Day 28 - post beehives

We finished building up the posts to full height, and were able to add a beam to go under the long span of the octagonal room of Pat and Wendy's house. Not sure why we didn't design this in before, but we were able to add it quite easily to the existing foundation pads.

The row of 'beehive' posts that will hold up the beam at the back of the houses, and the little offset post in the foreground to carry the projected bathroom and water tank above.

Three of the five posts that wil hold up the octagon tower.

We also got into the pit between the edge fo the excavation and the cellar wall to pull up the plastic that had been cast under the footing. This was an extremly messy job but was easier than we had thought by using the water in the trench to help wash away the sticky soil and mortar that had fallen into the base.

Day 27 - post collars

Pat worked on Saturday to mix a few loads of concrete to build up collars around the base of each of the posts. He also filled the holes of the first block. We were worried about the stability of these posts, especially with the super-size bed of mortar, and about these blocks being knocked off their footing during construction. When in doubt add more concrete!

Day 26 - posts

We started to build the concrete block perimeter piers. The top levels of the concrete pads had been set a few days ago using a long piece of wood and a level, measuring down in relation to the top of the cellar walls. Unfortunately, in our rush we added rather than subtracted the thickness of the plywood which will go on the underside of the ground floor structure (which will be on top of the cellar wall, but not on top of the piers)! This meant that the top of the slab was too low, and when this error was added to the substantial margin of error that we left (it is easier to make the pier higher than shorter) we had to put a substantial layer of mortar under the first block in some of the posts.
This kind of error is demoralizing, but we were able to deal with it without too much damage. We will build up the base of the post with concrete left over from another neighboring house build, to provide more stability.

We positioned the posts using triangulation - measured from two fixed points at the ends of the cellar wall - and a water level - buy using a clear hose filled with water - which we should have done in the first place!

The difference in levels and colour of the water at the base of the two cellars is significant - when viewed from the top of the party wall.

Submerged ladder ...

What happens when the site safety officer leaves for the day!

Flooding

A huge amount of rain fell yesterday, and most of the excavations for the posts were flooded this morning.
As was the cellar. One of the houses had more water than the other - indicating that there was a leak somewhere. Hopefully the plastic lining will deal with that.



We used a few hoses to siphon the water from the perimeter excavations into main pit (which is almost 1m deeper. It was a slow process but we managed to get all 15 pits cleared of water before the concrete truck arrived in the afternoon.

Day 23 - pier foundations

Today was another slow day, frustrated by weather and waiting for material delivery.

The plywood for the ground floor structure and the roof arrived, much more plywood than I thought we would use, but it is providing the main stabilizing structure for the house.


With all the rain and wind we have been gettign lately, We made sure it was wrapped up tight.


We cut and bent the rebar that will tie the piers to the footings, and tied them into position. Apart from the bolts and bearing plate for the main walls of the cellar, we are now ready for the next load of concrete.

Day 22 - planning

It was not a great day for working in site. It is raining, and we are waiting for delivery of threadded rods and timber. We spent most of the day planning the next phase of the build, but we did get onto the site to do a bit more prep work of the pier foundations

Day 21 - rebar in pad foundations

Another partial day on site - a lot going on these days and it is hard to get in a full work day. The next load of concrete is not coming until next Tuesday, so we have not been pushed.

Pat was able to cut up all of the rebar mesh for the pad foundations, and we set up all of the pads. Once we get the vertical rebar bent and in place (which will tie the concrete block piers to the concrete pad) we will be able to

Day 20 - preparing pad foundations

We were only on site for a couple of hours today because of the rain, the kids being around and needing to sort out some of the details for the next phase of the project. But we did accurately lay out the positions and base height of the perimeter posts - using the old fashion methods of triangulation with two long measuring tapes, and a long board and level.

We then prepared the basic formwork for the 15 pads - most of them 1m x 1m square, with a bit of extra digging in some places and some filling in in others.

Floor Framing Drawings

These drawings are part of the preliminary sequence of framing drawings prepared for the engineer, and detail how we are going to construct the framing of the houses.
Layout of the foundation of the two houses with cellar in the middle and series of posts to the front and back.

Ground floor framing constructed with 225mm x 44mm (10" x 2") beams and joists, showing the two hatches into the cellars. this floor will have glued and screwed plywood on the top and bottom to help transfer the horizontal loads onto the central cellar/bunker.

First floor framing.

Second floor framing.

Roof framing (plan view).

Day 10 - more concrete blocks

We almost finished the first course today. It is very slow going as the concrete floor is uneven and we are being more precise than we need to be in leveling and placing the blocks.


The mortar mixing station in the back of Pat and Wendy's house. The mortar is delivered in batches to the site about 100m away in buckets on the back of a trailer.

Leontien helping to level some of the blocks.



Site photo at the end of the day with the concrete blocks piles are going down. We laid another 52 blocks today (we are going to have to get faster at this or we will be in the pit forever).

Day 9 - starting the concrete block walls

It rained last night, and a fair amount of silt fell from the face of the excavation onto the plastic lining. We need to get the wall up in a hurry in case more subsidence happens.

It took us a while to get going, and to get into the rythem of block laying, and by the end of the day we had only laid 26 blocks.





The site at the end of the day.

Day 8 - concrete blocks

We removed the formwork for the concrete and prepared the site for delivery of the concrete block for the walls.


The concrete blocks were placed on the slab with amazing grace and precision.

The hollow concrete blocks are 21.5cm wide. We could have used a narrower block to satisfy the structural demands of the wall, but it would have been trickier co construct as most of the blocks need to be threaded down over the vertical rebar.

Most of the blocks for the walls fit into the slab, and if we are careful not to break any, we will have enough for the perimeter posts (we only have a buffer of about 6 surplus blocks out of the total delivery of 720!)

In total there is about 9.2 cubic meters of concrete in these blocks.

Day 7 - digging the post foundations

Today was a light work day. We had marked out the location of the 15 posts at the perimeter of the houses with chalk, and the extent of the excavation needed at each post, but when the operator of the digger started to excavate he felt that the depth of 1.5m that was originally specified by the engineer was too deep, especially in such hard soil, so he stopped. It was also felt that such deep excavations, would have required a trench which would have increased the risk of the sides of the excavation collapsing. After consulting with the engineer, we are going to go with shallower foundations under these posts.

Day 6 - concrete

The start of the concrete pour - made with Ecocem GGBS cement.

To fill the main foundation we needed 2 truck deliveries, and a fair amount of moving the stuff around.

This is what 14 cubic meters of concrete looks like (at 30cm deep). Two phrases come to mind - "over-engineered" and "ecological footprint". Ecocem is better than typical concrete, but it is still not good enough.

Frames of rebars were assembled and inserted into the wet concrete once it was leveled. These vertical rebars tie the footing base into the vertical walls of hollow blocks, the holes then filled with concrete to make one continuous structure for the base of the building. This was seen as necessary to deal with the horizontal and racking loading of the building (primarily from wind), and it allows us to use less structure on the perimeter of the two houses.

Robbie the donkey came for a visit to see what was going on.

The completed primary slab, with vertical rebars in place.

View of one of the cellar rooms with rebars for the perimeter wall and the structural fin walls.