WK18C: Waterproofing and Framing

So this week began with the framing phase of the project. While the first level of the project is below grade, the upper two floors are all out of wood and require a different team to complete. We are using York Construction. I’ve used them before on my house and love Angel and his crew. The owner, Nathan York is a pretty easy-going guy and always has good ideas about how to save time and money. The crew showed up on Tuesday for the “lumber drop” and loaded all of their wood onto the site. This included several heavy beams and required most of the first day to get everything stored on the hillside and in the lower floor area.

We expect the framing to take about 8 weeks and should be ready for our roof coverings in late October- Just when the weather will start to change.

The deep beams shown in this picture are what’s known as “drag struts”. Drag struts are structural beams that reduce the lateral drag on the building due to retained earth and wind loads. Our building is quite tall and thus requires a bit of extra help to reduce the tipping effect of the wind and any lateral forces created by earthquakes.

I went by the site tonight and they framers had put up all of their drag struts and next week will being on the joists that will sit between the struts. The project is starting to look like a building now, and it’s exciting to see how much progress we’ve made, despite the 1 month stoppage.

The site is quite dangerous right now due to the deep trenches that have been excavated for the waterproofing. The waterproofing began on Wednesday and involves three coats (or 90 mls) of a mastic waterproofing system. This is then covered by a drain board, and then supplemented by perforated pipe and gravel (stay tuned for this). The water proofers come by in the morning to put on a coat of the material, and then come back the next day to repeat. They do several walls in one day, and have a pretty tough gig, considering the vapors released by the waterproofing chemicals.

Having spread waterproofing before, I don’t envy them a bit. Prior to all of this though the walls and the footing have to be cleaned. I spent Monday in the trenches with a laborer sweeping and vacuuming the footing to prep it for the waterproofers. I had expected our masonry sub, Garcia Masonry, to take care of it, but after a couple of angry phone calls back and forth, we couldn’t come to an agreement and thus it was left to the Urban Operations to complete the task. Cleaning the footing is critical because the waterproofing wraps down the wall and over the footing, creating a leak proof (we hope!) covering. Water doesn’t like to go uphill, so it’s doubtful that there will be much chance of leakage.

WK17C: Concrete Phase Complete

This was a crazy but satisfying week. We began by pouring our final masonry lift, and finished up the week with a shiny new structural slab. I went by the site this afternoon and was happy to see that there are no visible signs of cracking. The clean-up crew that was on site today sprayed the slab with water before they left to ensure that as the concrete cures it has enough extra moisture. The water you see here was sprayed on at around 3pm. It will all be gone by the 6pm tonight- either through evaporation, or by being sucked into the concrete.

WK17C: Lower Floor Slab.

We began the week by laying out the rebar grid for our lower floor slab. Since the earth beneath the slab was not tested to certify it’s density, we are required to build a structural slab. In our case the structural slab consists of #5 rebar, 8 inches on center. This is an incredibly strong layout and the deck is entirely self-supporting, and also acts as a rigid diaphragm for the lower masonry walls and foundation.

You can see that that the slab is supported on concrete bricks called “dobies” pronounced “dough-bee”. These will support the rebar grid before the pour, and ensure a separation between the rebar and the sand.

Our slab is 6” deep and will have an “architectural” finish, in case we want to leave it exposed. I haven’t decided on that one yet, and plan to wait until we get to our finishes to see if the budget can afford another material or not.

The pour happened early in the morning on Thursday. Since the concrete is 3000 PSI and we’re in the middle of summer, the cooler hours of the morning are critical to the success of the pour.

As concrete increases in strength it’s heat-buildup also increases, and thus it cures faster. We have a full crew on site for the pour that includes finishers to make the concrete look it’s best at the end of the cure.
The pour was a success! We’re on to waterproofing and framing next week, and things are going to get a little crazy with so many different teams on site. We’re more or less still on schedule and should be done with the project by early April- 1 year from the time we started.

WK16C: Masonry Wall, 2nd lift & Plumbing

Back from Berlin, and back on the job, we proceeded to crank up production again in order to finish the concrete phase of the project. It’s been a long hot summer and after shutting the job down for a month I’m itching to get things moving again. We still have two weeks left of our concrete work and then it’s on to waterproofing and framing.

Our Plumber also put in his under-slab pipes, that will connect all of the plumbing to the sewer at the lower street. The tall pipe you see in the photo is to pressure test the system. This pipe is filled with water and the resulting pressure is left overnight. When the inspector comes the next day, he taps the pipe to see if any water drained out, which would indicate a leak.

After the plumbing lines were tested we then covered the pipes to protect them and then spread 2” of clean sand over the area in preparation for the slab. Next , 10mls of plastic sheeting called “visqueen” is laid over the sand to provide a moisture barrier. Finally, another 2” of sand is laid on top to serve as a leveling bed for the concrete. After that the rebar grid is laid out and the slab is almost ready to be poured.

The second “lift” of masonry as it’s known usually requires the most coordination. Anchor bolts for the sill-plate must be coordinated with the plans and any hardware specific anchor bolts must be triple-checked with the plans to ensure that nothing is in the wrong place.

In the last two feet of the wall you have what is known as the “bond beam”. The bond beam essentially holds the entire structure together by forming a super-tight joint at the top of the wall. It is also designed to absorb some of the compressive forces when the wall has to support the framing above. Our bond beam calls for 2 #5 horizontal bars top and bottom, with #5 verticals every 8 inches on center.