Condensation, Painting and Decorating walls & ceilings

Damp on the inside of an exterior wall is sometimes blamed on water penetrating from outside or rising from
the ground when the real cause is condensation. Cooking, washing, etc – it all produces water vapour which condenses on cold walls.

Totally blocking up fireplaces and draught sealing windows and doors, makes it worse, because with no draughts there’s nowhere for the water vapour to go. In London, fireplaces are not so much in use lately. Anything which keeps surfaces in the room warm will help. Double-glazing prevents condensation inside windows and lining cold walls with a dry wall ( stud wall ) and insulation stops the damp from settling there. It also helps with soundproofing the walls.

Damp patches: some alternative barriers

Where the amount of damp coming into a room is slight, it can be kept from spoiling the decorations by applying any waterproof barrier between the plaster and the paper. Ask your builder’s merchant what he has in stock and what he would recommend; the materials range from paint-on waterproofing liquids, through pitch-coated lining papers to metal foils and foil-surfaced plasterboards. Pitch-coated papers are applied with a special waterproof adhesive; so are metal foils – the adhesive used with these dries quickly and you’ll need to smooth the foil out at once, working gently with a soft cloth to get rid of any air bubbles, before it has dried. Overlap joins by about an inch. If you tear the foil, stick a strip of foil at least an inch wide over the tear. The foil surface can then lined and painted, or wallpapered. Nail or stick foil backed plasterboard in place, foil side towards the wall. This will act as a barrier against the damp soaking through and help protect inside surfaces against the formation of condensations.

Stain blockers can be used before painting, however, sometimes the damp stain will show through the final painting coats in time, if the damp problem has not been solved before painting and decorating. You might need professional Painters & Decorators for the job.

Keeping damp stains off interior decorations

The answer of most Painters and Decorators to the problem of damp spoiling interior decorations and plaster is a waterproofing lath material, made from a waterproof fibre sheet which lets air pass between wall and plaster, and makes a key for replastering or mounting plasterboard sheets;

You can get it from any builder’s merchant in rolls. But remember, interior treatment keeps damp from the interior surface of the room – it does not make the main wall dry. Sometimes waterproof rendering and one coat of water proof plastering can solve the damp problem before painting and decorating a wall.

Hack off plaster from damp wall, back to the brickwork, and a foot or so along any wall which joins the damp wall.Since wall will go on being damp, it’s worth painting it with a fungicide to sterilise bricks.

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External Walls, Painters & Decorators

Preparing and Repairing the outside walls

Rendered walls have a layer of cement-sand mix mortar on top of the structural brick or blocks, rather as interior walls have a layer of plaster. Except in rare cases where they have already been painted with gloss paint ( when you will be able to clean down and put on another coat of paint ) they are usually decorated with a cement based paint, a paint containing sand to give texture or with emulsion paint, which is cheap and holds well to masonry surfaces even out doors.

The Painter & Decorator, before starting work must tie back any wall plants and wrap them in plastic sheets. The floor must be protected in dust sheets too, don’t use plastic sheets as it can become slippery and dangerous. Scrape off any lose or flaking paint.

Small cracks in rendering can be repaired like internal plaster cracks, except that the filler must be one prepared specially for outdoors use.Larger areas of rendering that have failed should be hacked out until a firm edge is reached and then primed with a PVA & water mix for a good key and seal the dust. Then filled with a not-too-wet mixture of one part masonry cement to five parts soft sand. This put on with a steel float. If the rendering is much more than half an inch thick, do it in two coats, scoring the first one as it dries to provide a key for the second.

If the rendering is textured try to match this with the edge of the float or a brush. Pebbledash is rendering sometimes pre-mixed with small stones, but more usually applied flat and having small stones flung against it from a shovel and pressed in with a float.Examine it careful if you want a good match.

Brush down walls to get rid of dust and apply masonry sealer if the surface is powdery. Repaired cracks and other bare areas should be given and undercoat of emulsion paint. A surface which has never been coated before should be wetted a square yard at a time before painting. If it has been painted but is very absorbent thin the first coat by 10 % or so.
The second coat of paint, ( you will need two or more coats of paint )should be put on full strength. Where possible, don’t let an edge dry before paint the adjoining section.

If you require a free quote for painting & decorating your property in London, contact us.

Painters and Decorators in North West London

Our Painting & Decorating Company covers most of the North West London area.

NW1 Baker Street, Camden Lock, Camden Town, Euston, Euston Square, Marylebone, Mornington Crescent, Regent’s Park, Regents Park, Somers Town NW2: Childs Hill, Cricklewood, Dollis Hill, Fortune Green NW3: Belsize Park, Camden, Chalk Farm, Fenton Ho., Hampstead, Hampstead Heath, Primrose Hill, Swiss Cottage NW4:
Copthall, Great North Way, Hendon, Hendon Central, Holders Hill NW5: Gospel Oak, Kentish Town NW6: Brondesbury, Brondesbury Park, Kensal Rise, Kilburn, Kilburn Park, Maida Vale, Queen’s Park, South Hampstead, West Hampstead NW7: Mill Hill, Mill Hill East NW8: Abbey Road, Lisson Grove, St John’s Wood NW9: Colindale, Edgware Road, Kingsbury, The Hyde, West Hendon NW10: Church End, Harlesden, Kensal Green, Kensal Rise, Lower Place, Neasden, North Acton, Old Oak Common, Park Royal, Stonebridge, Stonebridge Park, Willesden, Willesden Green, Willesden Junction NW11: Brent Cross, Finchley Road, Golders Green, Golders Hill Park, Hampstead Garden Suburb, North End