As the colder temperatures arrived condensation on the inside of the plastic greenhouse cover became a problem. Additionally, I had a few leaks near the ridge pole caused when I installed it--entirely operator caused error. I could not put off working on the shed any longer.
The problem was that water was dripping down on the boat--much more from condensation than from the few leaks--and interfering in my work on the boat. What to do? After thinking about many options, and as always trying to keep the cost down, I decided to install an interior plastic liner. The key requirements were it had to be cheap, easy, and it couldn't have any holes. So I installed a 3/16" plastic cover wire cable I bought at Lowes with a turnbuckle on one end. I screwed eye-bolts into the bottom of the ridge pole as close to the ends of the shed as possible. Then I stretched the cable fairly tight. Next, I laid 4mm plastic over the cable and draped it 10' down on each side of the cable (the plastic came in a roll 100' X 20' which I also bought at Lowes. I cut it long enough to stretch from one end of the shed to the other plus a little extra so I would have enough to fasten the edges. Then I rolled the excess material around the edge and stapled it to the horizontal stringers at the appropriate height. To keep the top from sagging in I installed pine battens, that I ripped on my table saw from cheap 2X4s. I wrapped the top end of the batten in foam so it wouldn't puncture the liner and nailed the bottom of the batten to a horizontal stringer. The top 7/8 of the batten is free-floating so there are no holes in the liner except around the edge.
So far it works great. No water on the boat. Condensation drips down from the shed cover onto the liner then runs down the side and drips clear of the boat. This is certainly not a high-end solution but since the shed is temporary until the boat is finished there is no sense in spending more money on a solution than required to solve the problem.
Condensation liner installed.
I secured the edge of the liner by rolling and stapling the edge to a horizontal stringer.
Update to Vapor Barrier Liner 30 Sept 10
And then it rained, and rained, and rained . . . . I have never see rain like we have had here in eastern North Carolina this week. It has more or less poured non-stop for 3 1/2 days. As of tonight, since Sunday we have had 21" of rain! It is supposed to stop raining tonight with sunshine forecasted for tomorrow afternoon.
I got a little side-tracked today. The vapor liner has been sagging in the SRF for awhile. I installed last winter as a temporary solution to condensation forming on the inside of the single plastic cover (cold outside temps but warm air on the inside of the SRF). I constructed the vapor liner by draping cheap 4mm plastic sheeting over a plastic coated cable that runs the length of the shed just below the ridge-pole. The sides of the liner were held up by 1/4" strips of pine ripped from 2x4s with foam wrapped around the ends to protect the plastic sheeting. It worked fine last winter and spring but started sagging during the early summer and had finally become a droopy bag.
I did not want to spend a bunch of time or money to correct something that could be improved with a simple fix. I looked around to see what I had on hand. I ended up ripping about a dozen 3/8" thick X 1 1/2" wide strips from some 12' pine cut offs. I stapled and screwed them to the existing strips that were holding the vapor liner up. Now, instead of two independent pieces of wood supporting just the sides of the vapor liner I have bows that run all the way across the liner from one side of the SRF to the other. I should have done something like this last winter. But it's a slippery slope when you stop to work on a temporary requirement. Sometimes, perfect is the enemy of good enough. The liner is 100 percent improved.
Replacing the Vapor Barrier Liner Sept 2011
3 Sept 11 After Hurricane Irene I set to work to rebuild the vapor barrier (I took it down before the storm). I removed the old one because . . . well . . . it was old. The plastic sheeting used for the vapor barrier is not the same as the plastic used to cover the SRF. The plastic over the SRF is very heavy with lots of UV protection and is guaranteed for 5 years. The vapor barrier plastic is 4mm sheeting from Lowes without any UV protection. Thus, it was starting to fall apart and it was also pretty grimy from the residue created by the never ending sanding that took place over the last two years. I decided to use the same kind of plastic sheeting for the liner because it was cheap and it did the job I needed it to do.
A much improved vapor barrier.
The bigger issue was how to support the new liner. For the old liner I used strips of wood that I cut off of 8' 2x4s which I then stapled and taped together. To be honest, they were pretty flimsy and would get to flopping around whenever I had the transom hatches open and their was any wind blowing through the shed. This is the main reason I decided to take the liner down before Hurricane Irene. I didn't think it would survive the wind that would get through the cracks in the SRF. I thought maybe PVC pipe would work better and I bought a minimal amount to experiment with. After trying a few different techniques I settled on using 20' long 3/4" schedule 40 PVC pipe with bell ends. It is commonly used for sprinkler irrigation pipe. It's a little more expensive then non irrigation pipe but it comes in 20' lengths and because each pipe has a bell end I don't have to buy or glue any couplings. I added a 4' section of pipe to each 20' long section to give me a total length of 24'. Gayle helped me install them. First, we ran a new cable from one end of the shed to the under just under the ridge pole. Second, we draped the plastic, which we had pre-cut, over the cable and let it hang freely on both sides of the boat. Third, we put a single pipe together, bent it into position and clamped it in place. Fourth, I drilled holes through the pipe and into the bow frames. Fifth, I used a drill gun to install 2" #10 SS screws, which I have plenty of on hand. Sixth, we repeated the cycle. We started on the aft end and worked towards the bow end of the shed. It only took a few hours. I rolled the edges of the plastic all around and used a pneumatic stable gun with 18 gauge 5/8" staples to tack the plastic down. Finally, we finished off by ripping some 8' lengths of 3/4" by 3/8" strips off of some scrap 2x4s. I used 1" long staples to secure them over the previously rolled and stapled plastic sheeting. Nothing to it. I think it looks much better and hope that it is stronger too.