Exterior Finishing Suggestions

[Vancouver36]

Hi Everyone,

Looking for some suggestions on a finish for my 36" portable Pompeii here in Vancouver, BC. As you can see in the photo, I've applied the scratch coat of stucco to the dome insulation, but am not sure where to go from here.


A couple of questions:

1. Does the porous nature of firebricks make them unsuitable for exterior finish> My outer arch is firebrick and I would like to leave them exposed, but I wonder if the bricks would continuously wick moisture into the oven.

2. Any suggestions on finishing the front of the floor? As you can see, the insulating layer under the floor is exposed and will absorb moisture. Also, the smaller floor bricks near the front could be dislodged if a tool was to drag on them going in/out of the oven. I could just apply stucco to the insulation and face of the floor bricks, but I was hoping someone had another suggestion.

3. I have a bucket of Dryvit (Acrylic Stucco) that I plan to apply to the exterior of the dome and maybe the chimney. Does anyone that has used this product before have any tips on installation? What I've heard is it's a great product, as long as it's installed properly. What should I look out for?

Any other suggestions/comments welcome.

Thanks!

[ATK406]

Re: Exterior Finishing Suggestions

Congratulations on your build. I can appreciate that you would like to minimize the weight to keep your oven portable. Here are a couple of suggestions;
1) If I were you I would record some temperature readings on your scratch coat to see how hot that surface is getting - prior to installation of the Dryvit. Dryvit might be ideal but I would be concerned if the external temperature of your substrate would exceed 150-200F. You could probably experiment a little bit by applying the Dryvit to a brick and applying some heat to see if thermal expansion affects the bond.
2) You might be able to apply a sealer to the exterior arch, but a brick arch would probably be more robust and may permit some bolstering of your inner arch (see below). You could use wood and a silicone or rubber seal/sealant to prevent moisture from getting to your insulation layer.
3) Of greater concern to me is the design of your arch. It does not look like your current design includes much lateral support for your arch i.e. there is no buttressing (unless you have done something special with rebar/steel supports within the arch itself). Given that your oven is portable your arch will see dynamic loading as the trailer moves up and down. These loads may exceed the strength of your arch resulting in cracks and/or eventual collapse of your arch and chimney. Arches designed like yours usually require a buttress to support the side walls of your arch. In the interest of keeping the weight down, I would mount steel brackets to both sides of your arch and rigidly fixed them to your trailer. I would even consider a steel strap across the top of your arch to tie these two brackets together. In this way the dynamic loads of your trailer moving up and down would be supported by the brackets reducing the stress on the arch itself.

Just my two cents and good luck.
Regards,
AT

[JoeyVelderrain]

Re: Exterior Finishing Suggestions

cute oven. is that where it is staying on the trailer? looks like it will be difficult to work it

[david s]

Re: Exterior Finishing Suggestions

I tested my firebricks for porosity and discovered that their porosity is exactly the same as the solid red house bricks I have. I was surprised by this as I was expecting them to be far more porous. Not all firebricks are the same though, so just see how they go. Any waterproofing compound is likely to be destroyed by heat, but you could try some product.
Regarding the bricks and transportation, others have found that the bricks have a tendency to rattle to bits. Most mobile ovens are modular cast refractory for this reason. But you're here now so just use it and see how it goes, but do make sure you put shocks on that trailer.

Fire the thing around 10 times before attempting to apply the Dryvit.