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I would like to know if it is possible to convert a crawl space into a full basement. If so, how is this done? What techniques are used? Are there contractors who specialize in this sort of work?
The case I am considering is a brick veneer, wood frame, ranch style house with a block foundation. Approximately half of the home square footage is on a full basement, and the other half on a crawl space. The home was constructed in 1970. Any information, construction techniques, etc would be helpful. Thanks.
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2 basic methods :
excavate & shore...leave piers of block & earth.. excavate between the piers.. pour new footings and bring the block up to the existing sill...
then tear out the piers and repeat teh process..
the other method is shore, jack... move the building.. excavate... build new foundation & replace the building on the new foundation...
variations on those two themes
*Mike,Thanks for your message. Very helpful. In my case, since only part of the house is on a crawl, and it can't easily be separated from the rest, I would have to employ the excavate and shore method. If I understood you correctly this process would result in the new wall being built in multiple segments. Does the fact that the wall is built in segments cause any settling or leveling problems? Is this type of work unusual, requiring a specialized foundation contractor, or could any competent foundation contractor handle this type of job?
*Call the house moving co's in the area. They'll be able to, er, fill you in
*bradley... good masons do this stuff all the time...the excavation is the hard part... lots of DIY rent bobcats and have at it... but you could hire a good mason to handle the whole operation... including pouring your new basement slab when you're done...
*Did one by hand a few years ago (wheelbarrowed 80 yds of dirt) and used the berm method. This requires at least a semi-stable soil, even non-saturated clay will allow this method. This also assumes the crawl space foundation is at least 3 feet deep. Dig out only to within 20 inches of the exising footing, then pour concrete into forms that will leave a 24-30" wide embanckment, install shelves above. I was able to use truck delivered concrete by sluicing it into the forms thru a "new" window. Be sure to rent a vibrator so you do not have voids at the bottom of the pour, or you are asking for future water problems.
*Art,Thanks for your note. The berm method is a interesting approach to this problem. I live in the Detroit, Mi area so I think the local codes call for at least a 42" foundation depth, which means I could consider using the berm method. However, moving 80 yards of dirt by hand doesn't sound like a lot of fun. What dedication you have! I'm just too lazy I guess. If I understood you correctly, the new walls are poured 24-30" inside the perimeter of the existing foundations, high enough to clear the footing of the original walls, but not all the way to the ceiling. A shelf would be formed by pouring a slab of contrete from the top of the new wall horizontally to the existing foundation. Since there won't be any vertical loads applied to the new walls will they be strong enough to resist the soil load forces? Should the top of the new wall be somehow anchored to the existing foundation to help the new walls resist forces which might cause them to tip inward?
*Mike,Glad to hear that this type of work is not uncommon. I suppose the cost is the major deterrent, and the difficulty excavating around the existing foundation, and under the house.Once the new wall sections are built between the existing segments and piers of earth, how difficult is it to get the new wall to fit up tight under the existing sill? What I'm worried about is even loading of the new foundation, and how to avoid excessive settling once the new wall is constructed. Is this a problem? I suppose the first batch of new wall sections would become loaded after the remaining old wall segments are removed. Then how does one make sure the second batch of new wall sections are equally loaded to support the house? I'm concerned because one of the foundation walls will be a straight run of about 35', so I'm worried about the wall's ability to withstand soil pressure. Is a long, straight run like this cause for concern, or just me being paranoid?
*the mason can mud the sill solid.. no settling..as to soil pressure.. your local building code should address this.. if you have fairly stable soils.. simple reinforcing will take care of it.. the more questionable soils and the deeper the wall.. you may want to convert to 12" block... or lay up buttresses in the design... we're starting to get into site specific engineering here.. which of course requires site specific engineering...
*B.H.,You will save time and labor if you excavate as close to the exterior walls as soil conditions allow. Get shoring poles from the rental stores. If you don't have access to small scrap I-beams use 6x6's and 4x4's. This will allow you to shore as you go and as required for common sense safety. We do this work year round and always pour the footings and walls/blocks in one process. Doing the walls in segments is wasteful and placing retaining walls several feet inside the walls not only wastes space but labor.
*Mike,Thanks for your reply. You're right I probably am getting too specific with my questions. However, you have sorted me out on the settling question which was bothering me. As for the soil pressure issue, it's clear from your comments that proper design can cope with this issue. One further question: in general, would the "berm" method (build a new wall inside the perimeter of the existing crawlspace foundations) be more or less expensive than excavating around the outside of the existing crawlspace foundation and replacing the crawlspace foundation with a full height basement foundation?Brad.
*Dallas,Thanks for your note. It's beginning to sound like this sort of work is fairly common and can be handled easily by most competent masonry contractors. If I understood you correctly you are recommending that the most cost effective approach is to somehow support the house (and brick exterior), remove the existing crawlspace foundation and footing all at once, and finally replace it with a new full basement height foundation. How do you support the existing house while constructing the new foundation? I'm guessing you would use some type of beam set at regular intervals, passing through the existing crawlspace foundation, supported on one end by soil under the house in the existing crawl space and on the other end by soil at the outer perimeter of the excavated trench. Is this about right, or are there much better methods?Brad.
*Dallas,One further question: I'd like to get a ball park figure for the cost of this work. How could I make some estimates?Brad.
*call a building mover... they'll quote thewhole thing or pieces
*"could any competent foundation contractor handle this type of job? "You've used the key word 'competant' twice now. Use it when selecting a contractor. Many concrete boys don't know much other than "grunt" "grunt" "grunt". My apologies to the pros who are reading this - you know what I mean.I've done this kind of work a few times. What works best for me in most cases is to do the excavation by portions and place jack posts about every 4-6 feet depending on how big the building is. I dig deeper than the footing location in those specific places by hand and place a concrete bisquit and set upthe steel jack post directly in center of where the new concrete wall will be. Dig, set jack, move over, dig, set jack, move.........Then your concrete contractor can pour footers over the pads and form the jack posts into the centre of the wall, leaving it there as a sacrifice. There are plenty of ways to do it but this is clean and ends up with a solid wall. If you finish out with block, granite, or brick above grade then you can cut the posts out with a sawzall easily on at a tiome as masonry proceeds.
*Piffin,Thanks for your note. Placing the jack posts in the center of the new wall does sound like a very clever approach. One question though: do you place the top of the jack post under the existing crawlspace foundation footer, or do you remove a portion of the existing crawlspace foundation (and footer) so the top of the jack post is closer to the existing sill? I am asking this question because I have a brick veneer home and I wanted to understand how to support this type of wall construction. I hope I can find a good concrete/foundation contractor in my area who can do this type of work. I'm not sure how to do this except to start asking around and see how far I get with "word of mouth" reviews. Any other suggestions are welcome here. Thanks.
*Oops!, I missed the fact of the brick veneer the second time in here. I've only done this with total foundation replacement, removing a section of the old at a time. The total new wall without splicing has obvious strength and waterproofing characteristics.You'd need a diff system for supporting the brick as mine was with the posts under a wood sill beam. Sorry for the tease.
*Piffin,Thanks for your message. I was afraid the brick exterior would make things somewhat more complicated. However, it seems to me that your "jack post" method could still be used on my application. For example, place the jack posts as you described, but instead of removing all of the existing foundation, leave the top few courses of 12" block, and place a 3/8" thick steel plate on top of each jack post to distribute the weight across adjacent blocks. (this will support both the house and the brick exterior.) Remove the footing from the existing crawlspace foundation. Next, pour the new footings as you described, and build the new foundation in segments, (using block), between the jack posts. These segments would be triangular shaped. (wide at the bottom, narrowing to only a few blocks wide at the top.) Once these segments were completed the jack posts could be cut away and the remaining wall segments completed. This method is essentially a combination of the method described by Mike Smith in an earlier response, and your "jack post" method. Does this sound like it would work? Has anyone else done anything similar?
*Brad, the key is how the joists run. i.e. a simple ranch type with center support and all joists running normal or do you have joists at 90 degrees to each other. Some of these older suckers have 4-6 different sets of joist patterns. OK if it is a simple standard set-up and you can run I-beams down the length of each side, about 2 feet in, and extending out the ends and support 6x6's or 4" I-beams on the bottom flanges every 4-6 feet, depending on quality of your brick work, extend end of small beams outside and support with bell jacks, 6x6's or whatever is handy. on the house ends use the samll I-beams and shoring jacks as you excavate closer to the edge. if you block the top of the flanges properly against the joists and sill plate you might be able to avoid resting the outside ends on anything. i can send an attachment if you like, think I have some pics somewhere. Cost? Don't do SWAG estimates even for local Cornhuskers. Big mistake for the consumer to attempt to use them.
*Might work Brad but don't try to do it all at once. You'd have no diagonal bracong to keep it from swaying and sliding off the jackposts. A critical location to solve is where the steel adjustable post seats under your steel angle iron/plate. steel on steel slides real easy. then all the kings horses and all the kings men........
*Dallas,I would very much like to see the pictures you mentioned. I think they will help me understand the support structure you were describing in your last note. (you know, a picture is worth a thousand words...)Also, the joist structure on my home is fairly simple: the house rests on a rectangular foundation with all joists running normal to the two long walls, and resting on a center support.As for costs, if I understood your last comment, it sounds like the best way is to get a proper estimate from a contractor who does this type of work? What I was after was a "rule of thumb" to get an idea of the rough magnitude of the cost to see if this type of work would be a total budget buster, or a possiblity requiring a more detailed estimate.
*Brad, if I understand correctly you are only replacing half of the basement,i.e. the house is not going to slip/slide etc on the jack posts. If you are replacing all of the basement then piffin is very much correct, know of a few people that do rely on only jack-posts. DON'T. Know of at least one D.I.Y er in this area who had the house collapse at night. Squeeshed his friends skid loader. If your main beams extend out from the ends of the house and are solidly supported there shouldn't be any reason for danger, if not then you should build cribs our of 6x6's, R.R ties or whatever. there is some room for very careful tril and error with due caution, also remeber to use a good quality elasomeric type for water-proofing. have many hours of fun.p.s. if you go to Building Movers Stgructural Movers web page or IASM (International Association oif Structural Movers) you can track down people who be of direct help in your project.
*Dallas,Yes, I am only converting a portion of the total foundation into a full basement. Essentially the foundation is "L" shaped. The full basement is the vertial part of the "L", and the crawl space is the horizontal part of the "L". I want to convert the entire crawl space into a full basement. Hopefully, since the house resting on the crawl space is attached to the house resting on the full basement foundation, there won't be too much danger of lateral movement. However, it does pay to be very cautious.I'll look up the web pages you recommended to see if I can get a handle on how to support the house(and the brick exterior) while the foundation work is being done.By the way, did you have a chance to dig out those photos you mentioned in your previous note?
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I would like to know if it is possible to convert a crawl space into a full basement. If so, how is this done? What techniques are used? Are there contractors who specialize in this sort of work?
The case I am considering is a brick veneer, wood frame, ranch style house with a block foundation. Approximately half of the home square footage is on a full basement, and the other half on a crawl space. The home was constructed in 1970. Any information, construction techniques, etc would be helpful. Thanks.