Reducing humidity in a utility basement

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Old 03-23-15, 06:10 PM
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Reducing humidity in a utility basement

Hi, first time poster here. I'm sure I'll fail at keeping this concise, but the short version is I'm looking for advice towards reducing humidity and preventing sawdust from clogging a drainboard in my basement. I'm hoping some folks have solid advice on how you think I should proceed.

My situation:
  • 100-year old brick rowhouse in Baltimore
  • unfinished utility basement with woodshop and laundry space
  • previous owner Drylok'd walls 10+ years ago
  • considerable efflorescence and Drylok deterioration
  • first-time flooding after recent thaw due to neighborhood water breaks!
  • hired company to install interior perimeter / foundation drain
  • ~850 sq ft of wall, ~60 ft perimeter drain along 3 of the 4 walls
  • drainboard is open (not radon area), running about 6" up the wall

My concerns:
  • wasting electricity on dehumidifiers running 24/7
  • basement overly damp for woodworking (finishes take days/weeks)
  • exposed drainboard and pimpled Drylok are unsightly
  • efflorescence will continue to deteriorate the Drylok
  • drainboard will eventually get clogged from sawdust, debris
  • trying to not spend more than ~$1k on materials to finish

So I'm basically looking for additional options or affirmation that one of these will address my concerns. Hoping you have some ideas. I've read a hundred sites, watched dozens of videos, and nobody seems to have exactly what I need.

Pics and more details in following.

Cheers!
Sean
 
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Old 03-23-15, 06:34 PM
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Among many things considered, first thoughts were to remove the Drylok entirely. A combination of manual scrubbing, paint remover like Peel-Away, and water/soda blasting (likely damage the old bricks/mortar) would do the trick with lots of labor. Removed, I could waterproof with something like LastiSeal (penetrating polyester polymer), a silane/siloxane penetrating sealer, or a cementitious sealer like Thoroseal, Aquafin, Xypex, etc. That'd might address humidity the best, but would still leave the drainboard exposed/open.

For the drainboard, maybe a 10 mils barrier (attached via furring strips?), another drainboard, or a commercial product like Delta-Drain run up the wall, tucked in behind the drainboard, and taped to seal them together. Not fond of plastic running up the wall and having to cut holes for all the existing fixtures, but this would probably avoid having to do much with the Drylok other than scrape it down.

For aesthetics, I could leave the drain open, but add a small concrete ledge to a height above the drainboard with a removable permeable (foam) filter. Another option would be to frame studs with rigid foam insulation to cover the drainboard and wall barrier, but it'd have to be pretty wide/offset due to a plumbing main running down the wall.

Best options so far:
  1. scrape Drylok, install Delta-Drain, frame+insulate
  2. scrape Drylok, re-Drylok, concrete ledge
  3. remove Drylok, LastiSeal, concrete ledge

Thoughts? Other options?

Pics attached and in following that show some of the walls, grey drainboard, and efflorescence.

Cheers!
Sean

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Old 03-23-15, 07:03 PM
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Welcome to the forums.

I'm not the pro here.... just a few observations. It looks like you have a water problem and it was addressed on the inside of the basement with the french drain system and the coated walls. The coating on the walls is peeling off. That tells me that you have a lot of water outside your walls and no interior coating is going to stop the moisture from coming thru.

It needs to be addressed from the outside. One sure help is that the ground outside the house be graded away from the house. Of course waterproofing the walls from the outside is very effective and also very costly.

What kind of activity does your sump pump see ?
 
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Old 03-23-15, 08:11 PM
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Ah yes... That does seem to be the common response I read many times over across the web.

Remember this is a city rowhome and addressing it from the outside is basically a major no-go. Minimum $15k job, some quoted $25k+ because they have to put up notices, eventually bust up and replace about 80' of sidewalk (320 sq ft concrete removal minimum), create alternate routes for pedestrians, get worked in small sections, and otherwise create a massive neighborhood disturbance. Permits alone are over a grand. Insane. Remember the structure is also 100 years old with foundation in an unknown state, possibly minimal/no footers per today's standards, and disturbing that much of the surrounding ground could make the entire structure unstable, not to mention being impossible to reach one of the walls under my adjoining neighbor. I still love city life and this old house, but standard answers often don't apply.

The drain was just installed due to pipes in the neighborhood that burst, so it's unclear yet how much activity it will see or how much it will decrease the rate of efflorescence now that pressure is being relieved. That is why my original inclination was to seal up the wall hard with a penetrating sealer, but then I have Drylok in the way. So I either scrub and seal or cover it with a barrier that feeds into the drain, out of sight and not sharing air.
 
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Old 03-24-15, 02:09 AM
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I don't think I can tell you what you want to hear. You already know that the best results would come from work outside but being a city row house that isn't going to happen. That leaves managing the water and moisture (2 different problems) from the inside and you have set an arbitrarily low target to make that work "~$1k on materials to finish".

Water control and moisture management should have started when the foundation was constructed and nothing was done when yours was built because the basement was never intended to be other than a support for the building above. To try to play catch-up 100 years later, you will never get the results you are hoping for short of a major project.

There are companies that install a waterproof drain plane on the inside of your foundation and carry any water down to a perimeter drain. Whether your current perimeter drain is adequate or not and whether your foundation material can continue to deteriorate from the water and moisture passing through it would require some serious engineering and all of this adds up to a major investment and little of it falls into a workable DIY effort.

You know the old saying, he answers all prayers, but sometimes that answer is NO.

Bud
 
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Old 03-24-15, 05:03 AM
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Dehumidifier

wasting electricity on dehumidifiers running 24/7
Once the dehumidifier(s) dries the air, it only runs as needed, rarely 24/7.

I recommend dehumidifiers.
 
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Old 03-24-15, 06:02 AM
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Bud, I appreciate the candidness. I see this as trying to figure out how to make the best of an old situation. I can't make it perfect while also being fiscally responsible, but I certainly can make it better than I found it. I already have.

I can do drain plane work myself and at least seriously limit deterioration (that was two of the options I mentioned). Is a drain plane what would be best towards limiting moisture? Any of the cementitious or penetrating sealers should significantly halt deterioration.

I admit the $1k is completely arbitrary. And flexible. It comes from having already spent about $10k doing work myself and (the majority) hiring others when it was completely outside my experience, like installing the drain. It also is from surveying costs on dozens of options like a whole-wall barrier, penetrating sealers, soda blasters, and cement ledges. Very few options went over that budget -- paint stripper for that much wall, cementitious coatings, and hiring anyone to remove the Drylok (as it's obviously labor intensive) seemed to blow the budget. I do, however, have ample elbow grease, time, and inclination to do just about anything possible from the inside.
 
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Old 03-24-15, 06:09 AM
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Wirepuller38, I also recommend them, but even running 24/7 it ends up being suboptimal for woodworking. I suspect it's because the Drylok has deteriorated that too much of the wall is open so "as needed" is "all the time".

Re-Drylok'ing should keep it tight for maybe another 5 years. Should a penetrating sealer do better and prevent deterioration? Does anyone have experience with sealing old brick?
 

Last edited by brlcad; 03-24-15 at 06:10 AM. Reason: oops, this was supposed to be in reply to wirepuller38
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Old 03-24-15, 06:15 AM
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Address any water infiltration you can from the outside and then start running that dehumidifier.

Just because you don't want to do it does not make it any less the right answer.
 
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Old 03-24-15, 06:31 AM
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Both already done. I never said I wasn't running a dehumidifier or didn't want to. I'm looking for methods of reducing the moisture even further.
 
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Old 03-24-15, 07:30 AM
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Review this:
Wet Wall Proposal

Bud
 
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Old 03-24-15, 01:53 PM
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Interesting and a resource I hadn't come across yet, thanks!

As a research scientist myself, this is apropos. It basically describes an experimental setup that aims to control a number of variables, in order to evaluate the performance of different insulation options. The setup they describe behind the insulation is one of the options I mentioned (sealed full-wall drainboard ala Delta-Drain to above-grade). They include a vapor barrier / wrapping on top too, though several pros told me that wasn't a concern for my area or a house this old (it is what it is).

Maybe I can join that research project -- looks like they were taking applications.
 
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Old 03-24-15, 03:27 PM
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On a somewhat related note in regards to walls remaining wet as opposed to drying to the inside. For several years Building Science Corp and others were telling us, no vapor barriers below grade on basement walls. By maintaining some level of drying to the inside you were preventing the accumulation of moisture behind any wall finishing.

However, foam applied directly to basement walls also required a fire rated barrier, sometimes involving costs that exceeded the insulation project. A good solution would be to use Dow's heavy foil faced polyiso which met all fire ratings. But, it is also a extremely good VB, thus eliminating the supposedly beneficial drying to the inside. Upon further consideration, maybe testing, they changed their mind/s and said it is fine for walls to remain wet and we can use the foil faced insulation for the dual purpose of an insulating barrier as well as a fire rated covering.

My concerns remain with what we trap back there. Anything that can serve as food for mold will certainly result in plenty of it. And, they are, I presume, dealing with moisture vapor as opposed to liquid water seeping through. Too much water back there would necessitate the dimpled drainage plane and a place to drain to.

Bud
 
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