troubleshooting handbook - pavestone.co.uk · solutions if you wish to bring the colour of kadapha...

TROUBLESHOOTING HANDBOOK

The essential guide for solving stain issues and for correct installation

NATURAL STONE

1 Leaf staining

2 General weathering

3 Efflorescence

4 Black Kadapha turning grey

5 Jointing compounds

6 Sealers/impregnators

7 Brown staining

8 Fertiliser staining - brown spots/staining

9 Acid staining - brown staining

10 White circular spots on slate

11 Dot & dab, 5 spot and void bedding

12 Upside down installation

13 Blending packs

14 Spalling/butt jointing

15 Joints

16 Delamination/shaling

17 Granite veining

18 Picture framing

CONCRETE

19 Differential weathering

20 Efflorescence & air holes

21 Salt

22 Mosaic paving - General care

INDEX

LEAVES, BERRIES & BIRD STAINING

POSSIBLE CAUSES

Fallen leaves, berries, petals, bird faeces etc will stain paving as they break down if not removed.

SOLUTION

Sweep off all leaves, petals, berries etc on a regular basis. For any garden staining use Pavestone Patio Cleaner or for more stubborn stains apply Pavestone Black Spot and Algae Remover.

• Pavestone Patio Cleaner

• Pavestone Black Spot & Algae Remover (extreme cases)

TROUBLESHOOTING HANDBOOK NATURAL STONE PAVING 1

Tannins from

leaves

GENERAL WEATHERING

POSSIBLE CAUSES

Paving should be cleaned regularly. Poorly drained and shady/damp site conditions contribute to the growth of algae and lichen on paths and hard surfaces.

SOLUTIONS

• Pavestone Patio Cleaner

• Pavestone Black Spot & Algae Remover (extreme cases)


BeforeAfter

EFFLORESCENCE

POSSIBLE CAUSES

Lime bloom coming through the paving from the cement based mortar bed. This is a natural phenomenon and can happen at any time, however it is more common when any form of void bedding has been applied. Look for sporadic staining.

SOLUTION

Salts generally dissipate over time however you can use Pavestone Cement and Residue Remover.

• Pavestone Cement & Grout Residue Remover


Lime bloom

BLACK KADAPHA TURNING GREY

POSSIBLE CAUSES

After 2-6 months of being out in the open, exposed to UV light, slightly acidic rainfall and with natural weathering the Black Kadapha Limestone starts to fade to grey.

SOLUTIONS

If you wish to bring the colour of Kadapha back to black you can apply 2 coats of Pavestone Black Stone Rejuvenator and Sealer (see above right picture).

• Pavestone Black Stone Rejuvenator & Sealer


Restored to black

Jointing Compounds can leave a residue of resin on paving after installation, especially in extreme hot weather, but this will generally disappear over time. If it stays on for a prolonged period the Pavestone Resin Residue Remover can be used to remove it.

Sometimes Jointing Compounds can show signs of cracking. Generally the causes are that the compound has been installed too shallow, too narrow, not been mixed correctly, not ironed in or a combination of these.

When Jointing Compounds have not set after a few days it is more likely that the compounds have not been mixed correctly or it has been applied in the wrong weather conditions.

JOINTING COMPOUNDS


Resin stains

SEALANTS/IMPREGNATORS

In some cases, sealing Natural Stone is not necessary. It is personal preference of the consumer whether they want to enhance the colour of their patio or just protect the paving from staining. If you intend to use a sealer, you must adhere fully to the product instructions on the packaging.

Moisture on the surface, within the joints or even a bit of damp within the paving itself can cause some sealants to turn 'milky', effectively ruining the finished appearance. Those sealants sold as suitable for all surfaces (the jack-of-all-trades) tend to be more prone to this than some of the higher-end quality products.

The paving should be clean, dry, free from dust, detritus and organic material (weeds, mosses, algae, etc).

A small area must always be tested first.

Pavestone have a range of water based, breathable, impregnating sealers that can be used straight after laying as long as weather and site conditions allow. Always clean paving first as this opens the pores of the stone


Application error

BROWN SPOTS OR STAINING

POSSIBLE CAUSES

Iron Pyrites - blooms of rust coming from iron deposits within the natural stone.

SOLUTIONS

• Lithofin Bero

• Lithofin Rust-Ex

7TROUBLESHOOTING HANDBOOK NATURAL STONE PAVING

Rust blooms

POSSIBLE CAUSES

Moss killers and fertilisers contain Ferrous Sulphate which can leave iron traces on paving after over spread from lawns. Generally staining will be seen as spots alongside the edge of the lawn or flower beds. All fertiliser instructions advise you to cover paving prior to applying.

SOLUTIONS

• Lithofin Bero

• Lithofin Rust-Ex

FERTILISER STAINING - BROWN SPOTS/STAINING


Paving not protected

ACID STAINING - BROWN STAINING

POSSIBLE CAUSES

Acid should not be used on paving as it can burn the stone but also can bring the natural iron out of the stone.

SOLUTION

• Lithofin Bero

Example of paving before and after applying Lithofin Bero.


Before

After

WHITE CIRCULAR SPOTS ON SLATE - BLOOMING

POSSIBLE CAUSES

These are calcite mineral deposits on the surface of the slate. Calcite makes up part of the natural formation of slate and can appear as white 'flaking/blooming’ when exposed to oxygen and water.

SOLUTION

The cleaning method involves aggressive cleaning or scrubbing with the below product.

• Lithofin Builders Clean

Example of paving before and after applying Lithofin Bero.


Before

After

DOT & DAB, 5 SPOT METHOD AND VOID BEDDING

Any method of bedding using voids is not recommended by professional landscapers and can cause significant problems once the job has been completed.

Any method of laying that leaves voids underneath the paving is an installation error and is prone to future problems.

• Voids fill with water and create subsidence or instability in the finished patio. The resident water pools under the paving cause discolouration on the face of more porous paving.

• Voids cause paving to fracture when loaded due to lack of support.

• Voids may become infested by insects or burrowing animals.

• The mortar spots cause paving to be unstable and are more likely to rock when traversed.

This is NOT a fault in the paving and may not be cleaned.

Paving should ALWAYS be laid on a full bed of mortar.

If paving has been laid using void bedding, any potential uplift and re-lay is the sole RESPONSIBILITY OF THE INSTALLER.


Spot the problem?

DOT & DAB, 5 SPOT METHOD AND VOID BEDDING

This is NOT a staining issue and cannot be rectified by any cleaning product.

Paving should ALWAYS be laid on a full bed of mortar.

If paving has been laid using the spot method, any potential uplift and re-lay is the sole RESPONSIBILITY OF THE INSTALLER.

PROBLEMS ASSOCIATED WITH NATURAL STONE PAVING 11

Water will collect in voids

Paving stays

wet for longe

r

UPSIDE DOWN INSTALLATION

Natural stone paving should always be laid with the chamfered edge down. When the paving is laid upside down, it creates a joint that is too wide. The V shape makes the jointing more susceptible to fall out or to crumble.

In addition, the underside of the slab can also be over riven, incorrect colouring or even unsightly.

Attention should also be made when laying Granite. Ensure that it is laid with textured face up and smooth face down.

SOLUTION

INSTALLATION ERROR - No corrective action possible other than an uplift and re-lay.

ENSURE PAVING IS LAID THE CORRECT WAY UP

Natural stone is hand cut. The top edge will be clean and straight with the bottom much rougher.

Concrete comes out of a mould, with the detailed face on the smaller side.


Unsightly face and edges

Pointing will become loose

Natural Stone

Chamfer down

Concrete

Chamfer up

BLENDING PACKS

No Manufacturer can guarantee that products from different batches will have identical colouration.

Therefore, it is advisable that when using several packs of the same product on a project, the product is used randomly from all of the packs so as to achieve an overall blended appearance.

How the paving should look when paving is mixed from all packs.

2 projects where packs have not been mixed.


Looks like another shade?

?

SPALLING/BUTT JOINTING

When paving or block paving is butt jointed (adjacent slabs touching each other) it can cause a number of issues.

• There is no cushion between pavers thus causing a high risk of spalling ie edges breaking up.

• Butt jointing does not allow for any dimensional tolerances.

• A minimum 2mm joint should be standard practice for paving flags and block paving requires a sanded joint to allow some movement.

SOLUTION

INSTALLATION ERROR - No corrective action possible other than an uplift and re-lay.


Shaling

JOINTS

A consistent joint is difficult to achieve with natural stone due to the dimensional tolerances, therefore jointing spacers are not advised. Natural paving is best laid by the eye. Joints will vary with different products from 7 to 14mm on Traditional Paving to a minimum 2mm joint on Contemporary Paving.

Working from the centre outwards Circles should always be dry laid prior to installation to assure joints are correct.

Randomly laid paving should not consist of long straight lines or crossing points (where 4 corners meet).

Do not use spacers on all sawn edged paving, due to nominal dimensions.

Spacers not advised. Minimum 2mm joint. Crossing points and long lines.


Makes you cross!

DELAMINATION/SHALING

Delamination or shaling can occur with riven surfaces of natural stone such as sandstone, limestone and slate. Due to the nature of ‘sedimentary’ stone, created millions of years ago, the layers of stone can occasionally sheet-off. This can happen before and after installation. Once this delamination has occurred the surface below will generally be stable and the longevity of the paving will not be affected.

Care should be taken when cleaning the stone, especially with a pressure washer.


Surface below will be good and solid

GRANITE - VEINING

Natural veining is common on Granite paving, it is not a fault and will not affect the future performance of the paving. Check your paving slabs before laying to avoid a repeating pattern, as illustrated in the picture above.


Natural veinin

g

Picture framing is generally caused by water retention in a porous pointing joint and is exacerbated by poor drainage.

PICTURE FRAMING


Damp

around edges

DIFFERENTIAL WEATHERING

POSSIBLE CAUSES

Differential weathering can be caused by varying moisture movement in the early curing process. The darker areas represent the moisture cured parts of the surface, and these are usually in the centre of the slab as the production technique can sometimes inhibit uniform surface drying.

Other causes of differential weathering:

Packaging - subjects the paving units to sweating within the pack.

Atmospheric conditions - the weather can affect the paving in its early curing process and when newly laid.

Paving laid on the spot bed method causes voids which can contribute to the drying out/curing process resulting in patches.

The appearance of a slab affected by differential weathering can sometimes give the impression that the concrete surface is flaking, which is not the case. The perceived flaking effect is purely the shade differential between area of the concrete surface which have been subjected to the varying moisture conditions during the products early curing process.

SOLUTION

The effects are not detrimental to the product and not usually permanent and will become less apparent with natural weathering and with the passage of time.

TROUBLESHOOTING HANDBOOK CONCRETE 19

Should fade over time

EFFLORESCENCE

Photo also shows spot bedding.

POSSIBLE CAUSES

Efflorescence is a natural phenomenon that can occur in any concrete product and does tend to disappear with the passage of time and natural weathering.

Efflorescence is known as ‘lime bloom’ and brought about as the result of the normal chemical reaction between cement and water. When it is wet, the deposit becomes transparent and seemingly disappears. The occurrence of efflorescence is spasmodic and unpredictable but forms more readily when concrete becomes wet and dries slowly and therefore, occurs more frequently in the winter.

SOLUTIONS

Although there are efflorescence cleaners on the market, these can be a temporary solution. Be assured that efflorescence will generally disappear with natural weathering and time, however you can use Pavestone Cement and Grout Residue Remover.

AIR HOLES

Photo also shows spot bedding.

POSSIBLE CAUSES

Mainly occur during the manufacture of wet-cast paving slabs.

SOLUTION

Generally air holes/pin holes in concrete are small and not detrimental to the future performance of the paving.


Spot the voids?

SALT

POSSIBLE CAUSES

The break-up of paving surfaces can be due to the use of rock salt, which is generally applied on pathways or access routes. Rock salt should not be used on concrete paving and we state this in our brochure and on our website, most suppliers of rock salt will also state it’s unsuitability for the use on concrete and asphalt roads and pathways.

The detrimental effects of rock salt use can be seen clearly over recent heavy winters with the appearance of the unprecedented number of pot-holes on roads across the country.

SOLUTION

Once applied there are no resolutions, although without the further use of salt paving should not deteriorate any more, and in future winters the use of grit is recommended.


Never, ever

use

rock salt

MOSAIC PAVINGPrior to laying Mosaic paving should be handled with care and only stacked face to face.

Mosaic paving is pre-sealed with a protective coating which deters staining and algae & moss growth by creating a very low porosity to the surface. This barrier to the absorption of water helps maintain a much cleaner finish. However, they are not self-cleaning and will still need to be maintained and looked after. For everyday cleaning use soapy water, or a proprietary kitchen floor cleaner, applied with a broom or mop. For a deep clean, we recommend using Pavestone Patio Cleaner.

Use rubber furniture feet on tables and chairs to protect against scratching and marking of the tile surface.


Ensure furniture has rubber feet

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www.pavestone.co.uk

Pavestone UK Limited, Westington Quarry,

Chipping Campden, Gloucestershire GL55 6EG.

Tel 01386 848650

Fax 01386 849072

troubleshooting handbook - pavestone.co.uk · solutions if you wish to bring the colour of kadapha...

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