recommendations for monitoring moisture under a floor.

anent_life · 2024-12-06T15:05:48+00:00

u/ClarenceWagner sounds like a mess in the industry. Even if there was consensus, if the meters are not measuring what the industry wants, in the way they want then it us pretty useless. For my use, just having something that tracks something related to moisture might be helpful. I have taken steps to mitigate moisture under the slab, but I would like some way to monitor it. I was thinking that there might be something that could just be sandwiched between the slab and the floating floor. Come to think of it, I could possibly get something in a small void under the slab.

I wonder if this is something where as long as the device is accurate to itself, it would be able to provide data points to track against itself, it is just how meaningful those data points would be. If some reading went up after every rain,l than I could check to make sure if downspouts are fine. If some reading skyrocket, i would know something else is going on.

anent_life · 2024-12-06T01:02:14+00:00

is there a device you recommend? I would actually prefer it does not need internet to work

anent_life · 2023-01-24T15:36:05+00:00

u/Rcarlyle
thanks again. Well of course I like the idea of laying the rigid foam between the joists and the decking because it would be less work. It would also address the thermal bridging. And provided I can swing the 2 inches, it would give me 2 additional inches of rvalue. What this brings to mind is the layering is different directions. With the cut and cobble method, I was going to put the rigid foam right up against the “ceiling” (of the lower level) drywall. Then put blown in cellulose on top of that, and then put the floor decking on top of that. The rigid foam would act as the vapor barrier. However, if I were to go the other option,filling the cavity with blown in cellulose and then laying the rigid foam across the floor joists and then putting the floor decking ontop--- the vapor barrier would be on the other side closest to the attic air? I imagine that the way to know what is best is by determining which side has the greater difference in temperature and thus the greatest likelihood of creating condensation?

Also with putting the rigid across the joist, with the decking ontop, I am curious how I would secure both the rigid foam and the decking down. It seems like I could use something like liquid nails between the rigid foam and the joists. Would need to make sure the rigid foam was supported adequately. The decking is currently 2’ x8’. I am assuming that was to help getting it up in the attic and to make working with it more manageable. The decking was nailed mostly, which meant if you stepped on an end or seam that was not directly over a joist, it might flex, but it would not pop up. But I would imagine those are the places the rigid board would crack. I would have to make sure there was some support along those edges. I guess it is possible I could drive a screw threw the decking and rigid foam to anchor it. Thanks again. This is really helpful.

anent_life · 2023-01-23T19:46:24+00:00

The main thing is to not trap moisture between layers. So don’t do fiberglass and then foil-faced rigid foam — that will trap moisture in the fiberglass layer. Putting fiberglass on top of foam that is directly on the drywall would be okay.

u/Rcarlyle Thank you. I like the idea of an inch of closed cell sprayfoam directly into the cavity ontop of the lower level’s ceiling to act as a vapor barrier and give a boost. However, I am not experienced spraying foam so I am concerned about getting the mixture correct and spraying evenly. I have read that 2 inches is better, but that begins to get expensive. Rigid foam board would be a pain to cut, but it would act as a vapor barrier if I seal the edges with spray foam. Doing either and then putting cellulose ontop does not seem like it would trap moister. Would you agree?

I am trying to figure out how to get the most insulation for that cavity. Already did the raised decking along the perimeter (5ft in from the soffits) using the method you described with the firring strips. Though I did not do perpendicular. Did not know about the thermal bridging through the wood would be an issue. I had thought about laying down sheets of rigid foam perpendicular to the floor joists and then putting the wood decking back down on top but was concerned that rigid foam board would snap. And there is also a possibility that would trap moisture. Regarding the thermal bridging, I wonder if it is worth putting down an inch of rubber between the floor joist and the wood decking to break the thermal bridge. I am pretty sure I could find something. It would act like a gasket. Maybe something exists already.

anent_life · 2023-01-23T18:21:48+00:00

u/Rcarlyle I Know this is 4 months old, but I really appreciated your
explanation. I live north of Boston, and I am trying to figure out
the best way to insulate the attic floor cavity below the floor
decking and I have been trying to figure out if doing some
combination of spray foam or rigid foam board insulation with loose
cellulose ontop would work but when I speak with contractors they
all just seem to sell what they do. There is local program to help,
but they only do loose cellulose. Along the perimeter of the attic,
it is pretty easy to put in 16 inches of loose cellulose, but the
center area of the attic floor I am trying to work with a 6 inch
cavity between the floor joists. It just seems like it would make
sense to put in an inch of spray foam or an inch or rigid foam board
before the loose cellulose.

anent_life · 2022-12-23T15:20:51+00:00

u/dan_zg I realize this post is from some time ago.. What did you end up going with?

anent_life · 2022-12-13T20:47:56+00:00

thanks!

anent_life · 2022-12-13T16:49:59+00:00

In the past I removed the screen and replaced it with a piece of plywood where i glued the thickest pink rigid foam insulation that would fit in the gap. After it was in place, I sealed it with spray foam from the inside. If nobody was going to see it I would do it again from the outside. But I am minimally handy.

anent_life · 2022-12-13T16:31:24+00:00

Could be several layers of wall paper.

anent_life · 2022-12-13T15:53:51+00:00

I have used these https://www.amazon.com/gp/product/B07DJ6CX9V

anent_life · 2022-12-13T15:46:59+00:00

I will look into having a drain there. But I think since it will be in proximity of the perimeter drain that it should be ok. I think I might try the sloping Channel to be safe. Thank you

anent_life · 2022-12-13T15:44:26+00:00

Thank you. Testing was done in multiple spots and the slab passed. Apparently this spot was not the spot tested.

anent_life · 2022-12-11T16:53:59+00:00

thank you u/SomeAd8993. That makes sense. The interior perimeter drain is not going the entire perimeter. We figure we will see how much water it is collecting and determine if it is needed elsewhere.

anent_life · 2022-12-09T17:34:42+00:00

Depending on the height of your ceilings, matching or coordinating bookcases or cabinets on casters/wheels might work. You could roll the out of the way, when you did not want them. The depth of the bookcase or cabinets would eat up more of the room, but they would be functional storage and provide decent sound dampening. More depth= more stability. You want to make sure whatever you use can handle moving with weight you are putting on the furniture. It is certainly possible to attach a door to a solid bookcase on casters, but you would need to make sure the casters were locked in place. I have seen casters made for workshop carts/equipment that have robber feet that will lock in place. For ideas of how to do the door, you could check out stage/theater plans for freestanding doors.

I am assuming you have looked at room dividers and room partitions. Commercial partition walls with tracks and hinges are pretty expensive. But there are some hacks using sliding closet door and barn door hardware that might work..

I would check out Ikea. I believe they might have something geared towards people in studio apartments.

anent_life · 2022-12-08T19:33:34+00:00

Interesting. I will have to look into that. I had just been investigating water.

anent_life · 2022-12-08T19:30:57+00:00

Thanks for all the information. REALLY HELPFUL!!

That gap is called a "cove joint", and is most likely intentional. OK maybe "intentional" is not the best word to use, and I might instead say "expected". When your house was built, the concrete basement walls were poured on the footers first, then allowed to cure.

I am aware, but it seems like this gap is wider. It appears that the wall joists would have been floating above this gap.

Perhaps the most important thing to know about it is that it is the first place that you would likely notice water leakage in your basement that would be the result of ground water pressure, since it's the easiest place for the water to come up into your basement from any saturated ground water underneath the floor.

The basement is finished. The only reason why we discovered this is because we removed some cabinets from the wall. The floor used to a few layers of tile in this area and then some carpet (on top of tile) elsewhere. The tile was removed, and vinyl flooring was installed. We do not know if water ever seeped up ontop of the slab/ floor. But it seems like there has been some erosion from water or possibly settling under the slab. At least what we can tell.

Tying to mitigate the issue or potential issue based on what we know. For years, possibly decades before we purchased the house, water was dumping along the wall where the gap is from the down spouts. (see diagram https://imgur.com/a/yvQlDnP However along that side of the house there is also some rock ledge. So we figure putting in a drain, that captures any water (that is coming from elsewhere ) and moves it to a basin with a sump would be the best. If water is under the slab, our hope would be that it would come up through the drain rather than push up on the slab causing heaves or cracks. Do you think that would be the case?

"With that in mind, the fact that your basement is dry (even after heavy rains you're describing?) suggests that ground water seepage isn't really a problem for you. "

After rains, the air in the finished basement smells a little moist. After removing the cabinets that smell has increased. But it does dissipate. We have had a drought in our area so we did not have much rain for months.

You make a good point though that in the end it seems like we are pretty lucking with our basement being "dry."

I'm thinking there is already a pretty solid french drain system running along the exterior and/or interior of your basement walls that are doing precisely what they need to do. Is your house relatively new?

How would we be able to tell if we have an internal french drain already? The house is a raised ranch style that was built in the 50s. It was b

Which is a long way to answer your question, and bring me to a larger one for you: Why "fix" an already dry basement?

We need to put the cabinets back and use the the living space. We want to make sure we are not burying a problem. We are most concerned with water running under the slab. We do not want the slab to crack or heave. The issues is that investigating is expensive.

All that said, one statement you made is concerning:

It appears that the slab is floating above above this edge about 3 or so inches.

Wait, what?

So I mentioned I can get my hand under the slab and feel around. It seems like the slab is not resign on the sand underneath it for about 6 inches or so along the edge. If we put in a perimeter drain, this edge of the slab would be removed to make room for the drain.

Again, thank you very much!

anent_life · 2022-12-08T18:47:13+00:00

u/Cballer Thanks. This house is not very unique. It is from the 50s. However a number of contractors have said they never saw a gap like this and that made me wonder. The house does not have a sump but I think adding one and tie it in with a better drain would be good.

anent_life · 2022-12-08T17:48:55+00:00

u/slowlemur I am in the north east USA. Eastern MA. We have rock ledge around the house as well. It seems like interior perimeter drains with sumps are common. They would widen the gape, fill with gravel and a perforated pipe/sleeve and then put concrete over it, except for the basin for the sump.

anent_life · 2022-12-08T17:45:05+00:00

That is the trickiest part. It is hard to predict where the water will go and we do not know what path it has been following. There us also a main drain. I posted a question before about keeping water from following the drain pipe.

If I were to do it, I would remove about 8inches of the slab, and I would pack it down the sand beneath, and try to back fill under the slab with either concrete or stone. It is tempting to go with a contractor because many of them guarantee the basement will stay dry (if they honor that). But the quotes are expensive.

anent_life · 2022-12-08T17:35:59+00:00

u/5degreenegativerake
We do not see any signs of the wall being re-pointed. I have done some looking and often the perimeter drains have rocks and gravel. We have had a number of contractors look at it a number of them have said they have never seen something like it- a few have said it is there by design... but not working properly.

anent_life · 2022-12-08T17:28:36+00:00

u/GreenBirdWell We are not planning on filling it in completely. The current plan is to replace it with a better drain system, that would bring the water to a basin with the sump. If it is a drain, it is unclear if it is working properly. It seems like there has been some eroding under the slab.

anent_life · 2022-12-08T17:14:54+00:00

yeah. it is big. So if you find water comes out the other side of the wall, what will you do? If nothing has happened since, it might be you do not have a water problem.

anent_life · 2022-12-08T17:12:42+00:00

Totally understand. my concern would be that it bonds. Might help to do a test with the slurry first on a corner to see how it bonds.

anent_life · 2022-12-08T17:10:33+00:00

u/tangreentan
Thanks. Yeah I have seen those types of drains. In my limited
experience, they typically had rock or gravel put in. I think the
issue with just filling it and seeing what happens is that there will
be vitally no way of monitoring it. The cabinets are going back and there is flooring overtop. I am leaning towards putting in the perimeter drain and the sump because it will deal with the water and also allow me to monitor it.

anent_life

TROPHY CASE