Styrofoam Form for the vent arch?

[thebadger]

If I glue 2 pieces of styrofoam (4 inches thick) to make the template for my door /vent arches would the styrofoam be sturdy enough? I thought it might be easier to do this than using plywood. Plus it would be easier to get the styrofoam out.

Let me know.

Thanks
Dick

[brokencookie]

Re: Styrofoam Form for the vent arch?

I would think that should be plenty

Look here

http://www.fornobravo.com/forum/f8/36-oven-construction-pics-348.html

It looks like the foam is only one inch and help up the dome during construction without a problem.


Bruce

[Bob C]

Re: Styrofoam Form for the vent arch?

if you feel it is necessary to have a second opinion... the styrofoam will be plenty strong...if you have any apprehension at all, use the blue or pink board, it may have a little more strength. But you will be fine in either case

Bob

[gjbingham]

Re: Styrofoam Form for the vent arch?

Don't forget to leave shim space underneath the styrofoam forms. A couple of builders had their arches fall trying to pull the forms out.

[Xabia Jim]

Re: Styrofoam Form for the vent arch?

Don't forget to leave shim space underneath the styrofoam forms. A couple of builders had their arches fall trying to pull the forms out.

George, good tip. How long did they wait before pulling out the foam? I should think you can cut it to come out easier.

[thebadger]

Re: Styrofoam Form for the vent arch?

So it sounds like the styrofoam will be strong enough to support my entry arches . I just didn't want to build it and have the arch "shift" while it was drying.

I agree. My plan was to cut them out.

TIP: I used an old "electic turkey carver" (actually a new one that we got as a wedding present 8 years ago but never used it ) with the two blades to cut the styrofoam.

Thanks
Dick

[david s]

Re: Styrofoam Form for the vent arch?

Heavy duty plastic sheet works well for a shim over your formwork. Nothing wants to stick to it and form slides out easily. Also try to create what they call a release. That is a slope like a wedge so the form comes away easily.

[Frances]

Re: Styrofoam Form for the vent arch?

I used styrofoam boards for my archway - and I had to pull them early because of an accident with the vent pour, and I didn't have wedge thing and had to cut them out with a bread knife...

But it worked out fine. Wouldn't want to use anything else.

[gjbingham]

Re: Styrofoam Form for the vent arch?

Cutting them out is perfectly acceptable. A couple three shims under the bottom of the form can be easily pulled and the whole thing should come loose.

I think the current wisdom on how long to wait before pulling the forms is one week. If your bricks are custom cut with a keystone at the center, and with minimal mortar joints - 4 or 5 days may be safe. Why sweat it though. Give it a week. (I only lasted 6 days before I couldn't wait any more)

[wlively]

Re: Styrofoam Form for the vent arch?

I used 1" pink foam board "arches" as my form or support for the vent arch. Plenty strong. Since I went with a cut brick arch, for minimal joints, I pulled the forms soon after getting all the bricks in place together. I wanted to make sure, if by some chance the mortar bond completely failed the arch would still stand. Pulled the supports and the the arch held fine. Great feeling. I should say the sides or wall were set of course.

[gjbingham]

Re: Styrofoam Form for the vent arch?

Good report Wade. I figured that with tight joints well placed bricks, the arch should stand on its own immediately. This is the point though that butressing the entryway walls might help a bunch.