Hypertufa Arches like the Medieval Cloisters

desperationfalls(z5 MA)May 17, 2006

OK-so I admit that I'm enthralled with the old cloister

gardens which I've seen in Europe! I'd love to build

a couple of columns on my low back stone wall and connect

them with a 'ruined' arch and then grow ivy or wisteria

over the whole bunch.

Anybody have plans/ideas/websites which describe how

to make the arches (other than out of wood)?

There is a place on the Gardenweb which give explicit

directions for making concrete columns--so that is

available. I just want the info on how to make the


thanks much

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Oooooh...could I have a link to where it gives directions for making the columns?

    Bookmark   May 17, 2006 at 12:05PM
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desperationfalls(z5 MA)

Over in the gardenweb'Garden Accoutrements' is the following posting
this should work-
or go to that forum and look up 'column'
it is still there.

    Bookmark   May 17, 2006 at 1:02PM
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DebZone8(S.Puget Sound)

Desperationfalls, if you find information on this idea, will you please post it? It seems to me like you could do something fairly lightweight with styrofoam, lathe and a cement veneer for the arch. The amount of reinforcement would depend on how much weight it had to bear (wisteria will pull anything down). I also love the look and am intrigued...


    Bookmark   May 17, 2006 at 5:59PM
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Hey RD --- I took a look at the column recipe too. The "cardboard" forms (Sonatube is one tradename) are ok but can certainly be improved on. For starters, there's no reason to make them solid concrete and weigh a thousand pounds. Just insert a smaller tube inside the larger outer form, pour inbetween them and make it hollow. About two to three inches thickness will support a roof. But, even if solid I would still insert about four sections of light rebar to help prevent it ever fracturing through.

And the "natural" finish that comes from the "tubes" is pretty horrible to my mind. They always have a spiral stripe where the glue joint holds it together and its far less than interesting. However, there are some simple & creative fixes. One of the best I've seen was to lightly glue half-round trim moulding (the fake wood works best) flat side out, all the way around the inside of the tube running either full or partial length. When you tear off the outer cardboard & remove the half-rounds...voila!...a true fluted column! The moulding can be butted solid or spaced out (like me)for different patterns. Just about any trim moulding will work and can be used over & over again. Just remember to apply a little release before you pour.

Another trick requires two people, a very large funnel & some hose and gravel but looks great. Start with a plain tube placed & ready to pour. Working together, one person drops decorative gravel into the funnel & down through the hose against the outer wall as the other pours concrete in behind it. If you go slow & work your way around & up, you wind up with a column of fully exposed pea gravel that is quite unusual & attractive. Any type of material that you can get through a large hose & down into the form can work to form a bonded decorative layer on the outside.

Another trick similar to the first involves using real bamboo inside the form. On that one they had to grind/knock off areas where the 'crete had gone all the way around partially enclosing the bamboo here & there, but it was no big deal and looked rustically fantastic.

Long story even longer...just keep in mind that the tubes are just basic molds and can be adapted in an infinite number of creative ways. And...they are cheap enough that you can go wild with them. There are so many possibilities that I am considering a special column area on my new website just to demonstrate some of the things that can be done with them.

Til Then, All My Best,
PS: Should have that "sneak'a peek" thing ready soon

    Bookmark   May 17, 2006 at 6:12PM
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lazydaisy(z7 NTX)

Tango, do you have any ideas on how to do the arch that desperation was asking about? There was someone else in another forum asking about doing a round Chinese Moon entrance in stone (I suggested a hypertufa/concrete mixture and sculpting) and told him he should come over here and ask you about the armature and structure.

Regarding the arch, I was thinking if you poured footings for the base of the columns, have a pipe (or rebar) embedded which extends up the height (maybe higher) and then either place or build the columns over the footings/pipe. You'd build the arch as a third piece with a matching hollow pipe/or rebar (not sure how to get that to arch) which would attach to the two vertical footing bars creating the tension. Of course it would also all be mortared for effect and strength...

    Bookmark   May 17, 2006 at 9:34PM
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Hmmmmmmmm...any arch spanning two otherwise unsupported columns could be tricky. It would almost certainly have to be a "static" acrh, one that is not actively transferring its load outward as well as down the way a "dynamic" arch does. That lets out actually forming it from individual "stones" or elements. While there are a few of this type around, they are mostly in the "ruins" category and not very safe. A static arch could be cut & constructed from wood in such a way that all the load is pressing straight down onto the columns, then faced with a mortar mix or even 'Tufa over lath to simulate stone. A curved plywood face could easily conceal a standard roof truss type frame that can carry quite a lot of weight without adding very much. Should actually be fairly easy to build, just treat it like a plastering project and use tarpaper and thin wooden lath to support the mix. If the top of the columns were cast/made with a smaller, extended box shaped "tenon' on top, the arch frame could rest on the shoulders of the columns and also frame around it. That would tie the two columns together the same way the "lintel" stones connect the pairs at Stonehinge. And if a couple of large bolts were set into the top of the concrete, you could secure it downward as well. All of this would require very secure footers set several feet deep. I think the old general "rule" is half the height deep...but a friendly local engineer could tell you. Windloading on the arch could otherwise bring it crashing down.

Certainly a do-able project, but one that needs to be well planned and thought through. How about it folks...any actual structural engineers out there?

    Bookmark   May 18, 2006 at 12:31AM
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One thing that I've considered is using plastic water pipes, and making a re-usable mould. For short lengths it should be quite easy - cut the pipe in half lengthwise, clean up the saw-cut well so there are no rough edges, use waterproof tape on the outside of the seams and around the pipe to hold it together while you pour.

A base could be made very easily, even from concrete - just two concentric rings to hold the outer and inner pipes in position while you pour.

    Bookmark   May 18, 2006 at 5:06AM
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rockhewer(z4 WI)

Thanks Tango for pointing that out so well. Anything being built over your head height generally requires a bit of engineering to accomplish safely. The moongate thread in Gardening with Rocks is an interesting one and brings up the same issues.

An arch is stronger than a straight lintel for supporting or distributing weight but they genrally have walls to help disribute that weight/sress. An unsupported arch as you said is very hard to do.

This is an interesting idea though. I hope we can find some answers to help anyone who has a yearning to do something like this. Those moongates are an interesting garden feature to say the least.

    Bookmark   May 18, 2006 at 7:33AM
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RD --- PVC pipe does indeed make a very good reusable form. The only drawback I've noticed is that unless the saw kerf (the width of the actual material removed by the blade) is very thin...the finished shape winds up just slightly eliptical. Not so noticable on larger diameters, but prominent on smaller ones, so use the very thinnest blade you can find. Also, large hose clamps (the stainless steel screw-type used on most auto radiator hoses) work very well for securing the two halves together while pouring if you can find the big variety.

And tying the base to the columns is definitely a good idea. Pour the bases first, but embed some rebar connectors a foot or so long vertically into the wet 'crete that have an "L" bend on each end positioned so that they will anchor into the column when it is poued on top of the bases. That's the same technique used to tie concrete walls into foundations.

All My Best --- Tango

    Bookmark   May 18, 2006 at 10:59AM
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lazydaisy(z7 NTX)

Tango, this person was looking for the "ruins" look--might be the easiest way to get it! :)

Just throwing ideas out not a solution. There are a few variables to what I was actually thinking. One would be a much thicker column wall with the vertical footing pipe being attached to the inside wall of the vertical columns (small simple vertical anchor between those two). The third piece arch would have a smaller diameter pipe which would allow it to slip into the vertical column pipes (somehow being attached to each other). The arch would then be sitting on two stronger columns, the vertical pipes from the footings would be connected to the columns, and the arch piping would be pulled down "into" and attached to the vertical column pipes.

The rebar portion of that idea had something to do with something I read on how one company was doing preformed concrete fence walls. They had a system where they set up the footings with a rebar tension system and the cap was "pulled down" and created the tension as an added means of keeping it in place.

I'm not planning to build one of these anytime soon anyway but was just trying to get some ideas brewing. I figured you had a lot more experience with the tension/compression methods of the material.

Thanks for your reply!

    Bookmark   May 18, 2006 at 2:32PM
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desperationfalls(z5 MA)

Reponses have been terrific--what is a rebar anythign?

OK--gotta get this vision right. the arch in the
medieval cloisters which I'm seeing curves up the left
and right hand side and then meets in a point at the
top--no nice curved top arch. can we do this thing?

am taking major note of all the very very clever ideas
you guys/gals are simply terrific@

    Bookmark   May 18, 2006 at 10:03PM
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lazydaisy(z7 NTX)

DF, could you give us a link of what you're looking at specifically?

    Bookmark   May 18, 2006 at 11:02PM
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desperationfalls(z5 MA)

OK--these are pics of much larger arches than what I
am envisioning (the church up in Chelmsford, MA has a
cloistered walkway with arches about 4-5 feet tall--then
roofed over)

i think that these can still be worked according to
the suggestions--the supporting column would be onlhy
2-3 feet tall (sunk into the ground an additional 2 feet)-
and yes, I like the idea of using a 'hollow' center to
save weight and concrete!

    Bookmark   May 19, 2006 at 9:19AM
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ltd123(6A southern Ind)

Desperationfalls - while this is not exactly what you are asking about I think you might find Virginia Bullman's work interesting. Check out this site and see her "arch" formed by 2 figures with upstretched arms. I have seem close-up photos of this piece and they are beautiful. It shows another way to create the arch look without the keystone and all that math. You might be inspired to use 2 self supporting designs of your own to create the look you are going for.

Here is a link that might be useful: try this

    Bookmark   May 19, 2006 at 10:10AM
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Desperation --- Classic Gothic arches. Excellent choice and eminently doable using an internal box frame & plywood face as descibed above. Another trick borrowed from movie prop makers should also come in handy on this one. To get the dimensional "carved stone details" around the opening...attach flexible "polywood" trim moulding and cover it with a coat of your exterior mortar. It is the common household, non-wood variety trim found at most Big Box home improvement centers.

And "rebar" is the specially designed steel reinforcing rod used in concrete construction. Also avail at the Big Boxes.

As for a mortar mix to use, today there are literally hundreds of products & options. I would think one of the new "poly" or acrylic based exterior coatings could work well and be durable. "Plaster" ain't what it used to be, so a little lite reading and homework is a good idea. Below is a link to a range of specialty wall coating companies to get you started.

Good luck & keep us posted on your progress --- Tango

Here is a link that might be useful: Wall Sytem info

    Bookmark   May 19, 2006 at 11:13AM
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desperationfalls(z5 MA)

Tango, you are one veritable FOUNT of ideas/info!
You should make yourself into the Little and Lewis of
Texas!!! Thanks so much for your help and encouragement!
(LTD, neat arch idea and LAZYDAISY--love the idea of the rebar going up the columns to the arch level--THAT should HOLD'em!)

It will take me a few weeks to get to this project, but
will post pics when things get going.

again, appreciate all the great ideas and support!

if any of you do this, PLZ post pics.

    Bookmark   May 19, 2006 at 2:00PM
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nmgirl(8 S.NM)

Do the arches have to be entire? Why not give the impression of an arch? It would convey the "ruin" idea and might be easier to build, I'm guessing at that. Build the sides and the beginning of the arch but that's all. In other words, an arch that's collapsed.
A possibility?

    Bookmark   May 21, 2006 at 4:45AM
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tufftufa(Z9 coastal SC)

I live in coastal South Carolina. Anywhere you get hurricanes and gale winds you have to think about safety because garden "stuff" can knock out windows and take the roof off carports and possibly maim and kill.

Perhaps you might make or have made some sort of truly permanent structure and then veneer it with hypertufa "stones" -- Hypertufa troughs and planters are probably pretty safe, but a falling wall of concrete could be awful.

You might be able to make "wall" of arches with the metal lathe they use for stucco surfaces and support it with butrresses of the same material.

Just be careful...or if you do it, let us know who you are so we can keep our grandchildren out of your garden. (Forgive me, I don't mean to sound nasty but I'd be truly afraid of hypertufa over my head . . . or your's.)

Sorry to be a party pooper, 'cause I have fantasies of such a wall or maybe even a folly of some sort, but just because you can possibly make it of hypertufa doesn't make it something you ought to do.

I'm going to bake some peanut butter and garlic sandwiches now. Or maybe not.

Thanks for the inspiration, though.

    Bookmark   May 21, 2006 at 11:49AM
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DebZone8(S.Puget Sound)

Speaking of inspiration, I found these folks in Garden Design Magazine. Talk about gorgeous gothic arches...

Here is a link that might be useful: gothic arch work

    Bookmark   May 21, 2006 at 8:37PM
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desperationfalls(z5 MA)

No problem here--this wall would be no more than 4 feet high
and it would not ARCH over anything! If you follow links
to pics above or have ever travelled to see the 'cloisters', you would
know that they actually 'line' the side of a walkway and
do not span it over people's heads. To be sure, there is
frequently a roof connecting the two lines of arched walls-
but if we are to live our lives without roofs just in case
they might fall down during a hurricane, we are going to be
one cold and soggy group of people.

So, no problem here--yes, we have nor'easters here, not
hurricanes, nor earthquakes. keep your grandchildren safe-
tie your roof down as tight as possible.

    Bookmark   May 24, 2006 at 11:37AM
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rustinj(z7 AL)

Wow, now we're getting serious! Those arches look tough. I can't wait to see what you come up with.

    Bookmark   May 24, 2006 at 1:55PM
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tufftufa(Z9 coastal SC)

I really look forward to your project. Keep us all posted with pictures, please and notes on your techniques as you develop them.

We love our new house, but it's a condo and we have a nasty, white plastic fence (only kind allowed) and I'd love to figure out how to cover them up (I've planted vines so far). A cloistered wall would be perfect if only on the inside part that we look at.

Would you believe the underground utilities are placed so that we cannot dig anywhere in the little garden? So I'm hoping hypertufa (lots of it) will rescue me from plastic city.

    Bookmark   May 24, 2006 at 8:08PM
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Dena6355(z8 WA)

desperation falls,
I am thinking that either a large sand cast or a 4" piece of blue/pink foam cut to the shapes of your cloister arches may work. Brainstorming and have not thought totally through, but you could use a 4ft section of 4" blue foam, using big felt marker transfer a pic of your arches. Consider just making one/two of the arched sections for easier handling and working out the texture/detail while still damp. After your drawing is there using a serrated knife (there are other options for this but 1st thought)cut out your design. Tape the raw edges of the form with duct tape so you can release your form later. Bend some rebar or using straight pieces at least for the straight edges, set these aside. Lay your form on a flat space covered with plastic, and using a mix of concrete/tufa/lightweight mix to your liking, begin adding to the voids of the foam. Half way lay in your rebar, then add the rest. Once the mix has set up a bit you can carve the columns/cloister to your liking. This would be difficult to turn over, but with help you may be able to pancake it and turn it to be able to carve into the other side. Let the whole thing set up for several days before releasing from the foam. To create a more stable design you could incorporate a short length of pvc pipe into the column portions that would allow you to insert rebar into the ground, and use the pvc as stantion posts to hold in place, plus allowing you to reposition later.
As I am writing I think I would make it in no more than 2 sections at a time. In the pictures it appears they used 6" cardboard columns from a hardware store that had molding added on the inside to create the fluting.
It is so much fun to see what others have come up with.

    Bookmark   May 24, 2006 at 8:55PM
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nmgirl(8 S.NM)

Leave it to Dena! : )

    Bookmark   May 25, 2006 at 6:25AM
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desperationfalls(z5 MA)

Dena and Debzone--great ideas/plans.
You folks are amazing. Give you a challenge and the
creative genius gets together with the practical and
Voila! total cleverness!

I've got to read through all this stuff again and
really carefully and then figure out exactly the look
I am trying to build and then use a combo of the ideas
which y'all have created and build this piece.

thanks so much--if any of you gets the bug and creates one
of these anytime in the near future, plz post the pics!
we can only benefit from sharing the plans and the stories.

    Bookmark   May 25, 2006 at 10:11AM
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Dena6355(z8 WA)

Well I kept thinking about this idea, and the cardboard tubes at the hardware store, like I used for my columns. I originally planned to use the column mold I got at historystones.com. But after receiving them realized the column for me would be too skinny. Which brings me to your cloister ideas, and after looking at all the cloister arches (basically a fence or enclosure for a space or entry way to an area) the historystone mold for their birdbath may be just what you are looking for. Here is the link. The contents are on the left hand side of the webpage. You don't have to use all the pieces to the mold and could definitely use the base as the top also, then sand cast yourself an arch. Of course incorporate information about securing all the pieces together and making it stable on the ground.
Happy casting

Here is a link that might be useful: birdbath with column and stand

    Bookmark   May 25, 2006 at 7:34PM
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nathanhurst(VIC Aust)

I'd go with the render over foam approach, with a structural core of wood or rebar.

Tango is right that a circular arch pushes outwards as well as downwards. However, another arch shape is self stable. This shape is the catenary (y = cosh x) and is easy to make using a piece of rope or chain hung between two points so that the end tangents (slopes) are nearly vertical. Turn this curve up the other way and you have a self stable arch (it won't look very cloistery though :(

The St Louis Arch is a catenary.

An easy way to support lateral pressure is to make a 'ruined wall' on either side concealing a diagonal brace.

However, I'd just go with a simple plywood frame made in a box section, then attach foam, carve, render. Like movie sets. Even solid foam with some fibreglass mesh would work well - a very light design is safe because even if it does fall, it isn't harmful.

You should worry about it blowing over - steel fencing wire to a concrete block inside is probably enough. Looking forward to some pics!

    Bookmark   May 30, 2006 at 4:37AM
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nathanhurst(VIC Aust)

You've inspired me now. I'm going to replace our failing wood fence and gate with a ruined wall and arched doorway :)

I'll make the door out of timber with those old style square headed nails and a lift the bar type latch, the wall and arch out of cement over foam core with some solid timber or steel frame to hold the gate.

Thanks for the inspiration!

    Bookmark   June 1, 2006 at 3:22AM
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