How to Build an SCA Practical Iron Age Celtic Roundhouse In an attempt to add a more period feel to our camp, my fiancee and I decided to create a more authentic Celtic dwelling for us to live in at camping events. The first thought was to find a period Celtic tent design, and replicate it. After extensive searching, we found nothing useful. It seems that the Celts were not big weekend campers. There are some Roman tent designs from our time period (1st century A.D.), but we wanted something more Celtic in appearance. During a trip to Butser Ancient Farm in Hampshire, U.K. we saw interesting Iron Age Celtic roundhouse reconstructions that fit the bill quite nicely (see Appendix 1). The goal then became to replicate the roundhouse look, with something that was portable, roomy, and still structurally sound. The prominent details that I wanted to incorporate in the tent were that the roof should overhang the walls by a fair amount, the walls should be relatively short, the roof should have a peak at the top, there should be an entranceway that sticks out of the front, and that there would be no center pole to obstruct the usability of the inner space. I decided that a tent with a wooden frame and canvas skin would be the way to proceed. After investigating many alternatives, it seemed that a tent that used many of the construction techniques of a Mongol Ger (popularly referred to as a yurt) would be the most efficient and functional method to pursue. My first step in making a roundhouse was to decide what size tent we wanted to make. Although this description could be adapted to make practically any size tent, we decided to make an 18-foot diameter structure, with a 12-foot peak. We thought that this would be a comfortable living space, and also be big enough to entertain people inside when we chose to. There are five major portions of the roundhouse that need to be made. These are the lattice wall, the roof rafters, the roof ring, the doorway, and the canvas covering. I will explain the methods I employed in fabricating each of these different parts in the following sections. 1 Wall Lattice 1.1 Calculations In making the lattice, you have to figure out how long and how high the wall would be. The length of the wall is determined by the circumference formula minus the width of the doorway. Since the diameter is 18’, the circumference can be found by the formula, C = p x d where C is the circumference, p is 3.14, and d is the diameter. For my tent, C = 3.14 x 18 which is 56.52 feet. Subtracting 3 feet for the width of the doorway, leaves us with 53 ½ feet of wall to make. Roundhouses have characteristically low walls, so in order to stay in proportion, we made our walls 4 feet high. Figuring that the lattice would be opened so that the openings were roughly square, you can determine the correct length each of the laths in the lattice. To make square openings, all of the laths need to be at 45° to the horizontal. This means that if the height needs to be 4’, the length along the ground is 4’, and the lath length can be given by Pythagoras’ equation shown in the following figure: The laths could be cut at 5’8” as the figure above dictates, however the topmost rivet will be spaced 3” from the top, which will affect the circumference. In order to compensate for this, I cut my laths slightly oversized to 6’ 0”. 1.2 Cutting the Laths I cut three 4x8 sheets of 3/16 ” thick plywood to 6 feet long, then ripped each 1 3/8” wide lath out of the remaining 4’ x 6’ sheet using a table saw as shown below: After setting the tent up a few times, I have damaged many of the laths, and when I redo the lattice (hopefully soon), I will use ¼ ” marine grade plywood to avoid these problems and make the lath more resistant to dampness. This plywood will be more expensive, but it will give me more peace of mind. I suggest that you start with the ¼ ” plywood to save yourself the expense of having to buy plywood twice. 1.3 Drilling the Laths Holes are then drilled in the lath at 1-foot intervals starting with a hole 3” from the top. In order to speed up the drilling, you can stack the laths into tall bundles, and drill the bundle all at once as seen in the following pictures: Marking the hole locations with a completed lath. Drilling the holes. The wood clamps are holding a fence that I am pushing the bundles onto to keep the holes in the middle of the laths. 1.4 Assembling the Lattice Once the laths are cut and drilled, it is time to attach them together. I used pop-rivets for my assembly because they were quick and easy, but bolts, knotted string or rawhide could be used. I found that a very tight washer was needed to stop the pop-rivet plunger from pulling through the lath. In my case, 3/16” pop rivets needed 4mm washers. It takes about 200 pop-rivets to complete a 53’ wall section. To assemble the lattice, lay several laths on the ground parallel with each other. Then lay one lath on top of them leaning in the opposite direction. Make sure that all the laths have the 3” hole spacing at the top, and the 9” spaced hole at the bottom. Put a pop rivet through the topmost hole in the top lath, and the first bottom lath, slide a washer onto the rivet from underneath, and “pop” the rivet. Put a rivet sequentially in the remaining holes on the top lath, then put another lath on top, and repeat. Looking at the picture below, notice how all of the laths leaning to the right are behind all of the laths leaning to the left. Without this, the lattice won’t fold. Open the laths to the angle at which they will rest when the tent is assembled, cut one end square as shown in the picture below and continue assembling laths from one end to the other until there are 16 full crosses or X’s at the top, with three single laths that don’t have a pairing lath. This will eventually be one half of your wall. To begin the other half, pair these unpaired laths (single 1-3) with the first few laths of the second section as if continuing the wall around, but do not rivet these “single” laths to the laths of the next half of the wall. I find the wall more convenient to lift and store in two pieces. These two wall sections will be connected with nuts and bolts during tent setup and unbolted for takedown. Be careful to continue this wall when making the second half, as it is possible to make two wall sections that will not knit together. Careful comparison of the picture of the real lattice above, and the drawn lattice below it will reveal that the two are incompatible! The picture has the lath closest to the reader leaning left, while the drawing has the close lath leaning right. They have a different “handedness”, and no amount of flipping and twisting will make these two sections bolt together correctly. By the time I learned this, I had wasted around ten laths. Continue the 2nd half of the wall until another 16 full crosses are completed. Cut the far end square in the same way that the beginning of the 1st half wall was cut. 2 Making the Roof Rafters 2.1 Cutting the Top End The next parts to be made were the roof beams. I used 1” x 2” x 12’ vertical grained fir boards, but there are lots of light, strong, straight-grained woods that could work. Cut their ends at 52° by cutting a block at 38° on a chop saw, then using that as a guide, cut the rafters with the chop saw set square (0°) as can be seen below: Cutting them at this angle will allow them to sit flush to the top surface of the roof ring as will be seen soon. 2.2 Notching the rafters The rafters need to have a notch on them to sit in the crosses on the top of the lattice. This notch holds them in place, and keeps them from sliding. With a handsaw, notch the rafters about ¾” deep, at a 38° angle, 10’ from the top point, and 20” from the bottom. The finished rafters should look like the drawing below: The 20” of rafter after the notch allows the roof canvas to overhang the walls, and adds to the roundhouse appearance. The roofs of actual roundhouses would overhang the walls to protect the mud daub of the wall’s wattle and daub construction from getting wet. Thirty-five of the 36 rafters need to be finished in this way. The last rafter will intersect the doorway ridgepole, and will be shorter. 3 The Roof Ring For ease of measurements, my roof ring has 36 sockets to hold 36 roof beams. This means that each beam is 10° from the next one, which makes for nice, round numbers. For a smaller diameter tent, fewer rafters could be used. The ring is a sandwich construction having a top and bottom of ¼” plywood, and an inner core made up of many small pieces of cut wood.