Concrete Rumfords

Buckley Rumford Fireplaces
Concrete Rumfords
12/4/23

If you're going to pour a concrete wall anyway, you can add a fireplace and chimney for little more that the cost of the lining components and a few hours of work.

Our clay throat, smoke chamber and flue liners are the perfect "leave-in-place" interior forms. You can just stack them up and pour concrete around them. You do need to build a form to support the firebox and you will have to wrap the lining components with ceramic fiber paper so there is a bond break and just a little room for expansion.

Here's how:
1) Start with the concrete hearth base and lay firebrick for the inner hearth as with any masonry fireplace. See http://www.rumford.com/insta.html
2) Build a plywood form for the firebox. Level the box and lay the firebrick against the form from the back using refractory mortar. Since the box is level you can build a firebox this way in about 15 minutes so the time building the form is mostly recovered. Take the form away, fill any voids and wash the box. Put the form back in. The reason for the form is to support the freshly laid firebox so it will resist the hydraulic pressure of the concrete you're going to pour around it.
3) Set the clay throat as shown in the Instructions at http://www.rumford.com/instc.html only you're going to pour concrete instead of laying block around the components. Tape some ceramic fiber paper shown at http://www.rumford.com/store/paper.html on the back and sides of the throat. You could add the paper to the front of the throat and the back of the firebox but I don't think you need to as these components don't expand much with heat.
4) Now you are ready to build an exterior wall or chimney form and pour concrete around the firebox and throat - if you want to pour in a four foot lift. If you prefer pouring in eight foot lifts you'll have to lay some block behind the firebox and around the throat in order to support the damper and smoke chamber - like the Instructions at http://www.rumford.com/instd.html except you only have to build the back-up block, not the exterior shell, which will be concrete. You won't have to lay any block if you make your first pour to the top of the throat which will create the platform on which to set the damper and smoke chamber.
5) Four foot or eight foot lifts, the rest is fast an easy - just wrap the smoke chamber and clay flues with the ceramic fiber paper (cut it with a scissors and tape it on with masking tape) build your exterior concrete forms and pour the concrete. It should be just like pouring a wall in terms of the way you build your forms, place the rebar and consolidate the the concrete.