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Mega Anchor?
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| qwerty30000 |
Posted on 12-11-2008 09:07
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Joined: 15.03.08
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Has anyone here had experience or heard of anyone building a straw bale house on Mega-Anchors?
http://www.mega-a...
We are seriously looking at Strawbale for our next house. But due the the shape and slope of our land, a concrete slab is not an option.
I like the look of these mega-anchors they go in very fast (2 days or so), and once they are in, they are not going anywhere..
This video shows just have fast they are installed.
http://www.youtub...YHBtP9Tqro
And this one shows just how tough they are.
http://www.youtub...inftvnMX1Y
My question is, would it be possible to put a straw bale house on these? |
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| john mason |
Posted on 13-11-2008 05:40
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Joined: 09.05.08
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hi there
looks very clever this footing system.
i reckon the only difficulty you might have is if there is rock as we have here in the blue mountains.i can not see how the piles can be driven deeply enough then. maybe is you encounter sand stone you'll get through but otherwise you have to rely on conventional methods i.e. concrete pad and brick pier or 'uni pier' or stirrups with posts or stumps.
in general what you choose for your footings does not effect your ability to build in straw. there have been numerous houses built successfully of platform floors.
i'd suggest you get in touch with mega anchor and find out what their requirements are to issue an engineers certificate for the piers and then yous away,
good luck and keep us posted
harald STRAW AND CLAY |
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| qwerty30000 |
Posted on 13-11-2008 07:13
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I sent the chap at Mega-Anchor in QLD a photo of our block and a link to a video. I also told him that we are in a sandstone area..
He said that from what he could see, they would have no problem and that if they hit rock, they would just pre drill the holes.
Edited by qwerty30000 on 13-11-2008 23:16 |
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| john mason |
Posted on 14-11-2008 01:08
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pre drilling holes might be a costly exercise.but as long as he quotes or gives you a pretty firm idea about the cost involved to get the subfloor up and braced you should be fine.
to me it looks like a pretty good new way of going about it.
cheers harald |
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| qwerty30000 |
Posted on 14-11-2008 01:40
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harald wrote:
pre drilling holes might be a costly exercise.but as long as he quotes or gives you a pretty firm idea about the cost involved to get the subfloor up and braced you should be fine.
to me it looks like a pretty good new way of going about it.
cheers harald
I wonder if your average carpenter or builder 'charges extra' because they have to get the drill out.
"Sorry.. I had to charge you extra because I needed to use my mallet, screwdriver and the big hammer." 
(I'm only half serious)
The way I see it, if I am going to have problem with rock, I am going to have that problem regardless. |
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| john mason |
Posted on 14-11-2008 03:22
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me being an 'average' builder, would charge extra if i encounter rock during excavation. it is actually a standard part in any contract that encounter with rock is being charged extra. but as i said before maybe ,because this system is quite unique there are other ways of getting around this problem.
and if you have a lot of rock it can mean that your footings can be really shallow. the house we are living in at the moment, for example has footings at the back that are only 100mm ,4in, deep since they sit on rock.
anyways
they'll let you know whats required and how much it will cost. if they have a unit price maybe you could post it in the forum for the benefit of everyone since it is a interesting way of going about things |
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| qwerty30000 |
Posted on 14-11-2008 06:59
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I did see 'somewhere' that they cost $60 each.. BUT that was in a page that was written a few years ago (that I can't seem to find now) I would expect they are more than that now.
I did find this page however. They are documenting their entire build and this page is the one where they talk about the Mega-Anchors.
http://home.vicne...ations.htm
They look so neat, smart and strong once installed. And once you connect them all at the top (with a floor) they are not going anywhere. |
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Posted on 14-11-2008 19:47
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Joined: 01.01.70
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For what it's worth, I discussed these with an engineer I work with (in Qld) and his comments were:
"My first thought was, ugly...
Beyond that, they use 32NB tube, driven into the ground at each of those three CHS sections on the bracket, these rely on skin friction only to support the loads, therefore they are only suitable for clay soils. Now the thing to bear in mind for clay sites is that there is a depth of suction, equating to the depth at which tension cracks theoretically develop in the dry season, that has to be disregarded in design.
Of course they definitely allow you to get in quickly and establish a floor..
So, when considering the use of these on a project:
- you need a clay site
- the site investigation report has to give the engineer the skin friction available in the foundation material
- it would be beneficial if the site investigation report commented on the depth of design suction change (Hs) for the site
and they're still ugly...."
-AW |
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| qwerty30000 |
Posted on 15-11-2008 07:40
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Andrew
Can you explain what 'skin friction' is? I'm a bit of a noob at this stuff.
<edit>
I googled it and found this..
"The frictional resistance developed between soil and a structure or between soil and a pile being driven in it. "
So how does this relate to Mega Anchors only usable on clay soil?
Edited by qwerty30000 on 15-11-2008 07:46 |
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Posted on 16-11-2008 08:06
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My understanding, which is likely incomplete, is that clay soil is cohesive and essentially holds the tubes in place by friction (which is how most piles work). But, because the tubes are very narrow and therefore have a small surface area, a sandy soil, which is less cohesive, would not provide enough friction to hold the tubes in place. Just picture how difficult it can be to pull your boot out of mud as opposed to sand. In the case of a pile, the same effect would work to hold things up and to hold them down.
Soil is usually not just pure clay or pure sand, and there is virtually any mix in between (as well as silt, gravel and rock), and that is why the skin friction and depth of suction change are important to know.
I'm not sure how the Mega-Anchors will go on a rocky site, but I can imagine that a drill hole through solid rock would not result in a friction joint with the tube; unless the tube could be driven in, which would be a huge task for such a small tube. Not a problem if it is actually bedrock (because other types of footings might be easier and cheaper), but if it's a huge floater, it might not work. I'm just speculating.
Anyway, I don't claim to be an expert on the Mega-anchors, and neither does my engineer. I am sure the company could give you more guidance on where they can and can't be used. I also don't think the appearance is a major problem, especially for subfloors (as opposed to verandahs), as it is a very good idea to enclose the perimeter of the floor space anyway to improve the energy-efficiency of the house.
Edited by on 16-11-2008 08:07 |
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| qwerty30000 |
Posted on 16-11-2008 08:37
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Andrew
The way I see it, once you put the three poles in, the assembly is like a tripod buried in the ground. Most of the force on it would be down ways and the full force of that would be spread along the length of each poll. I just can't see how it could move down or anywhere in that circumstance.
But you are right, surely they have their own engineers who know the system and who's for the sake of their career would not put a tick on a foundation system that cannot do the job.
Each can hold a weight of 3 tonnes apparently.
Can you suggest any other system I should look at. I am by no means decided on the Mega Anchor. I do like what I have seen so far however.
As for their look, you are right in that you would not see them once the under side of the house is boxed in (I'm sure there is a technical term for that but I don't know it. )
I'd add to that the under side of the house would be very neat with these.
(Edit: spellin, and gramma)
Edited by qwerty30000 on 16-11-2008 19:17 |
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Posted on 17-11-2008 09:26
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Joined: 01.01.70
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I think the Mega-anchors look like a good solution. The next most eco-friendly and easy footing would be screw-piles, if you need the depth. A screw pile is like a long auger bit that is literally screwed into the ground; usually with a concrete cap on top, although it is not out of the question to fix bearers directly to them. The challenge with doing that is getting them accurately placed. If you don't need the depth or much bracing or tie-down capacity, then cypress stumps on a thin concrete pad and backfilled with rammed earth is a simple solution. In Qld you often do need higher bracing and tie-down capacity, though. I think you should definitely look at the suitability of the Mega-anchors for your design and site....and let us know how you go. |
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| jadejadelee |
Posted on 04-10-2009 06:24
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Posts: 2
Joined: 02.10.09
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Maybe is you encounter sand stone you'll get through but otherwise you have to rely on conventional methods i.e. concrete pad and brick pier or 'uni pier' or stirrups with posts or stumps.
Regards
Isilla
___
simulation de pret |
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Posted on 19-10-2009 04:27
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Joined: 01.01.70
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Hi Isilla,
Why do you say that? I need some context to your comment.
-AW |
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| greenturfdave |
Posted on 31-10-2009 08:54
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Posts: 0
Joined: 31.10.09
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I like the overall look. It's very well done and pretty clever but i guess this would take time to make.
Regards,
Magenta
Placement financier |
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