I live in a house that I believe was built in 1948. The basement walls are cinder block. I have areas of the walls that are stained and some areas that are crumbling. Some spots are bubbled and easy to push in. Not sure if it's the cinder block and/or the paint the previous owner used. When I moved in I was told there was a water problem in one corner and it had been waterproofed. I believe the waterproofing was done right because I don't really notice any new damage or worsening issues to the walls since I've been there. Most of the issues are in that corner but there are some other spotty areas. Most of the spotty areas seem to be confined to the base of the wall. My question is I want for now to just paint the walls to make it look nice. How do I go about preparing the wall to paint? Do I scrape as much of loose material off the wall as I can and then use some sort of sealer/paint? Any help would be greatly appreciated, Thanks.
would've been nice to see your area listed under your name so we'll guess northeast,,, cinder blocks never were a good material for most foundation walls but cheap compared to conc,,,compressive strength was fair enough to support most bldgs but the main problem was the lack of waterproofing on the exterior,,, not that anyone properly waterproofed exterior conc walls either but concis more resistant to wtr damage than cinder blks,,, hell, even conc blks are better,,, anyways, wtr runs downhill ( especially thru the loose backfill alongside fnd walls ),,, that backfill was never compacted properly for 3 reasons: 1, cinder blk walls don't have the lateral strength to resist compaction force; 2, wasn't rqd by code; & 3, cheap bldrs,,, that wtr dissolves soil's acid salts which then attacks lime in cement used to cast the blocks - hence, crumbling block.
most waterproofing is really wtr management - we manage leaking wtr instead of stopping it outside,,, in fairness to wtrproofers, most do try to resolve the problem,,, however, customers faint when they hear costs tin men being what they are, it has become a hit 'em w/big price solution then offer the lo-ball priced band-aid - that's why we have sump pumps warranty/schmaranty - its still wet & damage is still occurring,,, even most home inspectors are either ignorant of these issues OR stupid for not being more aware
all having been said, get a wood handled wire brush & have at it - you won't damage good block but may need to patch some w/hydraulic or mortar,,, finally paint 'er w/latex block filler paint .