How to repair flaking undercoat on a new plaster interior wall?

Suzza

Hi Folks,

The son in law had a some renovations done on an interior wall.  He tried to paint it starting with a sealer undercoat (there was some new plasterboard involved).  Unfortunately much of the undercoat has flaked and cracked at which point he gave up in disgust.

I have volunteered to fix it and paint his walls for him.  I figure it’s going to involve a fair amount of scraping and sanding but would be interested in any advice.  I have done a reasonable amount of painting in the past but this is a bit of new territory. Cheers Suzza

EricL

Hello @Suzza 

Thanks for sharing your question about painting your son in laws interior wall. Scraping and sanding will be on the agenda when you start your project. But before you start can you please investigate if this wall is near a bathroom or an exterior wall that has moisture problems. For example, if the gutter leaks along the exterior wall or there is a large crack exposing it to the weather outside.

If you do find a moisture issue, those will need to be addressed and repaired before you begin your painting revamp. I'm surprised that the paint flaked off so soon as your son in law has used a primer. Once you've prepared your plaster board surface, I suggest using Crommelin 4L Flat Aquablock Waterproof Primer Undercoat. AquaBlock will cover, seal and leave a paintable water-resistant coating to all surfaces prior to top coating with water based acrylic paints.    

For your topcoat, I recommend Dulux 4L Wash&Wear Low Sheen Vivid White Interior Paint tinted to your preferred colour. My best advice is to give the primer enough time to cure properly before putting the topcoat on. 

Here is a handy step-by-step guide: How to paint like a professional by @Peggers.

If you have any other questions we can help with, please let us know.

Eric