Paint stays on sound surfaces. It doesn’t stay on wood that has become even a little soft or moist (due to rain and temperature changes) or on masonry that moves or has moisture or some mortar chemicals in it.
Fact No. 2
Most decorators have bad or lazy habits. Mostly this is due to not knowing the above and from wanting a quick buck ahead of a good prod
THIS IS WHAT HAPPENS AT THE BEGINNING OF A DECORATING PROJECT:
The loose paint is scraped off and maybe sanded. Maybe all the good paint is sanded too. Obviously loose putties are removed (fall out).What is missed is not- so- obviously- loose putties are left, loose paint on the glazing is left, stringy and moist bare wood is left (because it is not seen as unpaintable), fillers bare added to cracks and bare wood (sometimes only powder fillers)
More often than not the window is simply painted first and what is unseen as faulty is now covered up, and only the very worst areas ‘treated’.
Really dirty windows and masonry are NOT washed. Green mould is not fully removed and treated.
The surfaces are painted and now look good for a while. If you look six months later, or even a few weeks later you will see cracks appearing on the tips of sash rails and sills. Not so long after that, after a winter or summer, you may see worse. More putties are seen to be cracking, etc
Within reason, a lot can be done to allay the scene above:
1.Employ a proper decorating company, and they in turn employ only trained-in-the-above facts and the following techniques.
2. Make sure you, as a customer have the opportunity to inspect for yourself all the preparations before paint is applied. You can see the key areas from open windows as the sills and bottom rails are the key areas. . Pick at the wood and see if it is solod and splintery or soft and stringy.
If there is a scaffold, and you are so inclined, get up and have a look for yourself, or go around with the Contractor who is checking the preps himself ( which he should do).
3. All bare wood or masonry should have a primer and extra undercoat.
4. All dubious wood should be drilled out, much like a dentist drills tooth, back past the rotten/soft wood and filled with resin filler ( Window care
System, or similar)
5. Putties should ideally be replaced in Windowcare product as linseed oil putties often wont have enough time to have formed a decent skin before painting.
6. Main-brand paints should be used. I is a common fallacy to assume the ‘ most reputable’ brand is vita. It is not. It is the preps that count.
7. Decorator caulk is NOT meant for external sealing. Only mastic/silicone sealers.
8. On masonry, the correct filler is cement base4d ( Toupre or similar). Not any other powder fillers, like Polyfilla.
9. Large rendered or painted brick surfaces often need a jetwash to remove dirt and mould and strip off loose and flaky paint better.
If wood is rotten it sometimes shows and sometimes doesn’t. A senior person in a Contractor Co. should go around with a pointed object and prod and poke in all the usually suspect areas and find it. Mostly this will result in a large Windowcare repair or wood replacement (hardwood ideall)
There aren’t any as the effect of weather and temperature will on their own move the best of surfaces in time. Ever notice how front doors don’t close in the winter, sometimes?
But you can greatly reduce the weather effect by good practice, as above.