Concrete pad in crawlspace

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  #1  
Old 02-22-15, 09:30 AM
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Concrete pad in crawlspace

Would like to eventually pour in a concrete pad in my crawlspace for extra storage/work space but, firstly I will need to get rid of the fill dirt and would like suggestions on breaking up and hauling out the dirt without constantly swinging a pickax and hauling it out in buckets, LOL.

This is part of a bigger project that includes removing some of my supporting columns and pads [in the crawlspace] in order to install a single support beam necessary when we remove a load-bearing wall directly above.

The contractor will be installing the new footing(s) and beam but, will probably leave the rest of the fill dirt in place -- so that will be my scope.

Not looking to disturb the foundation of the house [if that is possible by removing fill dirt] so this work will not be near the foundation walls.

Is a concrete pad in the crawlspace a good idea? Currently there is just plastic sheeting as the vapor barrier.

Thanks
 
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  #2  
Old 02-22-15, 09:33 AM
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How much depth of material are you planning to remove?
 
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Old 02-22-15, 09:36 AM
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As long as there are no existing moisture problems, a concrete pad a fine idea.

As for removing the dirt, I have done this a few times, and unfortunately, a pick axe and bucket is about the only way to go. If the soil is heavy clay, a small jackhammer with a wide spade blade on it might help break it apart.
 
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Old 02-22-15, 02:35 PM
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I would like to shoot for at least a 10'x10' area averaging about 3' deep [of dirt].

My crawl space does tend to smell musty because I believe my crawlspace ventilation is inadequate -- though no wet areas. I was thinking of cutting a new hole for better cross-ventilation and was wondering if there is something made [like an over-sized vacuum] that could suck out the dirt if I could run a big hose through the vent hole. The other possibility would be some type of conveyor belt.

In the future, I would like to make it bigger if possible [and if it doesn't create stability issues] because the total area is about 30x25 and about 6' high to the floor joists [if I can dig to the same depth part of it is currently].


Quick thought: Am I correct in assuming this is just fill dirt or, could it affect my foundation by removing this dirt from a center area?
 
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Old 02-22-15, 03:09 PM
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I used a conveyor belt on one job, but it was a custom built rig just for that purpose. Not likely you will find anything commercially available to do the job and fit in the space required. No vacuum short of a septic pumping truck would have enough power to move dirt like that.

There is a concern about disturbing your foundation if you dig below the current footings. If you do get too close to the footings you are looking at an underpinning situation, which would cost way to much just for a storage area. If you are far enough away from them, ( am thinking of minimum 5 feet but depends on how much lower you go) it should not be too much of an issue. Any dirt below footing level will be undisturbed soil, anything above that could be either undisturbed or just fill, depending how the hole was dug when it was built.

In addition, you may not have moisture issues now, but if you dig below your footings (and hence below your drain tile if there is any) you are almost certain to have some sort of water issue unless you are in a very dry location.
 
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Old 02-23-15, 07:41 AM
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Crawl space ventilation works one of two ways:
1. Seal the space off from the house, insulate the ceiling and provide multiple vents for outside air.
2. Seal the space from the outside, insulate the walls and provide access to the conditioned air of the house.
 
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Old 02-23-15, 09:15 PM
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Originally Posted by stickshift
Crawl space ventilation works one of two ways:
1. Seal the space off from the house, insulate the ceiling and provide multiple vents for outside air.
Good point. Have been in many crawlspaces where the joists were about a foot and a half between and the insulation was held in with either staples or string zig-zagging between joists.

My floor joists, however, are about 46+" apart [a few are narrower] but the insulation I am seeing is much, much narrower. what would be the best/correct way to insulate the ceiling of the crawlspace?
 
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Old 02-23-15, 11:27 PM
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Standard floor joist spacing is 16 inches on center although under certain circumstances 24 inches on center may be used. If your supports are more than 24 inches you may have what is called "post and beam" construction. If the "joists" have a thickness more than the standard 2 by x dimensional lumber (say four by six or six by six) then you DO have beams and not joists. This can be further determined if you have a "forest" of supporting posts.

Pictures would help make this determination.

At any rate, a sealed crawlspace is preferred over a vented space. There IS much more to this so stay tuned.
 
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Old 02-24-15, 07:33 PM
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Even though the house was originally built for ventilated crawlspace it can be converted? And is preferable?

Though when I don't let air circulate in there it tends to smell musty/damp.

Interesting, learning more everyday. Should have looked into this remodel years ago.LOL.

I have 2 photos and hopefully can upload both, though separately.

One shows beam spacing with a ruler and the other shows my posts. Not really a forest, just a line of about 8 or 9. House is only 1500+ sq ft.
 
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Last edited by tpring; 02-24-15 at 09:02 PM.
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Old 02-24-15, 07:56 PM
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Had to make it smaller -- Hopefully not too small.

These 'beams' are cradled in iron/steel 'stirrups' at each end.
 
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Old 02-24-15, 08:03 PM
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One more pic -- of cradle.
 
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Old 02-24-15, 10:10 PM
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If intense pick-and-shovel, by the bucketful, isn't your thing, you need to think outside of the box. Many years ago, an old DOT bridge design engineer I worked with excavated the entire crawlspace under his house in Santa Fe, NM, converting it into a very nice basement. He studied the situation for quite some time before coming up with a home-made conveyor system, using a hand-built steel frame holding a large rubber belt, powered by a washing machine motor. He would loosen and shovel just enough dirt onto the conveyor to fill his rusty wheelbarrow parked under the outfall end, which he then carted over to and unloaded (by hand) into his beat-up, old Dodge pickup.

I think it took several years to do the entire, 1000 S.F. space, but that included pouring new footings and walls as he went along. He and his Dodge often showed up on bridge demolition sites, scrounging old bent rebar from contractors that he would straighten and incorporate into his concrete pours.
 
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Old 02-25-15, 06:34 AM
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Originally Posted by bridgeman
He studied the situation for quite some time before coming up with a home-made conveyor system, using a hand-built steel frame holding a large rubber belt, powered by a washing machine motor. He would loosen and shovel just enough dirt onto the conveyor to fill his rusty wheelbarrow parked under the outfall end, which he then carted over to and unloaded (by hand) into his beat-up, old Dodge pickup.
That is great -- I am picturing Red Green. LOL
 
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Old 02-25-15, 01:40 PM
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Definitely post and beam construction. The subfloor is likely double tongue and groove car decking as well.

Yes, the crawlspace can be converted to a sealed space rather than ventilated. You would have to close the vent openings and insulate the sidewalls and foundation/footing (footings are usually pretty shallow in out area due to a high frost line, about a foot below existing grade) with rigid foam insulation boards. You also need to allow for ventilation from the heating system ductwork into the space. You would probably need to replace the existing plastic on the ground with a sealed vapor barrier as well.

As for digging it out...remember that all those posts are holding up the house above and that even after excavation you need those posts although they will obviously be longer. It IS a big job but it can be accomplished. The house I grew up in was originally constructed in about 1905 and then had the kitchen (about a 20 foot extension) added in the 1930s. The main house had a semi-finished basement (1x8 clear fir ceiling and plastered walls) but under the kitchen was just a crawlspace about 30 inches high. I, my brother and our daddy dug out about half of the space using five gallon buckets to move the dirt out. My daddy broke through the original foundation wall using just a hammer and cold chisel making an opening for a door. We used a wood chisel to make a mark on a wooden post near to where the new (for the kitchen build) footing had been poured and that footing never moved a millimeter while we dug. I'll add that on the outside of this wall was just dirt as well as being the walkway next to the driveway. Eventually we got a bit concerned that from rain and simply walking the dirt under the footing would give way and all heck would break loose. This was several years into the project. Eventually my daddy hired a concrete contractor to remove the last bit of dirt, shore up the footing, install forms and pour concrete under the footing and over the dirt alongside the drive way (after excavating several inches) and that was as far as we went. Prior to this work I had already poured a slab about four feet by eight feet and moved the water heater and heating boiler into the space, freeing up a lot of space in the finished basement. I don't recall if the rest of the floor was ever finished.

This was several years before my daddy died and my mother continued to live in the house for another seven years after his death before she died. I sold the house and it continued to stand for another two or three years and was finally demolished for the erection of a three-storey apartment or condo building.
 
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Old 03-02-15, 07:51 AM
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On a related note...

I have drawn a rough draft of my crawlspace and upper floor showing the layout.

The crawlspace is outlined in black, the current line of supports are in red, and the upstairs wall [to be removed] is in green along with the corresponding [5 or 6 red] support beams. The entry to the crawlspace is the opening on the left side.

From what I understand in order to remove the green wall, a glulam beam will need to replace it and must be supported at each end with a post. When supporting it at each end, the posts are then supported directly beneath each post essentially making each 1 tall post [at each end].

An issue that I am now seeing is that if I go through with this, I could end up with a post right in the middle of my entry, hence, making it necessary to move the entry [and spend even more].

Can the beams be supported in such a way that the support does not need to be directly below or, is it just a case of moving the entry?

edit: 3 feet inside the door is the air handler/heater and water heater.
 
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Old 03-02-15, 01:02 PM
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I suggest you move the entry.
 
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