Basement help

[chuey]

I got asked to dig a basement for a couple and I have never dug one before so I am wondering a few things. They asked for an estimate, what is the best way to estimate a basement? Another question I have is do I dig the entire hole to the depth of the footing or just to the depth of the basement floor? Any help would be greatly appreciated.

 

[rino1494]

Here is one that I just did.

 

[diggerdave1958]

Hi, Chuey. Well i would give them a price based on cubic yards excavated and around my area, we dig the whole basement to the bottom of the footings for the walls as they need to use pea stone under the basement floor for drainage.

Rino, in your #4 pic on the far right side is the slab outside the footing for a egress window or a fireplace ??

 

[RonG]

I never saw anyone dig a footing for a house without stripping the topsoil first.You just mix it all together and use it for backfilling?What do you use for topsoil for the lawn?Ron G

 

[rino1494]

I never saw anyone dig a footing for a house without stripping the topsoil first.You just mix it all together and use it for backfilling?What do you use for topsoil for the lawn?Ron G

Believe me, I wanted to, but HO didn't wanna do it.

 

[rino1494]

Rino, in your #4 pic on the far right side is the slab outside the footing for a egress window or a fireplace ??

Instead of using a precast bilco, they laid up block and built steps down into the basement.

 

[bigbob]

You almost never see a block foundation around here, all formed and placed concrete. Frost adhesion would rip the block apart at the joints!

 

[Komatsu 150]

We never see block anymore either but still somewhat common in Wisconsin. I don't get it, can't be any cheaper with the cost of masons.

 

[cummins05]

I keep a bullet level on the front window frame of the hoe level hoe level bucket helps with keeping the bottom as flat as possible.

we dig to the bottom of the footing but I dont worrie I just dig how ever deep the dig plan says from the survey point.

Some cribbers want a ramp dug in on the corner of the hole might be what he did in pic 4

 

[chuey]

Thanks for the pics and information. I also was wondering about when the surveyor stakes off the house perimeter. He stakes back usually 10 feet from where the actual basement wall will be correct?

 

[chuey]

A garage is also attached the home. Whats the best way to go about doing it? sorry for all the questions but I wanna get it right and its better 2 ask than to screw up.

 

[rino1494]

I layout the house by pinning each corner and stretching a stringline, painting it and digging 1 bucket width on the outside of the line.

As far as garage footers. You dig them down to the require depth allowed per code in your area or deeper until you are on solid ground. It is a good idea to dig them a little wide so they fit.

 

[RonG]

Thanks for the pics and information. I also was wondering about when the surveyor stakes off the house perimeter. He stakes back usually 10 feet from where the actual basement wall will be correct?

The stakes are offset usually on the ends of the excavation or the narrow ends of the house but will be in line with the long side of the house but that might include some jogs like a hatchway etc so you really need to check the print to verify what is what.You can quickly tell from the print and an engineers scale what they are using for reference.Make sure that your print has not been resized during the printing as sometimes happens which will throw you off.Double check by measuring some things that you can verify easily like the width of the road etc.The scale that the print is using will be called out on the print.
You can have the offsets staked any distance that you like if you happen to know the engineers and I have had them ask me sometimes if I had a preference.You can also move them yourself if you wanted to,I usually accept the 10' offset as standard unless there is reason to change it.
I have dug zillions of cellars with just a sight level and folding rule,transferring my elevations from the hub,working alone.It is not rocket science,it just requires thinking ahead and making the job work for you.Ron G

 

[792DLC]

1. Strip topsoil. We usually strip 10 to 20 ft more then the actual basement to account for slope away from the basement after backfill. Obviously depends on how deep you are the basement will be in the ground. The deeper you are the less you have to slope away. The shallower the more you would have to strip away to slope away from the house.

2. Stake out the house. We usually go only 2 ft wider then actual basement or sometimes 3ft on a lego basement (ICF) depending on what the contractor doing the walls and footings wants. String line it and mark it out with paint. Inverted paint cans are your friend.

3. Garage footings we usually line up the middle of the bucket with the center of footing. We can get away with this becuz we use a 6 ft twist bucket. We leave the center of the garage unexcavated.

4. We usually spread the dirt out with how the new slope will be away from the house (does this make sense). Level it and track pack it which just makes it easier for all the other contractors on the job. Sometimes we can't make it back to backfill right away and with an ICF basement we Will Not Backfill before 30 days of cure time. Plus if it rains the water runs away from the house and usually doesn't pool near the house. A picture would probably be better to explain this one I will see if I have any.

 

[tylermckee]

we pretty much do it exactly the same as rino, except we hardly ever strip topsoil first as we don't usually have any decent top soil, we just backfill 6 inches low and the landscaper brings in top soil. A lot of the houses we do you can only get a mini around the sides and to the backyard so we grade those areas close to finish grade and only pile enough spoils to backfill. Garages we usually only dig for the fotting, leaving an island in the middle if the soil is good.

 

[Tryin']

Gad, topsoil stripping?! I've only had ONE HO ask for that. . . Granted I mainly do Subdivision type housing, but even with the huge customs, the contractor just trucks it in.

Offsets are generally 10' x 10' from main foundation corners or furthest "bump-out". Fireplaces are sometimes, but back porches are usually not, included around here. I dig the footer lines to full depth and leave the middle (excluding interior footings) 2-3" higher to save gravel. Backfill after seven days of cure.

I'll stay out of the bidding area. . .

 

[bigbob]

Sounds like not to many of you save the topsoil, we call it Loam. I always do! good screened loam is about $18/yard loaded around here. Why throw money away! Sometimes there is only an inch or so of "Forest mat", we save that also.

 

[diggerdave1958]

Well it depends on what we are doing if we will reuse the topsoil, almost all the time we will reuse the topsoil on a septic field job. but if there is only 2-3" of topsoil on a basement job, i would have to be paid to strip it and stock pile it out of the way, because it would be in my way all the time

 

[swampdog]

Either the excavator operator or someone else on site needs to know how to check for the proper depth in all areas of the excavation. A poorly excavated foundation will require a lot of clean up and hand labor. It also can result in high costs for extra gravel and/or extra concrete.

We recently poured footings on a rush job where the know-it-all owner wanted the basement dug and the footings done in an afternoon. The excavator operator may have been good, but that day he could not take his time. The owner was in a big hurry and ordered the concrete trucks before the digging and forming was complete. The bottom of the hole varied considerably in depth. That made forming difficult too and cost the owner a lot for extra concrete. The footings varied from six inches to more than a foot thick in the low spots. Lots of concrete ran out the bottom of the forms and spread beside the forms too. And it required a lot of unnecessary fill and compaction under the floor.

Regarding whether to excavate to the bottom of the footing or to the top of the footing - the answer may depend on the soil conditions. The builder can save a lot of money if they do not need to add in 6 or 8 inches of crushed rock or gravel to build up the area again to the top of the footings. As someone suggested, sometimes it also works well just to excavate deeper for the footings and leave the rest of the area closer to the height of the top of the footings.

 

[CM1995]

Interesting read on the different ways to dig a basement, it's always been a rather simple task for me as far as the excavation world goes.

Down south, most all basements are walk-outs or drive-ins, meaning you will have at least 1 wall of the basement exposed to daylight. If the topography of the lot will not allow that then you construct a slab on grade or crawl space. The frost line according to building code varies from 12-16" depending on the area, so there is no need for deep foundations to get below the frost line. Further south along the coast, you will be hard pressed to find a basement.

This is the way I have always completed this task. Surveyor lays out your "box", meaning giving you the outer most dimensions of the house, usually without any offsets. Using the "box" hubs, set up a few batter boards, offset 10' or so to allow for excavation (your batter boards become your offsets so take care with them). Add 3' to the box hubs and all the inside dimensions to allow for your over dig. Pull your strings and lay out the house and its offsets and corners, painting a line where the excavation will go. Easy thing about this layout is it's just an excavation and precision to the 1" is not required, you check your final product and adjust if necessary but with 3' of over dig it's rare unless you really screwed up your layout.

I haven't ever had the surveyor set cut stakes on a basement layout. Being a builder as well as an excavator you learn how to "read" a lot to set the basement grade. This usually entails taking the highest point of the lot and determining the depth of the basement, taking into account existing slope towards/away from the proposed home. You need to have at least 12" of foundation wall above final grade to thwart termites (something down south we really have to be concerned with) and water runoff.

Once you have your basement sub-grade elevation, you all know what to do - pull levers and burn diesel. Now if you have a "drive-in" basement you will also work your drive way and turn around at the same time while digging the basement. This is probably one of the reasons why track loaders are popular down south for excavating basements. You are building the whole site at this point, usually moving cut from the basement to build the turn around or back yard if it's just a walk-out. It's just not as efficient with an excavator to do this.

Once you get your basement to the desired sub-grade, fine grade the area and double check your dimensions. Next the surveyor comes back out and resets the hubs for the house in the excavation. Footing contractor comes in digs footings, you rarely see any footings formed in this part of the country. After footings are poured, the wall forms are set and poured. After stripping the forms, the sub-grade of the basement floor is cleaned up with a skid and 4-6" of #57 is spread, any plumbing and electrical conduit installed, grade beams dug, vapor barrier, reinforcement and concrete. The gravel drainage layer is set above the top of the footing. This is also a consideration in determining the desired clear ceiling height in the basement. You will have 8-10" of gravel and concrete to deduct from your poured wall height, so a 9' poured wall height will yield a 8' 2" to 8'-4" clear ceiling height, as an example.

After a 7 day cure time, backfill and rough grade the site in order to get ready for the wood butchers.