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tim5055

Crawl Space Encapsulation

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Well, it's time to move forward from my septic issues and start working on other projects. For those who may not have seen any of my other posts, we purchased a 9 year old home in a lake front community just outside Columbia, SC. (I'm a south Florida guy, so to me a house is made of concrete blocks built on a concrete slab).

The house is on a crawl space, the entrance to the crawl is a double door opening into an area that has about 10' clearance and the crawl gets smaller as you move up the house. The smallest it gets is around four feet.

In the crawl area is the main floor air handler, and two water heaters. All utilities (HVAC ducting, water pipes and electric) are suspended from the joists in the crawl. Additionally the pool equipment (pump/filter) is just inside the door within the crawl.

It appears the contractor did a fairly good job with the insulation in the joist bays and all is in order as far as that goes.

The floor of the crawl is dirt and the contractor really failed in this area. It looks like someone just threw down some plastic and no where does it appear that there was any attempt to seal the plastic sheets together nor to the walls. There is a musty smell in the crawl, but not too bad.

The foundation walls appear in order and only one spot shows any water intrusion into the crawl. This one spot was where a hole was cut in the foundation wall below grade as an exit point for electric/water going to a detached garage. The space around the wires/pipe in this hole was just filled with what appears to be "great stuff foam". In a heavy rain some water does enter thru this spot, but not "running" water".

In one corner at the "low point" there is box and sump pump, but it does not appear to me to be a true sump. I don't see any evidence of any perimeter drains draining into this box.

Pulling back the insulation between the joists reveals a white powdery substance on most joists, mold of some sort?? I have been reading this forum for a couple of years. Mold is everywhere, so I'm not panicking...

I have called four companies to visit and express an opinion, but I know I will be talking to salesmen and they will want to sell me something.

I guess my first question would be, do I really need to do anything?

If I do need to do something, what do I need to do?

Tim

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Well, it's time to move forward from my septic issues and start working on other projects. For those who may not have seen any of my other posts, we purchased a 9 year old home in a lake front community just outside Columbia, SC. (I'm a south Florida guy, so to me a house is made of concrete blocks built on a concrete slab).

The house is on a crawl space, the entrance to the crawl is a double door opening into an area that has about 10' clearance and the crawl gets smaller as you move up the house. The smallest it gets is around four feet.

In the crawl area is the main floor air handler, and two water heaters. All utilities (HVAC ducting, water pipes and electric) are suspended from the joists in the crawl. Additionally the pool equipment (pump/filter) is just inside the door within the crawl.

It appears the contractor did a fairly good job with the insulation in the joist bays and all is in order as far as that goes.

The floor of the crawl is dirt and the contractor really failed in this area. It looks like someone just threw down some plastic and no where does it appear that there was any attempt to seal the plastic sheets together nor to the walls. There is a musty smell in the crawl, but not too bad.

The foundation walls appear in order and only one spot shows any water intrusion into the crawl. This one spot was where a hole was cut in the foundation wall below grade as an exit point for electric/water going to a detached garage. The space around the wires/pipe in this hole was just filled with what appears to be "great stuff foam". In a heavy rain some water does enter thru this spot, but not "running" water".

In one corner at the "low point" there is box and sump pump, but it does not appear to me to be a true sump. I don't see any evidence of any perimeter drains draining into this box.

Pulling back the insulation between the joists reveals a white powdery substance on most joists, mold of some sort?? I have been reading this forum for a couple of years. Mold is everywhere, so I'm not panicking...

I have called four companies to visit and express an opinion, but I know I will be talking to salesmen and they will want to sell me something.

I guess my first question would be, do I really need to do anything?

If I do need to do something, what do I need to do?

Tim

Tell me again - how many home inspectors reported to you on this house? Did they say anything about the white powdery substance?

A good pair of eyes onsite trumps an online forum nearly every time.

Marc

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Tell me again - how many home inspectors reported to you on this house? Did they say anything about the white powdery substance?

A good pair of eyes onsite trumps an online forum nearly every time.

Marc

One home inspector, no comments in the report about the substance.

So far the "online forum" has provided more information than the two inspectors Ive hired for my last two houses.

Hmmm, maybe this is an opportunity for you all. Video conference home inspections......

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The fact that neither home inspectors saw or reported on anything isn't at all surprising. Pretty common. Forget about them.

Yes, the white stuff is probably a "mold". You indicated there's visible moisture entering the crawl; that means the dirt is probably a bit damp/wet, even if it doesn't look or feel wet. There's no vapor barrier to prevent all that moisture in the dirt from evaporating up into the house.

The subfloor (probably OSB or plywood) is a vapor retarder, it holds the moisture down in the crawl. Since the moisture can't get out of the crawl, it finds someplace to condense.

Mold thrives on most/any organic surface; the insulation stuffed joist cavities are perfect. If the joists are manufactured, it's even more perfect; all that OSB has had the natural decay preventative components extracted as part of the mfg. process. A nice little microclimate with dew point arrives eventually like magic; the moisture condenses, you got mold.

Get a real vapor barrier on the crawlspace floor, air the joint out, then condition the crawl (heat or cool it like the rest of the house). Lacking moisture, the mold won't/can't grow.

If you get inspired, hire a cleaning service to wipe out the joist cavities, although personally, I wouldn't bother. There's a few million mold spores on every surface on Earth, probably more on your cell phone or computer keyboard than in the crawlspace. Concentrate on keeping the place dry; everything else will (more or less) take care of itself.

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Thanks Kurt. I guess my next question would be how much work needs to be done? Most of the websites for crawl/foundation companies are talking about multi layer vapor barriers that go up all walls and wrap all piers.

Is what you are saying the same as what they are talking about or two different levels of work?

I guess I'm asking are they going to try to sell me a Cadillac when all I need is a Chevy.....

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Pictures. . .

Well, I'm a little red faced....

I re-read the inspection report and it was commented on, but in the "STRUCTURAL COMPONENTS" section.

Two pictures in the report, but probably hard to see here:crawl1.jpgcrawl2.jpg

The comments in the reprot were:

CRAWLSPACE - FLOOR JOISTS: Found a mildew-like substance and blotches/patches of discoloration on the exposed surface of floor joists. Moisture content levels were in the 12%-!6% range at the time of inspection.

Note: Moisture levels found were on the higher end of the acceptable range. Moisture content levels fluctuate with seasonal weather conditions.

Note: Mildew most prevalent at the left rear section (lower clearance side) of the crawlspace.

Note: Mildew inhibitors, sprays and surface treatment, ground cover and increased ventilation can effectively control mildew build-up on framing members in damp spaces.

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Yeah, pics.

'Cuz the white powder might not even be mold. Everything you're describing makes it sound like mold is the high probability, but it might just be some harmless fluff.

But, if a crawlspace smells musty, the "vapor barrier" is visqueen tossed onto bare dirt, and you can see a bit of moisture leaking in here and there, you got a crawl that needs attention.

What I described is Crawlspace 101. Vapor retarder/barrier, condition crawlspace. Regardless of the "mold", you ought to do it.

What (most of) the franchises sell are really nice systems, and I won't dissuade you from investing in quality, but to some (large) degree, it's just a crawlspace. DIY. You should invest in some light weight scrim reinforced plastic sheeting; visqueen, in a word, is crap. It would be worth the extra expense to get some decent material.

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OK, between my writing and posting, you put up the pics. Sure looks like the fuzz to me.

Another hint.....

Your inspector did identify the issue, but in the usual canned report off the shelf software fashion, the information is obfuscated into near incomprehensible gibberish, hidden in the silly format.

If I was reporting it, the report would be relatively short and in summary format, there would be pictures, arrows pointing at the fuzz, and.....

"There's white (insert appropriate description here) fuzz on the joists, most likely caused by the damp crawlspace and lack of vapor barrier. You should (insert crawlspace improvements here), then clean up the (mold/fuzz/killer growth). If you are concerned about the health effects of mold, talk to your personal medical professional, then get back to me if you have additional questions."

Or something like that.

Don't be red faced. Pretty much all inspection report formats completely and totally suck. They ignore well established methods of reporting information to lay people. Inspectors love them because.....

1) They imagine all that obfuscation makes them appear technical and knowledgeable.

2) Everyone else uses them.

Report systems are a swamp of old bad ideas. Most of us in the biz are old guys, old guys really, really, really love MS Word, no one talks to anyone actually involved in the study and understanding of communication and/or rhetoric, and therein lies the problem.

Everyone gets together, either on the inter-web, at conventions, at "educational" seminars, or at the local pro society chapter meetings, and they all reinforce each others stasis.

It's what old guys do when they've run out of ideas, or never had any to begin with.

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That reminds me of this write-up that hangs on my wall:

The chimney is badly cracked by reason of settlement, throwing the weight and strain of said chimney against building and should any further settlement occur, would probably fall and carry part of building with it.

You are therefore required to immediately take down and rebuild same in a substantial manner.

It's a Cincinnati code inspector's report dated 25 July 1889.

Absolutely beautiful writing.

Marc

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Kurt has nailed it. There's a moisture problem causing the growth on the floor. Ground moisture, coupled with the moisture intrusion, AC inside the home, and the outside humid air used to ventilate the crawlspace causes the perfect environment for the growth. Your floor insulation is not helping either.

Very common issue for the Southeast. That looks to be like almost every floor system here in Charleston about 2 hours away from you.

From the pictures it's not terrible, but a vapor barrier alone will not stop it. Sealing off the vents from the outside air, condition the existing air with a dehumidifier and correcting the one spot of moisture intrusion that you noted is best.

Here's a few pictures of what a really nice crawlspace looks like after. This home was done from day one and shows no sign of growth. The downstairs air handler is located in the crawlspace and does not sweat either. Most people do not insulate the walls after removing the floor insulation, but it's an option.

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Marc, Kurt, Jim & Kiel -

Thanks for taking the time to educate me!! It's starting to come together in my mind now.

Most people do not insulate the walls after removing the floor insulation, but it's an option.

Now, that confuses me - remove the existing insulation? Even sealing the vents it's going to get cold down there, no?

Plus, with all the pool equipment down there I will be going in and out on a regular basis, as well as my thoughts of using the area with high clearance for a little storage. How might that figure in?

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The pic Kiel posted is a beautifully finished crawl. Running the VB up the piers (moisture migrates through concrete like a sponge), no joist cavity insulation, perimeter finished with insulation panels, conditioned, done.

Joist cavity insulation does very little to effect heating; it's another of those ingrained habits, aided by building codes that have just about everything related to insulation and ventilation wrong.

Removing the joist cavity insulation and insulating the perimeter of the area allows capturing all that lovely free geothermal heat emanating from your crawlspace floor. I'm betting the crawlspace would be warmer, not cooler, by taking Kiel's recommendations.

As an example, my >90 year old bungalow had 1st fl. platform joist cavity insulation, and nothing in the basement perimeter; in winter, you could sometimes see your breath down there. I ripped out all the joist cavity insulation, insulated the perimeter with 2"XPS foam (the pink or blue stuff) from the basement floor to the 1st fl. platform subfloor, then installed a thermal barrier of 5/8" drywall over the foam.

The basement went from being freezing to the warmest and nicest room in the house on a cold winter day.

Do it like Kiel's pics, you won't be sorry.

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Again, thanks for all the information. I think I will go into the presentations a lot more informed.

It's funny, the first company I called had photo's almost exactly like the ones Kiel posted on their web site. After I made an appointment I got a call from them asking questions about the job. it seems their primary focus is actual foundation repair and the do encapsulation in conjunction with those jobs. Luckily, no repairs needed here. He did point me in the direction of a couple of companies who specialize in encapsulation. As a final note, he said they used $3 per square foot as their guide for pricing the encapsulation.

I made appointments with three other companies and had them spaced out over a few days. Seems two of the three need to change days and all three ended up tomorrow. 9, 2 and 4.... It's going to be a long day.

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Since your lot is on a steep slope, make sure there is a good perimeter drain around the back side of the foundation to carry ground water away from the crawlspace.

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Well, it was a long day. Three "salesmen" spaced throughout the day.

Just as an aside, I found it funny that two of them provided copies of the book "Crawl Space Science: What to Have Done... and Why" . Funny, because the book was written for one of the companies and the competition was using it - even with the competitions name in it?? I'm confused about that. Book on Amazon. Anyone need a copy?

So, back to the day. All basically came up with the following:

  • There is some "growth" on the joists
  • Just shy of 3,000 sq feet
  • I should have it done

All three showed similar photos to what Kiel previously posted as a finished product. All three would install 20 mil barrier on the floor and all walls leaving a 6" gap below the sill plate to allow for termite inspection. All piers would be covered two to four feet above grade. All vents would be covered with foam blocks which would be foamed into place. The "system" would then cover them.

Salesmen #1. After two hours he recommends encapsulation, adding a dehumidifier, sealing all vents and adding a sump pump. I'm simplifying a little but $13,000 is the final number. (He uses his competitors book to sell his product). He comments on the "mold", but doesn't think it's a big deal or needs remediation. He states we will then need a yearly visit to clean the dehumidifiers filters and check the sump pump.

Salesmen #2 After two hours (and i have to explain that his time is up) he recommends spraying to kill the rampant mold I have, encapsulation, adding a dehumidifier, sealing all vents, installing a perimeter drain system, installing an air exchange system from the living space and adding a sump pump. Once that is done he wants to spray the area with a special "patented" spray that will kill any new mold for 6 months. He never did come up with a price, he will have to e-mail it to me.

Salesman #3 He is in and out in under an hour. He recommends encapsulation, adding a dehumidifier, sealing all vents and adding a sump pump. I'm simplifying a little but $10,000 is the final number. He comments on the "mold", but also doesn't think it's a big deal or needs remediation. As a matter of fact, he rubs it on one of the joists and stated that this stuff is everywhere and you are breathing it everywhere. It's his companies book #1 uses.

Both #1 & #3 said that the space under the front/rear porches (brick with stamped concrete would be blocked off with doors and that space would not be encapsulated. Both stated that water is always going to work its way through the concrete floors above so including them in the conditioned space will negate the object of what we are doing. #2 said he would encapsulate the area under the porches, but had no answer as to the water coming through the concrete.

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Well, it was a long day. Three "salesmen" spaced throughout the day.

Just as an aside, I found it funny that two of them provided copies of the book "Crawl Space Science: What to Have Done... and Why" . Funny, because the book was written for one of the companies and the competition was using it - even with the competitions name in it?? I'm confused about that. Book on Amazon. Anyone need a copy?

I'll sure take it. Let me know what the costs are.

Again, it's a gift to get this detailed feedback from you as you check the market on encapsulation. I dunno about others here but it's both educational and interesting to me.

Marc

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I got that book from another inspector who attended a seminar. It is in storage somewhere at the moment tho.

I think the encapsulation is a good product for an average house on an average crawlspace.

The guy who included perimeter drainage in his assessment is on the right track. You need to deal with groundwater and roof runoff drainage.

The green fuzz type mould will die if the wood dries out. Killing it is an extra step, like belt and suspenders. The reason moisture can be damaging to wood is that you could get a wood-destroying fungus growing under there. Then it would be correct to call for treatment of the mold.

You mention the piers. I would not let them cover wood posts with the membrane.

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I'll sure take it. Let me know what the costs are.

Again, it's a gift to get this detailed feedback from you as you check the market on encapsulation. I dunno about others here but it's both educational and interesting to me.

Marc

It's yours, PM me an address. I figure the couple of bucks postage as payment for the knowledge I've received here.

So far the estimates are $13,000 and $11,000 (rounded and including similar "options")

I got that book from another inspector who attended a seminar. It is in storage somewhere at the moment tho.

I think the encapsulation is a good product for an average house on an average crawlspace.

The guy who included perimeter drainage in his assessment is on the right track. You need to deal with groundwater and roof runoff drainage.

The green fuzz type mould will die if the wood dries out. Killing it is an extra step, like belt and suspenders. The reason moisture can be damaging to wood is that you could get a wood-destroying fungus growing under there. Then it would be correct to call for treatment of the mold.

You mention the piers. I would not let them cover wood posts with the membrane.

Thanks!

All roof run off is already captured and piped off the lot. One of the few things the original owner did correctly was grade the lot so water moves away from the house and into lower areas away from it. The main problem is that one of those lower areas is the septic drain field, so it always stays wet.[:-weepn]

The piers are all concrete block, no wood.

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Well, continuing....

A little more background on the salesmen.

#1 used two sales techniques I hate:

  • spent too much time on what other folks do wrong (with pictures & names)
  • used the "if you sign today I can give youX off" routine

#2 was nothing more than a mold scare monger.

As far as numbers, #1 emailed me a written quote while he was at my house. #2 & 3 said they would e-mail, but nothing to date.

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Hire number 3.

Tell him that if the work is done on time and if he doesn't leave a mess, he'll get an extra $200.

That is the way I'm leaning. I just want to see his written quote. As far as the extra $200, I tend to "tip" the workers on site for a good clean job.

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Hire number 3.

Tell him that if the work is done on time and if he doesn't leave a mess, he'll get an extra $200.

That is the way I'm leaning. I just want to see his written quote. As far as the extra $200, I tend to "tip" the workers on site for a good clean job.

That's a good practice but it's most effective when they know ahead of time that they might get a tip. Makes for a better carrot.

As for the stick, you could introduce them to your "quality control manager," pictured in your avatar.

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