8-8-10: Construction progress DKA second week (2 August 2010)

It is 2nd  of August and the “Ecodorp Brabant association” is at the start of the second construction week at the site of  “De Kleine Aarde”.  Early July there were already some  exercises in making foundations for the main superstructure, and at the 26th of July the construction of the pavilion and the re-arranging of the site started.



Because we still had to wait for the arrival of the materials for the foundation of the elevation and the trees for the main structure it was decided to continue with foundations.  First me made the foundation for the porch.  Here we decided to install the top side of the foundation parts about 20 cm lower than floor level.  This will give a possibility to also fix some horizontal beams for the porch floor. 
We only have a over-all design of the architect and a basic layout of the main structure.  All the details we have to develop our self during construction.  This will give a great challenge in learning to think about all the next steps and looking back to what we already have made.


And again we have to do some concrete reinforcement making.  Not a job to do all days but good to have it done once.  Being creative with steel rebar and wire.  These small foundation parts have not been calculated but we are shure, that the use of some left-over of the 8mm reinforcement, will be strong enough.



And, just some hours before the very middle of the week we received the 26m3 of foam glass gravel.  Geocell Nederland has been able to supply this with substantial discount.   We really appreciate the good cooperation with suppliers of the newer and/or more experimental materials.  The people of these companies are in most cases just starting their trade or their company and already had to invest largely in promotion, website, testing, etc. 


With 26m3 of foam glass gravel we have enough to make a foundation for the walls.  The remaining 10m3 can be used for floor-insulation in one of the two circular rooms.  The floor in the other room can optional be insulated with straw bales. 


To get a good idea of how we can build up the foundation between the foam glass gravel in the ground and the underside of the elevation we tested different dimensions of bags.  The first results indicated that we can use about 3 layers of bags (about 10 cm in height if they are filled).  And a bag of about 60cm wide will be good to give enough support to the box-shaped beam.



The choice for two different types of foundation (concrete blocks and foam glass gravel)  can possible lead to some difference in height reduction.  But we expect to overcome this problem: The main structure will support the highest weight and has to our expectation, the stiffest foundation.  On the other hand there is the elevation that has a lower weight and a more flexible foundation.  If the reduction in height for the main structure is the highest than this part will compress the elevation that is standing on a foundation that we expect to be flexible enough to keep the compression forces on the walls within acceptable limits.


And by the end of the week two trucks with trees were unloaded on our building site.  The wood looks good.  Already dry and without many cracks.  Possible this will change over the time if the wood becomes dryer due to the inner climate. 


The first trees that were unloaded are the long supporting beams of about 8 meter length.  And they are not only long but also huge in thickness and weigh.  At that very moment I realised that this could have been different if we had paid more attention to the process of calculation and safety factors.  A good learning point.
Calculations are based on a worst case load profile of storm and snow and rain etc.  Calculations are also in a safe way representing the stress that will occur in the wood under this load.  And wood can be different, so I expect that calculation are base on the possible weakest type of wood.  And the engineer will also add a safety factor to his calculation.  And the resulting dimension of the calculation will be enlarged to the next multiple of 100mm to give the final dimension.  And at last will the supplier of the wood bring us wood that has the final dimension as a minimum at one end.  But for bending stress we only need this dimension only in the middle of the length.  The result of this long row of more that 6 safety factor can be found back in four trees of about 500mm average and weighing about 1000 kg each. 
After realising all this, we made a plan for change.  Or we rent a transportable tree saw machine to cut the four trees down to reasonable smaller size or we request the supplier to exchange the trees for smaller ones.  After some phone calls we arrange thinner trees in exchange for bigger  once

Next week we will start preparing the tree’s. 
This will be the last week waiting for the permit.

Cheerful greeting from Wouter