Basements in Australia, What to Consider

Jackson on 07/02/2023 - 00:20

I have decided to add a basement to my planned home, but I realised that I don't know anyone with a basement. It will be dug out and mostly underground, and I am wondering what tips people have, especially the sort of stuff that you need to think about pre or during construction that you cant do later.

Of course there water proofing and double Ag lines and things to mitigate water ingress, but there's also choice of materials and their natural properties. Another thing is I want to make the most of the space, so I want to make sure it's ventilated appropriately, and have been considering whether it's worth putting in heat shifters to warm it or cool it depending on the weather. It will be in Sydney for reference.

I also don't want it to be musty, and I have heard of people putting their heat pump hot water in there to keep it dry, but I don't know if that would be an issue or make it too cold.

Anyone with any knowledge or experience in this area I would lbe grateful to hear from you.

Home & Garden

Comments

  • jv on 07/02/2023 - 00:29
    +1

    Basements in Australia, what to consider

    They are usually below the ground floor.

  • AustriaBargain on 07/02/2023 - 03:17

    Soundproofing is probably worth it if your children could be spending a lot of their adult life mooching down there.

    • Jackson on 07/02/2023 - 07:41

      It's basically concrete bunker, do you mean that the noise will just bounce off the hard surfaces? The ceiling/ground floor is also concrete

  • bargaino on 07/02/2023 - 04:07
    +4

    Why?
    Basements used to be dug in cold climates to get below the frost line. Not really a thing here.
    It makes more sense to build up than dig down, assuming you are short of space.
    How about a nice loft instead?

    • Jackson on 07/02/2023 - 07:43
      +1

      Additional space and council regs, lofts end up being considered a level when they are larger than a certain size (same as basements), however lofts end up breaking the maximum wall and roof height limits, so basement it is.

      On the climate part, I have read a few different things, on one hand people say it's always cool down there even in summer, which makes sense, but the I have heard it's also warmer than the rest of the house in winter. One of my main goals is to try to take advantage of that, either by using the basement in itself or shifting warm or cold air to other levels and vice versa

      • boomramada on 07/02/2023 - 08:04

        I don't think you gain much of economic benefit by cycling air. More like cycling the not so fresh air.
        However, perfect as wine cellar.

      • bargaino on 07/02/2023 - 11:30

        A basement has natural insulation and thermal mass. But you can achieve similar with a well-insulated home on a concrete slab. Internal brick walls even better, though I believe that's uncommon in Sydney.
        Ground-based heating/cooling does not really make sense in Australia. You are better off putting the effort into insulation, passive solar design, and a small reverse-cycle aircon.
        I can't say much about your council regulations :-(

        • Jackson on 07/02/2023 - 13:21

          It's quite uncommon as it's about an 80k option now for full brick homes, and that's not adding any space just a second inner skin of bricks. It much more popular to insulate as best you can with brick veneer or cladding.

          When you say ground source heating, do you mean where they put pipes into the ground and circulate a fluid? I have seen that on UK TV but yes, zero people do this in Australia. If you mean in floor heating, that's something that is done but I don't know how efficient it is compared to e.g. A/C.

          • bargaino on 07/02/2023 - 17:00
            +1

            @Jackson: I can't see why they don't put the bricks inside, and then insulation and cladding outside. Makes much more sense.

            For "ground source heating", I mean basements were traditionally done for that purpose, like the pipes, to get heat from underground in winter.

            • Jackson on 07/02/2023 - 17:16

              @bargaino: Not sure, but at least partially becuaee running services through brick work is a PITA

  • thatonethere on 07/02/2023 - 07:12
    +9

    Just make sure your builder has experience doing basements underground otherwise you ll have endless leaks etc next to impossible to fix with a house on top.

    • Jackson on 07/02/2023 - 07:48

      Yes this is the case, actually quite a few builders I spoke to have experience with this now and it's a highest priority of course.

      Having said that theres also contingencies, but hopefully you don't have to rely on them

  • Xistn on 07/02/2023 - 08:06
    -1

    Only cannibals and psycho's need basements.

    • Sinnerator on 07/02/2023 - 08:32
      +1

      I don't need one

    • Jugganautx on 07/02/2023 - 08:48
      +3

      I read this as cannabis.

      • Xistn on 07/02/2023 - 09:40

        Or a grow house too.

  • mskeggs on 07/02/2023 - 08:11
    +2

    Do you want to use it as a room, or just storage/workshop type space?
    Can you get some natural light, maybe long windows at ground level?
    Mum & Dad have a basement under ground on three and a half sides, as the ground slopes. The natural light was important, and the ability to open those windows for ventilation too.
    They had a pump & sump to drain water, and it failed once leading to an inch of water across the floor in a rain storm.

    If it was me, I’d explore any alternatives, as while it is cool in summer, it is hard to heat in winter.
    At the very least, I’d aim for exceptional insulation on all sides to allow temperature and humidity to be regulated.
    And however you drain water needs to be fully accessible if something goes wrong, not something you need to rip a floor up for.

    • Jackson on 07/02/2023 - 13:28

      I plan on using part of it as a theatre and games room (if possible, which mainly requires a dark space) , and part as a workshop and storage. There will be some ventilation, I can do what I want essentially as it's not built yet so I have an opportunity to set some thing up. There is a sump and pump, and yes accessible. There can be ventilation put in but not so sure about windows, although that would be nice.

      Did you find it got very cold in winter? Also did you have any ventilation aside from windows? I am wondering if the cold was from the ground or from it being always ventilated due to unsealed walls. Was it ever musty?

      • mskeggs on 07/02/2023 - 14:35

        The room had a security screen door, and was left open pretty much all the time except winter in Sydney. The windows were about 60cm by 2m at head height in the room, and two opened about 60x60 at each end.
        There was also an exhaust fan, but run infrequently to begin with.
        Temp was stable all year, but around 17-18 degrees. Cool and fine in a T-shirt in summer, but chilly in winter.
        All walls were double brick, with damp course low, and the ground dug away behind leaving, maybe 15cm gap? Ag pipe and blue metal trenched around. Bricks painted with the clear sealer, but otherwise exposed brick walls inside. Carpeted concrete slab floor. Lowish ceilings, 2.3 or 2.4m

        It was always humid, and got musty if shut up for very long. Eventually added a small exhaust fan, 15cm maybe, that ran continually to circulate air. Some improvement, but still not ideal. That cool humid feel you get stepping into a big cave or underground car park on a hot day.

        The bottom line, I think, is the limited sunlight, presence of nearby ground water/damp soil made the cooler temp of the brick and concrete a good place for condensation. So even with air circulation it was always a little clammy.

        If it was a bedroom or living area, probably would have bitten the bullet and run RC aircon to manage it, with the attendant energy costs. Would be better with gyprock walls too, I reckon.

        • Jackson on 07/02/2023 - 17:14

          Gyprock is pretty easy to put in, the real conundrum is the dehumidifying while not making it any colder. I will Def try to exten the AC to down there, but it would be good knowing the heat pump hws removed the water from the air all year round without worrying about addition energy costs. It's just unfortunate it will be colder and noisier

  • Motek Benzona on 07/02/2023 - 08:58
    +1

    Make sure you buy the right size gimp cage, hard to get refunds if you choose wrong

    • Jackson on 07/02/2023 - 13:29

      The Gimp's asleep….

  • Benoffie on 07/02/2023 - 09:04

    They are more common than you think especially in SA. Hard work engineering wise. Americans have best modern plans. Here, however, as you say, they're primarily used to escape the heat. Theyre also used for natural air-conditioning.

    A good builder/engineer needs to be your go to.

    • boomramada on 07/02/2023 - 09:12

      You sure? Why basement when there is an abandoned bank in Snowtown to escape the heat?

      • Benoffie on 07/02/2023 - 10:13

        🤣 hur hur

        Ayers House has one, I saw a place recently sell out at Balaklava with two full ones. Also, a guy started one and sold the place before finishing, think it was in Beverley from memory?. I'll try and find links.

        Balaklava - 28 Humphrey Street, Balaklava, SA 5461 https://www.realestate.com.au/sold/property-house-sa-balakla…

  • SF3 on 07/02/2023 - 09:08

    what to consider

    Trapdoor, booby trap.

    Screen always showing Live link of OzB.

  • bmxr on 07/02/2023 - 09:17
    +4

    Do a "half basement" if possible so that it is at least partially passively ventilated. Leave at least 500mm above ground below the ground floor slab and ventilate on two sides, this is how most of them are done in North America. Mechanical ventilation is costly and requires maintenance.

    • Debt Free on 07/02/2023 - 10:48

      Yes, Perfect— that’s the way a Cellar should be built.

    • Jackson on 07/02/2023 - 15:15

      Might be, a possibility, but the sides will be adjacent due to slope

      • bmxr on 07/02/2023 - 15:28
        +2

        Even if it's two adjoining sides, like above the door and a wall, or look at a mesh-panelled or louvred door for all or part, and you can get some passive, cross-ventilation. Your architect will know what to do.

  • Richmond Tigers on 07/02/2023 - 09:33

    The risk is something taking up residence there and yelling out "BERT, FEED ME".

    • BortBelcher on 07/02/2023 - 10:38

      "BERK, FEED ME".

      And ol' fatguts lives upstairs in the attic.

  • Cheaplikethebird on 07/02/2023 - 09:38
    +1

    How many plants are we talking?

    • Jackson on 07/02/2023 - 17:15

      Haha, 2 friends I know recently had their neighbours raided within a couple of weeks of each other, it happens.

  • JimmyF on 07/02/2023 - 09:38
    +1

    I also don't want it to be musty

    Split system AC for heating/cooling/drying will help rather than a HP HWS. Musty smells comes from either water leaking in or poor ventilating.

    • Jackson on 07/02/2023 - 16:12

      Yeah I can get a duct put down there, but realistically the hot water system will dry the room at no additional cost since it's taking moisture out of the room while it heats the water. But I might be able to get a builder to throw a couple of ducts down there with their own zone. The main issue is the room will be always colder, which might mean too cold

      • JimmyF on 07/02/2023 - 19:05

        HP HWS in a closed room like a basement will have its own set of issues. As you said, the room will always be cold, the HP HWS needs a certain volume of air to extract the heat from, so it might struggle to heat the water if not large enough etc. Check the manual and confirm what it needs.

        • Jackson on 07/02/2023 - 22:36

          Yeah I checked, it needs at least around a double garage, it's about 2.5 garage spaces in size.

          I really can't think of a better solution, yes you can pay for your AC to run on a heat cycle, or get one with a dehumidify mode, but this is free energy to get rid of the worse of the two evils, the musty smell and potential mould issues, compared to it being a bit cold.

          In this case, I wonder if it's better to blow hot air down or cold air up?

          Edit: I just thought of something, say the air is really cold, it could be shifted up on hot days to cool the ground floor. Just need some holes in the slab and heat shifters

  • Tee Rex Arms on 07/02/2023 - 10:03

    Jackson Dahmer

  • Debt Free on 07/02/2023 - 10:44
    +1

    In Melbourne basement is always cool. Open under the house on 2 sides to take full advantage of under the house cross ventilation, with door on 3rd. Concrete floor, 1 brick wall shared with garage wall. No water issues- normal plastic pipes direct water normally. Use it to make and store Passata, Red wine, barrels of Saurkraut, store bulk foods, store normal foods, hang meat to cure, hang herbs to dry and as a sit down little wine bar with a neighbour or two after work.
    Build it to suit the elevation of your land and never enclose it fully. No need for any insulation. Keep it simple with concrete floor and half walls on 2 or 3 sides. You will get you money’s worth out of it a million times over - build your Cellar.

    • Jackson on 09/02/2023 - 20:12

      Thanks, yes fingers crossed. I think with current house prices and the inevitable future rises, it's hard to say that you are overcapitalising if you live near a captial city and close to transport and amenities. Unfortunately it won't be open on 3 sides, it's mostly a bunker but ventilaton will be able to be put in once it's clear exacly where the floor is graded.

      What would you say about using it for more livable things, e.g. not just storage, but I like your idea of a bar, maybe a projector for movies (since it's dark) and maybe a workbench where if you are interrupted you can just leave things as they are and come back to them. Hoping to solve first world problems.

  • Debt Free on 09/02/2023 - 22:08
    +1

    My cellar was hand dug out after house was built on elevated sloping block. Listen to bmxr above to leave that gap above under house for ventilation. After it was dug out adjacent to garage, door was put in, concrete floor and half brick walls with slatted wood to make up top half of walls—- it is never draughty, always cool but not cold, and never warm. There is shelving on wall adjacent to garage, work bench and metal cabinets now where once there were 3 wooden barrels- 1 or 2 for yearly red wine making, and 1 for fermenting whole heads of cabbages. The adjacent garage has shelving and work benches plenty but plenty in cellar too. Perfect as a wine bar, and a place to just enjoy a little solitude, but very busy in the summer where most visitors found themselves first- slicing Prsut from a hanging smoked leg of pork to enjoy with wine straight out of the barrel, with home pickled red capsicums out of the jar. It has big fluorescent light inside.
    You can throw a big scrap of carpet on top of the concrete floor if you want cos it doesn’t ever get very dusty, just needs an occasional sweep. The door can be left open with visitors with no loss in ambience. We never needed to use it as a movie room- it is more a place to talk, catch up, reconnect with people at a leisurely pace, to wind down. A radio in the background sometimes. A cat always by your side.
    Best value room in whole house- paid for itself a million times over. Make it what you want and it will grow and change with your family needs.

    • Jackson on 09/02/2023 - 22:16
      +1

      We might be soul brothers, it's the place where dreams come true. The rest of the house is to eat, sleep and work, the real magic is going to happen in this basement! :-) It's basically the space you have that's unrestricted by the foibles of modern life

  • Debt Free on 09/02/2023 - 22:34
    +1

    It is the place where dreams come true for men, women, teenagers, neighbours, friends, family life, cats. A place to be alone, or connected to others, a place to create all manner of delicious and naughty things, a place to hide Everything and Anything, a place to Share and to Hoard—— a place which Never gets old.

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