basement building

[vipzach]

I am wanting to build a shop behind my house, maybe somewhere around 20'x 50'. I would like to build a full basement under it (lots of tornadoes in spring). Have any of you ever built your own? How did it go?

 

[Mark42]

Re: basement building

I remember helping my Dad add an outside door to the basement when I was about 17. We dug the hole by hand, about 8x8x7 feet. Framed and poured footings, then started laying block. Block gets heavy after a while, and eats leather work gloves up fast. It was not difficult, but very labor intensive. Then slap some tar on the outside wall to waterproof it. Backfill, add Bilco door to top. Then cut hole in basement wall, install door and we were done. <br /><br />I can't imagine having to do an entire basement on my own. <br /><br />One neat thing I saw was preformed concrete basement walls in 8' wide sections. They lower them in place with a crane, then bolt and seal the sections. Floor is poured about 6" over their base. No poured footing is needed. Can do the whole basement in two days. Walls come with ribbing, furring strips on place, and holes for wire and plumbing.

 

[one more cast]

Re: basement building

you could also use then Styrofoam blocks that snap together and then fill with rebar and cement.

 

[llfish]

Re: basement building

Dig your hole, form the footers and pour your concrete. Rent some forms and pour the walls. Save yourself some work and use an air vibrator to work the concrete. Just do not over do it or you will have concrete all over the place. Really a lot of work. In fact it could be cheaper to have someone do it vs all of the rental expense.

 

[craze1cars]

Re: basement building

That's a heckuva large shop to have with a full basement! Do you plan to drive cars in it or park anything gasoline powered in it? If so, it's really a garage, and heavy gas fumes and/or carbon monoxide fumes may sink into the basement and cause a massive explosion or deadly breathing hazard. Then there's floor strength issues. A basement under a garage is likely a code violation and you may want to consult you local building department to see if it's OK before you plan too much.<br /><br />If you just want a storm shelter, you might consider building a small one near or under your house, but separate from the workshop.

 

[Ron G]

Re: basement building

everbody here has sound advice,youll end up for that size basement speanding 3 or 4 times as much as the garage is going to cost to do it right.if its just a storm shealter check your codes and build an 10 x10 in one corner with an acess facing the house sorta mlike a cellar.

 

[vipzach]

Re: basement building

craze1, thankyou, the gas is something I never thought about. Yes, my boat and other cars would be parked in there. The strength could have been supported by colums and plenty of rebar. <br /><br />It was just a thought, I was thinking it might make a cool hideout for me to be able to watch football or whatever and not have the wife, kid, and dogs bugging the whole time.

 

[Wimperdink]

Re: basement building

I like the idea of a basement under a garage... or maybe just a big oil changing pit under one of the bays... can be used as storm cellar or pull the door off and use it for working under boats and cars and such.

 

[lakelivin]

Re: basement building

I'd suggest you pay alot of attention to waterproofing up front. VERY expensive to fix if you develop leaks after you're done (from experience). No way I'd risk using just tar as waterproofing.<br /><br />Alot depends on grade, soil type, etc., but you might consider things like drain tile with a 2' or so wide gravel barrier the height of the basement running around the perimeter. They make a stick on multilayer barrier I wish I'd used instead of tar (which will crack over time). Waterproof membrane next to the house, with a 'brillo' like outer layer that lets water get down to the drain tile. <br /><br />I'm sure there are people on here much more knowledgable than me about specifics, but I do know you want to address waterproofing effectively up front rather than have to try to fix it after it's done.

 

[craze1cars]

Re: basement building

Originally posted by Wimperdink:<br /> I like the idea of a basement under a garage... or maybe just a big oil changing pit under one of the bays... can be used as storm cellar or pull the door off and use it for working under boats and cars and such.

Actually, this concept is exactly what I was referring to. As an auto restorer, I once thought this was a good idea at one time myself until I did some research to plan a pit in my workshop. That's when I realized how unbelieveably deadly such pits are, and that they violate residential building codes in the majority of the US. If you ever get under a JiffyLube or such place that has pits, you'll realize how intense and high tech the construction is....High volume ventillation fans exhausting from the floor of the pit, fume alarms, all the electrical is shielded (sort of like boat electrical stuff) to ensure there can be no sparks, etc. Turns out that building a pit at home to code is cost prohibitive in the few places it's actually permitted. And building a pit at home that DOESN'T follow code is very dangerous.

 

[divo]

Re: basement building

I have a full basement below my garage. The garage floor is made of spancrete...its a precast concrete panel about 10" thick, 36" wide and full width of the garage. They layed them next to each other and poured a thin layer of concrete over the top. Its basically a garage under a garage. I have an exposed basement in the rear. There is a garage door in back just like in front. I am a subcontractor in new home building and see it a couple times a year in this area ( SE Wisconsin).

 

[vipzach]

Re: basement building

OK divo, you got my attention....tell me more. I am still worried about the point that craze1 brought up though.<br /><br />Divo, do you have any info on it, maybe a website. Maybe take a short drive, I will dig the hole, you finish the cincrete.........I've got beer! <br /><br />Seriously, any info would be appreciated. The area I am putting this in, has no codes.

 

[divo]

Re: basement building

Here's a website http://www.spancrete.com/sf_garage.html. Never posted a link before so if that doesn't work just go to www.spancrete.com then click single family....then garages. It is all up to local codes and is indestructable. No fumes or liquids could ever get down there from the top garage. They would have to go through the spancrete (impossible). a nuke could land in my back yard and the lawn mower wouldnt even be scratched...lol. I have wired some huge houses that had used spancrete for the first floor. They had 17' high ceilings in the basement with indoor inground pools. The spancrete was able to span the full width of the house with no interior bearing support.

 

[craze1cars]

Re: basement building

What Divo has sounds to me that it's built into a hill sort of like a walk-out basement, and not fully underground, so any fumes that may enter the lower garage can simply seep out of the garage door like any normal garage.<br /><br />But I agree that if your top floor garage is completely isolated from the basement with no air spaces, ductwork, or the like, it could work just fine and the fumes couldn't get in to build up. I suppose your stairwell to get downstairs would have to enter from the outside of the building, as opposed to being in the garage itself.

 

[divo]

Re: basement building

it doesnt have to be an exposed basement....i have seen many with regular underground basements

 

[lakelivin]

Re: basement building

Again, I'd make sure you were very conscious of ventilation and waterproofing considerations before construction. Wouldn't want to end up with an underground swimming pool during a catastrophe. Or have carbon monoxide issues if you had to light candles to see by while family rides out a tornado, etc.

 

[dtherrien]

Re: basement building

The very best way to do this....and it depends on the soil and digging in your area....<br /> 1.Poured foundation walls...have a foundation company do it. A 20x50 would cost about$7,500.You seal all the holes with hdro cement and the apply your coatings....and backfill the first foot with crushed stone.<br />2.the next best would be concrete blocks and it would be only alittle cheaper than poured walls.the rest of the process would be the same as poured walls. <br />3. Your floor system would be main girders with corrigated metal,then rebar and your 4" of concrete on top of that.<br />4.For ventalation there are many different basement windows you can install when you do your basement walls.<br />In my opinion there is nothing better than poured concrete walls with rebar....it is what everything else is compared too.