Year: 2015
Calcium Sulphate Screeds
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Video: Fix & Seal
Video: SuperGrip Challenge
Video: Tiling On Heated Floors
Video: Wet Room
Selection of Appropriate Paint Strippers
STRIP AWAY
REMOVES COATS OF
- Old Alkyd undercoat & Gloss paints
- Pre 1970s Lead based coatings
- Alkyd Varnishes
- Interior Artex paints (vinyl based)
- Vinyl Matt & Silk Emulsions
- Some “sprayed” exterior coatings.
SAFE ON SURFACES OF
- Softwood frames & doors
- Plaster / Brick / Concrete
- Glazed Ceramic Tiles, Glass & uPVC
- Cast Iron & Steel
- Stone & Slate
WILL NOT REMOVE
- Acrylic paints & stabilising sol’ns
- Polyurethane varnishes
- Two-pack epoxy paints
- Lime-wash / Snowcem
- Heat applied enamels & coatings
- Exterior paints with “Pliolite” resin
- Powder / automotive coatings
AVOID STRUCTURES MADE OF
- Hardwood timbers
- Veneers, Laminates &, Compressed board
- Resin – based plasters
- Aluminium & its alloys
- Gesso plaster
- Marble
STRIP AWAY LV
REMOVES COATS OF
- Water-based Acrylics
- Cellulose / Chlorinated rubber
- Polyurethane varnish & sealer
- Most exterior acrylic masonry paints
- French polish & Shellacs
- Pliolite based exterior paints
SAFE ON SURFACES OF
- All metals incl. brass, bronze & copper
- Aluminium and its alloys
- Hardwood timbers, oak & ash
- Fibreglass & uPVC
- Plaster / Brick / Stone / Concrete
- Softwood timbers
WILL NOT REMOVE
- Two-pack epoxy paints
- Powder / automotive coatings
- Heat applied coatings & enamels
- Lime-wash / Snowcem
- Old stabilizing solutions
AVOID STRUCTURES MADE OF
- Gesso plaster
- Veneers & Laminates *
- compressed board *
Treatment & Prevention of Damp & Dry Rot
Rot is one of the major causes of timber decay in properties and will usually found be found where dampness from any source has been allowed to become established for a period of time. This creates the ideal conditions for wood rot spores to germinate and spread as a fungal infestation which progressively destroys the structural integrity of all types of timber.
DIAGNOSIS
The correct identification of dry rot is important owing to the extensive and elaborate measures necessary to control and eradicate it. The recognition of the various diagnostic features of the timber, mycelium, the strands and fruiting body is important for a positive identification appraisal.
A) TIMBER
Timber is a cellular material comprising mainly of cellulose and lignin, which provides the timber with rigidity and strength. Dry rot breaks down the cellulose of the timber, leaving behind the lignin, which gives the timber a darker colour. This darkening is characteristic of brown rot. As the wood breaks down, it loses strength and weight which causes cracking and shrinkage to occur. The wood may also appear warped. The decayed timber splits into cuboidal pieces with deep cracks along and across the grain caused by the shrinkage.
B) MYCELIUM
Fungal growth is dependent on the development of the hyphae: Fine filaments which elongate and spread through and across the damp timber. As the hyphae grow, they form a larger mass. The mycelium, which can appear as a white, fluffy, cotton wool-like growth or silvery grey sheets. The mycelium can also be tinged with lemon-yellow and lilac patches. The skin or sheet will peel back like a mushroom cap in straight lines. A musty mushroom-like smell may be present especially when conditions promote activity.
C) STRANDS
White or grey strands, which conduct nutrients and water, are formed within the mycelium. These strands, which can be up to 8 mm thick, will allow the fungus to spread over and through inert materials and reach further timbers. This ability must be considered when inspecting a dry rot outbreak. The strands will become brittle on drying and will “snap” audibly. This brittleness will distinguish the strands from other similarly coloured wet rot stands.
D) THE FRUITING BODY (SPOROPHORE)
The fruiting body can be the first indication of dry rot, although its development usually follows advanced growth. Shaped like a fleshy pancake or bracket, the fruiting body has a centre section covered with wide pores or folds, orange or reddish-brown coloured from which spores are produced. These rusty red spores are released into the surrounding area and disperse on air currents as red dust settling on horizontal surfaces.
APPRAISAL
Where dry rot is present the inspection must be carried out carefully and methodically. Remove affected skirting boards and floorboards and examine the sub-floor area, checking for fungal growths and testing the joists by prodding with a screwdriver or similar implement to determine the depth and extent of the decay. Assess the sub-floor ventilation, checking for a musty mushroom-like smell which may indicate activity and debris, which may promote the spread of the fungus or the germination of the spores. Check the plasterwork adjacent to areas of decay by removing small pockets to determine the spread of strands behind the plaster. If necessary, remove random bricks to examine the cavity for any signs of the fungus.
Determine the cause and source of dampness and rectify to promote drying conditions, paying particular attention to rainwater, goods, bad pointing, flashings and bridged damp-proof courses. Where dry rot comes into contact with a party property, the owners or occupier must be notified and if possible an inspection carried out.
CONTROL
The principal aim in the control of dry rot is to identify and eliminate the source of moisture and dry the building as quickly as possible to reduce the moisture content in the timber to below 20%. This procedure may take a long time and although it forms the basis for eradicating the fungal infestation, secondary measures may be required to prevent further damage.
TREATMENT PROCEDURES
Cut out and remove all decayed timber up to 600mm beyond the visible limits of the fungal decay depending on site conditions and severity of the fungal growth. Remove all built-in timbers, e.g. wall plates, lintels, bonding timbers within the affected area and replace using steel or concrete.
Remove all timber debris from the sub-site area and any surface fungal growth, which may be present on exposed areas of masonry.
Rake out mortar joints in areas where masonry sterilisation is required and carry out a thorough surface treatment using a coarse spray of PALACE fungicidal irrigation fluid, applying two or three treatments. This treatment is essential to ensure all residual spores from the infected timber are eliminated to isolate an existing outbreak and prevent any future recurrence of dry rot by constructing a cordon sanitaire using a method of drilling and injecting irrigation fluid into masonry or brickwork to form a sterile barrier located as follows:
- Between an outbreak and timber in the immediate area which is not affected
- At the base of a wall with no DPC membrane established in infected wood beneath a solid floor
- To brickwork where fungal decay by dry rot has affected timbers or masonry in a party wall with adjacent property
- To isolate and protect built-in timbers which may be affected by are not readily removable.
Re-plastering of exposed brickwork should be carried out using PALACE Fungicidal Waterproofer. This is especially important in areas where a severe infection is evident or in a party wall situation where access is not available to both sides of the wall.
The replacement timbers should be pressure-impregnated and cut-ends retreated using PALACE Universal Wood Preservative timbers PALACE Timber-Treat Ecology. The ends should stand in the preservative for a minimum period of one hour to ensure penetration up the end grain. Residual sound timber in the area of the outbreak should be cleaned and treated using PALACE Universal Wood Preservative
To prevent any future recurrence of a fungal outbreak it is important that the property is well maintained to prevent any ingress of damp. Also, be sure all external protective measures are kept in good order
Guide: Tiling On Floating Floors
DESIGN CONSIDERATIONS
All tile fixing should be carried out in accordance with BS 5385: WALL & FLOOR TILING Part 3 1989 – Code of practice for the design & installation of ceramic floor tiles and mosaics. Section 14.4 of this standard emphasises the need for timber substrates to be more than suitable for carrying the expected load and they be stiffened prior to tiling. Ceramic floor tiling should never be installed on floating timber floors subject to heavy static or dynamic loads.
This latter point emphasises the fact that a timber base alone may allow deflection, which is beyond the tolerance of the ceramic covering to be applied, therefore the need for rigid sheeting and screw-fixing is essential to ensure stability and rigidity.
Floating floors, by definition, are not fixed to the base substrate and so, before tiling a floating floor, it is essential to determine that its structural stability is sufficient to meet the requirements of BS 5385, part 3, section 14.4.
A typical floating floor lies on a concrete base and is characterised by a layer of rigid insulation topped with flooring grade plywood or chipboard (18 – 20mm deep). The insulation layer should be of sufficient density to provide firm support to the overlaid board. Expanded polystyrene is not considered to be a suitable underlayment for a floating floor which is to receive ceramic. To further ensure the rigidity of this structure, the timber board can also be constructed as a raft fixed onto timber battens (45mm x 45mm) with the insulating material laid between them.
SUBSTRATE STRUCTURE
To prevent excessive deflection, it is essential that the board is 18mm – 20mm thick and that the insulating material is sufficiently dense and rigid to support the expected load without risk of excessive compression or movement.
Joints between the sections of chipboard should be tongue-and-groove located and bonded with a waterproof wood adhesive. Any dead joints between adjacent boards must be fully supported as butt-jointed edges to prevent deflection between the two.
All timbers used in the construction of the floor must be moisture-stabilised to the conditions expected within the finished location. Expected moisture-stability should be further protected by the installation of an effective damp-proof membrane within the base structure and provide sufficient heat and ventilation to control humidity within the service environment.
Timber surfaces receiving tiles should be clean, dust-free and clear of any surface coatings likely to impede the adhesive from forming an effective bond to the surface. The use of Tiler’s Primer (SBR) is also advised on all worn or porous timbers and composite boards.
The base substrate must also be even, level, stable and with no localised depressions or elevations likely to cause uneven compression of the insulation layer.
Where the above precautions have failed to secure a stable surface, free from deflection and movement, it will be necessary to overlay the existing board with water-resistant plyboard to a minimum 18mm resistant thickness, laid with staggered joints. Also, battens to support the boards should be fixed to the base substrate at 300mm centres and then install the insulating layer and overlaying boards prior to tiling.
N.B. Do not proceed to fix the tiles if, after all preparatory measures have been taken, the floating floor still shows signs of deflection or movement likely to exceed the rigidity required by the ceramic tiles when subject to the anticipated loading.
TILE FIXING
Use PALACE Super-Flex two-part adhesive laid using a floor-grade notched trowel to achieve a solid adhesive bed of not more than 6mm thickness.
GROUTING
Use PALACE Flexi-Grout for joints from 3mm up to 20mm wide. In grout situations where heavy trafficking is likely to result in more movement, Flexi-Grout mixed with Palaflex additive (pre-diluted 1:1 grout (pre with water)) will provide even greater movement tolerance.
N.B. All polymer-modified grouts should be cleaned from tile surfaces within 1 hour of being applied as they can be extremely difficult to remove when set.
MOVEMENT JOINTS
It is essential to ensure that the full perimeter of all floating floors is sealed with a silicone sealant-based movement joint to a minimum of least 6mm width (in accordance with BS 5385: Part 3 – 1989, clause 19 to 23). This requires joints at all perimeters of the tiled area, coincidental with existing structural movement joints in the substrate and across large floor areas at 8 to 10m intervals.