We had the most amazing weather. It was a gorgeous, calm, warm and misty all day – ideal for concrete work. In order to get the whole roof done in one clean shot we worked from early in the morning until after dark, violating our usual rule about not working to late.
At 5 pm I could no longer see well up on the roof. Suddenly a fierce wind blew up, dark clouds raced in dropping visibility to almost nothing, the temperature plummeted and snow began falling. I called a halt to work and climbed down off the roof. We began covering the fresh concrete roof with a sheet of plastic to protect it. A minute after we began pulling the tarp on the snow changed to light rain and then an intense downpour for about 30 seconds. We were soaked but the plastic was on and I think the roof is okay.
Will and I climbed up onto the low scaffolding to begin securing the plastic. Seconds later the wind calmed, the clouds vanished and the stars appeared. The temperature shot back up to 53°F – it was balmy again. It was an amazing five minute storm. I commented to Will that this was our warning – the contract extension for fall construction was at an end so we better finish up fast!
Interestingly, about 45 minutes later we drove down the mountain, to get a celebratory pizza at the general store, and as we descended into the valley we passed down into the clouds and then below them. In the valley it was raining lightly and you couldn’t see any stars at all. On the way home we rose back up through the cloud layer and above. At our house the stars were out – in the moonless night I could see even minor clusters.
When we started this morning we removed the protective plastic from our previous work and took off the books of insulation that had kept the concrete warm while curing. I started the day with a nice big cat walk up on the roof.
As the day progressed I gradually removed portions of the cat walk scaffold in order to finish the roof and patch the holes under the catwalk where the studs had come up from below to support the wood. Although I could now walk on the roof, it is very strong even with just the first layer of concrete, I did feel a bit like the cartoon character sitting out on the tree limb and cutting off the branch he was on…
The catwalk was supported on vertical studs that came up through the interior scaffolding and truss work. We laid the 661010 Welded Wire Mesh (WWM) form work and expanded metal lath around the catwalk supporting studs. When the studs were removed this left holes. I flipped down the flaps of lath and applied concrete to patch them making a unified roof.
Along with the catwalk I gradually lost my leash. I had a rope tied to three points on the catwalk with a figure eight knot and loop at the end. While working I had this over one wrist and gripped the knot. This gave me a safety and let me lay back down the side of the roof. This was easier and more flexible than using a climbing harness. In the end, after the catwalk with its attachment points was gone, my leash was tied to the top of the ladder which I anchored to the south side of the house.
Yesterday and today I have been walking on the roof. It feels very solid. I weigh 1,575 lbs per square foot. Yes, that figure is accurate, I checked my weight this morning. Of course, that is when I am standing on the ball or heel of one foot. That is 11 pounds per square inch (psi). What is even more impressive is I was often carrying buckets of concrete which adds another 61 lbs to my weight making it 3,000 lbs per square foot or 21 psi. The reality is the concrete is far stronger than those figures, probably well over the 1,000 psi point by now. The eventual cure for concrete should be around 3,500 psi at 28 days. That is a whopping 500,000 lbs per square foot – strong enough for a herd of elephants. I don’t think the roof is actually that strong as there are other factors than the pure compressive strength to consider!
To keep the ladder from pressing against the roof I projected the catwalk beyond the lip and added a T of wood to rest the ladder against. Buckets of fresh concrete are placed on the ladder side and I leave empty buckets on the roof side. That saves Holly or Will from having to swing them around the ladder when toting tons of concrete up the rungs.
By the way, we set a new concrete mixing record for our project. Ben mixed 59 buckets of concrete using two Husky Mortar Mixers for a total of 1.475 cubic yards of concrete (3,600 lbs) which Will and Holly hauled up the ladder to me on the roof for spreading in half bucket square carrying pails like those shown in the picture of the ladder. The final roof layer we added averaged about 1″ thick (making the total about 1.5″) with some thicker areas like over the outer rebar rib that is covered with lath along the north 1/3rd point of the roof and along the eves.
Outdoors: 47°F/33°F Misty, calm windy, snow, rain, downpour, clear all in 5 minutes.
Farm house: 62°F/53°F no fire
Tiny Cottage: 53°F/43°F