I found this forum when doing research before designing and building a trailer enclosure. Just to introduce myself a little, I'm a scientist by trade and have farming and woodworking as hobbies. In the near future that order might be backwards as retirement nears. This is my first "trailer" project, but I have built furniture and timber framed structures, giving me some amateur background to draw upon. Perhaps some of the design solutions and construction details would be of interest to this forum and I'm hoping to learn from the comments in order to improve future projects. I had the specific need to transport my Jacob sheep to the county fair and also to the "other place". I have a nice Aluma (R) open trailer with side fence and tailgate. The final structure I envisioned had five pieces that bolted together to form the enclosure around the existing structure. The enclosure needs to shed water, but it will not be left out in the rain for long periods (days not weeks). When not in use, the enclosure is to be broken down into parts stored overhead in one of the buildings. I'm thinking the enclosed trailer might also serve for camping if washed down. The front of the trailer is curved to reduce wind resistance and has an operable hatch allowing me to check in on the animals. Across the back, that is parallel to the tailgate, is a plywood wall with small gate that meters the entry and exit of the critters. The width-wide tailgate does not provide good metering of the sheep movement... they would all jump out together and run away.
Here is a picture of the Jacob sheep and trailer enclosure in progress. I created a album for the animal transport project where you can find many construction details I write about below
The sides have the advantage of weighting onto the deck floor and tying into the existing fence structure. For the first 2 foot wide bottom of the sidewalls, pieces of FRP were cut to a size that flexed into an opening at the top of the fence. The white FRP inside the aluminum rails of the fence presents a nice clean look. For two feet above the fence, I used exterior class 1 plywood bolted to upright posts that sit atop the deck and hold the FRP sidepanels against the fence. All the cut plywood endgrain was enclosed in solid wood edging that I made with a dado blade. After drilling bolt holes through the plywood for the uprights, I used standard quick drying wood filter, sanded and then coated with Rot Doctor CPES (R) as recommended on this forum. In front of the trailer is a curved, operable hatch that was tricky to build. I'll follow up with a separate post on that.
The most difficult design feature was the roof because it needs to span a wide space and shed the water a long distance. The roof solution utilized two complicated rails (left and right) with rabbets cut along on the outside edge that nest into the top of the plywood sides. I will epoxy a rubber gasket to the underside of the rabbets to shed water over the outward sides. There are 52" long ribs that span the space between the rails and spaced every foot. The ribs are wider in the middle of the span than at the ends in order to give a contoured look to the roof. A series of vertical dados (opposite the side of the rabbet) in the rails capture the end of the ribs. Because the dados glue joint into the rails is too short and fragile, I cut 7/16" wide grooves into the rails and ribs at right angles to the dados. Into the grooves I set rectangular plywood gusset supports that connect solidly the rail to the ribs. I glued and screwed the plywood gussets into place with titebond (R) II.
Also into the rails (this is the fourth cut feature) is a 1/8" groove cut with the table saw that is parallel and above the wide groove holding the gussets. Into this groove I plan to epoxy FRP sheets for the roof skin. I'm think this will be strong enough and I do not have screw through the FRP into the ribs. I will put epoxy onto the rib tops when the skin is set into the narrow groove. The rails of this design are easy to screw up because of all the cuts and the left and right sides are not interchangeable, but I took my time, marking with a pencil and triple checking and did not make a mistake. The wood for the rails and the ribs need to be relatively knot free for this design to work. I presanded all the pieces with #80 grit before the glue up to make the final finish process easier. The roof will get CPES and painted before the skin is applied. I'm thinking of taking the plywood to a professional artist to get some decoration. I'll followup with a post about the final assembly.
