On waterproofing and installing shutters

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.

I have ordered new MDF post-formed shutters to renovate my cupboards. I’m a first-time user and would like to know how many self–closing hinges should be used to install a 1.5 ft x 7 ft shutter so that it is supported adequately and all the shutters align properly.
Vandana Gupta, Hyderabad

The density of an MDF board is lower than that of a block board. Repeated opening and closing induces vibrations in the hinges, which take the entire weight of a shutter. Thus, if they are not properly installed, the screws tend to come loose.

As the hinges bear the weight of the shutter, it is important to choose the right model (ie heavy duty, with or without adjustment screw, 90 degree turn, etc), and follow the correct fixing methodology for a long-lasting, maintenance-free service. Incorrect selection or installation will lead to a sagging or worse, falling shutter.

One of the recommended brands for hinges is Hettich. The company has an extensive supply network, which means that their products are easily available. Out of their wide range, two standard cupboard shutter (cup) hinges are applicable to you: 35-mm (cup diameter) and 26-mm. However, go for the former as the  26-mm one is suitable for small and lightweight shutters. Assuming that you are using a 19-mm-thick laminated MDF shutter (for the given size), you should install atleast four 35-mm hinges on each one. Let the first and last hinge be about 75 mm from the top and bottom ends, and the remaining at equal distance between these two. These four hinges will be able to hold the shutter well and prevent sagging.

A little thought on the fixing technique. It’s not uncommon for workmen to repeatedly fix and remove shutters while adjusting their alignment. Now MDF does not have the necessary density to hold wood screws in place after they’ve been removed once and need to be fitted back. So it is advisable to insert a plastic expansion plug (such as the products from the brand Rawlplug) first in the board and then insert the screw in it. This plug is nothing but a plastic tube with a jagged outer surface and slits along its length. The serrated sides expand as the screw is inserted into the plug, while the rough outer walls provide the necessary grip with the MDF board. Sometimes, carpenters add a little adhesive (such as Fevicol) on the outer face of the plug to improve its hold.

If, at any point, the hinges come loose, ask the carpenter to tighten them carefully using a screw driver. Using a hammer will push the screw in its slot and destroy the ‘grip’ that it would have created for itself. Of course, you can also reinstall all the existing hinges a little away from the earlier location and put in more hinges for increased durability.

I stay on the 11th (top) floor of a highrise. Most of my walls show signs of water seepage at the bottom extending upwards to about one foot. They are more prominent in the walls near the bathrooms. I suspect leakage from a concealed pipeline. The wooden frame of the doors in the bedroom are also corroded and wasted. Is there any way to locate the leakage using humidity sensors, etc? Will pressure grouting stop the leakage or only suppress it?

A few additional thoughts and facts for more clarity. The main water supply pipe is on the outside wall, but those connecting the tap to the main supply (which pass through the wall) could be damaged. There are no pipes along the floor or below the floor slab of our apartment. We think a leak of a few drops per day for six years has added up to a sizeable problem! I am attaching few photographs for your reference.
RB Deshpande, Pune

Though it is difficult to pin point the exact source of the leak, the photographs give us a fair idea of the overall problem. Fortunately for us, there are a few companies who are using emerging technology to locate the exact source of leakage in embedded pipes. Recently, a few of these companies have even set up shop in India, or have collaborated with local plumbing firms. In time I am sure they will prove to be invaluable to the industry and so I would like to introduce them for pure academic purpose.

However, having said this, these high-tech vendors may or may not be keen to service a small job like this. Therefore, we’ll also try and locate the leak by using analysis and drawing upon previous experiences.
New technologies:

• Helma Water Management is a UK-based company that uses extremely sensitive hearing devices to locate the sound generated by a leaking pipe. There is only one Indian firm (in New Delhi) that claims to be associated with them.
  Parent company: http://www.hwm-water.com/halma-water-management-home/
  Indian associate: Kuldip Nautiyal, precision2001in@yahoo.co.in

• Hydrophones are slightly different from the above, but use highly sensitive sensors which detect leaks by measuring vibrations on the pipe itself. Hydrophones are ideal for long distance, large diameter and plastic (polymer) pipes.

• At times, it is difficult to locate a non-metallic pipe buried in the ground, let alone finding the leak itself. An experienced operator of ground penetrating radar can easily locate both the pipe and the leak.

• In gas injection and detection, hydrogen gas is injected into supply pipes and traces of the gas are detected using sensitive instruments. This is possible even if the pipes are buried in masonry or concrete. You can check out http://leaklocators.net/water.php for more information.

• You can use a low intensity electric charge to locate the source of leak. This works better for terrace waterproofing than plumbing pipe leakage.

As one cannot physically check all the locations for the problem, I suggest you engage a waterproofing expert to give you more comprehensive advice. There is always a possibility of more than one source of leakage. Let me try and advise to the best of my ability.

A couple of things evident from the description and photographs:

•   Dampness is primarily seen in a small band (one-foot-high) on the wall nearthe bathroom/kitchen floor with little dampness seen on other walls.

• The deteriorated state of the surrounding wall plaster and the door frames clearly indicates that this is an old problem.

Inference:

• The position of the damp band seems to suggest a low-volume leak arising out of the floor. The cause does not seem to be the supply pipes buried in the wall as they are often located a little higher than the upper edge of the band. The damaged portions would have looked slightly different had the leak emanated from a pipe buried in the wall at (say) 1 ft 6 in from the floor.

• The fact that this dampness is not seen from the apartment below also points towards low-volume leakage rising from the floor itself and not from the pipes in the floor slab cavity.

This leaves us with one strong possibility. The leak is most likely occuring at the tile joints along the junction of the wall and floor. Chances are that these joints were never grouted properly and have now opened up further. Excess water often collects and ‘sticks’ along these joints due to improper floor slopes and surface tension. It eventually finds its way into the porous masonry behind. Using capillary action, it rises till it reaches the plaster, where it spreads both vertically and horizontally till it evaporates completely. If unrepaired, these microscopic water channels make their presence felt through travelling dampness that damages everything on its path.

But this is not the only culprit. Even though you mentioned that there are no pipes below the flooring, I suspect water is surging from the joint between the discharge pipe below the floor and the finished floor itself. If it is so, this leakage will be small or will surely affect the floor below. Also, this type of leak is more profound in isolated locations instead of being so evenly spread as mentioned by you. Alternatively, small patches of dampness that are not linked to the kitchen or the bathroom could be old problem originating during construction (owing to improper floor laying, grinding, etc). It could also be the same leak travelling through sub-floor mortar to distant walls. However, the chances of this being the cause of the problem are small as a large quantity of water would be required for this to happen. Plus, water would have reached the lower floor earlier than the distant walls.

Now, to figure out a solution… low pressure grouting involving hand-pumping waterproof cement slurry below the existing floor, doesn’t always work, but is definitely worth a try. It completely depends on the experience of the team involved.

Simultaneously, or alternatively, you could simply remove the cement pointing material between the tile joints and refill the same with a waterproof grout of a matching colour pigment. This short-term solution will provide relief for at least three years. Ideally, you should replace the old floor and skirting tiles with new ones and treat the entire sub-floor with an acrylic-based waterproofing compound for long-lasting effect. Brush-applying three coats of Tapecrete (an acrylic latex polymeric additive) should do the trick.

In all conditions, the damaged wall plaster should be scrapped and replaced with a fresh one. It would be a good idea to use cement and sand (1:4 ratio), along with a waterproofing compound as per the required consistency. Sprinkle water on the newly plastered surface every six to eight hours according to the temperature of the room, for about 10 days.  The door shutter and frame can be repaired in case you don’t want to replace them. Wait for all the surfaces to dry completely before you start the painting process.