concrete floor attached to found. wall
Hello,
Some friends asked me to look at their cottage because they’ve been having a problem with a musty smell in their 4-year old cottage. It turns out they have some basic moisture control issues, but then I saw a few things with the structure that might be wonky, but I’m not sure. I haven’t seen this before so maybe there is some reason for it.
What I noticed was that the concrete floor of the crawl space is attached to the foundation wall. All my (limited) experience tells me and looking through the building code it is clearly indicated that there should be an expansion joint between the concrete floor and the foundation walls and footings. I have a picture and I’m going to try to put it in this post. If this is a problem are there any suggestions on how it could be fixed? I should also mention that part of their moisture problem may be that there was no moisture barrier laid under the concrete.
ok. I can’t figure out how to post a pic. clicking the “attach files” button doesn’t seem to be doing anything. I know there are instructions for this somewhere. I’ll just post this and then go find them.
back in a minute.
Live light enough to see the humour and long enough to see change.
-Ani DiFranco
Edited 12/11/2005 5:09 pm ET by luckypenny
Replies
it was internet security blocking pop-ups again.
I hope this worked. If it did here's the picture of the concrete floor running right into the foundation wall. This is at the access door.
Live light enough to see the humour and long enough to see change.
-Ani DiFranco
Don't have an answer, but here's the pic with the shadow areas opened up with gamma adjustment:
View Image
Sojourners: Christians for Justice and Peace
Thanks for adjusting that. I don't actually own a proper camera. I took that with the camera on my phone, no flash, just me trying to hold a flashlight and get the daylighting from the door. Live light enough to see the humour and long enough to see change.
-Ani DiFranco
its just a stem wall. 2+3=7
I don't think it is a standard stem wall, though that might have been the intention I guess. I just got these other pictures of the original construction. Here are the pics of the formwork for the footings and the gravel laid down.
I originally wanted to see these to see if the pictures showed if the holes from the form work ties had been sealed properly which it looks like they weren't. What do you think? Could those be filled with waterproofing material? It also looks like the waterproofing/damproofing that they have isn't heavy enough for their situation.
It's 4'-8" from the top of the finished crawl space to the top of the foundation wall.
The pictures of the footing form work also show where there is a deeper (black) hole at the location where the access door is going to be.
I also noticed it doesn't look like they poured any footing pads for the columns that were going to go in to support the beams. But you can see that they have but the beam pockets in the foundation wall.
oh and this is in the northern part of "southern" Ontario, not quite level with Ottawa, but getting up there.
Live light enough to see the humour and long enough to see change.
-Ani DiFranco
Edited 12/11/2005 5:08 pm ET by luckypenny
Okay, from what I see in the pics of the original work, it looks like a pretty decent job for a chalet. Many are built much less well than this one appears to have been.
You are quite right, however, that the floor slab and the foundation walls should not be connected. In that it's quite tricky--and not very useful--to do a monolithic pour of both the walls and the floor at the same time, the chances it was done that way are very small.
One other thing I noticed is that in this photo
View Image
it looks as if they were backfilling before waterproofing was put on the outside of the walls. This is not good, and if true, is most likely the source of the humidity problems. There is no remedy for this but to dig out the foundation, pressure wash it, let it dry, and then waterproof it properly before backfilling it again. That's not a winter job, so tell your friends they should think about that for late spring, once the ground has dried out some.
The new hot method of waterproofing foundations walls these days is to use a self-adhesive membrane, such as BlueSkin. This is expensive, and not always indicated. IMO, it might be overkill for a cottage crawl space, unless you have a serious ground water problem there. From the other construction photos, that doesn't appear to be the case as you are not sitting directly on the Canadian shield. If you don't, standard foundation tarring (2 or 3 coats) with bituminous pitch puttied over each form tie and along the footing/wall joint, should do the trick.
I can't tell, of course, if enough gravel was laid under the floor slab, or if there are thru-footing drains on the low side. If there aren't, and you have a lot of ground water running through that area in spring, you could wind up with under-slab pooling which will cause problems. The low-side footing drain is meant to allow that water to flow under the floor slab and keep on going downhill.
Footing drains can be retrofitted, and if you have to dig up the foundation anyway to waterproof it, that would be the time to do so. You need one 4-inch BNQ sched 40 pipe running through the footing on the low side for every 15 feet of footing length. Screen these pipes on the inside end with ½" wire mesh to prevent underslab gravel washout (assuming your gravel is ¾" net); then fill each pipe full with gravel, and screen again on the outside, to hold it in. That gravel inside the pipe is structural.
Dinosaur
Hold your ground!
I see in your eyes the same fear that would take the heart of me....
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
Unless it's just a shadow, it looks to me like there IS waterproofing on the wall, up to about a foot below the top.
Don
There is a very thin layer painted on. It might qualify as damproofing or it might not. But have a look at the closer up pics I posted in .10. It sure looks like they didn't fill the holes left by the form ties. A tradesman friend of theirs dug down against the foundation wall on the hill side where the driveway comes down right beside the cottage and said it looked pretty thin in that spot so he added some heavier waterproofing. He didn't have time to do the whole thing he was just trying to help them out at the worst spot. Stopped the water coming in but they still have a super high humidity problem.Live light enough to see the humour and long enough to see change.
-Ani DiFranco
Thanks very much for the feedback. I flipped through the original construction photos again and I don't see anything to indicate there are through footing drains like you described so that might very well be something they could consider adding. There might be some kind of a drain that was added later because there is a drain pipe going through the foundation wall from the outside to the inside under the deck at the front (low side/lake side) of the house. I attached the photo of that in case you're curious.
The more I look at these photos the more I think your right about the waterproofing.
One last thing about the foundation. Is the way they've done the access door alright? The OBC says the foundation wall should be insulated to 24" below grade, but because of the way the soil is graded around the access door this isn't how it works out. There is only insulation on the inside of the foundation wall to about 1' off the floor (you can see that in the photo in my first post). Live light enough to see the humour and long enough to see change.
-Ani DiFranco
The access door looks pretty standard. You pretty much have to grade them like that unless you want to go to the trouble of building a below-grade stairwell and put drainage below it and all that. Not worth it, IMO; unprotected below-grade stairwells are just trouble waiting to happen in the long run.
That set of pipes in this photo: where does it go? It doesn't make any sense to me without seeing the other end of it.
View Image
Dinosaur
Hold your ground!
I see in your eyes the same fear that would take the heart of me....
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
I accidentally erased a couple of the photos off my phone, when I was transfering them and unfortunately that was one of them. The way I remember it is the toilet drain and sink drains run along between/just below the floor joists from the other side of the cottage and connect to a main drain which is located just on the inside of the foundation wall opposite these pipes in the picture. The drain then runs down along the wall on the inside and then out again through the foundation wall below these pipes in the picture to the septic tank which is just beyond the end of the deck. The deck that these pipes in the picture are under.
Does that give you any ideas?
Some kind of venting maybe? But why so many holey pipes? And under the deck? Come to think of it I don't remember seeing a vent stack on the roof but there might have been. I wasn't looking at the plumbing.Live light enough to see the humour and long enough to see change.
-Ani DiFranco
Those orange caps on the ends of the pipes are what we call test caps; we put them on pipes that are not yet connected to whatever they are intented to service. It makes no sense for any DWV line to be sent through the foundtion wall above grade like that...nor does it make any sense for a thru-footing drain to be at that level. The whole purpose of a thru-footing drain is to drain off water from under the floor slab before it can rise high enough to weep up around the edges of the floor into the basement or crawl space itself.
It is just faintly possible they were meant to be the discharge line from a sump pump...but in that case there would have to be a sump inside the foundation perimeter, which I didn't see in the other photos.
So far, they remain a total mystery....
Dinosaur
Hold your ground!
I see in your eyes the same fear that would take the heart of me....
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
How tight has the house been built? Does it have decent venting from the kitchen and bathrooms? Do the owners like to cook a lot? Small houses have a harder time dealing with long showers and cooking moisture.
Cheers,
Don
It seems to be pretty tight, well taped vapour barriers lots of insulation, even vinyl flooring in the living/kitchen area. (Except for the crawl space which is heated and integrated with the whole house HVAC) There's a good fan in the bathroom but that's it for exhaust fans. And the HVAC has no exchange with the outdoors (ie. no HRV). So these for sure could be part of the problem too.
I'm trying to find out about HVAC systems that have specific humidity control. I know standard air conditioning also affects humidity but most systems don't have independant humidity control so people have to have a free standing dehumidifier. So far I've been put onto this company called Ecologix who (according to Jan Eakes' website) have supposedly cornered the market in Florida air conditioning because of this very feature. Then I also noticed that Lennox might have something, because they have a thermostat control where you can set humidity levels separately from temperature. Live light enough to see the humour and long enough to see change.
-Ani DiFranco
"Then I also noticed that Lennox might have something, because they have a thermostat control where you can set humidity levels separately from temperature. "I am not really knownledgable in that area, but what little I have seen they don't have true independent humidity control.But of these are for AC only.One scheme will drop the temp setpoint a couple of degress if the humidity is to high.The other cause the fan to run at a slower speed the first part of the cooling cycle.True independent humity control will be expensive and is used for meusems and the like.If this is a winter problem then an HRV would be helpful and if summer a dehumidifier, but have the AC unit check as sometimes it can be adjusted to better dehumidify.
(Except for the crawl space which is heated and integrated with the whole house HVAC)
are you saying that there are ducted supplies and returns feeding the crawlspace ?
spectacular building lot !
carpenter in transition
*chuckle* This reminds me of a much larger house that was just completed at the time. The owners were complaining of a funky smell and a few of our carpenters showed up to investigate. Turns out the bath exhaust wasn't connected to the exterior vent so all the humidity and bath funk was lingering in the attic and made it's way slowly into the living space.
All the best,
Don