorly. Decks have a hard life and simply aren't 50 year propositions - what matters most is occasional inspection and maintenance

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    I have never worked with concrete stumps, my mate in Vic said he fills the holes with concrete, then installs the stumps a bit high, lets it go off a little then taps them into the right height.
    Sounds like a PITA to me.
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    Quote Originally Posted by METRIX View Post
    I have never worked with concrete stumps, my mate in Vic said he fills the holes with concrete, then installs the stumps a bit high, lets it go off a little then taps them into the right height.
    Sounds like a PITA to me.
    Especially a PITA if you're on your own and trying to negotiate 1m+ stumps to set at the expected height. I had 18 stumps to concrete and took at least 45min each stump to get it right. Pulling up heavy concrete stumps out of fresh concrete is not easy nor is tryign to push them down even with a mashy hammer. Got to know what you're doing, have the right mix and the right method. If doing concrete, allocate plenty of time to muck around with the posts and bring a mate along to help lift the stumps

    best method for doing stumps I was recommended by a builder was:
    1) put stump in hole
    2) mix up a hard mix of concrete
    3) shovel in about 150mm of concrete
    4) lift up post (may need a second person to help) to desired height or a about 20mm above desired height
    5) line up To level and back fill with more concrete
    6) tap down stump if too high, if too low remove half the concrete and repeat step 4

    The other option is to attach the stumps to the bearer, lift the bearer up and back fill the stumps. Only problem with this I found is tightly attaching non-threaded rod stumps to the bearer - there was always a gap between the stump and bearer. II did do one line of stumps like this and I raised the line of the bearer about 10mm too high and once the concrete dried, I whacked the rod hard to push down the bearer - in one case I needed to make a small trim in the bearer to lower the height. I also found that doing this method gave no flexibility for the stumps as they dried and I had one stump that exhibited a crack after the concrete set - I ended up concreting around the stump around the crack to reinforce it

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    Default Decking Posts - What's the best method?

    We have never filled the holes with concrete,only a 200 mm pad at the bottom. To the best of my knowledge it wasn't recommended to fill the entire hole with concrete unless steel stumps were used. Every chippy or builder has there own way of doing things and the method described by me above is the way we found to be the most effective. It was definitely hard work and you had to work quickly. Not to disappointed that conc stumps aren't used in Tas so unlikely to ever have to do it again.

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    Never realised concrete stumps are a vic thing

    Before buying my first property I probably inspect over 2 dozen houses and anything this side of 1970 had concrete stump footings. Haven't seen many timber stump footing houses down here.

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    I did around 400mm worth of concrete with a 100mm concrete base/pad. Average depth was 600-700mm because that's where I found the good solid clay.

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    There's thousands of house still on original redgum stumps in victoria...

    You should of had a minimum of 150 under the stumps (this is your pad) there is no need to go anymore than 100 above the bottom of the stump.

    The simplicity of the process comes down to experience (like everything in life)

    If i was you, i would of set the whole subfloor frame on bottle jacks (or brick/whatever) and leveled and got it square..

    Then i would of used threaded Rod Concrete stumps and hung all the stumps and poured all in one go...

    No heavy lifting/rushing around or mixing concrete

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    Interesting ! Local builder who checked my soil recommended the 100mm min concrete pad and just pulling posts up to a string line.

    I have pretty tough soil but can see the merits of 150-200mm pad. So many differences between builders out there lol

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    Quote Originally Posted by YoungBolt View Post
    Interesting ! Local builder who checked my soil recommended the 100mm min concrete pad and just pulling posts up to a string line.

    I have pretty tough soil but can see the merits of 150-200mm pad. So many differences between builders out there lol
    The type of soil doesn't change the amount of concrete UNDER the stump...

    The type of soil changes the depth of the hole. Nothing worth worrying about now anyway.. if it was your house foundations i would be worried..

    Have you started the subfloor?

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    Thanks heaps for your advice and input

    I'm building a low lying deck varying from 200mm to 600mm off the ground. Part of a plan to make my slanting courtyard usablez

    subframe is built and boards are now being laid. Subfloor consisted of 90x45 joists at 400mm held down by uni-ties, 200mm batten screws and skew nails. Bearers are 2x09x45mm bearers with FLW of 1100'mm and 1200mm concrete post span along the bearer. Zero bounce on this bad boy.

    y3c7oax_d.jpg

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    Quote Originally Posted by YoungBolt View Post
    Interesting ! Local builder who checked my soil recommended the 100mm min concrete pad and just pulling posts up to a string line.

    I have pretty tough soil but can see the merits of 150-200mm pad. So many differences between builders out there lol
    Your "builder" needs to read AS1684 where 150mm minimum is specified

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