I thought I had a really nifty idea for a steam box.

We have an old (1920) stone house in Philadelphia and these types of houses are nearly impossible to insulate. The walls are 18" thick but of this total dimension, about 14" is the stone. There is a lathe and plaster wall over small furring strips attached to the headers and the space between the lathe and the stone walls is only about 1 1/2" - 2". Not useful for any kind of insulation.

When we remodeled a few years ago I came up with the idea of insulating the walls (which sorely needed it) by gluing rigid foam insulation to the existing walls, applying more dry wall over the foam, and then building out the window mouldings to accomodate the additional 1 1/2" of the combination had added to the walls.

It worked wonderfully. The house is much warmer in the winter and almost feels air conditioned in the summer the insulation does so much good.

Well, I had some of the rigid insulation left over and I thought it would make a really good steam box. You know, easy to fabricate with some duct tape, good insulation value to hold in the hot steam, light and easy to move around, cheap (zero) and all those other good things.

All went well until the second time I used it. The first time it was a dream. All the above and more. The steam stayed hot, the veneers bent easily and the job went quickly.

But the second time I went to use it, the "steam-box" had already become a limp and useless wreck. The steam penetrated the aluminum facing over the foam, saturated it, and caused it to lose any minor structural properties that it ever might have had.

End of phase 1!

Steam Box Redux

This was not the only steam box attempt that went awry. I had previously tried to use some 12" diameter smoke pipe but this also did not work well. I learned one thing from this attempt though. If you are going to make a steam box, make one that is not TOO MUCH BIGGER than the material that you are going to steam within it! That was the problem with the 12" smoke pipe; there was just too much internal volume and the steam cooled much too quickly.
 
I did make a better steam box after these failures however. It was almost as simple, not as light, but worked like a charm and has been working for a couple of years now. It is simplicity itself and the sketches show how.

I took two 12' 2 X 4's and cut a 1/4" deep by 1" wide rabbet top and bottom. Then I cut four pieces of 1/4 plywood to the size (width) that I wanted to achieve for the steam box. I screwed these ply pieces down into the rabbetts in the 2 x 4's. I put a little patch over the joint where the two pieces of plywood met. Then I made a plug for one end and screwed this into place. Then I made a plug for the other end which was a loose fit and had a handle on it. This would be the removable one. A loose fit, because I didn't want steam pressure blowing it out all over the neighborhood.

For a boiler I used a turkey roaster!

I cut a hole in the top and stuck in a piece of 3" smoke pipe and with a couple of elbows I connected it to the bottom of the steam box through another hole. I sealed everything up with some caulking.

For a heat source I used our gas stove with the steam box stuck out the window.

Worked great.

Of course, if you have some rigid foam insulation lying around, there is nothing to prevent you from gluing it over the plywood and thereby keeping the interior even hotter!

There are only two safety considerations to observe when building and using the steam box described above.

1. Proclaim your innocence until your dying day as to what happened to your wife's turkey roaster. Blame it on the turkey roaster gang that has been pillaging the neighborhood lately.

2. Only steam on the kitchen gas stove when your wife is away; preferably for at least a day. This avoids two problems; "What are you doing with that damn thing in the house?" and "That's my turkey roaster you turkey!"