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Lumps under sheet vinyl on a slab.

Richard Moore

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I've not seen anything like this before. Very typical mid 70's split-entry home with a finished daylight basement (these basements were often bare when new and finished later by the homeowner). Anyway...there was a 6x8 laundry room which appeared to have mumps in the old, glued down vinyl flooring.

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Probably 50 or so lumps and bumps spread around the room. The bathroom next door had just a few and you could feel even fewer in the glued down carpet in the hallway outside. These weren't just blisters. Felt much more solid than that. I suspect it is old efflorescence. I was able to get a peek inside one split bump and I think that was what I was seeing...but I'm far from being 100% certain. Just across the hallway, in the under-stairs closet I was able to get a look at the only section of bare slab...and...nothing! Which leads to my second choice guess that this may be tied to a one-time laundry room flood(???).

General grading of the rear yard (the side the laundry is on) was towards the home but the 8 feet or so right at the house actually had good grade, and there was no indication of repetitive flooding, etc. Downspouts were into drains, and well away from this area. There was a hosebib on the exterior wall just outside the laundry (my third guess as a possible source of water?). My Protimeter is next to useless on concrete, but my best judgement is that it wasn't an active issue. No odd smells, etc, that you would expect from a perennially wet basement.

So, I'm recommending the flooring be removed for investigation (it needs replacing anyway) and also suggesting they ask the seller about any history. I'm just wondering if you guys have any experience or other thoughts on this.

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So, I'm recommending the flooring be removed for investigation (it needs replacing anyway) and also suggesting they ask the seller about any history. I'm just wondering if you guys have any experience or other thoughts on this.

So instead of saying "investigation" why not just say remove the flooring and have the slab repaired. Your inspection was an investigation that found lumps under the vinyl.

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That's the first thing I thought of. I'd bet there's some moisture migrating up and creating those little efflorescent bumps of delaminated concrete.

Well, yeah, I'm also fairly sure it is efflorescence, as not much else makes sense. My head scratching has more to do with why it's so concentrated in one area and if it's migrating or migrated in the past tense. The more I think about it, the more I suspect a leaking hose-bib or hose just outside as the guilty party. But I'm done guessing. This is what I went with...

INVESTIGATE FURTHER and REPAIR: There are hard lumps and bumps all over the sheet vinyl flooring in the laundry. There were also a few lumps in the basement bathroom and some in the glued down carpet in the hallway outside the laundry. The cause of these could not be determined but my best guess is that it has been caused by a build-up of efflorescence, minerals leached out of the concrete by moisture. My moisture meter does not function well on concrete floors but this did not appear to be an active problem as there was no musty smell in the basement, the grading and soil conditions outside seem OK and the visible slab under the stairs showed no signs of problems…but I cannot state that with 100% certainty.

I can think of 3 possibilities. One is that the flooring was laid down before the slab fully dried and cured. A second is a one time flood from the laundry area itself. The last is the rear hose bib which is directly outside the laundry. A burst hose could have put a lot of water under the slab in this region. The sheet vinyl flooring in the laundry and basement bathroom needs to be replaced. At that time the slab should be evaluated for active moisture issues. You might also ask the seller if they know the history behind these lumps.

BTW...if you think that wallpaper was bad, check out this room. They "accented" the decor with the sink!

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The 70's were an ugly time for interiors.

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This is off the wall but it may apply. A couple of years ago I saw something very similar.

The carpenters rehabbing a house installed vinyl sheet goods with the usual mastic and it bubbled.

It turns out the vinyl was designed to be installed without mastic (or any type of adhesive). I think the sheet goods were made by Tarkett.

In some areas the vinyl wouldn't stick in other areas the mastic lumped into bubbles similar to what you photographed.

Made me think of this after seeing that high style bath sink. Might have been the same interior decorator.[:-paperba


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Well, everyone knows the lumps are ectoplasma. They had the Monsignor by to do an excorcism. He released 'em alright but Father forgot to tell the owner that the spirits aren't capable of passing through vinyl. WHAM! They hit the underside of that vinyl doing light speed and got spattered all under the vinyl.

Best not to mess with 'em.



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