Basement related question...basement forum recommendations?

[RichardNorman]

I know this isn't really a garage question per se but the door to my basement is in my garage so I am taking liberty. I apologize ahead of time!

1st, I have posted the question in a couple of basement forums but they seem to be pretty dead traffic wise. If anyone can recommend a site please let me know!

I'm from California originally so this whole basement thing is kinda new to me. I live in Maryland now.

There is a 2 inch gap between the floor and the cinder block walls around the perimeter of my basement. I have learned this is a perimeter drain used to move ground water that rises high enough toward the sump hole. I can see two drain pipes that terminate into my sump bucket so I am guessing that pipe runs around the perimeter of my floor and is sloped toward the sump. It works really well as I have only had water in the basement once and it was because the pump died.

I would like to frame off a small room in the basement so I would like to cover up that gap. I imagine it's a huge source of water vapor which is the enemy once you start finishing the basement.

I am receiving conflicting advice from two of my contractor friends. One says to go ahead and cement over the gap as the drain pipe is set and covered in crushed stone while the other says to leave it open as it allows you to more effectively drain water should I get water in the basement. He also says that ironically, it allows water to enter the basement in a more uniform fashion which reduces the likelyhood of a cracked slab from hydostatic pressure should the ground water swell after a really heavy rain.

Sooo....which is it? I see plenty of basements with out the gap in the area so I imagine it should be fine.....but then maybe it won't!

Damn it! I'm moving back to California!

 

[Mike in Ohio]

One reason you have the gap and others don't might be because you have alot of ground water close to your house. Maybe natural springs or your house sits in a low spot compared to those around you and the water runs your direction. One idea for your floor would be to lay treated 2x4s on thier side and put 3/4 plywood over them to make a subfloor to bridge the gap. It would serve 2 purposes, it would leave your drain functioning as it is supposed to and if your pump goes out again it gives 2 inches of margin before stuff gets damaged. Good luck with your basement. Mike

 

[RichardNorman]

Without sealing that open gap, that seems like a mold-tastic nightmare.

I've been looking at step by step directions on how to install an interior perimeter drain and sump pump hole online and some of them have you cover the gap between the wall and the floor and some don't.

When I look into the gap I see crushed stone. The more I read, the more I think covering the gap is an acceptable answer.

 

[Torque1st]

You might want to put something in the crack to keep the concrete you cover it with from filling in around the pipe.

 

[larry4406]

New house or old house? Many older homes did not have a perimeter drainage system installed when built. In those cases, one common technique is to cut in "trench" or trough to the floor slab as you discribed and route it to an area where the sump crock is installed. I saw this once in an older home, probably 1950-60's vintage as a retro-fit.

On new installlations, at least here in norhtern VA, you will have footer cross drains, an exterior drain tile system, and an interrior drain tile system with sump crock. The under slab area is prepped with #57 stone and a vapor barrier under the slab.

That said, if your system is working, is your trench/trough wide enough to install perforated drain tile in it, surround it with #57 stone, and then cap it with concrete? If not widen/deepen it with a concrete saw.

If our basement door leads to your garage, sounds like your house is partially buried into a bank with a partial walkout basement. With this scenario, you should be able to daylight drain your sump crock so as to not have to rely on a pump.

 

[RichardNorman]

The house is 13 years old and the basement is as it was built originally.

The gap is only about 2" wide and is filled with stone. I am pretty confident the crushed stone is surrounding a drain tile tube running around the perimeter of the floor at the footer level under the floor. The drain tile is draining into my sump hole and the tubes terminate about 12 inches below the surface of the floor.

 

[KELLHAMMER]

You might want to look into a basement waterproofing system that uses a PVC closure piece to cover the gap but still lets water past. Do a web search. Theres one called Squidgee Dry as a DIY system. Having that gap is a way to prevent any water coming onto the floor. A sorta of gutter if you will. It will prevent damage to the room. Standing water is worse than water that can be collected and drained/pumped away. Basements almost always need a dehumidifier. Mainly to prevent water intrusion, check your house for properly functioning gutters and downspouts that drain as far from the house as possible. Also, the grade around the house should be pitched away to prevent water collecting and sitting up against the foundation. Unless you have a high water table around your house usually storms are when people see water in the basement. A high water table would be relative to where the house is built, such as in a low marshy area.

 

[RichardNorman]

Thanks for the info.

To be clear, the basement is dry overall. I don't have a water problem per se and the only time I have seen water in the basement is after huge rain storms and it's only happened twice in the 10 years I have been there. Even in those situations, I don't think it would have happened at all if I had the sump pump installed that I have currently.

I will look at the PVC covers as that sounds like a really good soluation.

I don't plan to frame right up against the cinder walls because of having to clear some obstructions. I think the interior walls will be framed about 6" away from the cinder walls.

Considering that, there's no structural reason to fill that gap in. I'm just concerned about the water vapor that is likely rising from the gap from the materials below it. The slab has a 6 mil vapor barrier under it and it does not wick water through the cement. I have done the good ol' "tape plastic to the floor" trick to test for that. I have a piece of plastic that has been down for weeks with no moisture.

I suppose I could tape some plastic over a portion of that gap for a while to see how much vapor actually is coming from it.

 

[JohnK007]

If it ain't broke, don't fix it. Sounds like your perimeter drain is doing its job based on your statement that you never had water except when the pump went out. Figuring that that drain system was put in for a reason, why in the world would you want to modify or change it? Another thing to consider is the fact that you did get water when the pump went out, therefore your ground is susceptible to seepage without the system being intact. I'd be very hesitate to modify anything. A flooded basement is no fun!

I would be more inclined to use a PT sole plate and frame my finished walls 2" in from the concrete wall and leave the perimeter drain alone. I would put a poly barrier on the rough framing before rocking or paneling and perhaps cut a couple static vents in each finish wall that is against the concrete wall, six inches or so from the floor to permit air movement if mold or mildew is a concern.

Just another opinion to consider. Maybe I'm being overly cautious but once you seal that perimeter drain, you're committed.

 

[jkeyser14]

FYI, I would look at using aluminum studs and non-paper backed sheet rock for the walls. In basements where moisture could be an issue this will help prevent mold.

I also live in MD and plan on doing this when I finish my basement.

 

[Kevin54]

Back in the 60's they used to do basements this way in different areas. One housing development built back then has every single basement done that way. And it is for the reason stated....any moisture that would make it through the wall would go into that trough and to the sump pump. A few waterproofing places have a perimeter drain that you could put over that area and kind of looks like a baseboard. I have seen a few of the basements remodeled and they put down treated lumber sleepers over that area, visqueen on the walls, built a 2x wall over the concrete walls and finished it off as any room with no problems. How you do yours would all be dependent on the moisture in your basement. But if it's any assurance, I'd rather have a floor built like yours than concrete up against the block wall and have water running across the floor. Do a search for basement perimeter drains and you should find what I am talking about as far as the one that fastens on like a baseboard. But what you have to do is drill a hole into the core of the block to let any water out that may build up from pressure.

 

[RichardNorman]

If it ain't broke, don't fix it. Sounds like your perimeter drain is doing its job based on your statement that you never had water except when the pump went out. Figuring that that drain system was put in for a reason, why in the world would you want to modify or change it? Another thing to consider is the fact that you did get water when the pump went out, therefore your ground is susceptible to seepage without the system being intact. I'd be very hesitate to modify anything. A flooded basement is no fun!

I would be more inclined to use a PT sole plate and frame my finished walls 2" in from the concrete wall and leave the perimeter drain alone. I would put a poly barrier on the rough framing before rocking or paneling and perhaps cut a couple static vents in each finish wall that is against the concrete wall, six inches or so from the floor to permit air movement if mold or mildew is a concern.

Just another opinion to consider. Maybe I'm being overly cautious but once you seal that perimeter drain, you're committed.

That's my concern as well but to be honest, I'm not sure what function the gap between the wall and the floor serves. The actual functional part of the drain is under the floor next to the footer where the drain tile runs toward the sump.

I sealed up the walls with a portland cement based stucko water proofing product a while back. The walls are dry now but before, moisture would wick through the cinder blocks after heavy rains. It was never a leak per se but just wet blocks. From what I have been reading, part of the function of this gap may be to collect any water that may run down the face of the brick.

As I said, I am placing my walls about 6" away from the cinder walls so the gap is not a structural issue. I wasn't even concerned about the gap until I moved a particle board work bench top that had been leaning against the wall for a couple months over the gap of course. I found a good bit of mold or mildew on the side that was toward the wall and directly over the gap. Until that moment, I really hadn't though much about the water vapor that surely is emitted from that gap.

 

[dotell]

insulate and plastic on those back walls

 

[KELLHAMMER]

I have never liked the idea of using plastic in the wall. There are varying opinions on this. Placing the stud wall out further is fine. But, it should never be closer that 2 inches from the block walls unless it's Pressure treated wood. Plastic doesn't allow the wal to breathe. So high levels of humidity can allow moisture to get trapped. Like I said, every basement probably needs a dehumidifier. Really just to control the high levels of humidity that can occur in a basement. Trapping the moisture only makes it harder for it to dry out naturally or by dehumidification.

 

[RichardNorman]

I have never liked the idea of using plastic in the wall. There are varying opinions on this. Placing the stud wall out further is fine. But, it should never be closer that 2 inches from the block walls unless it's Pressure treated wood. Plastic doesn't allow the wal to breathe. So high levels of humidity can allow moisture to get trapped. Like I said, every basement probably needs a dehumidifier. Really just to control the high levels of humidity that can occur in a basement. Trapping the moisture only makes it harder for it to dry out naturally or by dehumidification.

Why do you recommend a gap of no more than 2" between the framing and the block walls? Is it because anything larger would produce a volume of unconditioned air on the exterior of the walls?

I also don't like the idea of plastic. The more I read about insulation and mold control the more I understand the plastic is a bad idea. The Buildingscience.com site provides very compelling studies pointing to that fact.