To seal or not to seal...the slab

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scotpru

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If this has been talked out I apologize in advance, new to the forum.

Finishing a basement (15 year home, walkout) 25% to remain unfinished utility area. Have a sump system and no current moisture problems. Do have a few spider cracks in the slab from settling that will be repaired but no structural issues. The external walls are also framed to the slab (cinder block wall for the below grade stuff) along with stairs.

Wondering what steps I need to take if any for the slab? I looked at penetrating sealers but it doesn't appear that the slab is porous enough (water pools) in its current state and would require additional prep. Also intending to put down plastic and foam on top of that prior to floor finishing.

Is the sump/plastic enough? Do I use some epoxy or paint sealer as another vapor barrier? Would any potential hydrostatic pressure would work it's way to the sump pit anyway? Do I just add a dehumidifier in the utility area where all of the plastic would terminate?
Not looking for "bulletproof" but what's reasonable and proper. Thanks in advance.
 
Welcome to the site.
There likely is no right answer maybe just different views.
Your slab should have drainage running to the sump and pump if required and a poly vapour barrier below the slab. Your blockwalls below grade should be waterproofed on the outside.
If those systems fail, no amount of sealing on the inside will stop it. If the water table came above the level of the floor it will find unsealed areas and find it's way in. Think about the 8" the block is sitting on all around the house and even if you seal the inside of the block wall it would just fil to the water table level and leak somewhere.
So if there was a problem with drain and sump system or wareproofing outside walls, that problem will show up and will have to be addressed whether you seal the floor or not
 
Thanks for the quick reply Neal! Makes a lot of sense and figured as much. I appreciate the feedback.
 
rent a school hallway buffer w/black pads & scrub the hell out of the floor's surface using a tsp solution - 1c : 4gal wtr,,, vac up the residue & let dry,,, apply coating of silicone siloxane - that's the best i can add to neal's advice
 

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