We’re considering buying a 1947 house with a crawlspace, then excavating a basement. Will it be possible to waterproof the outside of the basement walls?
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Not easily, but the fact that you're digging a crawl out for a basement is a substantial project in of itself.
Are you doing all the work from the interior?
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
The architect's idea is to work from the inside, keeping 2 to 3 feet inside the existing crawlspace foundation walls. He says he has a contrator with experience in this area. We understand we won't get a full basement. Then I got to wondering about the waterproofing aspect.
Sounds like a alot of work to only end up with a Michigan basement.
you'd have to use interior sumpsyou assume the existing is WPAnd you can make the new one WPBut there is still the in-between where it can siphon over
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The problem with digging inside the footings is you can still undermine the existilng footings to the point of no return. If you use block you will end up with a void or uncompacted soil next to the existilng footing. Not good. If you pour the wall you will use a ton of additional concrete and risk having the forms blow out since there is no good way to tie the half form to keep it from spreading. Last bu not least for all your effort you don't get much of a basement. My thinking is if you are going to loose all that space it's not worth the hassel, plus your waterproofing is a real concern.
Have you ever seen 'The Great Escape' ?
Unless your in a northern climate with deep, deep footings, how will you handle a footing shallower than your projected basement floor?
BruceM
Do a search. This was discussed 2 or 3 months ago...
Skip it and buy something else. Really.
Unless this house is the home of your dreams, keep looking. Putting a basement under an existing house is a major project and probably not worth the expense.
I helped a friend do this about ten years ago. We used my skidsteer to ramp down on one end and dig out the dirt. First we shored up half the house and removed the old footing along one wall. Poured new footing, new block. Did the same with the other long wall then the center beam then the ends. All I can say is never again. My labor was free as well as the cost of the skidsteer. Even at that it cost a fortune in time doing everything the hard way. The only reason the job was done at all was the existing footing needed a ton of work anyway and since the site and house was worth keeping it seems like the thing to do. Originally he wanted to hire it out but the low bid was $42,000. That said he took the summer off and did it himself with me helping nights and weekend. A work of caution, make sure the soil is up to the task. Soft crumbly dirt is a disaster waiting to happen.
Riverman,
I too am considering the same project, but live on a slope and have the advantage of having about 12 feet of headroom on the downslope side, and about 5 feet on the upslope, thus minimizing the amount of excavation. Although I will need to fill in on the downslope side.
My question to you is the details on how you shored up each long section of wall. I have several methods in mind to do it safely, but am curious how you did it on the project you referenced.
Thanks.
Shoring up the walls. The home owner had an advantage in this area since one of his friends had access to a dozen 6 inch x 20 ft. I beams. We knocked holes in the old foundation, slid the beams underneath the sill plate up to the center beam of the house concentrating on the load points of the building where ever possible. Those areas where we needed additional support but couldn't find a suitable location we built temp walls on the inside of the exterior walls utilizing headers and jacks to distribute the weight. The outboard ends of the I beams were cribbed and locked in place. Once we felt confident the beams couldn't roll we jacked them up to the point of being loaded, raising the wall 1/2 inch at most. This allowed us the ability to over dig the outside of the foundation by about 4 ft. The really harry part was running the loader, being careful not to hit the underside of the floor or knocking anything out of place. My machine has steel tracks so it could really dig. Once we got under the building we had to ventilate the area to keep from getting gassed. Neighbors and friends loaned us about a dozen box fans to move the fumes. This helped but after a while it still got to be to much so the owner rigged up an elaborate venting system using 16 inch ducting and a huge salvaged furnace blower.
"Unless this house is the home of your dreams, keep looking. Putting a basement under an existing house is a major project and probably not worth the expense.
Funny you should mention it. Ever done one of these? A guy I know wants to do just this, on an investment renovation project. I think he's nuts. He thinks he can double the square footage without increasing the footprint, with minimal visual impact from the street, and make a big profit. I'll probably be doing some of the work on the project, I'm interested to see how it turns out.
I've done a lot of work on two others of his projects, and so far everything he does is bass-ackwards, from a construction viewpoint. Lots of poor-planning, no planning, do-overs, overkill where it doesn't matter and underkill where it does, and just plain (from my persepective) goofiness. Lots of us subs on the job have tried to educate this guy, but he sticks with his "artistic vision", da#m the pro's viewpoint! But he's easy-going, appreciative, and the checks don't bounce.
Stuff like in-swinging single-glazed wood casements throughout the house - including in each of the two showers, flat roof with parapet walls with butt-ugly drain holes punched through every 24" o.c., gaudy and impractical kitchen/pantry cabinets, etc. etc. So needless to say, I'm real leery about his 'add a second floor in the basement' theory. Although I'm sure it can be done, I question the profitably and practicality of the venture.
I've done it a couple times.
It is more dangerous than most construction, and WAY MORE expensive
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Ah!. A Short message, must be typing one handed. Good to see you are well, will drive over to the woodshed and probably see update posts ont he surgery.
On basements, anybody 20 or more pounds overweight would do well to DIY dig one out by yourself with shovel and wheelbarrow, lose 20 lbs easy (but got it back>:(> )
Junkhound: I lost my 20 just digging the underpinning under one wall! Just pick and shovel work alone- we brought the backhoe back to haul the spoils out of the hole.
To the topic at hand- deepening a basement under an existing house is tough enough. Turning a crawlspace into a full basement is crazy. Tough to imagine how it could be done safely- for the structure or for the people doing the work.
PS: I hope I didn't just misplace that 20 pounds- I don't want it back!
That was my thinking, but I hadn't considered the safety aspects. There is virtually no one doing this here in Bakersfield, so I'm curious how they're going to orchestrate the whole thing. Basements are rare here to begin with, then to add one under an existing house? The soil is generally sandy, so I guess excavating won't be difficult from that standpoint, but shoring it up during excavation might. Their plan is to lift the house up 4' (its about 18" now), so they can have windows to daylight in the basement. Then they're planning a dropped, trench-like area all around the house. They plan on getting a house-mover to pick the house up and relocate it on the lot (about 5' over from where it is, so they can add a driveway along one side), then excavate and build the basement directly under it. They're talking about preserving as much of the original structure as possible, but the framing is 100 years old and nowhere near code. Stuff like 2x4 c.j.'s at 2' o.c. spanning 15', about the same for rafters, and so forth. Plus, the windows should all be replaced, and the siding re-done. Not much left to save, after all that. These guys are from the coast, where real estate costs are much higher, and I suppose they've seen it done over there. Their one saving grace is they bought before the boom here had peaked, so I guess they'll make out OK no matter what they do. They're already remodeling the detached garage into a granny flat, and their lack of a definite plan, and any kind of budget, or schedule, doesn't give me much confidence. They complain about being way over budget, but keep adding nonsensical cost upgrades at every turn. Their latest dumb idea is to re-use the old cabinets from the original house in the granny flat "for a little while", then put new cabinets in. Huh? Anyway, I haven't been swamped, so I'm grateful for the steady work. And I've made a few good connections with other trades on their job (I'm easing my way back into the construction game after a hiatus of a few years.) Part of me says to walk away, but there is a morbid curiosity to see how this will pan out, and the mercenary side that says don't walk away from a paying job. I guess I'll stick around for a little while (t&m), and walk if it starts turning ugly.
Edited 12/26/2005 12:07 am by Huck
that's a whole diff ball game. if they are relocating it, they should build the new foundation first and then have the house mover do his thing
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That was my initial thought - but they're only moving it over a few feet. So there's no room to build the foundation first, then put the house on it. I think I'll talk to them seriously about moving the house completely out of the way, then having the movers come back and place the house on the foundation/basement floor after its completed. Your post, and the other about the guy who got killed, have got me thinking about the issue of safety on this job.
> I think I'll talk to them seriously about moving the house completely out of the way, then having the movers come back and place the house on the foundation ....
I'd talk to the house movers first, before raising this issue with the clients. Given that these guys are confused and inexperienced and giving themselves expensive lessons, it would be better if their hired experts were to have their ducks in a row before talking to the clients.
-- J.S.
Yeah, point well taken. But I'm not sure I'll be involved in that part of the project. More likely I'll do the framing, or the siding, or the trim. Or maybe just the endless pick-up that these owner-builder type jobs seem to generate. But if I DO get a chance to talk to the movers, I'll definitely inquire about the feasiblity of moving it away, then placing it on top of the basement floor. Its very hard for the subs involved in these projects to get their "ducks in a row" because of the lack of organization, poor communication, jumbled sequencing, and constantly making changes, that goes on with these projects. Very frustrating.
Nothing to do with nothing here, but, in Bermuda lots of folks create basements. Of course there most all the island is a form of limestone, they use it cut for masonry block walls and cut thinner for 'shingles'. But then again they don't have to worry about ground water, not much of that, or foundation, since the 'bedrock' is the foundation.Let's not confuse the issue with facts!
I've been involved with a couple of these jobs and never understood why people did them. The houses had to be raised to allow room to dig the basement, form the foundation and walls, etc. There was a lot of engineering involved regarding soils analysis and strengthening the floor joists. A friend of my father got killed doing this. He was using a front end loader and it tipped under the house crushing him against the floor.
I'm sure that some houses may be worth it, but they're probably pretty rare.
Thanks Dave, I guess I see it the same. I doubt this house is one of the ones that's worth it, at least in my book. Sorry to hear about your friend's father, but I do appreciate the head's up on safety issues. I'll discuss it with the guys planning this, and see if I can get through to them. Like I told Paul, I think, if at all feasible, they should move the house completely out of the way, then come set it on the foundation once it's built.
That is what I'd advise if there is room on the lotr to move it, and stilll get excavating equipment in
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Will it be possible to waterproof the outside of the basement walls?
I would think that most codes are requiring pretty good measures for insuring the water infiltration on new construction is limited or eliminated. In my neck of the woods (North Georgia), new construction consists of pouring the footings per code. Pouring concrete for the walls. Spraying on a ribber compound on the exterior-side of the poured concrete walls. Laying down slab sub-bed, including plastic to keep moisture from coming up, and then puring the concrete slap itself.
Of course, this is for a walk-out basement. How much can you afford to budget for your basement addition? If its really going in then why not shoot for the gold and make it 10' tall basement so you can not have to worry about shallow ceilings when you sell the place later.
I helped do one when I was a kid.
We shoveled all the dirt on a conveyor and replaced 8' sections of block wall at a time.
We put the dirt on a flatbed truck and shoveled it off the truck where a guy wanted free backfill. ahh, those were the days.
My dad said all we got is time.