[chikitin]

Hi,

I need to apply a liquid rubber on my foundation wall. Is this a proper way to do that? Shouldn't I go deeper?

How many times do you apply the rubber? How much should I wait before putting the dirt back in the trench?

I got a damp crawlspace.

Any help would be greatly appreciated.

Thank you very much again.

 

[Nealtw]

That should be as high as the dirt outside and lower than the dirt inside but without a drain at that lower level the water could still find level inside by going under the foundation.

 

[chikitin]

That should be as high as the dirt outside and lower than the dirt inside but without a drain at that lower level the water could still find level inside by going under the foundation.

hmm... now you make me think twice:

Q1. why lower than the dirt inside?

Q2. I have three downspouts discharging around 12 feet away from the foundation with a good slope. Do I need to put a drain/footer pipe along the lowest part of the footing? I am thinking with the 1-foot eaves overhanging I don't get much rain there! Am I wrong?

 

[Nealtw]

hmm... now you make me think twice:

Q1. why lower than the dirt inside?

Q2. I have three downspouts discharging around 12 feet away from the foundation with a good slope. Do I need to put a drain/footer pipe along the lowest part of the footing? I am thinking with the 1-foot eaves overhanging I don't get much rain there! Am I wrong?

If you ave done what you can outside with drainage wait and see what happens, it was likely good for years until something changed. If it gets wet again, you want to pin point the problem and might be easier than going after the whole foundation.

 

[chikitin]

If it gets wet again, you want to pin point the problem and might be easier than going after the whole foundation.

Thank you again. I will see. It is going to rain on Wednesday hard.
Do you mean put a liquid rubber around foundation with french drain by the footing?

 

[Nealtw]

Thank you again. I will see. It is going to rain on Wednesday hard.
Do you mean put a liquid rubber around foundation with french drain by the footing?

Wait and see how bad the problem is and see if you can locate the problem area if it is still leaking.

 

[AllanJ]

Normaly you put the tar on down to the foundation footing.

Your choice of whether to put the French drain down now (at the footing) or to wait and see if you get water inside the crawl space and put down a French drain just outside or just inside the footings in the future then. In any case the French drain needs a sump pump pit or a gravity drain pipe going out to daylight.

A rainstorm before you fill in the ditch proves nothing. You need the ground level finished and sloping away from the house to evaluate rain performance with.

 

[chikitin]

Normaly you put the tar on down to the foundation footing.

I will do that. Thank you.

Your choice of whether to put the French drain down now (at the footing) or to wait and see if you get water inside the crawl space and put down a French drain just outside or just inside the footings in the future then. In any case the French drain needs a sump pump pit or a gravity drain pipe going out to daylight.

A contractor just came by. He said I need a french drain inside by footings and drill a 4" hole for foundation all drainage pipe. He said I don't need a sump pomp.

A rainstorm before you fill in the ditch proves nothing. You need the ground level finished and sloping away from the house to evaluate rain performance with.

I will surely do that.

Thank you very much for you time.

 

[dj3]

There is a cement base sealer called THOROSEAL made for concrete, footings, foundations and stucco applications. You mix it with water to a paste consistency, then apply it with a wide brush and let it dry. It seals and waterproofs.
Better than tar, less messy than tar.
I've used it with positive results for years. Look it up.

 

[APA]

Hi,

I need to apply a liquid rubber on my foundation wall. Is this a proper way to do that? Shouldn't I go deeper?

How many times do you apply the rubber? How much should I wait before putting the dirt back in the trench?

I got a damp crawlspace.

Any help would be greatly appreciated.

Thank you very much again.

Do you have HVAC ductwork in your crawl? Is it dripping? If so, in humid NC, vents should be CLOSED in the summer. All that hot, humid air enters your vents, cools, and condenses in your crawl. I solved my damp crawl by closing all the vents but two on opposite ends of the house, running a box fan to circulate air, and installing a regular 70-pint dehumidifier with a built-in pump. When I say damp, I mean DRIPPING! I did a radon test just to be sure about closing the vents and it came back at 0.9 pCi/l which is way below what is even considered a mild risk. The humidity in my crawlspace in now 42% and the dehumidifier hardly ever kicks on. I realize this is a jackleg way to do things, but the crawlspace repair company wanted $7K to seal and dehumidify my crawlspace...

 

[APA]

Do you have HVAC ductwork in your crawl? Is it dripping? If so, in humid NC, vents should be CLOSED in the summer. All that hot, humid air enters your vents, cools, and condenses in your crawl. I solved my damp crawl by closing all the vents but two on opposite ends of the house, running a box fan to circulate air, and installing a regular 70-pint dehumidifier with a built-in pump. When I say damp, I mean DRIPPING! I did a radon test just to be sure about closing the vents and it came back at 0.9 pCi/l which is way below what is even considered a mild risk. The humidity in my crawlspace in now 42% and the dehumidifier hardly ever kicks on. I realize this is a jackleg way to do things, but the crawlspace repair company wanted $7K to seal and dehumidify my crawlspace...

Also be sure to have at least a 6-mil vapor barrier in place...

 

[chikitin]

There is a cement base sealer called THOROSEAL made for concrete, footings, foundations and stucco applications. You mix it with water to a paste consistency, then apply it with a wide brush and let it dry. It seals and waterproofs.
Better than tar, less messy than tar.
I've used it with positive results for years. Look it up.

Well by Tar I meant " Black Jack Liquid rubber 57". Not sure if it is the same!

Are you talking about this or this?

Thanks again.

 

[chikitin]

Also be sure to have at least a 6-mil vapor barrier in place...

Yes. Now the soil is kinda saturated. I guess I need to replace the vapor barrier and this time I make sure they are sealed together maybe with dock tape.
Should I cover say 2-3" of the bottom of walls for better insulation?

 

[chikitin]

Do you have HVAC ductwork in your crawl? Is it dripping? If so, in humid NC, vents should be CLOSED in the summer. All that hot, humid air enters your vents, cools, and condenses in your crawl.

No I do not. So I guess based on the inspector recommendation ( attached above), I need to leave it open all year long! But a friend of mine who owns a construction company up in Raleigh, NC. he told me to keep them open in the summer and close the vents in the wintertime. But what about the days we have thunderstorms and rain in summer! This is so confusing. Everyone has a different opinion.

I solved my damp crawl by closing all the vents but two on opposite ends of the house, running a box fan to circulate air, and installing a regular 70-pint dehumidifier with a built-in pump. When I say damp, I mean DRIPPING! I did a radon test just to be sure about closing the vents and it came back at 0.9 pCi/l which is way below what is even considered a mild risk. The humidity in my crawlspace is now 42% and the dehumidifier hardly ever kicks on. I realize this is a jackleg way to do things, but the crawlspace repair company wanted $7K to seal and dehumidify my crawlspace...

I bought a "Tjernlund UnderAire Crawl Space Ventilator — Deluxe Two Crawl Space Fan, 220 CFM, Model# V2D" and install it yesterday. I set the humidity to 50% and has not stopped. I have a bit of water in the crawlspace and I have removed the vapor barrier around the spot I got water. I have all the other vents open! I will try your approach as it makes sense to me! My crawlspace is pretty small and should not add much to my electric bill.

 

[APA]

I bought a "Tjernlund UnderAire Crawl Space Ventilator — Deluxe Two Crawl Space Fan, 220 CFM, Model# V2D" and install it yesterday. I set the humidity to 50% and has not stopped. I have a bit of water in the crawlspace and I have removed the vapor barrier around the spot I got water. I have all the other vents open! I will try your approach as it makes sense to me! My crawlspace is pretty small and should not add much to my electric bill.




Leaving the vents open while running a dehumidifier means you are basically dehumidifying the outdoors. Close the vents and run the dehumidifier continuously. Also put the vapor barrier plastic back on the ground.

 

[chikitin]

Leaving the vents open while running a dehumidifier means you are basically dehumidifying the outdoors. Close the vents and run the dehumidifier continuously. Also put the vapor barrier plastic back on the ground.

This is not dehumidifier. It is a ventilator fan. I just emailed them about it and they responded to me the following:

"Air is your friend even if it’s moist air so I don’t recommend closing any of the vents because you need good cross ventilation. Closing the vents could increase the humidity thus defeating the purpose of the fan.

Do you also have a vapor barrier (minimum 6 mil plastic) installed on the floor of your crawl space or is it a dirt floor? If you have a vapor barrier great, if it’s a dirt floor the fan will still work but it will just spend much of its life trying to pull moisture out of the dirt."

 

[APA]

This is not dehumidifier. It is a ventilator fan. I just emailed them about it and they responded to me the following:

"Air is your friend even if it’s moist air so I don’t recommend closing any of the vents because you need good cross ventilation. Closing the vents could increase the humidity thus defeating the purpose of the fan.

Do you also have a vapor barrier (minimum 6 mil plastic) installed on the floor of your crawl space or is it a dirt floor? If you have a vapor barrier great, if it’s a dirt floor the fan will still work but it will just spend much of its life trying to pull moisture out of the dirt."

Sealing the earth, closing the vents, and installing de-humidification is what all the current literature suggests.

 

[chikitin]

Sealing the earth, closing the vents, and installing de-humidification is what all the current literature suggests.

Sealing the earth yes.

But there is no scientific reasoning behind: "closing the vents, and installing de-humidification"

I suspect that this is what the business owners want to sell. What research lab has suggested that? I didn't find any research behind your claim.

https://scholar.google.com/scholar?hl=en&as_sdt=0,34&q=closing+the+vents+AND+de-humidification&btnG=

 

[gkreamer]

I found this: https://www.thisoldhouse.com/heating-cooling/21015190/the-crawlspace-vent-question

It references Advanced Energy in NC and www.crawlspaces.org

Doing research for my own crawlspace.

Sent from my Pixel 4 XL using Tapatalk

 

[chikitin]

ُThank you for sharing. I am also in North Carolina. It seems they are in the experiment group sealing all the way up to the wood!

None of the contractors were telling me that b/c they wanted to be able to check for termites without removing the seals.

What I am using is ventilation fan.