Re-tile a floor or a bathroom: over the old tiles or out, then the order list
Re-tiling starts with one decision: lay the new tiles over the old ones, or break the old floor out first. The answer sets the adhesive, the cement and sand, the floor height at the doors and how many days the room is out of use.
By Bulan Sarkar · Updated
Tap every old tile with a coin first. If only a few sound hollow or are cracked, and the doors can take about 12 to 15 mm more floor height, you can lay the new tiles over the old ones with an adhesive whose data sheet lists existing tiles as a base. Otherwise take the old floor out. For a 12 × 10 ft room in 600 × 600 mm tiles with skirting, order 38 tiles (10 boxes of 4) from one batch and shade. CPWD's 2023 analysis of rates uses 5 kg of adhesive per m² of floor at a 3 mm bed and 10 kg per m² of skirting, which is about 70 kg, or 4 bags of 20 kg. On a mortar bed it uses 3 bags of cement and about 10 cft of sand for the same floor. Grout after 24 to 36 hours, and keep heavy use off for about two weeks.
The decision: plan the re-tile and buy the material yourself?
Yes, for a room or a bathroom floor where you buy the tiles and adhesive and pay a tiler for labour. This page takes you from the tap test to the order list, the delivery check and the days the room stays shut.
If a contractor quotes one rate per sq ft with material included, they order. Skip the counting, but still do step 1 yourself, ask in writing whether the old floor comes out, and get the batch and shade code of the tiles on the bill.
Get a civil engineer to look before you lay a new floor over an old one on an upper storey or a balcony, and if the old floor has sunk, cracked in long lines or moves underfoot, or if water is leaking to the room below. A bathroom that leaks needs its waterproofing redone by the contractor before any tile goes down.
The steps, in order
Tap-test the old floor and measure the door gaps
Have ready:a coin or the handle of a screwdriverchalk, and a steel tape
Tap every old tile near its corners and centre. A firm tile gives a sharp click; a tile that has come loose from its bed gives a dull, hollow sound. Mark each hollow or cracked tile with chalk and count them.
Then measure the gap under each door that opens over the floor, and in a bathroom, how far the floor trap sits below the tiles. Laying over the old tiles raises the floor by the new tile's thickness (printed on the box) plus the adhesive bed, so a 9 mm tile on a 3 to 6 mm bed adds about 12 to 15 mm.
Decide: over the old tiles, or out
Have ready:your count of hollow and cracked tilesthe door gaps from step 1
Lay over the old floor only when all of this is true: hollow or cracked tiles are a handful you can cut out and patch, the doors can lose 12 to 15 mm or be trimmed, a bathroom floor still drains to its trap with the new height, and you can buy an adhesive whose data sheet names existing tiles as a base. A general adhesive like Nerolac's Classic lists concrete, plaster, mortar beds and masonry, not old tiles, and asks for smooth surfaces to be roughened.
If hollow tiles are spread over the room, the floor sits too high already, or the bathroom has a leak, take the old floor out down to the base. The new tiles then go on a fresh bed: CPWD's standard is a 20 mm cement mortar 1:4 bed with a cement slurry over it, or adhesive on a level, cured base.
Count the tiles and boxes
Have ready:room length and width in feetthe tile size and tiles per box from the shop
Work in whole tiles: floor area plus skirting, divided by the area of one tile, plus 10% for a straight lay (about 15% for diagonal), rounded up to tiles and then to boxes. A 12 × 10 ft room in 600 × 600 mm tiles with 4-inch skirting needs 38 tiles, which is 10 boxes of 4. The tile calculator does the same arithmetic.
Ask for every box from one batch and one shade code, written on the bill. The tile order guide explains the codes and what to do with a mixed delivery.
Work out the adhesive, or the cement and sand
Have ready:the floor area in m² (sq ft ÷ 10.764)the data sheet of the adhesive you will buy
CPWD's Delhi Analysis of Rates 2023 gives the quantities per m² for both ways of laying. For the 12 × 10 ft room (11.15 m² of floor, 1.36 m² of skirting):
Bed CPWD figure For the 12 × 10 ft room Adhesive, floor, 3 mm average (item 11.44) 5 kg/m² 56 kg Adhesive, skirting, 6 mm average 10 kg/m² 14 kg Mortar 1:4, floor, 20 mm (item 11.41.2) 0.024 m³/m² of mortar, 0.38 t cement and 1.07 m³ sand per m³ of mortar, plus 3.3 kg/m² cement slurry 139 kg cement (3 bags), 10 cft sand So the adhesive route is about 70 kg, or 4 bags of 20 kg. The mortar route is 3 bags of cement and about 10 cft of sand for the floor, plus one bag of adhesive for the skirting. Large tiles need a thicker bed: read the line for your tile size on the bag's data sheet, and if it asks for more than CPWD's 5 kg/m², buy by the sheet.
Plan the days the room is shut
Have ready:the tiler's start datea place to move the furniture for two weeks
CPWD allows 0.2 mason-days and 0.2 helper-days for each m² of floor laid, in adhesive or on mortar. The 12 × 10 ft room is about 2.2 days for one tiler and one helper, plus a few hours for the skirting, so plan on three working days of laying. Taking up an old floor and clearing the rubble comes on top: a 20 mm bed under a 10 mm tile is about a third of a cubic metre of broken material for this room.
The Nerolac Classic data sheet says to wait 24 to 36 hours before grouting a floor and about 14 days before full traffic. Keep the room to light use after grouting and bring heavy furniture back after two weeks.
Check the delivery, then watch the first rows
Have ready:the bill with the batch and shade codea straight edge, or a 1 m level
Read the codes on every box before the truck leaves, then lay 30 tiles out by a window and look at them from 1 m, the way IS 13630 checks surface quality. IS 15622 asks for at least 95% of tiles to be free of visible defects, so one or two rejects in 30 is within it and a box full is not.
When laying starts, check the first rows with the straight edge. Each tile should sit flat with its neighbours, and on adhesive the back should be fully covered: the data sheet asks for 100% cover and for tiles over 1 sq ft to be buttered on the back as well. Tap a few tiles the next day. A hollow sound on new work is the time to lift and re-lay, not after the grout.
Grout, clean up and keep the spares
Have ready:the grout colour chosen with the tilera box for the spare tiles
Grout once the waiting time on the adhesive sheet has passed, clean the haze off the tiles the same day, and keep the room to light use. Put 2 to 4 spare tiles from the same lot in a labelled box with a photo of the carton label and the bill. A cracked tile years later is a one-tile repair only if you still have the shade.
What goes wrong
Variants: what changes the steps
A bathroom floor
If the old bathroom floor comes out, the waterproofing under it usually comes out with it. The adhesive maker's sheet says waterproofing goes on before the tiles, so ask the contractor which product they will use and how they will test it before tiling. Use anti-skid tiles on the floor and keep the slope to the trap. This page covers tiles and material only; pipes and the trap are for a plumber.
Large-format tiles (600 × 1200 mm and up)
Large tiles need a flatter base, a thicker bed and adhesive on the back of the tile as well. Buy by the data sheet's line for large tiles, which can be 7.5 to 8 kg/m², and check that the product is rated for your tile size: Nerolac's Classic, for example, is for vitrified tiles up to 4 sq ft on floors.
Wall tiles in a kitchen or bathroom
Walls use the skirting and dado figure, CPWD's 10 kg/m² at a 6 mm bed, and the adhesive has to be a 'T' type that stops tiles slipping down the wall. The maker's sheet gives the waiting time before grouting a wall, which is shorter than for a floor.
Tiling in a home you live in
Do one room at a time and keep a route through the house. Breaking out an old floor is loud and dusty, so seal the doorway with plastic and plan the rubble pickup before the first day.
Tips and tricks
- Tap the old floor yourself before the tiler quotes. Laying over and taking out can differ by days of labour.
- Measure the door gaps with the doors closed. A 12 mm rise that fits at the hinge side can still catch at the lock side.
- Ask the tiler which trowel they will use for your tile size, then buy the adhesive from that line of the data sheet.
- Buy one spare bag of adhesive only if the shop takes back unopened bags, and check the packing date: Nerolac gives a 12-month shelf life sealed.
- Photograph the carton label with the batch and shade code before the boxes go into the store.
- In a bathroom, pour a mug of water near the trap after the floor is laid and before it is grouted. If it doesn't run to the trap, lift those tiles now.
What we would do
We'd tap-test the floor and measure the doors before asking for any quote. With only a few hollow tiles and room at the doors, the new floor can go over the old floor with an adhesive made for tile-on-tile, and buy it by the data sheet. In a bathroom, or with hollow tiles across the room, the old floor comes out and the waterproofing is redone before tiling. Either way, order whole boxes from one batch and shade, grout after the waiting time and keep four spares. The repaint plan pairs with this one if the walls are being done in the same month: paint after the tiling, so the rubble and dust don't spoil fresh walls.
Print the working copy
Re-tile order sheet: one room, from the Re-tile Planner. One A4 page with tick boxes and blanks; it prints in black and white.
- 1. Tap test and the decision
- 2. Tiles
- 3. Bed material
- 4. Days
Frequently asked questions
Can new tiles be laid over old tiles?
How much tile adhesive do I need for 100 sq ft?
How much cement and sand do I need to lay tiles on mortar?
How many days does it take to re-tile a room?
The source we built this on
Also used: Nerolac Tile Adhesive Classic technical data sheet (substrates, consumption by bed, 24 to 36 h before grouting floors, about 14 days to full traffic, 12-month shelf life; read October 2026), IS 15622:2006 clause 6.1 and the 95% surface-quality requirement, and IS 13630 (Part 1):2006 clause 7. The 12 to 15 mm height rise assumes a 9 mm tile on a 3 to 6 mm bed; read your tile's thickness on the box.
This plan covers tiles, bed material, ordering and checks only. A floor that has sunk, cracks in long lines or leaks to the room below, and any extra load on an upper floor or balcony, is for a civil engineer; pipes and drains are for a plumber. Wear eye protection and a dust mask while old tiles are broken out.