Foundation Masonry Layers

May 10, 2012
Day 20: Foundation Masonry layers

Last post talked about components that make up foundation of the house. This post focuses mostly on masonry work. First, it may be obvious, but just to be explicit, house construction requires a LOT of water. Till the super-structure is completed, almost every activity, starting from excavation, making cement, watering foundation and walls, compacting earth metal, and many more that I will only realize in due course. On an average, expect to use up 20,000 litres each month i.e. about Rs 2,000 on an average.

Masonry work is done with a set of cement concrete blocks that are "glued" together with cement mortar. You might recall that excavation was about 900mm deep. Each block is about 150-175mm tall and including mortar height of each block would roughly be 200mm. Foundation of a house is typically up till plinth which generally is 450mm above the ground level. This implies several layers of foundation masonry.

In our house, ground at the rear-end of the house is 300mm lower than that at the entrance-end.

Hence, plinth-level will be 900 + 450 + 300 = 1650mm from the excavation level. Considering each layer of masonry is 200mm, total number of masonry layer at rear-end is about 8 and at the entrance-end is about 7.

 

The section view of cement blocks is sketched here. As is evident each layer of cement block works its way towards the center. Space on the outer periphery is filled with earth metal whereas the space between cement blocks is filled with cement mortar. I was surprised at the speed with which this work got done.. It took workers just a little over one week to do about 4 layers across most of the house.

Columns: There are 4 columns to bear the load of the first floor balcony and the family room areas. Excavation for columns is about 1500mm. Base of the column is filled with mortar. Then a steel column of about 3000mm is erected as shown in sketch here. Rings are tied approx 150mm from each other to hold the column together. Finally, they'd pour cement concrete around it to create the actual column structure.

Center-line marking pillars: Towards 4-minute mark in the video is description of center-line marking pillars. Center-line marking is to mark center-line for all the edges. Picture shows marking of center-line for window. Blue squares are center-lines that were already marked for main edges of the room. Those were the basis for excavation to occur.

Additionally, a new center-line is now marked (shown with red rectangle) for where the window edge on ground floor would be established. The center-line is marked with pillars (refer to the video) that will remain placed until ground floor actually comes up. These center-lines are marked throughout the house wherever a nook changes the direction of the primary edge of the room.

Finally, this video shows the actual work to build that column described above.