Guides
Roof waterproofing basics
An integral waterproofing compound goes into the mix at the concrete or plaster stage, and IS 2645:2003, the Bureau of Indian Standards specification it has to meet, caps the dose at 3 percent of the cement's own weight. Dr. Fixit Pidiproof LW+, the liquid this shop stocks, is dosed by Pidilite's own instruction at 200 ml for every 50 kg bag of cement.
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Jay Shree Infra keeps waterproofing liquid on the accessories rack at the Saharsa godown, for Saharsa, Supaul and Madhepura. Not every pack size is on the shelf every morning, so the litres you need is a phone call. What holds regardless of which can is standing is the standard the compound is made to and the dose the maker prints, and that is what is set out below.
An integral compound is mixed into the concrete or the plaster itself, at the cement stage, before the pour goes down. That is a different job from a membrane or a coating painted onto a finished surface, and the two are not interchangeable on a drawing that names one of them. IS 2645:2003 exists to check what a compound does to the mix it goes into: whether the treated cement still sets in time, still reaches its own grade's strength, and lets less water through than the same mix without it.
The standard
What IS 2645 checks before a compound earns the mark
The four tests IS 2645 runs on an integral waterproofing compound, and the dosage cap fixed in the standard's own scope.
Scroll the table sideways to see every column
| What is checked | Limit the standard sets | Tested under |
|---|---|---|
| Compound dosage | Not more than 3 percent of the cement's own weight | Fixed in the scope of IS 2645 itself |
| Permeability to water | Under half the water percolation of a plain specimen made without the compound | IS 2645, clause 3.1 |
| Setting time | Initial set not brought below 30 minutes or cut by more than a quarter of the plain cement's own time; final set capped at 600 minutes and not stretched by more than a quarter | IS 2645 clause 3.2, tested under IS 4031 (Part 5) |
| Compressive strength | 3 day and 7 day mortar cubes still clear the cement's own grade minimum, and come in at least nine tenths of a plain cube's strength | IS 2645 clause 3.3, tested under IS 4031 (Part 6) |
| Chloride content | Not more than 2 percent by mass, and the maker must declare the true figure | IS 2645 clause 3.4, tested under IS 6925 |
The four test clauses and their companion standards are from the Bureau of Indian Standards' own Product Manual for IS 2645, published under its Scheme-I licensing rules: clause 3.1 for permeability, clause 3.2 for setting time against IS 4031 (Part 5), clause 3.3 for compressive strength against IS 4031 (Part 6), and clause 3.4 for chloride content against IS 6925. The manual also fixes the sample size for each test at 500 gm or 500 ml, and requires a compound to be licensed separately as powder form or liquid form.
The dosage cap is the line worth remembering on site: a compound cannot make up more than 3 percent of the cement's own weight, by the standard's own scope. More is not stronger; it is simply outside what the standard has tested.
The other four rows are what a compound is checked against once it is in the mix. Permeability has to come out under half of a plain mix made without it. Setting time cannot run away in either direction, quick or slow, by more than a quarter of the plain cement's own time. Compressive strength at 3 and 7 days has to stay within one tenth of a plain mortar cube, and still clear whatever the cement's own grade requires on its own. Chloride content is capped at 2 percent by mass, and the maker has to print the true figure rather than a round one.
The liquid we stock
Dr. Fixit Pidiproof LW+, dosed the way Pidilite prints it
Pidilite's own dosage for Dr. Fixit Pidiproof LW+ is 200 ml for every 50 kg bag of cement, and that figure is on Pidilite's own product page for the liquid, not a figure this counter has rounded. The method it publishes: mix the cement, sand and aggregate dry, add roughly two thirds of the gauging water and mix again, then add the LW+ into the last third of the water and bring that into the batch. A low water cement ratio, under 0.5 by Pidilite's own instruction, is part of the same method, not a separate step.
Pidilite lists roof slabs, columns, beams, footings, RCC water retaining structures and the plaster coat on interior and exterior walls as where this liquid goes. That is a wide list, and it is why LW+ rarely travels alone: sariya and cement for the same pour, and cover blocks for the same slab, are usually on the same order.
Before and after
The fall in the roof, and the water after the pour
A compound in the mix does not decide which way water runs off a roof; the slope does. A flat pour holds water in whatever low point it settles into, compound or no compound, so a screed graded to a fall towards the outlet is the mason's job before any waterproof mix goes down, not after. Where the roof is already flat, that grading is the first line item on the order, ahead of the liquid itself.
Pidilite's own instruction after the pour is to cure the concrete or plaster as per good construction practice, and it names no fixed number of days for LW+ itself. The days that matter for a slab are worked out on the curing (tarai) guide, which carries the figures; an integral compound does not change that count.
What the liquid does not cover
One sack and one can are not the whole answer
A waterproofing liquid is one part of a dry roof, not the whole of it. The cement type and grade the drawing calls for, the cover over the steel, the slope under the screed and the days of tarai after the pour all sit alongside the compound, and a leak can start from any one of them being wrong even where the dose in the mix was exact.
This shop puts no percentage and no promise beside the liquid; what Pidilite publishes about it is on Pidilite's own pages, cited below. What the counter can settle is which pack is standing, how many bags of cement the dose has to match, and what else is riding the same vehicle: cement, sariya and cover blocks off the accessories rack.
Sources
The standard's own manual, and Pidilite's own page
Two pages from the Bureau of Indian Standards and one from the maker whose liquid stands on our floor.
- The Product Manual for IS 2645:2003, with the four test clauses and their companion standardsBureau of Indian Standards
- The catalogue record for IS 2645, with the title and the technical committeeBureau of Indian Standards
- Dr. Fixit Pidiproof LW+, with the dosage, the mixing method and the areas it is meant forPidilite Industries (Dr. Fixit)
Questions
Chhat ki waterproofing ke sawal
Chhat me pani rokne ka sabse pehla kaam kya hai?
The dose and the standard, in that order: an integral compound goes into the mix at 200 ml per 50 kg bag by Pidilite's own printed figure for Dr. Fixit LW+, and IS 2645:2003 is the Bureau's own specification the compound is checked against before that. Read the bag count out on the call and the litres follow from it.
Dr Fixit LW+ kitni matra me dalna hai?
200 ml for every 50 kg bag of cement, as Pidilite prints it. Mix the cement, sand and aggregate with about two thirds of the water first, then add the LW+ into the remaining third and bring that into the batch, keeping the water cement ratio low.
Sirf waterproofing liquid dalne se seepage ruk jayegi?
No, and that is not this counter's claim either. The compound is one part: the cement type and grade the drawing calls for, the slope under the screed, the cover over the steel and the curing after the pour sit alongside it, and any one of them going wrong can start a leak even where the dose was exact.
IS 2645 kya check karta hai?
Four things on the treated mix: permeability under half of a plain mix, setting time within a quarter of the plain cement's own, compressive strength within a tenth of a plain cube at 3 and 7 days, and chloride content capped at 2 percent. The compound itself is capped at 3 percent of the cement's weight, which is the standard's own scope and not a test result.
Pour ke baad kitne din tarai chahiye?
Pidilite's own instruction is to cure as per good construction practice, with no fixed day count against LW+ itself. The number of days that actually applies to a slab is on this shop's curing guide; ring +91 6202 967 218 and we will match the pour to it.
Before you order
What settles a waterproofing order
Each one decides something the standard's own figures cannot.
How many bags of cement is the compound going against?
The dose is fixed at 200 ml per 50 kg bag, so the bag count is what turns into a litre count on the call.
Is this a roof slab, a tank, a bathroom or a plastered wall?
Pidilite lists all four for this liquid, and it decides what rides the same vehicle: cover blocks and sariya for a slab, nothing extra for a wall coat.
Does the roof already fall to a drain, or does a screed need to go down first?
A flat surface holds water regardless of what liquid went into the mix, so this gets settled before the pour, not after it.
Which pack size, and how many?
Litre for litre against the bag count decides the can, and what is standing on the shelf that morning is a phone call.
Is cement or sariya loading on the same vehicle?
Say it on the first call. One bill and one vehicle usually covers the cement, the liquid and the steel for the same pour.
Contact
The bag count sets the can
Litres follow bags, not the other way round, so read us the cement count for the pour and we will say how much Dr. Fixit LW+ that dose calls for. Tell us if it is a slab, a tank or a wall, and whether the roof already has its fall, and the rest of the load, cement, sariya and cover blocks, gets fixed on the same call.
Shop hours: All 7 days, 9:30 AM to 6:00 PM