Beginning the design of yet another house (agressive amateur). Small in-fill lot in the oldest part of town. Albuquerque. 7″-10″ rain/year. How to get more square footage? Basement!, says I.
We don’t do that here. Frost line so shallow that we do slabs. Assuming that I can find a concrete guy whose eyes don’t glaze over at the word……know that I will have to either do or supervise like a hawk the water-proofing. Trying to remember my girlhood East of the Mississippi, but it won’t come back to me.
The caveat about location. 1/2 mile away from the Rio Grande. I’ve hit damp sand in this neighborhood b4 at about 4′. Don’t think so with this lot. Sits on a little weird rise about a block long. Willing to dig a test hole. If normal, the dirt should be caliche in seams to about 3-4′, then river sand.
Have read the archives about French drains and basements and it seems that even you wet people have some disagreements. Can’t drain-to-daylight.
So, the questions are: concrete block or poured? Then some type of gooey black tar stuff, right? Should I go ahead and put the gravel, perf pipe and the barrier cover? Know this sounds stupid, but exactly where should that be? I would think down at the footer level of the basement to get it below the walls and the floor. Don’t tell me to go to planning/zoning/plan check people….their eyes glaze over too. Sure that I can do it any way I want….but want to do it properly.
If I hit wet sand should I bag it? I won’t hit the aquifer….that’s about 35-40′ in this area. Or, alter my plan in some way? This can’t be hard since basements are so common in areas where you get 30″-40″/year.
Replies
Hard to say about the wet sand. What is the sand on top like? Is it really sandy, loose stuff? If so, I can tell you that you should plan to excavate a lot larger hole than you may have in mind, because what you don't excavate is going to cave in, and you don't want that to happen when you've got your forms in place and a cement truck sliding down into them.
In Wisconsin, land of the basement, there are crazy cement truck drivers that will still drive up to the edge of excavations like this but down there, you may have more trouble convincing them to do it. If they can't drive close enough to chute the perimeter, you've got 3 options:
Pump by boom
Pump by hose
Wheelbarrow
All cost a lot more, in one way or another. Your idea of a practice dig is a good one, except if you're disturbing the earth below where a slab would be placed, you'll have problems down the line from that too--settling and cracking, or troublesome compaction to minimize the settling and cracking.
More info later but consider all that first.
Eastern gurlhood means you are a desert rattess, right?
For your situation, with a lack of expertease in the area, I would look into using Formadrain system to pour the footers and lead them to a basement sump pump. You can pipe it up to lead above gfrond sloping away. giving the water someplace else to go other than in through the wall is at least sixty percent of any basement water proofing job. Don't try to stabd up against a flood, just convince it that it wants to go someplace else.
I've worked in the southwest and a block foundation there is usually acceptable and more common than poured concrete. But Block is more porous and harder to waterproof. You'll need to paint on a slurry of Thorocoat sealer to seal the open pores, followed by foundation coating. To be sure, and depending on your budget, there are foam and fabric products that you can lay against the wall which provide weep channels for the water to follow down to the perimeter drain/formadrain. That may be un-necessary with you sandy soils which will let water pass through quickly. The foam would help keep it cooler in summer though.
Caliche'? If I remember, that is a mineral/clay layer that you can't grow anything in. Keep it away from the foundation if you can because clays will expand when wetted, placing horizontal loads on the foundation wall. If you do anticipate such forces, the block wall can be reinforced with ladder wythe in the joints and with pouring the cores full every four feet and sticking rebar in. The joints should be tooled as this makes them stronger and more water resistent. My memory is that your area has a lot of slap-dash labour from south of the border. They work hard but standards are sometimes a little lax and the masonry is not so neat. If the block is laid in hot weather, have them keep the m damp while curing with a plastic cover, wetting agent in mix, or sprinkiling a burlap cover to slow evaporation. Cement products need to cure, not dry. If the water is baked out of the solution before it kicks, the bond will be weaker and powdery, so anything that slows the evaporation rate will help make a stronger wall. Strength is good because walls that move and crack are walls that leet water in.
You might also consider building the basement so it is only about four, five feet down. That lessens your odds of water intrusion and lets you have nice windows for light so it feels comfortable. If these are bedrooms down there, you need egress windows by code, in case of fire.
Another option would be what we call ice blocks. These are like large Legos that are made of foam and snap together. They are hollow foam and once stacked and braced, they make the forms for a poured concrete wall that can be waterproofed in similar manner. It is stronger than the block, quiet, and well insulated. Several brands available but i know they were common in the SW years ago so you should be able to find some and a concre6te man who is familiar with them.
Luck!
You can use soil removed in excavation to berm up around the home to run water away from the foundation, but I really don't think you've got too much to worry about, just that one summer thunderburst.
Go for it. You'll save on air conditioning.
Don't forget to call Digsafe, especially in an old city area. No telling what has been buried there.
Excellence is its own reward!
Edited 4/15/2002 10:31:55 AM ET by piffin
This is great stuff....keep it coming.
The dirt at the surface appears loose....but when it gets wet you pick up several inches on your shoe bottoms. Clay. Underneath the loose stuff (6-8"), hard as a rock. Then, there should be seams of it from the surface down several feet. Some of it is so hard that you have to use a post hole digger to plant a 1 gal container...talking about the neighborhood, not this particular lot. Then, at about 3-4' you should break through to the river bottom. The Rio Grande has meandered through here for thousands of years. The entire valley was river bed at one time or other.
Never thought about the truck caving in the hole...thanks. My test hole wouldn't be below the level of the basement slab. I just want to see if I hit any wet sand b4 I start. Another guy bought another in-fill lot down the street and did what piffin suggested...partial daylight basement. His lot is probably 6-8 feet lower than mine. I watched the hole. No damp sand. Now that I think about it, he had a hard time getting the sand to stay put.
I stopped by to ask him if he hit any water, he said no. He did his with block and yes, getting block work done here is no problem....and yes, it can be "slapdash". That's why I need to understand this process thoroughly. He's kind of a yahoo, said he had all kinds of trouble with the city over his basement, so don't want his advice. Rumor has it that he started building with no permit and they shut him down. I saw no water-proofing of any sort on his block walls. I drive down this street every day, so I didn't miss it.
I assume that "ice blocks" are insulated concrete forms, right? I know exactly one person who built a basement here with them about 10 years ago. Since basements are so uncommon, the guys didn't brace enough and he got blow-outs. His walls have some interesting waves. He's also got different topography....up near the mtns, far away from the river, sitting in decomposed granite. Guess I could use Rastra, but it's pretty pricey.
And, as far as the slope away from the house....since my husband and I are both from the East, and we do get torrential rains in the summer...we're always careful to do the final grade properly.....getting it away from the house and creating some kind of ponding area. The guys who do the final grade for us always look at us as though we're crazy. The last house we did had and open, interior courtyard. We made the plumbers run a drain out to a deep rock-filled pit well beyond the house. They thought we were crazy too...but the plumbing inspector loved it.
Think I need a sump pump in any case? Or just if I hit water of some sort? Finding a sump pump in this town should be interesting....altho they do use them for office buildings downtown....they always hit water there...also close to the river.
Am unfamiliar with Formadrain, but will start researching...
We do use insulated concrete forms. If done properly they can't be beat! try the arxx websight for more info http://www.arxxbuild.com. This should be a help to you. I'm not familiar w/term "in-fill". What does this mean, a lot that is comprised of misc. fill dirt?
No, not fill dirt.....just a term for a vacant lot in a long-settled neighborhood. Sorry if I confused you.
They do basements in Miami? Florida?
I'm not from Florida, It's a given nickname that rhymes w/ Sammi. I'm fairly new to the ICF market but going into it "hot and heavy". First project is a whole house about $200,000. job ( my own spec house). Been trained yet still wet behind the ears in this venue!
Miami
I build houses with insulated concrete forms for the walls. It will cost you more, but not much if you do it yourself, and you will get the added benefit of R-25 insulation, an extremely quiet basement, and a cheap pour if you do it yourself. Another benefit to ICF's that I use is you get attachment surfaces for drywall, siding or whatever else you may want to attach without additional furring or studding out. You may break even over the cost of paying for a concrete contractor to pour footings, set wall forms, and pour them, thus getting the insulation for say, free. You could even dig your own hole. It sounds like you may not have a problem with caveins after all. I do like Piffin's suggestion about leaving some of the foundation out of the hole, with the following in mind:
It will make your house taller. You should design with that in mind.
You'll lose some of the benefit of the ground providing a very cool basement. I would suggest spending extra money for well insulated windows with low-e glazing to help.
Good luck. If you'd like more information about the icf forms, email me:
[email protected]
Mad Dog
I really like this kind of foundation waterproofing:
http://www.deltams.com/deltams/index.html
It's a plastic sheet - Not a paint on kinda thing.
Truss Designer Extraordinaire
Not just for basements, there are tons of icf homes in the phoenix area in arizona. they are quiet and well insulated so living costs are low.
As to sump pump-
A. You alway need a perimeter drain when building a basement or crawl space.
B. That drain needs to drain to someplace.
C. If there is no daylight frain, you need a sump, unless you do a big french drain(the rock pit)
Do U feel us nudgeing you to icf's?
Excellence is its own reward!
I would dispute your statment that you "always need a sump pump with a basement'.
We do 4' footers and basements here in Wyoming without pumps or drainage systems all the time. If there isn't moisture present in the test hole I would think twice about going to that expense. Just my experence from another arid part of the country.
I agree about the icfs.
Doug
Doug,
If you'll read again the words that I wrote, you'll see that I never said that you always need a sump pump with a basement. I said that you always need a perimeter drain. Then I went on to say that the drain has got to lead SOMEPLACE. A sump is one of three optoions I mentioned. Another is a large french drain. Where you are the soils are all large gravel type such as is used for making french drains.
The lack of moisture present at the time you dig the hole is absolutely no indication of whether drainage is needed. There are wet seasons and dry seasons. Different types soils handle those changes differently and it is the rare ones that can perform well at all times. So we plan and build for the worst case scenario. for instance, it seldom rains in Tucson, but we still use waterproof roofing to cover the shell of the home there.
Excellence is its own reward!
Have a look at http://www.xypex.com if you decide to go with poured concrete.
-- J.S.
It seems you are describing interbedded sand and clay only in the upper 3-4 feet. And uniformly clean sands below that. That seems very unlikely.
Since all that material was deposited by the river, what you see now (at different current depths) was once fast stretches of river, slow inside bends, and flood plains. So you likely have alternating layers of sand, silt, and clay of varying thicknesses all the way down. Your local water district probably has "potentiometric" maps of the uppermost aquifer. These look like a hiker's topo map and show the undulating upper surface of the water table. Comparing that to the ground elevation quickly gives you the depth to water. A friendly hydrogeologist at the water district could also give you good info on typical seasonal fluctuations in the water table from spring to fall as well as during extreme flooding.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
David,
You're probably right..I'm going on previous knowledge of two other houses built in this area plus the hole I saw down the street. I've had wells drilled....I even rammed one by hand once. For enough feet that I care about all I've ever seen was sand below the clay level. Sometimes it was damp...thus my question. But, even the wells are shallow....60' to lots of water going down to 100-150 to get great taste. But, you've given me an idea to check with the city hydrologist. Thanks.
Assuming that I find dry sand do you all think that I could just trench/rock/waterproof around the perimeter or do I need an honest-to-god sump pump? 7-10" of rain/yr, gully washers in the summer for 30 minutes then stopping. Very unusual to get a slow, all day rain. But, it does happen. Very, very unusual to get all day rain for multiple days. But it does happen. But even then the ground's so dry that it doesn't soak in all that far.
As far as ICFs....use them all the time for stem walls. Kinda partial to rastra because it's so easy to shape into that adobe look and requires minimal bracing. Built a 100' garden wall last year to test it as a house material. We know one of the NM distributors. We helped him for a week putting up the walls on a new house on which he had the contract. We wanted to see how it went. Only drawback is the weight for DIYers. The 30" blocks are 300lbs. You can get 15" ones that are "only" 150 lbs. You can do it with a small rental crane thingey, but you need to rig an attachment so they don't shatter/crumble. I could have the walls erected but that cuts into my profit. We have lots of time. Don't have real jobs anymore. This one will be cake. Last time I checked none of the styrene products could come close. Who wants to correct me? Sammi?
We still haven't decided the building material. ICFs may still be a little esoteric for quick resale...and thanks to the '96 tax law we don't live in them long. Real adobe has a certain mystique that commands top dollar. And, yes, you can have a basement with adobe. Stem wall from hell, but it can be done.
Would like to hear from the gentleman from Wyoming a little more on what he does exactly when he finds no evidence of water. And thanks to all for the advice on water-proofing materials. I'll study up on them.
If indeed your sand is draining that well you might be able to get by with no sump but it only costs about 350 to add to the end of a drain line. You figure out if the cost is worth the peace of mind it gives - how well finished will be your basement?
Excellence is its own reward!
Piffin,
ok,ok,ok. I've never even seen a sump pump. Suppose that if I put a bath down there I'll have to have one of those chopper/shredder things and pump up too. Never seen one of those either. This may get interesting.
And you know that roofs in Tucson are to keep the sun off, not the rain out :o).
LOLExcellence is its own reward!
Perki: "Assuming that I find dry sand do you all think that I could just trench/rock/waterproof around the perimeter or do I need an
honest-to-god sump pump?"
No. There is certainly the "peace of mind argument" but you are so far ahead of the curve in your understanding and practice of good surface drainage that I wouldn't suggest you bother with a sump pump. For that matter, with your roof drains daylighting elsewhere and good surface contouring, I'd argue that simply using clean sand for backfill could serve as your water collection and drainage system for what little water would get to the basement wall.
You're doing much more research than is typical for homeowners or for contractors to perform. Some people have skipped all the drainage and pumping in cases where they needed it. Hence the general recommendations to put in drainage piping and pumps "just in case". Just in case you dig a big bathtub in clayey soils. Just in case the water table is 1 foot below the bottom of your excavation. Just in case you live in a rain forest. Etc. If you are going to blindly pick a design for an unknown site, then play it safe. But why do research unless it is to act on the results of that research?
David Thomas Overlooking Cook Inlet in Kenai, Alaska
Ok, I've got options. I like options. Dig my test hole, talk to the hydrologist. Maybe talk to a well driller...they always seem to know everything. Make sure that I don't back fill with any of the clay. Maybe get the soil analyzed at the bottom of the hole b4 my final decision. Research the water proofing suggestions.
Just read the discussion about gypcrete as an underlayment for tile. Didn't know that. Gotta have infloor radiant, gotta have tile, the basement thing, then a wooden subfloor...jeez. Like swimming against the current around here. Maybe I won't have tile. Been hankering after heart pine....or maybe mesquite.
Think I'll sit down one more time with the zoning code for setbacks, try to get creative, and see if I can't come up with something more "normal".
Are you all like us? We need a 1500sf house and a 4000sf garage. In fact, if I could get away with it I'd just live in my garage. Maybe a giant metal building, airplane hanger thing. Little apartment and big room for toys and tools. Travel. Bring home the motorcycles, exhange for the whitewater canoes. Dump the canoes, get the sailboat. That's our dream. Just a couple more houses........*slaps self*
Thanks again....will try to not wear out my welcome here.
"Are you all like us? We need a 1500sf house and a 4000sf garage. "
I know of a house up here that sold without being looked at. The husband liked the shop so much, he said, "We'll take it." before even going inside the house.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
Good advice as usual David. I can't really relate to the lack of rainfall, but for me, I'd spend the couple hundred to add the sump pump in a heartbeat, having been through some serious basement floodings caused by runoff from neighbors and ground saturation alone. It's a horrendous, heartbreaking mess when you've got living space under water, and insurance DOES NOT cover it. If your basement floods, do what my insurance agent says: Take a hammer and bust open a pipe, call a plumber and act really dumb. Then you're covered though you're also ethically bankrupt to an extent.
This to homeowner: Why go through all that nonsense about gypcrete, radiant heating, wood subfloor? Do you need a lot of heat there? I'd tile over the poured floor or do stamped concrete or just stain it. Forget all that other stuff, especially if you're not going to keep the house. What am I missing?
MD
Well, desert does not always mean hot. This is high desert at 5000'. Need heat. Teens to 20s in the winter. Snow every once in a while to get our attention.
Shelley
Not here to correct, just to question. ICFs are really light and empty until stacked and poured full. Unless I missed something, it sounds as if we're talking about different things. The question; are we on the same page? ;)
Miami
Rastra and Perform wall are made from a slurry of cement and styro beads. Rebar inserted in grid system. Blocks large. Heavy. Edges crumble if you're not careful with it.
But you can round, smooth and shape it...can make it look like adobe. Blocks glued together with urethane. No wire or scratch coat on the stucco. Doesn't require much bracing at all. Last time I checked, r-value much higher than any of the styro products. Popular in the SW 'cause the factories are close.
http://www.rastra.com
Shelley
Yes, I know you need heat. But how much? Your heating season can't look like Wisconsin's, and few people here spring for the system you've described.
But, maybe you're wealthy and don't mind all the fuss and added expense. Or watch "This Old House" where they make it seem standard.
Mad Dog,
Can't tell you "degree days" not that knowledgeable. No, not as bad as WI...brrr. Lived in MN once.
But, we do "normal" heat here. Even tho winter days will be 48-50, nights are cold because of the altitude. Actually, radiant infloor the norm here in the upper end....because slabs are the norm. A natural fit. And, I despise, loath and detest forced air. We were doing baseboard back when we had to explain to people what it was.
No, we're not rich. But because we do most of the labor ourselves we can afford to spend more on materials and infrastructure. Always build them as tho we're going to live in them forever. Ya never know. People we sell them to never appreciate it, but we do it anyway.
I like piffin's mission statement...."excellence is it's own reward"
Have not heard of that product. Think it would work in cold climates?
Sure, why not?
They use it Europe. They have r values posted for Denver. And, the r values they show are for the block only. Not the plaster/stucco or anything else that you add.