Thanks to all of you! The corrugated wooden strips I have seen would require kerfing. Like your sketch, Eric. I think that I could use a horizontal wood strip every 10-12"...attached with those wire ties. After attaching the panels, was thinking that a few strands of #9 wire from the base of one side, over the arch (16'-full panel), to the base on the other side, may add strength...or is that excess? doninalaska, sounds like you have done this for your needs. How much did you overlap the panels? This hoophouse will be used in a windy area. I like to locate the open front to the south (a modified Wood's open-air poultry shelter). The north side will be tarped with chicken wire over, or smooth Polymax type panels, I noticed in the recent Farmtek Growers Catalog. Overall goal is to renovate and not have to do so for many years. Do not plan to order the chicks, until project is complete!

This hole is the only way into the attic except for the small vents at the peaks of the house on both ends, so a hole would need to be cut larger. That part of the house is 3 stories with the attic above the 3rd story (it is low and would only be good for storing boxes and holiday stuff). The existing hole I think was added just so the PO could get into the attic to upgrade the wiring (there are remains of knob-and-tube wiring, but it is all inactive (just the ceramic parts and a few lengths of wire.) So it is either cut the hole bigger to insulate, feed insulation in one bat at a time, unroll a roll in the room & feed into the attic unrolled or don't insulate. To me, the hole seems to be the best option The PO did drywall over anything in the house. Everything is drywall now, no plaster that is visable anyway. I'll check the existing hole to see if there is plaster, the existing hole just has a square of drwyall screwed up to 2 pieces of wood to close the hole, PO's didn't seem to care if it looked good or not as the drywall hole-cover isn't even painted. I've got drop clothes and will put a fan blowing out the window and shut the door to the room (it is just a storage room). the only time I go to the third floor is to feed my cat and clean the litter box or go into my 'Lego room"

Avoid these fiberglass doors at all costs!!!! We are in zero degree weather and the door has major drafts all over. The bottom gasket gave out less than a year later. We could not even close the door until I figured out that there was wood blocking the deadbolt. The door warped in within a month and there is now a strong draft at the top of the door. Feather River has very liberal specs for warpage which allow for drafts. The door was "installed" (butchered in) by a Home Depot contractor (Sayre "remodeling") but the drafts themselves are a result of bad quality materials and manufacturing. The (rude) contractor installed the door and then claimed all the screw plugs were missing and that we were to contact Feather River for replacements. Feather River claimed they no longer had them and sent our a brown crayon to fill in the screw holes! No really ... that's what they did! I put in an attorney general complaint and miraculously they found some plastic plugs to send out. The side panels are askew. All three windows in the door have drafts and I am finding frost deposits around the window frame where the drafts are. Wish we kept our original door ... these doors and their customer service are absolutely horrible! https://www.youtube.com/watch?v=E2EVpuoBJes

what kind of tools are you working with? screwdriver? drill? what kind of screws? metal screws? wood screws? wedging & gluing wood into the gap isn't a lasting fix. the supply register should screw into the supply box in the attic. if the supply box is 3" above the ceiling... then it is installed incorrectly. this leads to conditioned air leakage at the supply box, which causes condensation. wet sheetrock will show water stains & crumble. the person who installs duct & supply boxes is low paid guy on hvac crew, few know how to run duct properly or install supply boxes. so you'd have to really look for someone willing to do this properly. ideally supply box is nailed to 2x ceiling joist on one side & framed with 1xs at minimum so that supply grill can be screwed into wood by angling the screw slightly. this usually doesn't happen, so that leave screwing supply grill into metal supply box. its hard. busdriver...that they had two people working to install supply boxes is suprising. using the drive isn't a bad idea..its what they had on hand and would keep supply boxes flat to attic side of ceiling, usually the 3" screw will pick the supply box off the attic floor...as I suspect has happened at this lady's house. sealing the supply box to the attic floor is important. 30% of the air that we pay to condition leaks into attic. the things I see when working on ducts in attics over the years are horrifying...there really needs to be a lot of improvement in duct installs. best of luck op.