Styrofoam structures

[grandpopswalt]

Hi Guys,

Have any of you had any experience using Styrofoam outdoors? I've developed a fairly decent technique to make “stone” walls using rigid Styrofoam sheets. However I don’t know how it would stand up to the elements. I paint it with house paint, which should provide some UV protection. My concerns are warppage and moisture absorption.

Walt

[Capt Bob Johnson]

Moisture should not be a problem as it is a closed cell foam. Think of all the styrofoam drinking cups you have used, they held water without absorbing it! Warpage may be a horse of a different color. I'd hazzard a guess that you'd either have to use real thick stuff or find a way to back or reinforce it. Just to throw an idea at you, what about gluing some hardibacker to it. You'd have the rigidity & strength of the cement board coupled with the workability of the foam.

[Rene Schweitzer]

Walt,
Years ago in GR, Peter Jones wrote about a technique using Styrofoam covered with concrete. Doesn't sound exactly like what you're asking, but perhaps something else to try?

[grandpopswalt]

Bob and Rene,

Thanks for the input. The backer board is very promising. A laminate of cementbaord and Styrofoam using construction adhesive might just do it. I'll dig through my back issues of GR for Peter's article, I'm open to all ideas.

Walt

[bman36]

Walt,
My guess is it would hold up well over the years, especially if it is painted. Let us know what you find. Later eh...Brian.

[Anonymous]

Walt, make sure you use foam safe construction adhesive, some have a tendency to melt through.

[Anonymous]

Walt,

I do remember seeing a website a few months ago where someone had used red Styrofoam to make a stone viaduct. They had scribed a stone effect into it (using a soldering iron - if I remember correctly) and then painted it. The comment they made was that it had not lasted as well as they hopped, and the red colour from the foam was leeching though the paint.

Now I don’t really know anything about Styrofoam you have over there, but if it is any thing like the styrofoam drinking cups we have here, there is no way I would be leaving that outside as a top layer, painted or not.

By the time you have covered it with cement board, haven't you lost the best property, that you can easily carve it?

If it was me, I would be trying to carve extra wide and deep slots, and then put a thin cement slurry over the top and see if you can still see the stone pattern. I am not sure how well concrete will stick to it, but you can get paints that you can apply to surfaces that help cement to stick to it. With a concrete surface you know it will last outside.

Do you guys have light-weight or airated concrete? It's like a concrete building block that they pump air into, so it's got thousands of little air bubbles in it, so it is really light, and easy to carve. It's called Hebel concrete in Australia, and now it's just come to NZ. It's briliant stuff to carve stone walls out of, and because it is real concrete it lasts outside.

Glen.

[Anonymous]

Rocky, I posted it somewhere before.... can't rember though. Any way they make a thinner cement produst used in construction today MADE to cover styrofoam. they use it to simulate limestone sills and such. Check with a supplier of stucco materials they'll know exactly what it is.

[grandpopswalt]

Glen,

Thanks. I did a web search and found a US distrbutor for Hebel. I've requested product description, pricing, etc.

Matt,

Do you think the good folks at Home Depot would be of much help in locating the product you mentioned?

Walt

[Rene Schweitzer]

Walt,
I happened to come across the article on styrofoam "stone" buildings (had a photocopy in my in basket for reference to another article). It's by John Wenlock and his column name was Across the water. May-June 1988 issue.

Rene

[grandpopswalt]

Rene,

Thanks. I hope I have a copy of that issue. If not, can it be made available on-line?

Walt

[Capt Bob Johnson]

Glen, I was saying to use the backerboard behind the styrofoam to provide rigidity and strength, yet use the foam for it's carvable quality. I also like your idea of using a cementisious (sp???) coating over the foam. It sounded like walt wanted to use it as a retaining wall kinda thing. Perhaps both methods would really provide something that would stand the test of time; back the foam with backerboard for strength, but cover the surface after carving with the slurry to give permanance.

[Anonymous]

QUOTE: Originally posted by Capt Bob Johnson

Glen, I was saying to use the backerboard behind the styrofoam to provide rigidity and strength, yet use the foam for it's carvable quality. I also like your idea of using a cementisious (sp???) coating over the foam.

Sorry Bob, my mistake.

Over here we have a type of Limestone that they used for buildings back in 1900. It carves easy too, trouble is that is soaks up water like a sponge. A friend make some really nice tunnel mouths and bridge abutments with nice detailed stone work in all of them. However in winter it soaked up the water. Then the frosts came and it froze. When it thawed the water expanded and it exploded it apart. So the ones that weren't damanged he put a cement slurry over to protect them and he hasn't had any problems since. That's where I got the idea.

Walt, if you do get some Hebel (and the price is right) here is a website how to use it.
http://www.users.bigpond.com/huntergpmj/gregs/hebel.htm
Over here they make blocks 550mm long X 200mm high and widths can be 50, 100, 200 300. They are quite expensive, but you only need a few to get a good result.

Glen.

[Anonymous]

Walt, I doudt home depot sells it, but you try. look in your phone book for a local stucco supply house, they will have it. I research it the last time this came up and her it was a 60lb to 80lb bag for $ 25.00ish i believe.

[SandyR]

Rene, didn't Jim Strong have an article some years ago in GR, describing how he made buildings of styrofoam covered in vinyl patching cement? I don't have a comprehensive index, so I would have to go through all twenty years of issues!
SandyR

[grandpopswalt]

Glen,
Unfortunately Hebel is only available in pallet lots so that's out of the question. However I may be able to find a dealer who's willing to sell or give me a sample.

Rene,
I found the article you mentioned. It's in the "across the water" department so I assume the author is English. At one point he talks about coating the Styrofoam "I spread on a thin layer of outdoor grade filler. This is the white, putty-like material sold in hardware stores for repairing holes in walls. It appears to be based on a gypsum powder and some kind of adhesive in emulsion". Anyone care to guess what this product would be called here in the States?

The article states that structures constructed this way, gypsum coating over Styrofoam, have fared just fine with no maintenance after being outdoors for 8 years, sounds good to me!

Walt

[Anonymous]

Walt, I'd be leary myself in reguards to using gypsum products out side. Although i have seen a gypsum board with a yellow fiberglass coating on it used for commercial constuction. If you do try it, prime all of it twice before finish coats. IMHO oil based primers run circles around latex! latex O.K. though for top coats.

[kstrong]

Matt and all,

Check out this thread over at MyLargeScale.com:
http://www.mylargescale.com/forum/topic.asp?TOPIC_ID=26764

My dad wrote an aritlce on using styrofoam and vinyl patching cement to make buildings in the April '96 issue of Garden Railways. Rene will have to check to see if they may have back issues, but I doubt it. The techniques are briefly described in the MyLargeScale thread.


The buildings shown here are built using that technique.

To the question at hand about using styrofoam in the raw outdoors, you'll be fine, but remember--it's styrofoam, and not known for its strength. The retaining wall in the above photo is styrofoam, painted with latex paints. It stood up fairly well for around 5 years until Dad finally got around to building one out of concrete. It was a little beat up from stick hitting it, but that's about it. If nothing hits it, it'll last a while. I'd paint it, certainly, but it's not going to disintigrate in front of you or anything silly like that. He's still got a tunnel that's built from styrofoam sheets. It's held up well, except the walls have bowed in slightly, and every now and then a large locomotive takes on the additional role of "tunnel widener."

As for using gypsum based products outdoors, I'll remind you that gypsum is a limestone product, and caves are formed when water seeps into limestone formations. I'll leave it to you to extrapolate from there. Suffice to say that no amount of sealing keeps the water out.

Later,

K

[Anonymous]

I've used styrofoam as a bridge, tunnel portal and building foundations. The only problem that I've had with it is frost heave. Other than that it looks great and it's pretty sturdy as long as you dont accidently bump into it.

[Rene Schweitzer]

Kevin,
Checked, and the April 1996 issue is out of print. Anyone can order a photocopy, though.

Rene

[Anonymous]

Hi grandpopswalt
That sounds like polyfiller or spakfiller spelling?? but I thought the pre mix exterior stuff was grey in colour not white.
Get the powder and mix it with water and a little pva that will give the nice plastic mix that will not crack as easy once dry. paint with exterior finish of choicee
regards John

[vsmith]

Water Putty has also been used to seal foam models with a great degree of success. Although youd most likely have to sculpt the details into the putty before it hardens, only using the foam as a support structure.

[Anonymous]

G.R. february 1995.Article by Jack Verducci.

[johnbruce]

Walt,

I live in England and I have found that what we call masonary paint provides good protection for styrofoam. I also use clear silicone filler as an adhesive for joining the stuff.

Regards,

John

[Anonymous]

Used white styrofoam in our garden railroad building a via duct . Use 5 sheets laminated them together with construction glue stagering the joints and painted with white cement for a cement finished viaduct. Heavy rain water run off flows through with no damage. The only time we have had to perfform any tough up is when a tree branch has fallen on it. Has been in the garden railway for over 3 years and does not crack when the below freezing weather comes and when the sun shines on this structure either.


Mikadosurp