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Board Concrete Formwork

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  • Closed Accounts Posts: 1,011 Nina Bald Quiche


    Ive done all our garden walls in this. Very easy to do yourself if that way inclined. Also did an internal wall too.

    Trick is to make sure the concrete is well aerated in the form and it will follow the timber grain nicely.
    Determine the depth of timber you want to see. In my case i opted for the 225mm high timber boards. Stacked two high for a low rise wall. If you are looking for a higher wall I would start to consider foundations with Rebar intertwined with foundation wire.

    Form the timber shutter.
    I also drive in 1m steel rods at 1m intervals into the ground, leaving say 400mm protruding on the centre line. This prevents wall rotation.

    Any carpenter can easily form these. Just ensure access for a truck to make life easier.

    7bRJwQMl.jpg

    You can also create planters, here I did a narrow wall with narrow planter. bit more work invloved though with the shuttering.

    O52lcM8l.jpg


  • Registered Users Posts: 607 ✭✭✭ tedimc


    Thanks for this - it looks great. A couple of questions if you don't mind:
    1. Apart from aeration, did you use any additives? I did see some mention to super-plasticizers on the web, but not sure how I could go about getting this added to the readymix.
    2. Did you need any release oil on the boards?
    3. Any plans to paint it, or just leave bare. If leaving bare - are you thinking of sealing it?
    4. Any control joints? What span are the walls?

    Re DIY - happy to give it a shot, but I'm looking at 100M+ along the front boundary (1m high) and maybe another 25M+ along the back retaining wall about 2M high.

    A nice project for the summer...………..:eek:

    Was considering the planters too actually! Would be a nice touch and should soften the look of the bare concrete.


  • Closed Accounts Posts: 1,011 Nina Bald Quiche


    No additives. Standard concrete. Delivered and poured direct from truck.
    Release oil can be used, although in the end I found no need for it.
    Leaving it bare, you can see the timber imprint. No sealing it.
    Each bay is 4.2m long. The standard length of timber available. I made up three bays in total, poured and struck carefully. The 3 bays then moved along to the next section. I did about 80m in total with the same three bay formwork. See picture 1 above, you can see the form lying in the background after being struck.

    If your going for 1m high then thats a different ball game, you will need a foundation and a a lot more rebar. Shuttering will need to be a lot stronger too to stop it from bursting.


  • Registered Users Posts: 10,919 ✭✭✭✭ Calahonda52


    You will need foundations, below the frost line for those walls.
    I don't understand the word aeration in this context.
    I have always used a small concrete vibrator for such work which gets rid of any entrained air so am puzzled..
    IMO, you are better off putting in the foundations and then use 4" blocks on the flat, piers and expansion joints at every 6m, with foundations to match the piers.

    Much quicker, especially for such a large project


  • Registered Users Posts: 607 ✭✭✭ tedimc


    You will need foundations, below the frost line for those walls.
    Agreed - I was planning on reinforcing and foundations.
    I don't understand the word aeration in this context.
    I have always used a small concrete vibrator for such work which gets rid of any entrained air so am puzzled..
    My fault - I meant vibration.
    IMO, you are better off putting in the foundations and then use 4" blocks on the flat, piers and expansion joints at every 6m, with foundations to match the piers.

    Much quicker, especially for such a large project
    I am considering that also, but I like the thoughts of this kind of finish. I was also curious as regards the cost - if it would be cheaper than block. Based on materials alone, it looks like it might be, but I need to get a view of labour.

    The other issue I have with blocks, the front wall is along a narrow back road. I was thinking of the affect a truck, van or trailer would have if they rubbed up against it when two vehicles are passing. It thought the reinforced concrete would be more resilient.


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  • Registered Users Posts: 1,530 ✭✭✭ Dudda


    The 4" blocks would be a lot easier and a fraction of the cost but not as nice.

    I've designed a few board marked walls. Here's a recent one that shows the finished product, formwork and rebar: https://www.instagram.com/p/B8L8iHuH587/

    Regular concrete from the truck, vibrate to remove the air, standard sawn timber, no need for oil (and if you do use oil do a test wall first to ensure the oil doesn't stain the concrete). You can stain but no need. If you want to create more variation you can use the plastic spacers window installers use to move the timber in and out more. You can use different lengths and different widths of timber or all the same. The higher the wall the more support it will need as the concrete is extremely heavy.

    For a garden wall I'd suggest pouring a foundation and a kicker (4 inch high or one board first line of the wall in one go with rebar sticking up out of it. Then you can build your formwork off this. You'll have to do it in lenghts about 4 meters long. You can't have it 100m long without joints. For these day joints I'd suggest you have a small batten say 1" inch square that creates a vertical shadow gap recess. These can look very good if designed in properly.

    This is going to be expensive in concrete alone and take a while but it's all very doable from a DIY point and time is what a lot of us have in the current pandemic. I'd suggest you build a wall 1m wide and 1m high as a test one. On one side use 100mm boards and the other use 150mm boards or whatever you want. Use this test wall to decide on the finish and pattern you want. See below example sample wall
    30856285_162545944425259_5021970564743430144_n.jpg?_nc_ht=instagram.fdub4-1.fna.fbcdn.net&_nc_cat=107&_nc_ohc=VsYu45XoC0wAX8e9o7Z&oh=c2c74ffd99cb9b33bbb620e407effdf5&oe=5EDB813E


  • Registered Users Posts: 10,919 ✭✭✭✭ Calahonda52


    Truck resistant concrete will require properly designed, bent and fitted rebar which is a world of hurt in terms of cost and work.

    Foundations will also need to be upgraded.
    .
    Have you PP for building a new wall so close to the road that it risks being nudged by passing trucks?

    You may need to step it back


  • Registered Users Posts: 607 ✭✭✭ tedimc


    Dudda wrote: »
    The 4" blocks would be a lot easier and a fraction of the cost but not as nice.

    I've designed a few board marked walls. Here's a recent one that shows the finished product, formwork and rebar: https://www.instagram.com/p/B8L8iHuH587/

    Thanks Dudda - that wall looks amazing. I'm definitely sold on it for the back of the house. I'll need to start planning!


  • Closed Accounts Posts: 1,049 ✭✭✭ GinSoaked


    Some more of it in Ireland check out Waterford Library http://mcculloughmulvin.com/projects/waterford-city-library

    WCL_WCL11.jpg


  • Registered Users Posts: 607 ✭✭✭ tedimc


    Truck resistant concrete will require properly designed, bent and fitted rebar which is a world of hurt in terms of cost and work.

    Foundations will also need to be upgraded.
    .
    Have you PP for building a new wall so close to the road that it risks being nudged by passing trucks?

    You may need to step it back

    I'm trying to arrange a meeting with the planners at the moment to see what the situation is. There is an old existing wall/ditch there but it's in need of a lot of attention. Not only am I querying the planning, I need to check if they have any road upgrades planned in the near term.

    They may push me down the route of a stone wall, as all the neighbours have one. But my only issue with that is the cost.

    If I go block, I'd need to plaster&paint or render the wall for it to look right. And a 100m long white wall may stand out.

    I was thinking something like this may work well:search?view=detailV2&ccid=RPSgWNnp&id=BC88FCC205EC78557F3D7094331F703FA160F026&thid=OIP.RPSgWNnp7_l93mwA2Te0wgHaF7&mediaurl=https%3A%2F%2Fst.hzcdn.com%2Ffimgs%2Fecb143f100a2fb1b_1808-w500-h400-b0-p0--.jpg&exph=400&expw=500&q=concrete+wall+with+creeper+plant&simid=608052267943201353&selectedindex=242&adlt=strict&shtp=GetUrl&shid=2c69af33-a20e-40f3-ada7-2f753860ceb1&shtk=Q2FzY2FkaW5nIFBsYW50cyB8IEhvdXp6&shdk=Rm91bmQgb24gQmluZyBmcm9tIHd3dy5ob3V6ei5jb20%3D&shhk=u1curAIunDDBXQtyNxfQI6CxLruZm802lQvQOw1stz8%3D&form=EX0023&shth=OSH.2YYk6%252FkU3oXRx2GgZgbolA


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  • Registered Users Posts: 607 ✭✭✭ tedimc


    GinSoaked wrote: »
    Some more of it in Ireland check out Waterford Library http://mcculloughmulvin.com/projects/waterford-city-library

    WCL_WCL11.jpg

    That's awesome. Jeez - libraries have got a lot nicer since I used to have to cram in one....


  • Registered Users Posts: 14,890 ✭✭✭✭ CJhaughey


    Bantry library was one of the original libraries made from poured mass concrete, its a pretty cool building when you consider the time of construction and the look.


  • Registered Users Posts: 1,128 ✭✭✭ kieran.


    GinSoaked wrote: »
    Some more of it in Ireland check out Waterford Library http://mcculloughmulvin.com/projects/waterford-city-library

    WCL_WCL11.jpg

    Seriously good quality of workmanship there. Bravo to the contractor who did that.


  • Registered Users Posts: 1,530 ✭✭✭ Dudda


    CJhaughey wrote: »
    Bantry library was one of the original libraries made from poured mass concrete, its a pretty cool building when you consider the time of construction and the look.
    The Berkley Library in Trinity College Dublin is a few years older and would have influenced Bantry. The base is board marked concrete and has it inside also with other types of shuttered concrete throughout.
    http://archiseek.com/2010/1967-berkeley-library-trinity-college-dublin/


  • Registered Users Posts: 607 ✭✭✭ tedimc


    I'm now busy googling Le Corbusier and his 5 Points of Architecture.....

    "In accordance with Le Corbusier’s belief that poured concrete should reflect the material into which it was poured, timber marks can be seen on the exterior surface of the building."


  • Registered Users Posts: 1,530 ✭✭✭ Dudda


    tedimc wrote: »
    I'm now busy googling Le Corbusier and his 5 Points of Architecture.....

    "In accordance with Le Corbusier’s belief that poured concrete should reflect the material into which it was poured, timber marks can be seen on the exterior surface of the building."

    You know now you can't just show the wife your plan. You have to present an artistic vision and overall concept, which is true to the original function and material that tells the story.... of a garden wall.


  • Registered Users Posts: 3,704 ✭✭✭ Metric Tensor


    Dudda wrote: »
    You know now you can't just show the wife your plan. You have to present an artistic vision and overall concept, which is true to the original function and material that tells the story.... of a garden wall.


    Top level wife-ology there!


  • Registered Users Posts: 3,704 ✭✭✭ Metric Tensor


    GinSoaked wrote: »
    Some more of it in Ireland check out Waterford Library http://mcculloughmulvin.com/projects/waterford-city-library

    WCL_WCL11.jpg


    I'm a structural engineer and I love exposed concrete in good context but until I saw this picture the board look never landed with me - but this one awesome.


  • Closed Accounts Posts: 1,049 ✭✭✭ GinSoaked


    I'm a structural engineer and I love exposed concrete in good context but until I saw this picture the board look never landed with me - but this one awesome.

    What you don't get a good sense of from that picture or the architects website pics is how well that combines with the old brickwork of the original library building I'll see if I can find some pictures.


  • Registered Users Posts: 4 jaeita


    Determine the depth of timber you want to see. In my case i opted for the 225mm high timber boards. Stacked two high for a low rise wall. If you are looking for a higher wall I would start to consider foundations with Rebar intertwined with foundation wire.


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  • Registered Users Posts: 607 ✭✭✭ tedimc


    Dudda wrote: »
    You know now you can't just show the wife your plan. You have to present an artistic vision and overall concept, which is true to the original function and material that tells the story.... of a garden wall.

    Ha ha - true, but she is still waiting on the plan for the house she is living in!!

    I wonder if she will even notice that I put in a wall?


  • Registered Users Posts: 607 ✭✭✭ tedimc


    jaeita wrote: »
    Determine the depth of timber you want to see. In my case i opted for the 225mm high timber boards. Stacked two high for a low rise wall. If you are looking for a higher wall I would start to consider foundations with Rebar intertwined with foundation wire.

    Yes, I think reinforcing and foundations are a must. I’ll probably also put in a bit of a heel slab as I’ll be backfilling a little behind it.

    I was actually think of running the boards vertically, and maybe even of slightly varying thicknesses. The wall will be about 2M high. I was also thinking of setting the boards up in sets of 3-5 and then re-order them for each pour and maybe rotate them. just to make it more random without needing to build a new form every pour.


  • Registered Users Posts: 10,919 ✭✭✭✭ Calahonda52


    With 2m high formwork you will need bolts across the bottom.
    With proper rebar, the 3-5 at a time will make fitting and removing the stop end v difficult and you will see the joints.
    When I first started pricing this work in '75 in the UK, these stop ends were always pricey and troublesome.
    .
    For the simplest job, ride the horse in the direction it wants to go.


  • Closed Accounts Posts: 1,049 ✭✭✭ GinSoaked


    I've never done this work but its always occurred to me that perhaps you'd get a better finish if you raised the grain on your formwork planks.

    Something like a good hard pressure wash to cut out some of the softer parts of the grain?


  • Registered Users Posts: 1,530 ✭✭✭ Dudda


    GinSoaked wrote: »
    I've never done this work but its always occurred to me that perhaps you'd get a better finish if you raised the grain on your formwork planks.

    Something like a good hard pressure wash to cut out some of the softer parts of the grain?

    Surprisingly you don't need to I think. We did a sample on one project where we sand blasted the timber to expose more grain and the finish of the original rough timber was preferable.

    Now a lot of this is personal preference. Things like the board size, variation of boards, amount of grain, exposing of bolt holes, etc should all be experimented with on a trial sample until the client is happy. You can't modify it after.


  • Registered Users Posts: 4 jaeita


    jaeita wrote: »
    Determine the depth of timber you want to see. In my case i opted for the 225mm high timber boards. Stacked two high for a low rise wall. If you are looking for a higher wall I would start to consider foundations with Rebar intertwined with foundation wire.
    Stacked two high for a low rise wal l. If you are looking for a higher wall I would start to consider foundations with Rebar intertwined with foundation wire.


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