Tips on water pressure, load-bearing walls…



Architect Navneet Malhotra is a perpetual student. He loves to break myths and unmask the true cause for bad work by constantly sharing experience… “Path to gaining knowledge is through sharing,” is his motto.


We have a two-storey house with an underground water tank and an overhead tank on the first floor. When we went to purchase a rain shower, the vendor said we wouldn’t have enough pressure for the shower to operate. He said that we would need at least 25 feet between the overhead water tank and the bathroom. Alternatively, we would need to install a pressure pump on the water supply line. Is this right?
Amit Saha, via email

The head of a rain shower is designed as a large plate with evenly-spaced perforations. Each of the holes often has a polymer nodule inserted in it to help focus the flow of water. Because of the large surface area, these showerheads require a greater rate-of-flow of water. Traditional bathroom plumbing pipes have inner diameters of 0.5 in or 13 mm. These pipes are not able to supply the requisite water quantity to such a large surface area, which is why we need pipes of a larger circumference or an increased water pressure.

Increasing pressure through building height or mechanical pumps: Ideally, we need about
15 m to 20 m of head (height) or atleast 5 floors between the bottom of the water tank and the faucet in case the inner diameter of the pipe is less than 0.75 in or 20 mm. This height will give you water with froth in it. But for a rain shower, you will need 9 m to 10 m of head (height of three floors) or above to give you the best result. You can increase water pressure locally by installing an online hydro-pneumatic pump on the shower line. This pump has two chambers seperated by a flexible partition. One chamber is filled with compressed air, while the other one can take in and throw out water. The compressed air induces pressure into the adjoining chamber by pushing the flexible partition between them. It also has a pump and a level-controller that automatically regulates the quantum and pressure of water in the discharge line.

Unfortunately, increasing the pressure of water in old (probably rusted) pipes is never a good idea. It may lead to bursting of the pipe (rarely) or an annoying drip from the head even when the fixture is in an ‘off’ position.

Increasing pressure by changing the water-carrying capacity of the pipes: Water pressure can also be increased by replacing supply pipes of a smaller diameter with those having a larger cross-section. This is especially effective when the main supply pipe from the overhead tank to the bathroom in question is increased in size. Replacing this vertical supply pipe is easy; just disconnect the old one and attach the new one at the same location. In some cases, the old pipe may be buried in the wall, and may prove difficult to uproot. Though you have the choice of placing the new pipe at the same location on the exposed masonry surface, this looks untidy and even ugly. It may be better to look for an alternative route for the pipes. You could easily find an obscure corner in the rear elevation of an alternate plumbing shaft. Make sure you don’t add too many bends as this will defeat the purpose of the exercise. The exposed pipes can also be camouflaged if alternative location is not possible.

A vertical supply pipe of diameter 4 in or 100 mm will be adequate even if your overhead water tank is placed just above the bathroom roof. All internal supply pipes should have diameters of equal to or more than 1 in or 25 mm. But remember, this exercise will bear fruit only if the number of bends in each circuit is less than or equal to 5. You will, most likely, have to redo most of tiling around the shower/geyser area if you take this option.

Our ancestral house in Kerala has load-bearing walls and slanting tiled roofs with a wood frame. I am keen on removing a 4.5-in-thick wall between two rooms. It is 8 feet long. Is this safe? Do I have to remove the entire wall or can I retain the portion above 7 feet as it extends up to the bottom of the truss (15 ft to 18 ft in height)?
Abhilash Kiran, New Delhi

Though most 4.5-in-thick walls are not designed to carry load, it is always safe to take precautions before commencing with such an exercise. Start by attaching temporary structural support members from the roof to the floor on either side of the wall. You can use metal pipes or wooden poles, whichever are easily available. Just make sure that this temporary scaffolding is adequately populated, safely connected to the roof and firmly placed on the ground. Having securely surrounded the wall in question, you can start by marking the level below which the wall has to be removed. I suggest you retain the masonry above the desired height of the opening. For an opening 2.4 m (8 ft) wide, you could use two mild steel (MS) channels of 100-mm depth (ISMC-100). Make sure their length is equal to the size of the opening plus an additional 400 mm for adequate bearing of 200 mm on either side. These two channels, embedded back-to-back in the wall, will act as a ‘lintel’ and help transfer the load of the masonry onto the walls.

Mark the size of the opening on the wall. When you position the MS channels on the wall, you’ll notice that it extends by 200 mm on either side of the opening. We now need to cut holes (1 ft x 1 ft wide) in the wall to house concrete beds on either side of the opening so that the channels can sit on them when the masonry in between is removed.

As soon as the concrete bed is firm (7 to 10 days), you can create a 100-mm-wide chase in the masonry wall along the defined length of the channel. Make sure that the depth of the chase is no greater than half the thickness of the wall. Place the C channel in this trough such that the top horizontal face of the channel is in contact with the masonry above along its entire length, while the vertical face is depressed in towards the rear masonry surface and is in plum. Secure this channel at this location using a high-strength wet mortar (1 part of cement : 3 parts course sand). Let the channel be for a few days. Keep the mortar joints moist. Now chase the rear face of the wall immediately behind the first channel and repeat the process. When completed, the two channels will have their vertical faces touching each other. You can now remove the wall below this MS lintel. Wrap the rough masonry and metal surfaces with chicken wire mesh and apply wet mortar to embed and provide final shape. Apply plaster of paris wherever required and paint.

I have recently inherited an old house from my parents which I plan to sell and buy an apartment in South Delhi. I am looking for a 3,000-square-foot place. I am keen on vetting the new place for design flaws so that I don’t end up spending time and money on the apartment after we move in.
Pradeep Shastry, Noida

Good design is a subjective term. What is good for you, may not work for someone else. Having said this, you can make sure that the apartment of your choice is simple and useful in its beauty, and makes use of natural elements. Below are some design pointers for buying an apartment.

Storage: In order to save space and money, most builders don’t provide adequate storage. Each bedroom will probably have 6 ft to 8 ft of cupboard space which is sufficient to store clothes, but then where do linen, shoes, travel bags, sports equipment, etc, go? Most new home-owners make additional cupboards in every room or convert a puja room or study into a store. This could be good negotiation tool while buying an apartment as you can force the builder to provide additional storage.

Natural light and ventilation: Most new apartments provide large openings with fixed glass that has no security mechanism or grills. Even the ones that open, don’t have fly screen shutters. This design saves the builders cost, but limits fresh air, security and visual privacy. In fact, pollution (both noise and dust) and the fact that the apartment may be centrally air conditioned are reasons given by builders for providing very few openable windows. But do check for the number of openable and fixed windows, and the alterations that can be done.

Even badly designed and incorrectly-oriented windows are a problem. The amount of heat coming in will depend on the location and orientation of the window in a room. The ones opening towards the south will bring in the winter sun, while those facing the west will allow a lot of summer heat.

If an apartment needs lots of artificial lighting, electric outlets and extension cords, or a large investment in window coverings, the overall design could be a problem. Remember, you will also have to keep all these windows clean!

Designated gym, study or games’ room: Having specialized rooms is a great idea, provided you are inclined towards that particular activity. Keep it real about what works for you and what you already do, instead of what you could see yourself doing in a space. Many a time, these specific spaces become a dumping ground for boxes and bags. On the flip side, if there’s something you really want to do but aren’t doing currently, a new space and furniture may make it happen.

Disorganized kitchen space: An apartment may offer an open kitchen space, which may not be suitable for your way of
life. Correcting cabinet positions and shelf divisions become additional expenses. Sometimes, the space allotted for
the refrigerator/washing machine is insufficient for the model you already own. So breaking and redoing can be an
expensive proposal. Kitchens are most often the first places to be termite-infested. So look out for signs of dampness near
the washing areas.