any way to raise the elevation from foundation?

[bigeye]

We are starting to build a new house.
However, the foundation was put too low. Concrete is like 2-3 feet below where they should sart with.
We stopped right there after we've done the beams. Slab is not there yet.
Is there a quick patch we can do to raise the foundation?

Just from technical perspective. Assume there is no other issue like city code etc.

 

[GeoPaveTraffic]

Is the foundation a cast concrete wall? Is there a basement or a craw space? Give us some information on what the foundation looks like today, and what you want it to look like and we may be able to come up with some ideas.

 

[Qshake]

Where is the house located? The general area will give an idea to the local seismicity which may greatly impact the responses from the group.

For example - Are you in CA? If so then recommendations with cripple walls would be made with great reservations. Unreinforced masonry may not even be possible.

The more info, the better the response.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[bigeye]

The house is in Utah. I haven't checked with city though.
Let's assume there is no legal issue (i.e. city allows daylight basement), and the environment condition allows the action (i.e. doesn't require reinforcement whatsoever).
Look at the house only.

The foundation right now is just with beams (1-2 feet wide, 1-2 feet deep concrete allow the house base). We will have a 8' basement. So I guess there will be concrete wall sit on it and form my basement.

I just want to know technical wise, for house itself, if it's foundation beams already set low, is there still a way to adjust it and raise the basement, hence the elevation of the whole house?

Thank you so much GeoPaveTraffic and Qshake. Your advises are highly appreciated.

 

[oldestguy]

I am sure these fellows will give good advice. I'd use a different term for "beams". We normally call these foundations "footings".

Why not consider a 10 foot available height for the basement? That is pretty standard around here for new houses. It makes development of interior stuff,like air handling easier and maybe some day you want to install a hot tub, needing that extra clearance when you bring it in? Use a tall, wide door however.

Go to it guys.

 

[bigeye]

sorry, maybe I used the wrong term. What is beams and what is footings? The thing I am describing here is the very first step. The 1-2 feet wide, 1-2 feet deep concrete lines along the location of the walls of each room. And also along the frame of the house. I think it's beams for each room and the whole house

Any other suggestions besides asking for a 11 foot basement?

 

[GeotechPE]

Is the top of foundation 2 to 3 feet below the ground surface both inside and outside the foundation? If this is the case and you want an 8 foot basement ceiling, then lay the extra block to obtain the desired first floor elevation and place the basement slab on the existing ground surface (with an aggregate blanket and vapor barrier). Your footings will be deeper than most, but thats ok.

If it is not 2 to 3 feet both inside and out the foundation, more information will be needed to make sure unbalanced earthpressures are controlled.

I also agree with oldestguy, a 10 foot basement height is great for your duct work, plumbing, etc. But note, if the ground surface inside the foundation is 2 to 3 feet above the foundation, you may have to excavate down the 2 feet (8 + 2 = 10) on the inside of the foundation to create the ten foot height. Without basement walls this excavation would not be difficult.

 

[TDAA]

You could backfill the interior, giving you the original height. The will keep lateral loads the same as the original design. Since the walls are not poured yet, I would have them do the tall basement. Might need a bit more reinforcing, but the you could finish that, and have nice clearance even around the ducts.

 

[oldestguy]

A few more points. The writers need to know what sort of basement walls you plan to have, block or poured concrete?

A block wall is not nearly as strong as a concrete wall. In my view either needs reinforcing horizontally. If you can do vertical reinforcing, do so and keep reinforcing more toward the inside face, if possible.

The main problems I see with either foundation is attempting to back fill it before the house loads go on. Many a wall has either deflected in or even collapsed with early backflling.

On the 10 foot height, if some day you want to place a humg ceiling to finish off areas, that can be at the usual 8 ft. ceiling height and won't look so cramped as with an 8 ft. initial height.

A long list of recommendations could be made in addition to above, but no early backfill is my main suggestion. Again, it may be easy to build the house with backfll there, but at least the deck needs to be there. The more weight, the better it works.

Your contractor may balk at doing a 10 ft. wall, since his forms may be only 8 ft. Well, there are ways to go higher with the usual pre-built forming systems and I am sure you can find a guy who can do the job if you look. I'd not combine blocks with concrete walls.

 

[bigeye]

Thank you all for the recommendation.

The fundation will be made of concrete.

I am planning to make the footings taller. Say, pile another 3-4 feet thick concrete on top the current footings. And we will start from there.

Will this be the simpliest?

 

[cvg]

I would suggest you get your builder involved to help you make this decision. He will have to guarantee the work, so he should be part of the decision making process to determine what can be done. You probably also need to run this by the City to see what they will permit. I assume you do have a permit? If you are acting as your own general contractor, you probably should consider hiring somebody locally to help you with this decision.

 

[bigeye]

Sure. I see what you mean.
I do have the contractor.
I just want to get some rough ideas here so that he cannot cheat me on this. Coz I feel like he will treat me like a dumb and say this is how it is and we cannot make the elevation any higher than this.

 

[Qshake]

Well for starters piling more concrete isn't the best solution since you will wind up with a cold joint between the old and new concrete. This will be a location where water will seep into your basement.

Being in Utah I assume that you'll have little to worry about with freeze thaw? If you do, say your in northern Utah in the mountains (?) then you definitely won't want a cold joint where water will get into and freeze thereby expanding and creating more problems.



Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[looksatstars]

Not sure about everyone else but I am having a hard time picturing the problem. To me, your site is excavated and you have the footings around the perimeter of the building but that is it. Why not just bring in loads of gravel and just bury the old footing. Bring the site up the 3-4 feet. Compact the new fill and make new footings and start over again.
Would that work?

 

[oldestguy]

Hey guys:

Isn't this the best suggestion yet bylooksatstars??

Makes a site more easily worked also, no mud.

 

[TDAA]

I like the taller basement walls. Have the contarctor pay for it - he screwed it up. It might cost him as much (in time and dollars) as scrapping the old foundation, filling, and reforming for new foundations, etc. than it would be to add a bit of steel for better lateral load resistance and keep moving. I say take the benifit it provides.