AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |
Back to Blog
Cooked plaster fireplace1/23/2024 The hearth could also be sculpted to create a storage and drying bay for wood. We wanted our firebox close to the ground to keep our feet warm however you may choose to raise your firebox up and build a cob or stone hearth for sitting on. Our cob mini wall was tall enough to conceal the insulation as outlined below. This little cob wall should be as level as possible and is made using regular cob (ours was 1 part Burkeville Readi-Mix, 1 part sand, with lots of straw). It also provides a surface on which to rest the front-most floor bricks of the firebox. ![]() The purpose of the cob is to raise up the floor of the firebox so as to house sufficient insulation beneath the bricks. We built a small cob wall over the front stones. To avoid cob failure, ensure that your concrete is either non-continuous (ie composed of clustered pieces rather than a solid poor) or that you incorporate a water break (such as a stone layer) between the concrete and the cob to prevent wicking. When using concrete as a cob foundation, be aware that it exerts a strong suction force and can wick water from the ground up in to the cob wall. The holes of the cinder blocks were filled with gravel. We arranged rocks on top of the foundation, using boulders to support the benches, concrete cinder blocks for the base of the back wall, and small rocks to line the front. Schematic of foundation with overlayed firebox outline. The foundation provides drainage beneath the fireplace and, we hope, will also prevent it from sinking too quickly or unevenly. You will need your foundation to extend below the frost line for your climate. We filled the foundation hole with sharp gravel. Our foundation also extended out to the sides because we planned to flank our fireplace in cob benches. With this basic shape in mind we dug the foundation giving ourselves roughly 8” extra girth on the back and two sides for the walls. The inner foot print of our fireplace’s firebox is 3’ wide in front, 18” wide in the back, and 12” deep forming the shape of an isosceles trapezoid. It is close enough to the house for easy trips to the loo but far enough away that it feels very private and outdoorsy. We chose a previously unused piece of our land, well sheltered from the East and North by trees and open to the West and South for sun. ![]() We are already brainstorming ideas for our next fireplace project! With this one being our first attempt however, we kept the design pretty simple. ![]() At many points during the construction we had significant doubts that we would end up with a working and pleasing fireplace! Having built this one, we now see how much room for creativity and art there is in a cob fireplace’s construction. We started by working out the inner structure and the outer form just naturally took shape around it over time. When we started we really didn’t have a solid vision of how our fireplace would turn out. This blog gives the dimensions that we used but to respect copyright laws we refer you to Weismann’s book (referenced at the end) to learn about the ratios and rationale on which our fireplace is based, as well as cob construction in general. Ours is a Rumford style fireplace, characterized by a forward leaning back wall and angled sidewalls to direct heat forward rather than up through the chimney. The measurements of our fireplace were based on the detailed explanations that can be found in Adam Weismann and Katy Bryce’s book, Building with Cob. Below are the step by step instructions of how we went about building our fireplace. Our family, friends and pets love sitting in front of the open fire and we regularly gather there to drink hot cocoa or a beer and to roast chestnuts and marshmallows. Hopefully some of you are inspired to build one of your own. We had a lot of left over clay soil (Burkeville Ready Mix) from building our pizza oven and tandoor so that is what we used to build the fireplace. In the end however, we decided to stick with what we know and build one from cob. ![]() We toyed with the idea of building one using an old propane tank or of refurbishing an old cast iron stove. It has been a dream of ours to have an outdoor fireplace for some time.
0 Comments
Read More
Leave a Reply. |