Your thoughts on my basement plans

[EddieWalker]

A little more info. Our main goal is to add on a large 24x48 room that has 12 ft walls and exposed beam ceiling with a 6:12 pitch roof. If all goes well, I hope to start on the dirt work in the spring. Just need to finish a few projects over the winter first and save up enough money to get started. This is my number one priority project, and something I've been day dreaming about for years!!! Off to the side there will be a 16x16 sun/garden room for my wife. This is what she has been dreaming of having for years.

The dimensions for everything is pretty much set in stone. After the two tornadoes that came so close to us last winter, we go to thinking that it would be nice to have a tornado shelter. First, and most obvious plan was to build it above ground into the corner of where I plan to build a new workshop. Simple, easy and effective. But not really ideal. One of those projects that I'm working on now is a canning/processing room on the other side of our house from where the new room will be built. Karen is really into gardening, and we are both borderline preppers with a desire to be as off the grid as we possibly can. Storing food and supplies is always going to be something we will never have enough space for. The canning room is 12x24 with quite a bit of storage space, but we can see where it's not going to be enough fairly quickly.

Out thinking then turned to adding a small basement. In all reality, I could make it a lot smaller, but with the size of the room above being 16x16, I feel it just makes more sense to use the walls of the basement as footings for the sun room above it. Access will be from an exterior door inside the sun room that leads to stairs down to the basement where I will install another door. I'm still unsure about this lower door. I doubt a standard exterior door will be enough is we are hit by a tornado. I can get solid core doors used in commercial buildings that would be a lot stronger, then add extra hinges with longer screws to hold it in place, and add a massive bolt system to lock it into place. This is all in the air as I tend to let the smaller details wait until I have something to work with and then make a final decision then. Under the stairs will be a camper type portapotty with plastic bags. I plan on having some cots down there, or a couple of futons and lots of shelving for canned foods. I don't see any need for heating or cooling it year round since we will rarely go down there except to increase our food supply. To keep warm, I'm sure we will just stock it with blankets or maybe an electric space heater if we have power, if not, we are in survival mode and just going to listen to the battery radio and huddle up in blankets.

 

[MossRoad]

Sounds like a good plan. I hate tornadoes!! :laughing: About the scariest thing on earth.... Except for lighting!

 

[Wood_Butcher_Dav]

Eddie,
Since youæ±*e still planning stages keep in mind that you may have to get in the room in the middle of night with maybe no power.

Look at commercial grade steel doors with high density foam core they have options for additional top and bottom latches that are rated.

About 2 years ago a cat2 tornado went right down our main street, bent the police radio tower which had a warning siren which never went off. We live about ï½½ mile from town, wife was in great room and me in our bed room not knowing the forecast, she found out thru face book that something was going on after the fact. About a week later some thunder storms came thru our area and we sat in our storm room that time. :laughing:
Dave

 

[westcliffe01]

Eddie, just consider: The cost of gravel, foam board and pex at the early stage of a project like yours, is just a drop in the bucket. If you don't do it, there is no second chance. Given that it is such a hot climate for so much of the year, I think that, if finished out nice, a basement like that can be a cool, quiet place to go when it is hot out. When I say finish out, resist the temptation to stud and drywall the walls too. That kills the effect of the thermal mass. You don't want the experience spoiled by damp surfaces and musty odors. I have been in many a horror basement here in MI.

 

[dragoneggs]

Personally I think it is foolish to build that much space for only emergency use. Our basement is home to a guest bedroom/wine cellar (a big hit with company). Also a sort of man cave with pool table. Wife doesn't think she appreciates the space as much as me but she forgets she stores her garden harvests among other things in this space. You being a DIY kind of guy, should really think about a multi-purpose room. My two cents... Again. I'm probably over a nickel at at least now. It can be a wonderful retreat on a hot day. Or a place you can crank the tunes if you are into that. Bottom line... Moisture will be your bane so deal with that from the start.

 

[jk96]

Personally I think it is foolish to build that much space for only emergency use. Our basement is home to a guest bedroom/wine cellar (a big hit with company). Also a sort of man cave with pool table. Wife doesn't think she appreciates the space as much as me but she forgets she stores her garden harvests among other things in this space. You being a DIY kind of guy, should really think about a multi-purpose room. My two cents... Again. I'm probably over a nickel at at least now. It can be a wonderful retreat on a hot day. Or a place you can crank the tunes if you are into that. Bottom line... Moisture will be your bane so deal with that from the start.

I'll second dragoneggs comments. We just finished out our basement recently and love the space. It's quiet, cool, and great hangout place for both the kids and us. Might be worth the effort to at least plan for finishing it at a later time. Rough in materials to get it ready for future use would not add much to the cost.

 

[EddieWalker]

Thank you for the suggestions of finishing out the basement, but I'm an outdoors kind of guy and unless I'm sick, like I am this week, I am going to be outside doing something during the day unless it's raining outside. In the evening, I like to watch TV or movies, which will put me in my future great room with the biggest screen I can afford. I'm hoping for something in the 100 inch range because my 55 inch screen is just too small!! I want to be in my great room, it's what drives me to do this, and where I feel will be my happy place when indoors. My current happy place is too small at 15x18, so it's going to become our dinning room when this is all said and done. Just like the two bedrooms and a bathroom upstairs that I never go to, I doubt I will ever go into the basement unless it's to put something in there for my wife. Odds are very good that she will be the one going in there for her stuff. Other then a place to be safe during tornado warnings, I have very little interest in this space other then creating it.

 

[jk96]

Looking forward to seeing your build. We have a 65" tv upstairs in the great room. Ended up with a projector downstairs since we can control light. Projector screen is 112" diagonal. We enjoy it more than going to the movies. We tend to watch regular tv upstairs but everyone heads to the basement for movies. If light wash wasn't an issue with the projector we would have one upstairs as well.

 

[MossRoad]

Thank you for the suggestions of finishing out the basement, but I'm an outdoors kind of guy and unless I'm sick, like I am this week, I am going to be outside doing something during the day unless it's raining outside. In the evening, I like to watch TV or movies, which will put me in my future great room with the biggest screen I can afford. I'm hoping for something in the 100 inch range because my 55 inch screen is just too small!! I want to be in my great room, it's what drives me to do this, and where I feel will be my happy place when indoors. My current happy place is too small at 15x18, so it's going to become our dinning room when this is all said and done. Just like the two bedrooms and a bathroom upstairs that I never go to, I doubt I will ever go into the basement unless it's to put something in there for my wife. Odds are very good that she will be the one going in there for her stuff. Other then a place to be safe during tornado warnings, I have very little interest in this space other then creating it.

I think a lot of folks (like me) treat our basements just like another room in the house. Its warm and cozy when its brutal and -10F in winter and its cool and refreshing when its pushing 100 in summer. Ours isn't finished. We've got storage, our laundry room, a chest freezer and an extra refrigerator, a work-out area with a weight stack and a Nordic Track, and a ton of food and water and a computer and TV to watch while working out. But... ours sticks out of the ground 2' and we have small windows. It serves a different function than what you want yours to serve as. If we ever build a new house on our property, it will have a walk-out basement on one side, but will have a full concrete room in one corner for storms.

Will be watching your project. They're always interesting for sure. :thumbsup:

 

[MossRoad]

Duplicate post removed.

 

[BitChin1]

Eddie have you looked into Permanent wood foundation? Almost what you have described and you can remove the issue/concern of forming and pouring the concrete. PWF likes the idea of a dry exterior wall; avoid water getting there in the 1st place, waterproofing the exterior is some does get to it, and then crushed stone and drainage path if considerable amount gets down to the footing level - this last area you still need to decide how to deal with as has been discussed, but path to daylight is best option, followed by dry well or interior sump pump.

If you are near the top of the hill, can buiuld slightly elevated, use red clay to divert water away (possible layout a water blockage of sorts under the clay (foam, pvc sheet etc) - decent roof overhang and guttering to divert water away you may be able to avoid surface water concerns - then it is just a question of ground water or seapage water getting to the foundation - might work? how bug of a disaster is it if water does get into the space?

 

[EddieWalker]

Good question. If water got into there, It would be bad for the simple reason of mold and probably become a nasty area. I'm still doing my research and working on a plan, but have not ruled out my original thought of using a heavy duty liner to seal off the entire space with a plan B of incorporating a basin under a corner of the slab that I could use to collect and pump out water if my idea fails.

I'm not familiar with Permanent wood foundation. What is that?

The finished floor height of the room above the basement will have to be the same as the 24x48 room that I will be building off of my house, which will be the same as the existing foundation height. There is great drainage away from the house on 3 sides with the driveway being the only thing above the height of the slab on the fourth side. There will be about 30 feet of dirt between the driveway and the addition for me to create a big, wide ditch to ensure water drains away from the house on all four sides. I love ditches and creating paths for water to travel!!!! With my red clay, I have serious doubts of any water getting up to and against the foundation of the house.

 

[BitChin1]

Good question.
I'm not familiar with Permanent wood foundation. What is that?

The finished floor height of the room above the basement will have to be the same as the 24x48 room that I will be building off of my house, which will be the same as the existing foundation height. There is great drainage away from the house on 3 sides with the driveway being the only thing above the height of the slab on the fourth side. There will be about 30 feet of dirt between the driveway and the addition for me to create a big, wide ditch to ensure water drains away from the house on all four sides. I love ditches and creating paths for water to travel!!!! With my red clay, I have serious doubts of any water getting up to and against the foundation of the house.

Eddie the PWF is a foundation made from treated plywood and 2x8's - foundation is a bed of compacted stone - plywood is treated for underground and protected from soil/water by waterproof membrane.
Permanent Wood Foundations - Southern Pine

google for other links but this approach seems to be similar to what you are contemplating but would be significantly simplified as you do not need to pour the concrete wall (and if you plan to leave the plywood "forms" in place the concrete does nothing for you except add complexity and COST.

Everything I have researched (was thinking about this for the house I built a few years back) does seem to focus on making sure you have a dry basement by avoiding water getting to the foundation - but that starts with good stone foundation (typically with drainage to daylight or sump pit), and surface drainage away from the foundation along with "surface cap" - I would suggest layer of clay sloped away from building on top of crushed stone backfill and possibly add concrete apron. Use of gutters also will help.

Getting rid of the need for the concrete walls would make this a basement you could build in a couple hrs! (after excavation) - you could use several different options for waterproofing - as others have stated already I don't think you want to create a "boat" - certainly the full wrap waterproof layer would be good, but it should protect from dampness or for the event your primary approach fails (primary being to keep water away from foundation) - If you get significant water around your "perfect" waterproof layer then you will have a boat (you would then being drilling holes to relieve pressure to sink the boat)!

 

[STF]

Eddie, sounds like a good project. I believe with the membrane and such you will trap water which will eventually find its way inside.
Hydrostatic pressure is what they call it.
I did all the right things with my basement - 8" of gravel below slab, 24" against perimeter concrete wall, French drains etc.
Then one day it flooded after only a moderate rain, week later flooded again. Ruined a lot od stuff in the process.
I put in a Zoeller sump pump, had the water exit 30' away from the building and that eliminated the problem. Matter of fact if you procure a blue plastic 55 gallon drum you can turn that into a sump basin, I've found that to be far superior to anything on the market, and a whole lot less expensive.
A backup generator is pretty much a must if you leave the property for even a few hours, it is all that will stand between you and a flooded basement. Good luck.

 

[EddieWalker]

Thank you. I appreciate the link and enjoyed reading what they had to say.

One of my personal observations when digging and filling in trenches is that even years later when everything appears to be solid, the fill dirt is always different then the undisturbed dirt. I doubt it will ever be the same, but until it is, it will always absorb more water then the undisturbed soil. Grass grows better there for this very reason. What I'm seeing and my thinking is that in traditional basements, they have to back fill around the basement wall with something. It does not matter what you use because whatever it is, it will hold more water then the surrounding, undisturbed soil. Since this is going to happen, getting rid of the water that is now being allowed into the surrounding area outside the walls becomes the challenge. Gravity says water will go down as far as it can, then fill up the hole. Since the bottom of the soil under the basement is also undisturbed soil, what you have done is create a pond with a room inside of it. The challenge in all basements is how to get rid of the water that you have created a place for it to travel to.

I also feel that basements are just bigger french drains. Dig the hole, fill it with gravel and it fills up with water. What to do with the water is the next step in the process, but if you had never dug the hole, water would never be in the ground to any significant level, and you would never have to deal with what to do with it once it fills up that hole.

If anybody has done any significant digging with a backhoe or excavator, you will learn real fast how much water is in the ground at different depths. I have places where I can dig down four feet and have it fill up with water during the middle of summer. Where my house is, I can dig down 12 feet, and have, without any sign of water or even moisture on the sides of the hole.

My thinking is that with the rubber liner up against the sides of the hole I dig for the basement, when I pour concrete, it will force the rubber liner solid against the undisturbed soil. The only path for water to get down into the ground there is going to be along that seam, or outside edge of the rubber liner, which is going to be very tight because of the weight of the concrete, and it's ability to form to the shape of the wall. Cost of this much concrete is insignificant compared to building with block, sealing the block, buying drainage gravel and creating a drain line to where it comes out on it's own, or installing a pump to remove the water that I'm inviting into the sides of the basement walls and storing under the basement.

Swimming pools that are done in concrete do not float out of the ground. Fiberglass pools do because of the fill material that goes in around them after they are placed in the ground. This fill material becomes a storage location for water to build up until it floats an empty pool upwards. This is why they fill fiberglass pools as they back fill them.

I do not believe there is any chance of my basement floating if done the way I propose. The floor alone will be a very thick slab poured before the walls. Then the walls will be poured at the same time as the slab for the addition, with one wall of the basement being part of the footing of the addition.

I'm enjoying the research into this, and appreciate everyone's thoughts, suggestions and concerns. They make me think harder about this, and force me to look into what is done and why it's done. For me, this is a lot of fun!!!

 

[Streetcar]

PWF can affect sale value.
Concrete pools can float.
The house can cause the surrounding soil to dry out leading to pathway for water to access the basement

 

[BitChin1]

PWF can affect sale value.
Concrete pools can float.
The house can cause the surrounding soil to dry out leading to pathway for water to access the basement

Also concrete can also hold significant amounts of water and will wick any water it contacts.
Eddie I think your key for a dry basement regardless of the lining or build materials is to start with a dry location (sounds like you have this) and design to shed/keep water away from the walls/foundation. Pouring the concrete as the "fill" material certainly can provide for a well compacted fill

after reading your last post I think you are proposing a wall that has the edpm as the exterior layer, followed by concrete then your interior forming - is this correct?
If so the aspect you need to think about is how smooth you can make the excavated walls (dirt) and how much the edpm will need to stretch as the concrete fills it and presses into any cavities - not sure how much the edpm will stretch w/o tearing (I have used it for a couple of koi ponds and the material does seem to be able to stretch but you should be confident that the need does not exceed the ability.

 

[EddieWalker]

Yes, that's my plan exactly.

I'm no longer thinking that leaving the plywood on the interior forms is a good idea because of the potential for mold to form behind it, against the concrete. I thought it would be nice to have wood on the walls, but I don't really care too much what the interior walls look like since I'm planning on halving shelving along all of them and then put some cheap futons in front of the shelves and a fold up table off to the side.

 

[BitChin1]

you will need to consider air circulation/ventilation and possibly dehumidification - any warm/moist air entering thsi area will condense on the concrete walls that are un-insulated as the ground temp will cool the concrete.

Will be good area to store root vegetables and wine

 

[jfh28]

Eddie........being in the northeast I deal with basement moisture problems all the time.........from experience I can tell you that you will regret taking the approach you are every time you walk down there.......I don't care how careful you are in installing the rubber membrane and anything else.........water will find it's way in....it's got a nasty way of finding any little weakness in your system.......lol....if it's ground water it will be from hydrostatic pressure.....if its from a monsoon rain it will be any crack or loose seam in the rubber........save yourself the cursing and aggravation.....give the water a path away from the basement.......install a foundation drain pipe and run it to a drywell and/or put in a sump pit and pump........it's cheap to do now but a nightmare to do later.........Jack