Here are my thoughts after making my own pavillion due to being too cheap to just buy one off one of the many fine tent purveyors such as Past Tents.
Cost and materials
- 36m hopsack red canvas off ebay £50 inc postage, 10m red webbing off
ebay £5.50 inc postage, D rings £3 or so, thread £2 or so, getting
poles made/donated by Sean £50. Total cost £110? Owning your own lovely
medieval tent: priceless.
First, and I can't emphasise this enough, DO YOUR RESEARCH! Some collected links which may be of use are listed in Daisy's del.icio.us tents tag. Decide what you want and design it. I decided that I wanted a medium (roughly 14ft diameter) minimum-fuss octagonal pavillion style tent with a central pole which would break down for transport. At this stage, I was planning not to use poles to support each corner and instead simply guy out the structure for strength. That's because I didn't realise how big 14ft really is. I'm not saying it wouldn't have worked without side poles but it would have taken up a huge ground area and probably sagged quite a lot. Some research into canvas showed that a common width is 5 feet (152cm) which is about perfect for the width of a single wall. You could buy narrower canvas and sew it into larger widths if you like - this would be good for a stripy pavillion.
Geometry showed that the minimum total length of canvas needed for an octagon with walls 6ft high and 5ft wide is about 32m. You can do it with less if you make the roof triangles up separately (cut a rectangle down the diagonal, sew together down the outside edge to make an isosceles triangle, this is one roof panel) - do your own maths for that. You really need to be careful with the maths on this - double check all your calculations. Octagon geometry link: http://mathworld.wolfram.com/Octagon.html Here's a lovely polygon layout calculator and another one. Too late for me, but very useful!
So, the maths. Obviously, your sides are easy, decide the length of
each side and sew eight of them together (well, 7 and a door). Working
out how big to make the triangles that make up your roof is the
complicated bit. If you were making a flat roof, you'd need to find out
the inradius of the octagon i.e. the distance from face to face, NOT
corner to corner. This is the length of triangle needed to make all 8
triangle just meet in the centre. The inradius (r) = 1/2 (1 + sqrt2) *
This means that my pavilion doesn't have seams joining the walls and roof. This is probably good for keeping drips out but may not be so good structurally as that is where all the tension is, so maybe a seam isn't a bad idea. I may at some point in the future add an internal 'extra bit' along the wall/roof join, more as something to pin my banners to than for strength but it all helps.
So, you've cut all your pieces. Big aren't they? Somewhat surprising that the pointy bit is longer than the actual walls, but that's hypotenuses for ya. Right then, sew it together. All the webpages recommend using a flat-felled seam (like the one on denim trousers). Yeah, well good luck to you, there's no way you can fold that much fabric like that for the sizes we're working on. Other tent-makers seem to have managed it but not me, not on my little machine anyway. Nope, instead I used the much much easier and faster welt seam (sew fabric face to face, then on the 'wrong' side (i.e. the inside of your tent) pull both bits of seam allowance to one side and sew another stitch line through all three layers. Lovely and strong, and even better because all you see, even on the inside of the tent, is the nice finished edges of the canvas (assuming you're using a full width as the length of your sides). Pulling it all through the machine is problematic but manageable.
I reinforced every few feet of stitching and at the corners, just in case the crappy thread I was using snaps at any point. Reinforce the corners and particularly the apex of the roof with webbing as you go along (it'll save you pulling 4 whole sides of the tent through the machine to do it once all 8 sides are sewn together). I reinforced each wall-roof angle with a straight bit of 1" webbing. I also put a straight bit of webbing on each seam leading up to the apex (not all the way up, about 6 inches for each strip). When all 8 sides were on, I added two additional bits of webbing which bridged opposite seams which makes a sort of 'cradle' to support the central pole - and mainly to distribute the weight fairly evenly across all seams. This was all done by guesswork, I've no idea how other people strengthen their apex but it seemed to work fine.
I covered some webbing with canvas and used a couple more 5" strips to reinforce the corners of the door where a lot of tension will be. The (guesstimated) principal of reinforcing I used was simply to think about where the stress points would be and then add webbing to spread the tension.
made guy attachments using webbing, which I covered with the canvas so
they looked nice. I sewed about 5" of covered webbing vertically on,
from the outside of each wall-roof corner, not forgetting to slide a D
ring on before sewing down the second bit of the loop. OK, I forgot for
one of them but it was sewed on so sturdily that it wouldn't come off.
Ah well, does the same job. My sewing machine didn't really like going
through two layers of webbing and several layers of canvas at the same
time. This stage took longer than expected due to reluctant machinery.
At the bottom of each seam I made a loop with a D ring on the end of a
5" strip, the free end of which I sewed over the seam itself. These are
for pegging it to the ground. I only sewed the first inch or so of the
webbing to the actual tent - this was because I had no idea how much my
seam allowance might have affected the overall height of the tent (and
didn't have the pole yet to test it). Leaving them hanging quite free
meant that they could allow for height differences in the walls by
either hanging vertical (maximum height) or being pulled out horizontal
(minimum height). Gave me about 4" of adaptability.
that's it. The finished tent: isn't it splendid? It is shown here
erected with the poles on the outside as I haven't put holes in the
corners for the spikes to go through yet. Worked fine though.
used this tent all summer at Maelstrom and man, do I love my tent. I
really had The Fear for this project - a big cash outlay for something
which either works or it doesn't... but it was much easier than I
thought it would be. Buying in the poles certainly helps... and at
£500+ for a similar size professionally made it was my only option
really. It does leak in incredibly heavy rain, and the walls get wet to
the touch but don't drip in steady moderate rain. It has not shrunk or
gone mouldy (yet)... and it's had some pretty rough weather to deal
with. It's a sturdy tent and copes well with wind.
Yes, I added holes so that the poles (which have a spike on top) can go on the inside instead of the outside which will make it look a bit neater. There weren't any washers or eyelets big enough for the spikes to go through so I made my own out of spare bits of wonderflex (a kind of plastic that I had hanging around the house). Sewing them on was a bit of an irritation - I painted some PVA glue onto a bit of spare canvas and cut out doughnut-shaped pieces big enough to cover the plastic. Then I made a hole in the existing canvas which frayed a LOT. So after that I painted glue onto the tent as well, then sandwiched the plastic washer between the two non-fraying canvas bits, then sewed around the outside and inside of each doughnut. I will at some point add either velcro or simply ties at the bottom of each pole to keep the tent from blowing about too much as well.
I also added eyelets to each corner where the top of the side poles are. This was initially because I thought that the spike would fit through them (doh!) and it didn't. But all is not lost because I'm going to thread rope through them to hang the internal banners off. It'll be nice and easy because each end of the rope will simply loop over the protruding spike outside the tent. That'll save me safety-pinning them direct to the canvas and risking tears.
I made the poles - the centre one is a one inch diameter dowel, and the wall poles are planed 1 inch by 1 inch pine. It's very soft and liable to warp, so we painted them with wood seal in a nice oak tint. The centre pole is split into two for ease of transport, and joined with a locking collar of a cylinder of metal, just larger in diameter than the dowel. It's a bit bigger to allow for potential swelling in the wet. I got this from the Metal Supermarket, found here: http://www.glasgowonline.co.uk/info/17005/ which was very helpful, and was £7 for 2x two foot lengths of mild steel pipe. Two bolts and wing nuts used to attach it.
It's worth mentioning that the wood for these black and white ones (nicely planed 1inch square wall poles and finished dowl), ropes for guys (waxed cotton), screws, nails and eyelets cost around £200 for all three tents. She also applied some waterproofing to one of the three. We tested one of the un-waterproofed tents when it was damp and it didn't keep out a hosepipe on its roof (unsurprisingly). We've yet to ascertain whether the waterproofing will be worth the £45ish it cost.