Crawl Space Encapsulation

3,032 Views | 30 Replies | Last: 4 yr ago by sellthefarm
harge57
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My house sits on a hill, in which the SE corner of the lot is highest grade of the lot. Everything runs from the SE Corner to the NW.

Despite french drains and gutters, water seems to be seeping under the house and into the crawl space on the SE corner. We also have some visible mold in that corner of the house in the crawl space.

I had one company come out, and have a couple more coming out tomorrow.

They gave me a few options.

1. Regrading under the crawlspace and adding in draining and a sump pump, dehumidifer, and humidity monitors. -$6K
2. Adding full encapsulation plus the above is +$9k for a total of $15K
3. Scrubbing and spraying visible mode ($2.50 a sq. ft for ~1000 sq. ft of area) - $3K
4. Vent cleaning - $2K

For sure I think I need to do 1 to make sure we prevent the water from coming in/staying in

He mentioned I could hold off on number 2 and see how it goes with just the pump, and then come back in and do the full encapsulation if I was still having issues.

He also said that I could skip the scrubbing and spraying of existing mold if I did full encapsulation as the "mold would go dormant".

I am in Dallas.

Anyone have experience with similar issues? Advice? Should I just go all out and do everything? Start without the encapsulation and see how it goes?
JP76
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What is your grading like the first 8-10 ft from the perimeter of the house ?

I personally like to see 1/4" a foot.

Normally when I see this problem in the field and it isn't resolvable from gutters or drains we then resolve it from regrading and or adding dirt while sometimes incorporating swales and berms into the picture. I can tell you first hand if you allow the moisture to stay under the subfloor long term you will end up rebuilding all of the beams,joists and subfloor.

Do you have crawlspace vents on all sides of the house and are they unblocked ?


Can you post some pictures of the yard and foundation ?


mAgnoliAg
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From the outside looking in I don't like their solution. Basically they're saying it's fine to keep letting the water come in as long as we grade it to a low point and pump it out. Best solution would be to get rid of the water before it gets to the house. If it's subsurface water, you might need a deep French drain, if it's surface runoff, you will need better surface drainage than you currently have as that is obviously not doing it's job if this is the case.
harge57
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harge57
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I am pretty sure it is sub-surface water coming up from under the footer.

The drain out front takes water from a gutter, and only seems to collect surface water through the grates on the top in the picture.

I think water was coming in at the surface, and the sills were replaced and this drain was put in to solve that problem, as the previous grade was higher than the footer/sill. I think that problem was fixed, but I seem to still have a problem with the sub-surface water.
mAgnoliAg
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During droughts is it still soggy down there or is it bone dry? If it's bone dry then it is probably not subsurface water. I'm not a big fan of the drainage you have in place for a few reasons looking at that picture. I could tell more from a front view. Any surface drainage on the right side of the house?
harge57
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mAgnoliAg said:

During droughts is it still soggy down there or is it bone dry? If it's bone dry then it is probably not subsurface water. I'm not a big fan of the drainage you have in place for a few reasons looking at that picture. I could tell more from a front view. Any surface drainage on the right side of the house?
The right side of the house is all concrete that drains to one large grate that goes to the alley. That seems to drain really well, but from the crawl space it looks like moisture is coming from under that footer a bit too.

I was down there last week after a rain and it seemed dry. With the 3 inches of rain we have had in the last few days this is the first I have seen water down there. It definitely looks to be coming from under the footer not above it. That is what I mean by subsurface.

Thanks for the help.
harge57
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Does this view help?

AggieFactor
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What part of Dallas are you in? I live in a neighborhood just east of White Rock Lake and there are multiple spots in that neighborhood where far enough down the slope, the underground rock actually pushes the ground-water back up to the surface. We have a few houses in the neighborhood that are at the bottom of these hills and have had to install sump pumps in their crawlspace to counter this problem, and you will see them still pumping out groundwater for almost a week after a rain event.
mAgnoliAg
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Ok that sounds good for the right side. It sounds like it might be surface water not being caught and removed leading to the seepage. True subsurface water is from a spring or like what we see often now, land developers developing lots on old stock ponds
harge57
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I am very near the top of the hill in the surrounding area, so not likely sub-surface the way you are explaining it.

Is the drain that only collects water at ground level not the appropriate drain? We had the drain put in and the sills replaced when we bought the house to correct this issue, and I think we corrected the issue of water coming over the footer, but there is still water getting in.

harge57
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A few more pictures.





I am also wondering if this random water shutoff box is causing issues. I think they just ran the hard drain pipe around this? It is roughly on the other side of the footer as the low spot with water in the crawlspace pictures. It is definitely lower than all the drain grates so all the water would go there first.




harge57
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I talked to the guy who put the surface drain in the front of the house and did the foundation repair, and he is going to stop by tomorrow.

He speculated the answer may be a french drain in the front.

I am a little worried about trusting this guy, since he obviously didn't foresee this happening, but I will give him a shot.

I think the reason he went with the solution he did is because he was fixing a different problem. The ground level was above the sill plates, causing water to drain in at the surface and had ruined the sill plates.

They replaced the sill plates, lowered the ground level in the front of the house and put in this drain to prevent pooling since they lowered the ground level.
mAgnoliAg
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Zooming in on this shows that the grate on the inlet/catch basin is above grade. This means the water has to fill up to that level to go in so you always have standing water after rain there.
harge57
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That may be partly my fault. One of the sprinklers in that area was broken off (probably by them), and I had to dig it up and replace it. I did not realize the importance of the grade in that area.
mAgnoliAg
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harge57 said:

That may be partly my fault. One of the sprinklers in that area was broken off (probably by them), and I had to dig it up and replace it. I did not realize the importance of the grade in that area.

Just a few general drainage notes:

We never put inlets right up against the house because it is difficult to grade towards them and if they fail or the city drainage backs up the first place it backs up is right by the house.

We always have the grate grade at least 4-5 inches below the grade next to the foundation and like you've noted a minimum of 2-3" of foundation showing.

I don't want to trash your contractors work necessarily just telling you how we do surface drainage. However, 80% of other drainage contractors do it just like your guy did so you definitely aren't alone
sellthefarm
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In my opinion the water is seeping down against the outside of the foundation wall and then coming up from underneath. The only way to completely fix this issue is to regrade your front yard so that it slopes away from the house for about 5 or 10 feet and capture the surface water out away from the foundation. That yard never should have been allowed to slope all the way to the house like that.

At the very least I would move that grate out from the house a couple of feet and lower it several inches.

Don't do a pump. Keep the water out.
harge57
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Any recommendations on who to call to get this sorted out?

I don't really feel confident in anyones answer. The crawlspace guy wants to encapsulate, this foundation guy seems a bit out of his element. Would like to let an "expert" take care of this one, but don't think I have found one yet.
sellthefarm
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Your need a civil engineer. I happen to be one but not in that area. And sometimes it can be tough to find one that will do residential work. Best bet is to find someone that can come up with a design and then bid it to a contractor instead of letting the contractor come up with the design. Surely there's a PE on here in the area that can help you out. Keep bumping the thread to the top.
wbt5845
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I don't know about the water, but you got one hell of an arachnid issue that need to be addressed.
mAgnoliAg
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My boss is an Aggie civil engineer with drainage focus. I'm a drainage project manager
BosAG06
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You can try these guys. We had a complex drainage issue and they were the only ones who wanted to do it the right way out of 3 others. They aren't the cheapest but will give you an honest opinion and do it the right way. The owner himself will come out, assess the situation and provide you a proposal.

http://drainagespecialists.com/
harge57
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Thanks for the drainage specialist recommendation. I am calling them now.

Had two more companies come out today.

One suggested the sump pumps and encapsulation again.

The other company can't fix the water issue as it apparently only works on mold remediation, but his preference was to stop the water before it gets into the crawlspace with a deep french drain.

Still not sold on what the best path forward is. The most professional and thorough guys have been the crawlspace guys suggesting the sump pumps.

Gary79Ag
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A good civil engineer will get you on the right track to properly resolve your issue the right way!
AnchorFoundation
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Water always wins. Address the problem as far out on your lot as you can and incrementally work in towards beam.

Drainage solutions are difficult, but effectively tackled with common sense. Go for the biggest bang for the buck item and then reassess. Continue that implement and assess strategy until you have the problem mostly handled. But, it can always rain harder then it did today, for a different duration, over a different period, from a different direction...it will find its way in.

Easy wins: DIY type stuff
DX the flexible gutter downspout extension and move it to the road via PVC.
Catch the water from high side neighbor and move it to the road via surface drainage
Never allow downspout extensions to run in same pipe as drainage system. They can be parallel if need be, but the must be independent of each other.

Harder wins but doable:
Install thick mil plastic (think shower pan liner) on exterior of grade beam to keep water out.
While you have that trenched...get rid of the flexible "french drain" and install a correctly designed one. You'll be amazed at the amount of crud that has probably built up in it. When installing new PVC system, ensure you have a way to periodically clean it out.

Last line of resort: Underneath the home
Sump pump installed near the point of entry after you've corrected 85% + of the known problems.
Mud pump the void that has a been created around and underneath the beam allowing water to enter.

Do NOT encapsulate. That would be great if you were designing and building the same home on the same lot today with some major modifications. You CANNOT reasonably expect to keep water out of a pier and beam home that was built 60ish years ago.

But keep in mind water always wins. Your crawl space will get wet at some point, it's not the end of the world. Keep after it, it took a long time to get to this point, it will take a long time to get out of it.
harge57
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I think I found an issue, now that its raining again. It looks like the first drain next to the downspout is full and the rest of them are dry. I think it is disconnected between the first drain and the second.

Not sure if this fixes the big problem, but if that downspout is essentially dumping underground against my foundation, that likely is a huge part.

Drainage co. I called last week will be here tomorrow.

First box


Second box

AnchorFoundation
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Keep them parallel if needed, but separate. You should not have downspout extensions running in the same pipe as the "French Drain"

Disconnected, filled with crud, or caught a belly in the line because it wasn't ridged like PVC.... wither can happen and the results with a wet crawl space are often the same.

Take the opportunity now to make a few easy fixes if they present themselves.
mAgnoliAg
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THIS IS WHAT HAPPENS WHEN YOU PUT ADS (BLACK CORRUGATED PIPE) IN THE GROUND.

How long ago was this installed? Even if it was flowing freely the water would still have to rise against the foundation a few inches before entering the catch basins because they were installed above grade leading to standing water staying against the foundation with nowhere to go.
harge57
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Installed in June by the foundation guy when we bought the house.
harge57
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I just got the drainage estimate back.

My options are both $15k:

1. Fully encapsulate crawlspace, install drainage, sump pump, etc inside the crawlspace, install dehumidifier, hygrometer, etc.

Pros - Fully encapsulated crawlspace with dehumidifier will give me full confidence in no moisture in the crawlspace, probably better for resale
Cons - Not fixing the source of the problem

2. Do the french drain with sump pump etc.

Pros - Fixing the problem before it gets under the house
Cons - May still have humidity issues under the house, won't monitor

sellthefarm
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The recommendations on this thread are better than either of those two options. Go outside the house, in the yard, and divert the water around the house, or divert it into inlets and pipes that then go around the house. This needs to happen several feet away from the house and it needs to happen at least 6" below the elevation of your floor structures (beam, sill, whatever you want to call it).

If you do that and you still have a wet crawlspace, then put in the sump pump.

I have very serious concerns with the whole encapsulation idea and there is absolutely no way I would do it in my house (for the record I have a sump pump under my house, but it was built in the 30s and is all kind of weird underneath)

I said it once on this thread already, but you really need to talk to a Civil Engineer and not a drainage company.
sellthefarm
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Just to be clear, where are they proposing to put a french drain?

It looks to me like most of your problem is surface water, or very near surface anyway, so I think normal surface inlets would work. They just need to lower, further away from the house, and with better slope to their discharge than the ones you have today. Use smooth pipe not the corrugated stuff, as someone mentioned earlier.
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