History:
I have been plastering for 13 years as well as gaining experience in other trades. My journey started with a family run business back in 2004 . I now run my own business. L.A.Property Care where I cover all aspects of property maintenance. For private and corporate landlords.
Answers:
Personally i would sand down the walls properly to get rid of the old paper adhesive or wash well with sugar soap. use easy fill from b&q not polly filla to fill holes cracks and any slight marks. polly filla is a no no! horrible stuff. sand the wall smooth. then paint with matt emulsion mixed with 30% warter for the base coat then without warter for the second coat.
If you want to not spend out too much just paint it. if you would like to modernise then you can overboard and skim it. if your just going to paint it then use a brush as it gets better coverage. a roller might not get in the pattern as well and will more likely make a mess from splashing.
This stuff can be a pain in the back side, wet the wall down get a good professional scraper and scrape it section by section. let dry thoroughly then power sand down well then wash down with sugar soap. you could try mixing a bit of baking soda and a cup of vinigar in with the warm warter prior to scraping this may help immensely.
No! skrim tape over joints before plastering.
You will need a plasterer. depending on the size of the damage and how much needs to be replaced taking into account rubbish needing to be removed will effect the cost, usually these repairs take a day. costing anywhere between 250 to 400 pounds