First thing to do will be to dust down the internal brick walls. This will remove loose, poorly binding material.
If the bricks are unpainted, there will be two potential things to treat here. Potentially invisible / hard-to-see mould spores and efflorescence.
We recently answered a question on treating mould on internal unpainted brick wall.
Efflorescence is white salt deposits created when the render finish was drying as it was applied. Anything cementitious that dries will leave behind a salt deposit as the moisture evaporates. This unfortunately needs to be neutralised with a mild acid solution. Apply the acid, allow to dry and you’ll be good to go. Because you are dealing with acid, it is essential that you chat with our expert staff in-store to go through all safety precautions.
If you’re painting the surface after clearing the efflorescence, this may take more than two coats on a rough surface such as brick. And don’t forget to use the appropriate long nap roller for the job.
Because all paint products are unique and different and have their own layers of complexity, we always recommend visiting your nearest Inspirations Paint store and speaking with our expert staff about the finer details of your paint project to make sure you get the job done right the first time.
Hope this helps. Be sure to let us know how you go.