Having water intrusion on 3 of 4 walls in the crawl space. In getting 2 of 5 bids so far, one contractor wants to control the water from inside the crawl space with perforated pipe and a sump pump. The other contractor wants to use drains on the outside perimeter. Makes sense to me to catch the water before it comes in. What are advantages/disadvantages of each?

Had a similar problem with a house I lived in a few years ago. It was more a groundwater problem with water coming up into the crawl space. There was never any puddling but the ground was always damp and squishy.

Only had 18 inches of dirt against the crawl space on the outside so they recommended doing the sump pump and perforated pipe around the block wall on the inside of the crawl space. We did it and it seemed to worth as advertised. The buyer was happy with it as well. The cost was around 5k or so.

I have been though this whole process. Since buying my home in 2005, I have always had high moisture content in the wooden joists to the point of it starting to even be detrimental to the insulation in the crawl space, as well. And, the soil under the house was always wet to the pint of being muddy in places.

My first effort to correct the situation was to install trenched filled with gravel around the inside perimeter of the crawlspace and sump pumps that relayed to water to one pump, them outside to a pre-existing drainage grate. I lived with this system for several years but it really only produced a marginal moisture content reduction. I don't recall the cost of all that but it was prob $4 to $5K at least, for about 2400 sq ft of crawlspace.

In the last several years the humidity levels under my house had created sweating problems on an AC duct that is jammed up against the plywood subfloor to the extent that water was wicking into my wood floors and causing them to buckle. The floors flatten out in the winter and then repeat in the summer months.

Finally I bit the bullet and had a crawlspace encapsulation done, which included the installation of a very thick vapor barrier, sealing off all the openings in the crawlspace and sealing off all penetrations of footings, etc coming up from the ground. Additionally, the system included installing a de-humidifier. I insisted on two de-humidifiers.

This has solved my problem, although I did have to increase the "dryness" setting late this summer. The humidity level was still too high to prevent that sweating, (running about 75%. After increasing the dryness setting the humidity now has dropped to 46% or so and may actually be a little too dry. I have read that 55% seems to be the ideal target.

So, I currently have the sump pump system, which is covered by the vapor barrier except at the pump locations (for service), as well as the described encapsulation. The encapsulation cost about $8K including the dehumidifiers.

I still hear the sump pumps run when we have heavy rain, and the de-humidifiers are dumping into that drain system as well to be pumped out from under the house.

I suspect that you are likely having ground water infiltration as well as runoff infiltration. I have never heard of a pump system being installed outside the foundation, but have seen french drain systems used so I guess a pump would further facilitate such a drain system.

Personally, I would rather it be under the house to better ensure that water was being pumped out which would also take care of any groundwater infiltration.

We installed a french drain around the two outside walls that were seeping into the cinderblock. Also tied in the gutter downspouts so they drained away from the house as well.

I wanted the water taken care of before it got near any slab or footers so there was less chance of settling affecting my house. Seems like letting the water enter your crawlspace before removing it provides conditions for your footers or supports to sink in wet soils...

quote:

Originally posted by sunburn:
Having water intrusion on 3 of 4 walls in the crawl space. In getting 2 of 5 bids so far, one contractor wants to control the water from inside the crawl space with perforated pipe and a sump pump. The other contractor wants to use drains on the outside perimeter. Makes sense to me to catch the water before it comes in. What are advantages/disadvantages of each?

Without seeing pictures of existing conditions, neither of these things may be effective. I'd want to evaluate the conditions outside the home first. Do you have downspouts that shed water 3-5 feet from the foundation? Does the soil around your home slope away from it? Do you have high groundwater or other conditions that will push moisture into the crawlspace?

Any solutions that are passive and non-powered are better. Anything that could prevent the water from getting into the crawlspace is better than simply pumping it out.

What is the construction of your crawlspace walls, what is the ground under the crawlspace, is the crawlspace vented... stuff like this is best "eyes on." Pics would be helpful.

What arc wrote. (I was waiting for that.)

I cannot over-emphasize the value of proper grading and downspouts. We used to get a regular river of water flowing into our sump well when it rained heavily- or long-enough. I fixed from grading issues near the house and we had gutters installed with downspouts that kick out about 4-5 ft. Now we hardly get any water in the sump well at all, unless it really pours for an extended period.

We have a high water table. Our house has a 4' crawl space. The grading is that high - higher than our neighbors. All downspouts have the equivalent of a french drain.

Our crawl space still uses a sump pump. It kicks on during heavy rain storms, but the house seems to stay dry underneath. The entire dirt floor is sealed with plastic.

Our foundation is also sealed on the outside like a basement. You can see the black water sealant peaking out of the grass.

Downspouts shed water to the perimeter of the property. Front of house has heavily landscaped slope towards house. Side and rear of house heavily shaded so lack of evaporation an issue. Record rains over the summer made the water intrusion much worse.Clay soil on sidewall outside moist down to footer.
A third contractor wants to dig the outer perimeter, clean and seal outer wall and put a drain along the footer. Also wants to encapsulate crawl space with 50 mil membrane, sealing and insulating vents. Walls around crawl space 2x4 stud.
So far, I like this guys ideas/solutions best.

Third guy has the right and complete answer. I've been there and done that.

quote:

Originally posted by sunburn:
Downspouts shed water to the perimeter of the property. Front of house has heavily landscaped slope towards house. Side and rear of house heavily shaded so lack of evaporation an issue. Record rains over the summer made the water intrusion much worse.Clay soil on sidewall outside moist down to footer.
A third contractor wants to dig the outer perimeter, clean and seal outer wall and put a drain along the footer. Also wants to encapsulate crawl space with 50 mil membrane, sealing and insulating vents. Walls around crawl space 2x4 stud.
So far, I like this guys ideas/solutions best.

I would vote for your third contractor.

I agree with J3e and arc: The third guy sounds like he wants to it right.

That being said: I think you really should consider doing something about

quote:

Front of house has heavily landscaped slope towards house.

That's a problem, and it's better to eliminate problems than compensate for them.

If it's not reasonable to fix it entirely, and it's probably not, then a swale, to gather the water and lead it away before it gets to the house, may do the trick.

We have one of those between the garage and the next door neighbour on one side. His elevation is higher. The swale collects the water and leads it away, down towards the front of the property.

It turns into a veritable river if it rains heavily enough or long enough, and during spring snow melt. If it wasn't there, all that water would go under the garage, end up in in the drain tiles surrounding the foundation, and, eventually, in the sump well, where it'd just have to be pumped back out.

I will address the slope of the front yard with the contractor. I appreciate everyone who took the time to bring their input.