Digging a basement out of a crawl space. [Archive] - Suzuki SV650 Forum: SV650, SV1000, Gladius Forums

: Digging a basement out of a crawl space.


Orange_4x4
09-11-2010, 12:12 PM
Our house has a basement under 2/3 of it, and a crawlspace under the other 1/3. The basement has a 8 foot ceiling, and the crawlspace has about 4 foot of headroom. I did some investigative digging, and it appears that the crawlspace has block walls that extend down as far as the rest of the basement, but for whatever reason the dirt was never removed to make it a basement.

At first I planned to finish the crawl with a vapor barrier, as it does not have one. But now I am considering how much extra effort it would be to remove the dirt and put in some drains & a sump and pour a concrete floor and make it a basement. It is roughly 600 sq. ft and 4 foot of dirt to dig out. The dirt would have to either be hauled up the stairs and outside, or some sort of hole would need to be made to gain access to the outside, as currently there are no holes to the outside in the crawl or the basement. I could leave the dirt in a pile outside until I decide what to do with it, probably use it to level other parts of the yard.

This sounds like a LOT of digging and carrying small buckets of dirt outside to me. The soil is pretty soft and sandy, and dry. But there are a lot of rocks in the soil too. I am sure it could technically be done, but I am having a hard time estimating the amount of man hours a digging project like this would take, and is there an easier way to do it than all by hand? I really dont think a walkout is an option, so getting a bobcat or similar type machine in there is not likely an option.

Any thoughts? Would you try to dig it out, or just seal it up and leave it a crawl?

Richy_T
09-11-2010, 12:23 PM
The walls in the crawlspace may go down as far as the basement part but I bet the basement walls go down even further.

I've thought about the same thing but I do have access to the outside. If you want to do this, I would think you would want to think about making exterior access.

Orange_4x4
09-11-2010, 12:53 PM
The walls in the crawlspace may go down as far as the basement part but I bet the basement walls go down even further.

I've thought about the same thing but I do have access to the outside. If you want to do this, I would think you would want to think about making exterior access.

The block sits on a footing. The footing is the same depth for the basement as the crawl. they really are built the same, just the crawl still has dirt in it. It sounds odd, and it is odd, but that is how it is. If it needed a new footing and deeper walls, I would not even consider it, but since the foundation is already correct, I think it could be doable.

Outside access would be makeshift at best, the grading is not really conducive to it, the best I could do would be a hole out the side of the basement and then going up stairs outside to grade level. With the extra time to do all that outside, I am doubtfull that the time savings on the inside would even be worth it, since it still would not allow a bobcat access to the basement.

Richy_T
09-11-2010, 12:59 PM
Dig a hole in the basement to put the dirt in :)

Orange_4x4
09-11-2010, 01:09 PM
Dig a hole in the basement to put the dirt in :)

:sbmfacepalm:

RichDesmond
09-11-2010, 01:10 PM
I don't have any helpful details worth mentioning, but my ex father-in-law did this. Except there was no basement to start with, he did it from scratch. Apparently he started by digging a shaft next to the house and then tunneling under. Dug it all out by hand, placing supports as needed. got the dirt out by the bucketful with a pulley system. Had a floor poured, but other than that did it all by hand, by himself. Then bought a bunch of woodworking equipment and proceeded to build most of the furniture in the house. Really nice stuff, it all looked like it came out of a high end furniture store.

This may seem a little excessive, even crazy, but if you met my ex mother-in-law the reason for it would be crystal clear. ;D

Richy_T
09-11-2010, 02:48 PM
I think with those kind of circumstances and hand-digging, I'd be looking at some kind of conveyor for removing the dirt.

Richy_T
09-11-2010, 03:01 PM
May be relevant.

http://diggingitout.blogspot.com/2005/04/day-2-foundation-wall-has-been-cut-out.html

bighammer
09-11-2010, 03:09 PM
I guess I'm curious how you know that the depth of the footing is the same all around. You're sure it doesn't step up someplace? Is there a trench around the perimeter of the crawl?

Orange_4x4
09-11-2010, 03:21 PM
I guess I'm curious how you know that the depth of the footing is the same all around. You're sure it doesn't step up someplace? Is there a trench around the perimeter of the crawl?

It is a square, the 1st wall is common to the existing basement, although it is also useless, since it is not load bearing, it is really just a block partition between the crawl and basement. That one is obviously the same depth as the rest of the basement. Out of the other 3 walls, 1 is a continuation of the back side of the house, common with the existing basement wall. That is the one that was checked. The 2nd wall is 90 degrees and is the far outside wall of the side of the house, it is not a common wall to the other basement walls. The 3rd wall is also shared with the garage and is also a common wall with the front side of the house. I suppose I could also dig 2 more holes and check the other 2 walls to be sure.

The crawl almost looks like an addition at first glance the way it appears constructed, it even has black waterproof coating on the crawlspace side of the shared basement wall, but the central steel support beam goes clear from one side of the basement all the way through to the other end of the crawl, in one continuous run. And the way the joists are framed you can tell that it was all done at the same time. So either it was a really weird foundation design, or a last minute change of plans on the build size.

alpineski26
09-11-2010, 08:17 PM
I say go for it. How do you move a mountain, one shovel full at a time. Keep at it and it will get done.

Edit - some rough numbers: 2400 cubic feet of sand to move.

1 five gallon bucket is 2/3 of a cubic foot. guess it takes 3 shovels of sand to equal a cubic foot. so you are looking at 6200 shovel fulls.

if you shovel at a rate of 10 per minute it will take you 620 minutes just to shovel...say triple that time to lug up the stairs so 2000 minutes of labor with beer breaks.

2000/60 = 33hours. so basically spend an hour a day it will take a month.

Orange_4x4
09-11-2010, 08:54 PM
May be relevant.

http://diggingitout.blogspot.com/2005/04/day-2-foundation-wall-has-been-cut-out.html

I finally got to read through the blog. He was lucky enough to have the grading to do a walk out, which allowed a bobcat, which is a major time saver for sure. But he also had a TON of posts to remove. I have 1 post in the middle of the whole area, and it dont even look like a big deal to remove it temporarily, since it is a steel beam. I would need to relocate the bladder tank, probably put it over on the existing basement side with the water softener and filter, etc. And there is a water feed that would need to be re-plumbed that feeds water to the back garage. Overall it would be pretty simple. All the HVAC could stay where it is.

One thing that troubled me on his build was all of his moisture leak problems. I predict mold in his future even with the spray waterproofing.

Orange_4x4
09-11-2010, 08:56 PM
I say go for it. How do you move a mountain, one shovel full at a time. Keep at it and it will get done.

Edit - some rough numbers: 2400 cubic feet of sand to move.

1 five gallon bucket is 2/3 of a cubic foot. guess it takes 3 shovels of sand to equal a cubic foot. so you are looking at 6200 shovel fulls.

if you shovel at a rate of 10 per minute it will take you 620 minutes just to shovel...say triple that time to lug up the stairs so 2000 minutes of labor with beer breaks.

2000/60 = 33hours. so basically spend an hour a day it will take a month.

Or, hire some Mexicans at $10 an hour and it will be done in $400 (rounding up). ;D

AlexS
09-12-2010, 12:33 AM
I say go for it. How do you move a mountain, one shovel full at a time. Keep at it and it will get done.

Edit - some rough numbers: 2400 cubic feet of sand to move.

1 five gallon bucket is 2/3 of a cubic foot. guess it takes 3 shovels of sand to equal a cubic foot. so you are looking at 6200 shovel fulls.

if you shovel at a rate of 10 per minute it will take you 620 minutes just to shovel...say triple that time to lug up the stairs so 2000 minutes of labor with beer breaks.

2000/60 = 33hours. so basically spend an hour a day it will take a month.

That's quite amazing, I would have thought it would be a much bigger task. But that is all assuming that you are working at full rate the whole time, and I imagine it is quite ball breaking work, so you would be at half speed much of the time, maybe less as 10 shovels per minute seems high.

xbolloxx
09-12-2010, 12:37 AM
When my father opened his first restaurant, It didn't have a basement, just a crawlspace, he was under there every day for 6 months digging dirt out into buckets and sending it up with his dishwashers and what not. Now the restaurant has a full basement with a walk in deep freezer.


Where there is Will there is a way. 600 sq feet is a lot of extra space.

Orange_4x4
09-12-2010, 12:41 AM
That's quite amazing, I would have thought it would be a much bigger task. But that is all assuming that you are working at full rate the whole time, and I imagine it is quite ball breaking work, so you would be at half speed much of the time, maybe less as 10 shovels per minute seems high.

It would actually be significantly longer, as the 3 times longer to take the bucket outside is completely unrealistic for my layout. More realistically it would look like this:

Lets say I could fill 1 bucket per minute. That would be a reasonable pace to maintain, even at 1/2 speed. That is 3600 buckets to load. That is 60 hours of straight shoveling without carrying anything outside.

Now from where I would shovel to a location to dump the bucket outside, would be about a 4 minute round trip up and down a flight of stairs and over some hilly terrain in the yard. Thats 240 hours of transporting buckets.

So thats 300 hours without breaks by my estimate. This is of course assuming the bucket really is 2/3 cubic foot as stated. I did not bother to verify that.

Orange_4x4
09-12-2010, 12:43 AM
600 sq feet is a lot of extra space.

Indeed. Some might even say its enough to make a game room, or a home theater. ;D

AlexS
09-12-2010, 12:45 AM
Orange, I can loan you 5 kids for bucket carrying, they could create a chain, and you could keep them for a month or longer. Just wear ear plugs and you will be fine! ;)

ShortCourse
09-12-2010, 01:50 AM
May be relevant.

http://diggingitout.blogspot.com/2005/04/day-2-foundation-wall-has-been-cut-out.html

God ******. I hate when someone posts something totally random like this, and then i end up reading through it... before i know it, its been an hour and a half.

Orange_4x4
09-12-2010, 01:55 AM
God ******. I hate when someone posts something totally random like this, and then i end up reading through it... before i know it, its been an hour and a half.

You mean like this?

http://www.garagejournal.com/forum/showthread.php?t=51567

Richy_T
09-12-2010, 03:47 AM
I finally got to read through the blog. He was lucky enough to have the grading to do a walk out, which allowed a bobcat, which is a major time saver for sure. But he also had a TON of posts to remove. I have 1 post in the middle of the whole area, and it dont even look like a big deal to remove it temporarily, since it is a steel beam. I would need to relocate the bladder tank, probably put it over on the existing basement side with the water softener and filter, etc. And there is a water feed that would need to be re-plumbed that feeds water to the back garage. Overall it would be pretty simple. All the HVAC could stay where it is.

One thing that troubled me on his build was all of his moisture leak problems. I predict mold in his future even with the spray waterproofing.

Sometimes what it takes is to see that someone else did it,

I'm sure that with a Bobcat, you could get some slopeage in a couple of hours. You still need to tear out some wall of course. All in all, it's a minor part of the job though. If you want it, go for it. I still have some windows it's taken me a year to get to...

Richy_T
09-12-2010, 03:56 AM
God ******. I hate when someone posts something totally random like this, and then i end up reading through it... before i know it, its been an hour and a half.

Don't ever go to TVTropes. I just lost a week.

MagpieTear
09-12-2010, 06:44 AM
...

Orange_4x4
09-12-2010, 10:12 AM
Sometimes what it takes is to see that someone else did it,

I'm sure that with a Bobcat, you could get some slopeage in a couple of hours. You still need to tear out some wall of course. All in all, it's a minor part of the job though. If you want it, go for it. I still have some windows it's taken me a year to get to...

Part of the issue is that there are only two possible walls that a walkout could even be attempted, the back of the house and the far side. Out of those two the back has the problem of getting too close to the septic field, and also a lot of trees and landscaping in the way that would need to be re-done. Also the yard goes uphill the further back you get, so a walkout would make lead to the problem of the natural grade working against you. So I would shy away from that for fear of damaging the septic and the expense of redoing landscaping. The side is more likely, but its only about 15 feet from the house to woods. 15 feet is not enough to make a 8 foot deep hole and grade it out, it would just be a hole. So I would need to clear a LOT of trees to push it back further to make it a smoother transition. That would be a lot of extra work with all the trees. Also there is a gas line on that side of the hose that would need to be relocated. For whatever crazy reason they brought the gas meter back to the middle of the wall, instead of the front corner closer to the road. Now that line is in the way of where any access to the outside would be. Also it would be ideal to take the walkout to the front of the house, for the same grade issue mentioned before of going uphill to the back. But taking it to the front leaves the problem of still getting the gas line and meter back in. And then you pass by the garage foundation, which is likely not as deep as the basement, so then I cant to all the way level and would have to go back up hill again. See why I say its not really setup for a walkout? I think I could maybe get away with 2 windows, thats about it.

Richy_T
09-12-2010, 11:17 AM
Gotcha. Maybe back to the conveyor then...

aschendel
09-13-2010, 09:27 AM
i'd do it, sounds like a great / rewarding project.

a.s.

p.s. i think we should all make a pact to dig these out before building our houses next time, then the future owners won't be stuck with all of this crazy work.

J-Dog
09-13-2010, 09:35 AM
Make a game out of it. Pretend you're tunneling out of prison. :p

Verbal Kint
09-13-2010, 10:10 AM
Make a game out of it. Pretend you're tunneling out of prison. :p

Fill your pockets with dirt, and casually stroll around the yard and scatter the dirt via you pant legs.

He could be done in a mere twenty years. ;D

Verbal Kint
09-13-2010, 10:17 AM
Or, hire some Mexicans at $10 an hour and it will be done in $400 (rounding up). ;D

This does seem to be the quickest way to complete this task.

Although, they may not be pleased if you pick them up in San Diego, for some digging in Michigan.

http://www.weareca.org/images/period07/d-salvadorians/salvadoran-migrant-workers.jpg

Orange_4x4
09-29-2010, 09:23 PM
I guess I'm curious how you know that the depth of the footing is the same all around. You're sure it doesn't step up someplace? Is there a trench around the perimeter of the crawl?

So I finally got around to doing some more investigative digging tonight, and you were right. There is a step in the footing. I went right to the far outside wall and hit footing almost immediately. So there goes my plans for an extended basement.

Now I guess I will just have to turn this thread into my adventures installing a vapor barrier in my crawl space. More updates to come. :D

bighammer
09-29-2010, 10:42 PM
So I finally got around to doing some more investigative digging tonight, and you were right. There is a step in the footing. I went right to the far outside wall and hit footing almost immediately. So there goes my plans for an extended basement.

Now I guess I will just have to turn this thread into my adventures installing a vapor barrier in my crawl space. More updates to come. :D

Not necessarily. If the wall is bearing the floor and roof weight, it's a bit more complicated. If it's parallel to the floor joists and trusses, you might be able to knock out a big hole and remove dirt that way. You'd have to over-dig enough to put in a new footing and wall.

Orange_4x4
09-29-2010, 11:07 PM
Not necessarily. If the wall is bearing the floor and roof weight, it's a bit more complicated. If it's parallel to the floor joists and trusses, you might be able to knock out a big hole and remove dirt that way. You'd have to over-dig enough to put in a new footing and wall.

You just want me to go dig some more dont you? :D

Once I hit the footing on the outside wall I did not dig the 3rd wall that is shared with the garage. However the outside wall is parallel to the joists, so now I will have to see if the footing under the garage is all the way down or not. That wall supports the joists.

bighammer
09-29-2010, 11:11 PM
I will have to see if the footing under the garage is all the way down or not.

It's not.


But hey, you could re-do all of that side and have a door and stairway up into the garage.


Get digging, winter's coming.

Richy_T
09-29-2010, 11:12 PM
Not necessarily. If you settle for a smaller basement, you could "step" the wall in. I'm considering digging some of my basement down by about a foot and will step in a foot from the wall so that I don't disturb the footings. Similar principal but different depths.

Orange_4x4
09-29-2010, 11:15 PM
It's not.


But hey, you could re-do all of that side and have a door and stairway up into the garage.


Get digging, winter's coming.

I think I will save that project for my 10-15 year plan. For now then it sounds like vapor barrier is the ticket. I got to get cracking on it before too much longer, we have high radon levels because of all the exposed crawl space dirt. I have money that needs to be spent on bathroom remodels and painting the whole house before I do fun stuff like foundation rebuilding.

Orange_4x4
09-29-2010, 11:19 PM
Not necessarily. If you settle for a smaller basement, you could "step" the wall in. I'm considering digging some of my basement down by about a foot and will step in a foot from the wall so that I don't disturb the footings. Similar principal but different depths.

I think if I ever did dig it out, it would be like Pete is saying and dig it all out and rebuild the foundation to match. But that is more that I wanted to get in to right now with other priorities to tackle first.

Richy_T
09-29-2010, 11:33 PM
Yeah, it's a fairly big job of somewhat dubious value. I'd consider extending the house above ground first.

Michelle
09-30-2010, 04:54 AM
So I finally got around to doing some more investigative digging tonight, and you were right. There is a step in the footing. I went right to the far outside wall and hit footing almost immediately. So there goes my plans for an extended basement.

Now I guess I will just have to turn this thread into my adventures installing a vapor barrier in my crawl space. More updates to come. :D

At least you have a frost wall...1/2 mine is on post with a below grade crawl space. There is about a 10x9 area where the ground is so high to the floor joists that I cannot crawl there...So I'm getting a hand trowel, plastic toboggan, and a rope, and excavating out.
I also have to put down vapor barrier, and try to dry up the space...I can smell the dampness in the house on that side. I have already put in some clear stone,layed out tarps (to crawl on, and to protect the vapor barrier from rips) and it has helped a lot.

Orange_4x4
09-30-2010, 10:54 AM
At least you have a frost wall...1/2 mine is on post with a below grade crawl space. There is about a 10x9 area where the ground is so high to the floor joists that I cannot crawl there...So I'm getting a hand trowel, plastic toboggan, and a rope, and excavating out.
I also have to put down vapor barrier, and try to dry up the space...I can smell the dampness in the house on that side. I have already put in some clear stone,layed out tarps (to crawl on, and to protect the vapor barrier from rips) and it has helped a lot.

Luckily, I do have good headroom all around the whole space, average as I mentioned before is around 4 feet. There is a heat duct so it hangs about a foot lower, but still no biggie.

Currently there is fiberglass batt insulation installed on the 3 outside walls of the crawlspace, so I have to remove all of them. I will try to be gentle so I can re-use them, they are in good shape, but in the way of the vapor barrier install. I also have to rake the ground level and remove all of the rocks at the surface in preperation for the barrier. There are a LOT of rocks, and with all of the digging it is not even close to level.

Luckily though the ground is VERY dry, all sand, and is very easy to work with. We had some heavy rains the other day and even my 4 foot deep hole to the one footing did not get any water in it. It is a very dry space thankfully, so I am not going to worry about putting a sump pit or anything in it. I will be putting in a gas perimiter venting system for either a passive venting, or active subslab depressurization system hookup for the radon. Then I was thinking about putting down a layer of roofing felt to act as a protective layer for the vapor barrier. Then the vapor barrier. This (http://buyplasticnow.com/vaporblockplus20.aspx) is what I am going to use for the whole space.

I also have to relocate the well bladder tank, as it sits in the corner of the crawl. And I have to seal the cracks in the basement floor, put a seal on the existing sump pit in the basement, seal the floor drains, etc. etc. and test for radon again.

GeorgeZboy
09-30-2010, 11:29 AM
I'm real late to your party, but I would have cautioned against excavation anyway. CMU walls that are back-filled would generally not be built soundly enough to retain the soil load on just one side and could have collapsed inward. If you ever excavate, you may need to add reinforcing pilasters at the very least.

My sister and brother-in-law hand dug a basement under their house (MD coastal clay!) to replace the shallow foundation that was there. It involved lots of evenings with a small shovel and buckets, stepped footings, and in the end a party with lots of friends to get the last big chunk done with bucket brigade efficiency. It CAN be done with enough patience!

Orange_4x4
10-27-2010, 05:04 PM
I got almost all the supplies I need for the vapor barrier install now, including the vapor barrier itself, the air gas venting mat for the perimiter venting under the vapor barrier and all of its related accessories, dozens of tubes of sonolast NP-1, hundreds and hundreds of feet of 2 sided butyl rubber sealant tape, etc. etc.

Only things left to get now are a sealed sump pump lid and the accessries neccessary for that, and a new bladder tank for the well (old one is way undersized to me).

I am setting a project goal to get the vapor barrier installed by November 14th. Also included in that timeframe will be the new bladder tank and related plumbing, and sealing of the sump pit, and sealing of the cracks in the basement floor.

I will update with my progress and pictures as I go. I have never done a vaper barrier / radon remediation project before, so much of this will be learning as I go, hence the (hopefully) realistic timeline. :D

BeerThirty
10-28-2010, 10:42 AM
Wait, is that--

--2 weeks? ;D

Orange_4x4
10-28-2010, 10:49 AM
Wait, is that--

--2 weeks? ;D

2 and a half. Experience tells me 2 weeks is not enough. ;D

LSCYCLING
10-28-2010, 11:16 AM
I was late and just read the whole dang thread. I was hoping you would dig!! I wanted to do this at our old house but the wife didn't see what I saw, so of course no go.

RandyO
10-28-2010, 11:27 AM
my dad just had a basement excavated under his house, the structure is a 175 year old (big school district) 2 room school house that was just supported above the ground on fieldstone pilings, no footings, no frost wall

my brother ( is a general contractor) did the work, excavation was done with a small Bobcat skid steer, he placed a CO detector under the house, when the alarm went off, he'd stop, take a break, let the air circulate under the house then start again, it was kinda complicated, he had to put house moving timbers under the house to support it till he got lally collums in place

LSCYCLING
10-28-2010, 11:37 AM
I should have taken a picture of it. But on one of the islands here there's an old house that really doesn't look worth a d*mn to not tear down a rebuild. Instead they lifted it probably about 10 to 15 feet, whatever height for a decent garage. Built the garage and then they're going to lower it back onto the new footing. Has huge steel beams for the lifting supports, it really doesn't look like it was worth it for that house but I'm guessing it was to get around permitting. We're remodeling not building a new house!!

RandyO
10-28-2010, 11:42 AM
, it really doesn't look like it was worth it for that house but I'm guessing it was to get around permitting. We're remodeling not building a new house!!

happens a lot around here on existing non conforming lots, especially waterfront. I have to send my field crews out to locate the existing structure, than relocate it after complete to make sure they didn't move it or expand

LSCYCLING
10-28-2010, 11:44 AM
happens a lot around here on existing non conforming lots, especially waterfront. I have to send my field crews out to locate the existing structure, than relocate it after complete to make sure they didn't move it or expand

that's got to be it then as it's not direct on the water front but it's across the street from it and from my understanding have some pretty tight codes on the island.

Richy_T
10-28-2010, 03:06 PM
my brother ( is a general contractor) did the work, excavation was done with a small Bobcat skid steer, he placed a CO detector under the house, when the alarm went off, he'd stop, take a break, let the air circulate under the house then start again, it was kinda complicated, he had to put house moving timbers under the house to support it till he got lally collums in place

Wow, pretty dodgy. CO binds to the haemoglobin. Just cause the detector stops sounding doesn't mean it isn't accumulating in your blood. I won't say he got lucky because he may have been operating under safe parameters but I suspect he doesn't know that he was and I know I wouldn't risk that. Let alone all the other crap that comes out of a Bobcat exhaust.

Orange_4x4
11-21-2010, 10:52 PM
I I am setting a project goal to get the vapor barrier installed by November 14th.

So, er, ummmm....... I have not started this project at all yet. :D

But I have a very good excuse, we listed our cabin for sale, and we got a buyer immediately, so I have been spending the last couple weeks moving everything out of there. So today I brought the last load of crap back from the cabin. We actually closed on Friday, but had an agreement with the buyers that we would have the rest of the weekend to finish clearing out the pole barn since we were closing so fast.

Now we are headed in to a holiday week, including a prime shopping time, so I doubt much will get done this week at all, plus I have to finish cleaning up the last of the leaves around here. So I am revising my project goal now to December 9th, since I am leaving for another canoe trip on the 10th.

Michelle
11-22-2010, 02:54 AM
That's OK..I have about $300.00 worth of high density foam board sitting under my house that haven't gotten around to installing yet. I have to install all the joist hangers on my floor joists before I can put the second layer of foam core up...so I've been putting it off.

That butyl you mentioned..I'm assuming it is the same as acoustic sealant but in tape form? Have you tried it before? Does it work good? Sounds easier than working with a caulking gun...less messy, especially since I am in a very tight crawl space. I have used butyl before at work in the film industry, but never in a construction application.

Orange_4x4
11-22-2010, 09:42 AM
That butyl you mentioned..I'm assuming it is the same as acoustic sealant but in tape form? Have you tried it before? Does it work good? Sounds easier than working with a caulking gun...less messy, especially since I am in a very tight crawl space. I have used butyl before at work in the film industry, but never in a construction application.

This is the one I got: http://www.bestmaterials.com/detail.aspx?ID=17654

Which as far as I can tell is the same thing as what the radon barrier manufacturer sells, but at a significantly cheaper price. http://buyplasticnow.com/butylsealtape2x50.aspx

I still have yet to install it to test it, but it looks like it should work pretty good.

Orange_4x4
12-29-2010, 10:19 PM
Yesterday I finally started my crawlspace project. So in 2 more weeks I should be wrapping it up. :p

I removed all of the fiberglass batt insulation that was in there and bagged it all up to be disposed of. That revealed the 2 outside walls to have moisture trapped by the vapor barrier of the insulation, and the block walls were wet. Luckily, there was not any visible problem with mold yet, but it was not a good situation. Already the walls are looking much more dry after just 24 hours of no insulation. I did find a disturbing break in the footing where foundation steps up from the basement depth to the crawlspace depth. There is about a 3 foot gap in the footing on the outside wall, and on the opposite garage shared wall. It makes no sense to me why it would be like that, and looks like an easy entrance for any critter that can dig a shallow hole. So I think I am going to have to make some forms and pour some concrete to close it off and make it a little harder for critters to get in. Add that to the list. I am starting to contemplate if a concrete floor over a vapor barrier would be a better solution to make sure no large rodents ever get in. Pics attached.


Before:
http://i55.tinypic.com/2vk01me.jpg

After:
http://i54.tinypic.com/10qfozb.jpg

Missing footing?!:
http://i54.tinypic.com/9bk8wi.jpg

bighammer
12-30-2010, 07:06 AM
The piece over the break is a lentil. It's a beam made to fit in with the block and bridge the gap between the 2 foundation heights. Seems to be holding even though they put it in sideways. :facepalm:

Crawlspace depth should still be deeper than any critters would dig. I wouldn't worry about it.

Why is all your bridging hanging loose? Attaching those might firm up the floor above.

Whatever Dude
12-30-2010, 07:12 AM
Lintel is a horizontal block that spans the space between two supports.

Lentil is a bean.
:)

bighammer
12-30-2010, 07:20 AM
Used 'em. Never spelled 'em. Thanks :dizzy:

GeorgeZboy
12-30-2010, 07:50 AM
Yep - that lintel is deliberate. The only reason I can think anyone would do that is to allow for a pipe to be installed later when they didn't know exactly where it would be. What kind of slacker mason doesn't see "TOP" and give the thing a flip???
EDIT: Thought of another reason: Is that a boulder poking out there that they didn't want to blast?

+1 on repairing the bridging.

Concrete block is extremely porous and the moisture you are seeing may well be coming from the exterior, particularly since you said the crawlspace is quite dry. (The mortar isn't quite as porous, but it's close.) Be sure you have a good finishing system on the exterior. The point where you stand the most risk is where the wood sill is sitting on damp concrete. If you don't have a sill sealer there to break the contact and keep the wood dry - do NOT close that sill off as it will rot and collapse (if carpenter ants don't eat it all first). The good news is block with no finish is pretty much inedible to mold so there shouldn't be a problem on that surface.

I'm going to have to go back a bit and review your game plan...

Whatever Dude
12-30-2010, 09:45 AM
+1 on the belief that there must be a reason they left an opening in the wall and installed a lintel...its not just a missing footing.
Maybe they anticipated you digging out the crawlspace someday, and installing a basement access door from the outside?
Former secret entrance for drug running? Slave trade? :)
Poke around under the lintel and see what you find.

Orange_4x4
12-30-2010, 10:59 AM
The piece over the break is a lentil. It's a beam made to fit in with the block and bridge the gap between the 2 foundation heights. Seems to be holding even though they put it in sideways. :facepalm:

Crawlspace depth should still be deeper than any critters would dig. I wouldn't worry about it.

Why is all your bridging hanging loose? Attaching those might firm up the floor above.

Crawl space has 1.5 to 2 blocks showing on the most exposed part of the outside wall, which means only 3 blocks and a footing to dig under. Thats about 2.5 feet by my calculation. All of that dirt in the picture that looks freshly dug under the picture of the lintil is what worries me, although that is directly under the garage floor, in an area that had a ton of ant activity when we moved in. The ants are all gone now (I killed em), so I dont know if the freshly dug dirt was all them, or more critters too. Would pouring concrete under the existing lintil be a problem with expansion or anything, or could it be done to get the extra depth?

There is also a lintil 180 degrees from the one I took the picture of that is on the back side wall of the house, perfectly symetrical in placement with the other one where the 2 foundation heights step.

Bridging has always been loose. House was built in 1990, and 20 years later the joists are still straight! :) I will get to nailing them in while I am down there, I just havent got to it yet. Thats only like that in the crawl, the basement area has all of the bridging nailed properly.


Yep - that lintel is deliberate. The only reason I can think anyone would do that is to allow for a pipe to be installed later when they didn't know exactly where it would be. What kind of slacker mason doesn't see "TOP" and give the thing a flip???
EDIT: Thought of another reason: Is that a boulder poking out there that they didn't want to blast?

+1 on repairing the bridging.

Concrete block is extremely porous and the moisture you are seeing may well be coming from the exterior, particularly since you said the crawlspace is quite dry. (The mortar isn't quite as porous, but it's close.) Be sure you have a good finishing system on the exterior. The point where you stand the most risk is where the wood sill is sitting on damp concrete. If you don't have a sill sealer there to break the contact and keep the wood dry - do NOT close that sill off as it will rot and collapse (if carpenter ants don't eat it all first). The good news is block with no finish is pretty much inedible to mold so there shouldn't be a problem on that surface.

I'm going to have to go back a bit and review your game plan...

I dont think it is a boulder, I think it is just some small rocks under the lintil. The ground is very rocky and sandy in general, but I will poke around there and see what I find. It wont be the first time I have been surprised down there. I am pretty sure the moisture is coming from the outside, especially the way it was trapped at the vapor barrier. Next spring/summer I plan to excavate that wall and re-apply some waterproofer and insulate the outside of the wall. That should reduce the moisture considerably. Its only 2.5-3 feet of digging, so it should be easy to do.

I was planning on capping the blocks with aluminum faced insulation board (whatever its real name is - impervious to mold and moisture). Are you recommending against that it sounds like due to trapped moisture? If so I would consider drilling weep holes now in the bottom course of blocks to stay under the vapor barrier for drainage. I would still prefer to keep the tops capped as insulation and part of the radon barrier.

+1 on the belief that there must be a reason they left an opening in the wall and installed a lintel...its not just a missing footing.
Maybe they anticipated you digging out the crawlspace someday, and installing a basement access door from the outside?
Former secret entrance for drug running? Slave trade? :)
Poke around under the lintel and see what you find.

Garage basement?

Whatever Dude
12-30-2010, 01:56 PM
Concrete shrinks as it cures, so no worries about expansion cracking the lintel.

Perhaps the use of the lintel was intended to avoid a weak spot at the "step" in the foundation? If the rest of the foundation wall is X blocks high, and you step up 2,3, 4 blocks (whatever it is), then at that step the foundation wall is actually X - 2,3,4 blocks and a weak spot is created (without use of a lintel I mean). Adding a lintel ensures that the load is partially spread back to the full heigh foundation wall. Just might be crazy enough to be true. :)