Floor Height for an Indian House

When you complete the excavation and are ready to get the floor mat and columns done, the next step in the process is foundation and plinth beam. For these works to commence you need to first decide on the floor height. To decide on the floor height one has to consider the following aspects.

1. Geography of the place

The most important aspect is to consider whether the area you are living in a water logging area. This requires you to visit the area in the rainy season. Or check news articles on water logging in your area. That should be a good pointer to start with. Next approach your neighbours who are living in the area for long. They should be able to give you some clue on any known problems.

2. House placement

Is your house at the end of the road or is your house the lowest point in the area. Is your house in the intersection of two roads and both these roads cave in near you house. Now this should give a clue on whether in the future if there are some drain issues and water logging does happen, will you suffer from water entering your house.

3. Road height.

Having considered [1] and [2], the house of our ground floor should be measured from the current road height. So the current road height is your reference. You should consider atleast 3 to 5 rounds of tarring of the roads in your lifetime of 30 to 40 years of the house. So the road height always increases. Any increase in road height means that your house will sooner or later going to be at a height of the road or lesser. So there is a higher chance that any rain water sweeps to your house irrespective of whether its a water logging area or not.

 

So a safe height for your house is nearly 3 ft to 3.5 ft from the road height at a minimum. Your parking and compound area can be slightly lower than floor area to create another barrier[may be .5 feet or 1 feet]. Try not keep it lower than that even if its not a water logging area. If it is a water logging are the best suggestion I would give, having seen issues in my in-laws place koramanagala is to consider making ground floor a parking only area and then start your house from 1st floor. If you want to understand the seriousness of this issue and want to feel the pain of water entering your house[not clean water but mix of drain, sewage, etc] and then even an inch of water in your house can cause you unnecessary distress to look at your furniture, valuables submerge in water. The water seeps through windows, doors, sewage pipes directly from bathrooms, everywhere the water level simply rises. Instead choose smartly and decide if its a water logging area to start at first floor.

You have now decided your ideal floor height X feet.

 

Construction using the decided height

Now you have decided on a number for your floor height. That is lets say X feet. Now using this information you need to decide where to stop the column such that you can finish arrive at the ideal floor height X feet.

Here is an illustration

1. Granite or vitrified tiling along with levelling the floor takes around 3 to 4 inches of work.  [ A=4 inches ]

2. Bed Concrete with large jalli stones takes around 4 to 5 inches of work

3. Plinth beam size is provided by structural engineer. It is normally 15 to 18 inches based on the house dimensions and load.

4. If you plan for 3 course foundation or 4 course foundation you need to add roughly 9 inches for course. Note that stones are normally not same size. So you need to measure the average height of stones and decide a rough figure. so if you go for 3 course it is

= 3 course x [ 7 inches stone + 2 inches concrete] = 27 inches height roughly.

= There is an layer of levelling concrete of 3 inches height  put ontop of the last foundation course which acts a base for plinth beam.

So a 3 course foundation for this example calculation covers 30 inches in height.

Now to find foundation base point,

we have to add [1] + [2] + [3] + [4]

= 4+4+15+30 inches = 53 inches = 4 ft 5 inches

Now if we want to reach a height of lets say 3 ft 6 inches [ 3.5 ft ] from the road, your foundation bottom should start from

= 3ft 6inches – 4ft 5 inches = – 11 inches

 

Similarly lets derive the column stop point. 

Base of plinth beam = [1] + [2] + [3] = 4 + 4 + 15 =23 inches

Plinth base point from road = 23 inches – 3 ft 6 inches

= 19 inches

= 1 ft 7 inches 

This implies 2 things

1. The column should end at base of plinth beam which is 1ft 7 inches above the ground.
2. That our foundation bottom should start from – 11 inches below the road height.

Summary:

1. Mark the floor height of 3.5 ft on a wall close to the road, measuring from the road height. Transfer this height to all 4 corners of the building using a water level tube or using the laser levelling machine[ see in this blog ]. [ Do not use road to measure the height each time, instead use this new mark ]
2. Now using this measurement reverse calculate the column height to be stopped for plinth. This is 23 inches below this mark.
3. Similarly dig upto a level of 53 inches from this mark. [ You will end up digging 11 inches below ground level ] for the foundation. A normal foundation is around 2 feet width and runs all along the ground floor walls or plinth beams [ drawing provided by engineer ].

Hope you had a good time understanding this concept. Read further other concepts and do post your comments below. Thank you.