Construction guide Field Series Episode 3 Basement
Basement
Construction Field series Episode 3 – R.C.C Basement bed
In this episode our technical staff will explain proceedings after following steps discussed in last episode:
-Marking for excavation
-Excavation
-Compaction
-Basement Bed P.C.C (Plain cement concrete)
-Termite Proofing
Step 7 to be discussed: R.C.C Basement bed which will include brief tutorials about:
-Toe wall for holding R.C.C bed concrete
It is a temporary wall which is made by using bricks or concrete blocks for holding the concrete of R.C.C bed, other than bricks, shuttering material such as steel plates, wood planks and palai sheets can also be used to hold concrete together.
-Vapour barrier for seepage protection
This step is carried out after making P.C.C bed and above discussed toe wall. As the name suggests, it serves the purpose of protecting basement from seepage especially in areas where water level is very close to ground. Most reliable method for vapour barrier is using PVC membrane sheets, however due to higher cost, alternate and economical method has been discussed in this video in which bitumen and polythene sheet is used as vapour barriers.
-Reinforcement
Reinforcement is carried out as per structural drawings for basement R.C.C bed provided by the structural engineer. There should be no compromise in reinforcement of R.C.C bed as it has to hold the weight of whole retaining walls.
-Water stopper PVC for joint protection
PVC water stoppers are placed at joint of R.C.C bed and R.C.C retaining walls. It is mostly available in width of 9 inches and is placed such that it suppresses half (4.5 inches) inside R.C.C bed during pouring and remaining half in R.C.C retaining walls, hence making a barrier and joint protection.
-Concrete pouring 1:2:4 M15
M15 concrete pouring is composed of 1 ratio of cement to 2 ratio of sand to 4 ratio of crush aggregate and mixed with 24 to 25 litres water. Bed concrete should always be vibrated using a vibrator so that the mixture blends together. Better blending means more strength. After concrete pouring, it should be cured for at least 10 days to gain comprehensive strength.
RCC(Reinforced cement concrete) structure have a higher cost, and basements are constructed in RCC structures. Financially it is out of budget for most of us to afford basements. However it has many benefits e.g. extra living space, controlled temperatures in summers and winters both, safe from outside pollutions such as noise and dust etc. Basements can be designed for complete and partial accommodations. A complete accommodation includes master bedrooms with washrooms along with other divisions such as living area, store, servant room etc., whereas partial accommodation only includes later divisions. Partial accommodations are recommended more since it does not have wet areas such as washrooms & kitchens hence not requiring installation and maintenance of septic/liquid waste disposal systems.
Introduction:
Field series Episode 3
Dear Mohsin,1)At my plot,ground water level is 82 feet.Is it recomended for me to use membrane sheet at floor of basement.basement is 6 feet below ground level.2)Soil bearing test is essential for basement?
1: No its not necessary to use membrane sheet. Normal vapor barrier as explained in video can work
2: Soil test is always good and better to have before proceeding.
Thanks brother
Thanks
Really appreciate, your quick response.
Please also tell standard heights for ground and first floor.
10’6 or 11 ft each
Hi, Mohsin can you please tell what is good ceiling height for basement ?
10 ft
If we use sunken areas for the light and ventilation of basement then how do you manage water in rainy season especially when it really pours. Will we have to use water pumps to pull water ? And if we do not use sunken areas then what choice do we have for proper ventilation and light ?
Yes sunken areas have drain pipes that drain the rain water to septic tank or storage tank. Automatic pumps are installed in those tanks that pump out the water to main tanks. This is very common and standard practice.
Incase of no sunken areas only option left is the ventilators. But those vents are so slim that proper ventilation and light can not be obtained
Thanks for sharing basement construction guide.
Everyone desires for a home of their dreams where they can relax and unwind after a hectic and tiresome day. Everyone wishes for a house that is well equipped with all the necessities such as spacious and well-kept rooms, good storage areas, and neat baths and of course a basement.
I just write an article on advantages of constructing a basement with complete guideline of constructing a basement. Review it as well.
Mohsin bro you are great
JazakAllah for the love bro 😍
Dear Mohsin – This is useful information and guidance. I want to construct basement in D12/2 Islamabad. The area has water level is high – chances of seepage are high, since there is mud within five feet. what is recommendation.
If the soil consultant has recommended piles, must go for it. And use pvc membrane sheets for water proofing as vapor barrier before the raft.
I read If you are constructing basement in an area where the water tables are high, do not build a basement it will affect the foundations of your house if flooded.
Source: https://blog.graana.com/pros-and-cons-of-constructing-a-basement-in-pakistan/
Mohsin, if i go for 1700 sft ground floor area and 500 sft basement area, then will only the 500sft basement area have concrete foundation and external walls and the rest of the foundation of ground floor will be normal brick foundation? How will this affect the per sft rate of grey structure of whole building?
Yes only 500 sqft basement area will be concrete rest will be normal brick foundations. This should not have any affect on your per sqft rate of grey structure of whole building as in standard practice labour rates for basements & upper floors are decided separately and all such aspects are taken into consideration while deciding the rate.
Mohsin, if i go for 1700 sft ground floor area and 500 sft basement area, then will only the 500sft basement area have concrete foundation and external walls and the rest of the foundation of ground floor will be normal brick foundation? How will this affect the per sft rate of grey structure of whole building?
Hey. Is it possible to construct partial basement in a house? e.g. covered area of ground floor is 1700sft and we want basement aligning with ground floor walls of 2-3 rooms covering around 400-500sft Is this possible?
Yes this is possible and very much in practice😊
Secondly, Mohsin, I’ve read that there are issues of mildew, extra humidity and radon in basements. How can i counter these 3 issues?
All three issues are due to humid environment and improper ventilation. Basements with sufficient sunken areas will never have these issues.
What do you mean by sunken area?
Very simple term, area that is part of basement but is not covered/closed and used for air, ventilation, light etc.
Mohsin, thanks for the quick replies. One more thing. In case of partial basement, how is the foundation constructed? I mean there would be a combination of brick walls whose foundation made of bricks would be at a different level from the slab foundation of concrete basement. How would this work?
If you go through complete episodes of Construction guide field series for basement construction, you will get the answer. I have explained in video how other foundations are constructed.
Many thanks. Very useful information.
Thanks.