I have a 1970 built detached house, brick ground floor and tiled first floor. At the top of the brickwork is a cement board facia about 3/8 of an inch thick and about 15 inches high, running around the outside of the whole house, about 30 yards total. It came ready coloured in white when the house was first constructed so the cement board looks quite shabby after many years of weathering.
About 10 years ago I painted the cement board with exterior gloss but I have just scrapped it all off quite easily, some in large flakes, so it has never bonded properly to the cement board.
I used this as some neighbours had professional decorators paint theirs at the time and that is what they used. So much for copying professionals eh!
Could you advise me what preparation, undercoat and topcoat I should use on my exterior cement boards please. Dave
Remove as much loose paint as possible and any powdery residue before painting again.
For a traditional gloss finish the correct procedure would be: 1 coat of alkali resisting primer* 1 coat of undercoat 1 coat of gloss
*you may find the surface absorbs the first coat of primer quite readily, if this is the case you’ll have to re-coat until you get a semi-solid finish.
For a water based gloss finish (such as Dulux Weathershield) 1 thinned down coat of undercoat – either weathershield or any quick-dry, water-based undercoat) 1 full coat of above 1 coat of quick drying, water-based gloss
*you may find it difficult to get a good finish with a brush with this system because the paint will be drying as you go. A short pile mini-roller is better.
The following method is very likely what your neighbour’s decorators used though (unless they were very professional) 1 thinned coat of white exterior masonry paint 1 full coat of masonry paint or slightly thinned undercoat 1 coat of gloss