Beginners guide - Problems/Solutions

[monty]

Hello

Just thought I'd pass on a few guides that I've read over the last few months and thought they would help the tilers just starting out.

For the more experienced tilers it will be bread & butter but I'm sure you will correct them if you don't agree (as it's only a guide) or add to them.

Well here goes with the first one.....all this info is from weber tiling soutions handbook... http://www.netweber.co.uk/tile-fixing/find-the-right-solution/problem-solutions.html


Substrate diagnosis

8 key points to check....



1. How to check the flatness of the substrate

The flatness of the substrate should be checked with a 2 m straight edge mounted on 3 mm spacers.In the case of direct bonding of the tiles, any defects should not exceed - + 3 mm (IE high points not touching and low points no more than MM below) under the 2 m straight edge.



2. How to check the hardness of the substrate

The substrate must be both hard and resistant in order to avoid cracking or disbanding at a later stage.

* Check the surface hardness by scratching it with a pointed tool in several places.The scratch must be superficial.

If the substrate is not hard enough, it must be removed until sound material is reached.

* Plaster walls should be brushed with a stiff brush and then wiped to remove any loose material.Also check the in-depth of existing screeds or plastered walls.



3. How to check the stability of the substrate

* This check mainly concerns wooden floors laid on joists or battens, wooden panels and, more rarely, partitions.

* The flooring panels or strips must not move when walked on.Partitions must not flex when pressed by hand.

If this is not the case, reinforce the floor with noggings between the joists and replace the boards. Brace unstable partitions.



4.How to check the porosity of cement-based substrates

Cement-based substrates must have normal absorption in order to avoid premature water loss from the cement-based adhesive and to ensure that the bond can develop correctly.

* Pour a little water onto the substrate

* If the water is absorbed in less than 1 minute the substrate is considered as excessively porous and requires priming.




5. How to check the adhesion of the excising covering

* Check the adhesion of existing tiles or rigid floor tiles by tapping with a hammer.

* Any hollow sounding tiles or tiles with poor adhesion must be removed and replaced by similar tiles or the substrate reconstituted with the appropriate product.

* to check the adhesion of existing paint carry out a cross-hatch test using a suitable knife or cutter.Emulsion paint is not suitable for tiling over.

* Score the paint in small 2 x 2 mm squares over a total area of 10 x 10 cm.

the paint is considered suitable for tiling if 80% of the area of the small squares remain bonded.If not, the paint must be removed mechanically.





6. How to clean the substrate

* Eliminate any traces of plaster with scraper. Carefully remove any dust and then apply suitable primer, if necessary, on existing tiles,, paint, wood or vinyl tiles or appropriate primer on cement or gypsum-based substrates.

* If the existing floor covering has been removed, eliminate any traces of adhesive so that no film residues remain, only residual coloration of the substrate.On acrylic or neoprene adhesive residues carefully remove any dust and apply suitable primer.On bituminous or epoxy adhesives apply appropriate primer.

* On concrete, remove any residues that may affect the adhesion, such as superficial free lime or traces of oil, using high pressure cleaning, sanding, abrasive cleaning, etc.




7. How to check if the substrate is dry

* Plaster substrates must not have more than 5% residual moisture during application (depending on the ambient conditions, a plaster finish reaches this level of dryness from 2 weeks to several months).A minimum of 4 weeks drying time must be allowed prior to tiling.

Anhydrite screeds must not have more than 0.5% residual moisture before being covered.

Cement/sand renders and screeds must be left for 2 weeks and 3 weeks respectively prior to tiling unless special fixing methods are employed.




8. Priming

* Gypsum plaster should normally be primed before applying a tile adhesive.If the adhesive is cement-based, it must be primed with suitable primer.

Anhydrite screeds must be sealed with suitable primer before applying any cement-based product, leveling compound or tile adhesive.

 

[LM Ceramics]

some good points there monty which will be very helpful for new tilers and even some so called experienced tilers as well. excellent post mate you get a thanks from me

 

[monty]

Problems/Solutions

Tiling onto wood



Problem

The floor will deflect according to the load applied and the stiffness of the structure ( joist size, spacing etc).

If the adhesive is not flexible or laid thick enough to absorb the amount of movement, the tiles will either delaminate or crack. Large tiles will exacerbate the deflection across each tile's width.

​

Any inadequately supported joint will cause a highly localised movement which will crack the tile.

Joints may be supported by joists, noggings, or each other's tongues and grooves.

​

Wood expands and contracts with changes in ambient temperature at a different rate to mortars, ceramics and stones.

As a further complication, timber expands much more across the grain than it does along the grain (this is not really a factor with manufactured boards such as plywood).

​

Wood swells if it gets wet even with changes in atmospheric humidity.

This can be a problem in potentially wet areas such as showers and bathrooms and also if the wood is not dry when installed (e.g. if it has been kept outside).




Solution



Overboard with plywood or tile backer-board


The most secure system for tiling wooden floors is to screw fix another layer of boarding over the top of the original timber. This increases the rigidity of the floor, prevents localised movement and if a water-resistant tile backer board is used virtually eliminates moisture-related movement. Screwing the boards down also helps prevent any pullout of fixings.

Stage 1:
Assess and prepare the floor
​

Make sure that the floor will be capable of supporting
the expected load. It must be stable, well supported,
ventilated underneath and level. Verify that the extra
height from over-boarding can be accommodated.
Brace any areas that need extra support with noggings
between the joists. Any defective boards should be cut​

out and replaced. Screw the existing floor to the joists.

Stage 2:
Fix the over-boarding
​

Use WBP grade plywood at least 15mm
thick. Prime the back and edges of the
plywood​

​

. Lay the boards
so that the joints do not coincide with joints
in the existing timber and leave slight gaps
between the boards to allow for expansion.
Screw the floor every 200 to 300 mm. Leave​

a movement joint around the perimeter.

Stage 3: Fix the tiles
​

Fix the tiles into a solid 3 mm bed of​

​

suitable adhesive.
Leave joints at least 3 mm wide for
grouting and make adequate
provision for movement (around the
perimeter and dividing large areas​

into bays).

Stage 4: Grout
​

Leave the adhesive to set for 2 to 3
hours if a rapid adhesive has been
used or 24 hours if a standard
adhesive has been used. Fill the
joints between the tiles with​

a suitable grout.



Tile directly onto tongued and grooved boards or sheets


It is possible to tile directly onto tongued and grooved wooden floors by using a highly polymer-modified 2-part adhesive, providing that the floor is rigid enough and the tongued and grooved joints provide effective support. If the tiles are larger than approximately 400 mm square, over-boarding is recommended

Stage 1:
Assess and prepare the floor
​

Make sure that the floor will be capable of
supporting the expected load without
undue deflection. It must be stable,
ventilated underneath and level.
Ensure that each board is effectively
supported by its adjacent boards without
localised movement. Replace any defective
boards and insert noggings between the
joists if necessary. Screw the boards to the
joists using two screws per board at every​

joist.

Stage 2: Fix the tiles
​

Fix the tiles into a solid bed of adhesive. For
small tiles this bed should be 5 mm thick
but for larger tiles it is necessary to increase
the bed thickness. It may be necessary to
back butter the tile to achieve this.
Leave joints at least 3 mm wide for grouting
and make adequate provision for movement
(especially around the perimeter and​

dividing large areas into bays).

Stage 3: Grout
​

Leave adhesive​

​

to set for 2 to 3 hours. Fill the joints between the tiles with​

​

suitable grout.​

 

[enduro]

Keep this up guys then nobody will need to go on a training courses...:lol:

 

[monty]

Achieving a suitable adhesive bed

Problem

The adhesive bed performs a number of
functions: it sticks the tile to the surface;
it absorbs differential movement
between the substrate and the tiles; it
protects the substrate from water; it
absorbs deflections; it enables the tiler
to adjust the height of each tile; it
accommodates limited errors in the
substrate. There are a number of ways
that an improper adhesive bed can
cause problems in the life of the​

installation, as detailed below.

1. Voids behind the tiles allow access to any water that penetrates the grout

This can cause a damp, musty smell in showers.

Any water leaks are made worse by having channels available for water to run through.

Externally, any trapped water can freeze and the associated expansion can push tiles off.


2. Voids leave floors susceptible to point loads

Ceramic tiles are inherently brittle and therefore any area of the tile that is not fully supported is vulnerable when subjected to a localised load. Examples could be: a chair leg, something being dropped, or any heavy item on small feet such as a kitchen appliance.


3. The thickness of the adhesive bed is also important

If the bed is too thin a cement-based adhesive may dry out very quickly and not gain strength.

In the case of floors where some movement is expected the adhesive is required to give and its ability to do this is severely limited if it is applied too thinly.


4. Variations in the adhesive bed will show through some tiles

Some tiles and natural stones (e.g. limestone and marble) will show a shadow on the face where the adhesive is in contact behind. Voids will be visible from the front of the tiles.

Areas where there is no contact between the tile and the adhesive bed will not be bonded. A 50% contact will therefore result in only 50% of the overall bond strength across the tile.



Solution

Using the appropriate trowel helps to
ensure that an even layer of adhesive
is achieved and leaves ribs that allow
for adjustment of the tile height. For
wet areas, exterior areas and all floors,
it is necessary to achieve a solid bed of
adhesive under the tile. The adhesive
should be applied in a consistent
manner using the correct type of
trowel. On walls the adhesive should
be applied in horizontal parallel
strokes for dry areas and vertical
strokes for wet areas. Do not apply in
swirls as this causes air pockets to
form. The tile should be pressed into
place with a twisting and/or sliding
action to ensure a good contact with
the adhesive. It is recommended that
during fixing, an occasional tile is
lifted back up, to verify that the​

desired contact is being achieved.

Walls in exterior or interior wet areas
​

Notch size: 8 x 8 mm​

Tooth width: 8 mm

Solid finished bed 3 mm deep


Wall tiles in interior dry areas

Notch size: 6 x 6 mm​

Tooth width: 6 mm

Ribbed finished bed with at least​

70% contact (3 mm deep)

Mosaic tiles
​

Notch size: 3 x 3 mm​

Tooth width: 3 mm

Solid finished bed 1.5 mm deep


Floors

Notch size: 20 mm diameter semi-circle​

Tooth width: 10 mm

Solid finished bed 3 – 6 mm deep




Large tiles

If the tiles are very large or have large
studs or ribs on the back it may be
necessary to back-butter the tile as well
as spreading the adhesive on the​

substrate.

 

[Grace'sDad]

Nicely done Monty - really useful post with some great illustrations too

Out of interest, where did you get this quote from:

"Score the paint in small 2 x 2 mm squares over a total area of 10 x 10 cm.
the paint is considered suitable for tiling if 80% of the area of the small squares remain bonded.If not, the paint must be removed mechanically."

It's a new one on me!

 

[DHTiling]

mmmmmm...Weber tiling solutions handbook springs to mind.....:lol:

 

[graham31]

mmmmmm...Weber tiling solutions handbook springs to mind.....:lol:

thought i reconised it............

Great post useful info

 

[monty]

mmmmmm...Weber tiling solutions handbook springs to mind.....:lol:

You only know because i told you through PM Dave...:lol::lol::lol::lol::lol:

 

[DHTiling]

You only know because i told you through PM Dave...:lol::lol::lol::lol::lol:

I have the weber book and reco'd the photo's... and you confirmed it....