Using stone (Boulders) to construct foundation wall?

[Morpheos137]

Hello I am located in CT. I have harvested a large number of boulders from clearing a house site on raw forested land. I figure why not put them to good use and incorporate them into an underground or above grade structural wall and fill the gaps with concrete. It seems it would save a lot of concrete from pouring a pure cement wall / footing. I am just trying to figure out how to do it according to code.

Another idea I have is using the boulders to actually build structural exterior walls of the home again bonding them together with concrete. The problem I have is again doing it according to code / a formal house plan.

A third idea I have is replacing a concrete slab for a home with a boulder stone floor. I have a machine that I could use to create a level floor / footing in lieu of a slab extending beneath the frost line using the boulders. Again the problem is not execution but code compliance. I would place the boulders in a grid tiling pattern and run utilities, radiant heat, through the trenches between boulders and again fill the gaps with concrete to create a level, bonded floor slab composed of boulders.

Does anybody a recommendation/reference for a local architect to come up with a formal code compliant building plan to incorporate my boulders? Located in CT, east of the river, Windham County.

 

[steveray]

Hello I am located in CT. I have harvested a large number of boulders from clearing a house site on raw forested land. I figure why not put them to good use and incorporate them into an underground or above grade structural wall and fill the gaps with concrete. It seems it would save a lot of concrete from pouring a pure cement wall / footing. I am just trying to figure out how to do it according to code.

Another idea I have is using the boulders to actually build structural exterior walls of the home again bonding them together with concrete. The problem I have is again doing it according to code / a formal house plan.

A third idea I have is replacing a concrete slab for a home with a boulder stone floor. I have a machine that I could use to create a level floor / footing in lieu of a slab extending beneath the frost line using the boulders. Again the problem is not execution but code compliance. I would place the boulders in a grid tiling pattern and run utilities, radiant heat, through the trenches between boulders and again fill the gaps with concrete to create a level, bonded floor slab composed of boulders.

Does anybody a recommendation/reference for a local architect to come up with a formal code compliant building plan to incorporate my boulders? Located in CT, east of the river, Windham County.

You could look into Cartier Structural Engineering or...Kathy LaCombe is an architect and Building Official out that way...Those are the only 2 I "know" out that way...

 

[Joe.B]

 

[ICE]

Might be a problem incorporating reinforcing rebar.

 

[Joe.B]

Hello I am located in CT. I have harvested a large number of boulders from clearing a house site on raw forested land. I figure why not put them to good use and incorporate them into an underground or above grade structural wall and fill the gaps with concrete. It seems it would save a lot of concrete from pouring a pure cement wall / footing. I am just trying to figure out how to do it according to code.

Another idea I have is using the boulders to actually build structural exterior walls of the home again bonding them together with concrete. The problem I have is again doing it according to code / a formal house plan.

A third idea I have is replacing a concrete slab for a home with a boulder stone floor. I have a machine that I could use to create a level floor / footing in lieu of a slab extending beneath the frost line using the boulders. Again the problem is not execution but code compliance. I would place the boulders in a grid tiling pattern and run utilities, radiant heat, through the trenches between boulders and again fill the gaps with concrete to create a level, bonded floor slab composed of boulders.

Does anybody a recommendation/reference for a local architect to come up with a formal code compliant building plan to incorporate my boulders? Located in CT, east of the river, Windham County.

Do you know the seismic design category?

 

[Joe.B]

 

[Yankee Chronicler]

View attachment 15973

Connecticut didn't amend that in adopting the IRC. The sticky wicket is the "shall not support a soil pressure greater than 30 pounds per square foot per foot ..." part. You're going to need a civil engineer or geotechnical engineer to investigate the specific soils where you want to build this, and determine whether or not the resulting pressures will be within the 30 psf parameter.

The superstructure still has to be anchored to the foundation to resist uplift and lateral displacement, so you'll also have to have an engineer design an anchorage detail.

 

[bill1952]

How big is a boulder in your view? To me a boulder is a lot bigger than you can pick up with out a hefty machine.

 

[Morpheos137]

Funny we have post and beam colonial era houses in my area with boulder basement walls that have been standing for 250-300 years. And yet the building codes require an engineered foundation to build something with sticks and OSB and vinyl. Sorry frustrated.

 

[bill1952]

I've lived in two houses with limestone foundations/basements and no problem. In a non seismic area, probably not too hard to get accepted.

 

[Yankee Chronicler]

Funny we have post and beam colonial era houses in my area with boulder basement walls that have been standing for 250-300 years. And yet the building codes require an engineered foundation to build something with sticks and OSB and vinyl. Sorry frustrated.

I live in southern New England. There are certainly some colonial houses that were built on rubble stone foundations, but I've looked at a lot of them and pretty much all of them used stones that were at least rough cut to shape, not fieldstones as pulled from the dirt, and laid up carefully, not just piled randomly.

 

[Yankee Chronicler]

Funny we have post and beam colonial era houses in my area with boulder basement walls that have been standing for 250-300 years. And yet the building codes require an engineered foundation to build something with sticks and OSB and vinyl. Sorry frustrated.

Until the department I worked in was downsized and several positions were eliminated, I was (until July 1) an assistant building official in a mid-size town in Connecticut. Last year we had a house collapse in town. It was one of those old post-and-beam colonial houses to which you refer. It collapsed because the original stone foundation couldn't resists the weight of the soil after we had a week straight of heavy rain.

I'm sorry if you find building code requirements to be frustrating. You are not alone in that opinion. Nonetheless, the state has adopted the codes and -- by law -- the codes represent the minimum standard for what the state considers to be a safe building. The codes actually allow for a lot of innovation, but new, alternate, and innovative construction doesn't fall within the prescriptive parameters of the code, so you need a licensed design professional to prepare the design and provide some assurance to the building official that your alternative design will provide a level of safety equivalent to the prescriptive requirements in the code.

 

[bill1952]

Methods and systems that in the prescriptive code have also failed. The question should be which have failed more by percentage.

I suspect the reason rubble stone foundations are not in the code has more to do with the home building businesses than it's suitability and safety.

 

[BN4537]

Funny we have post and beam colonial era houses in my area with boulder basement walls that have been standing for 250-300 years. And yet the building codes require an engineered foundation to build something with sticks and OSB and vinyl. Sorry frustrated.

We have some here too... we used to have a lot more before they failed and were removed. Remember that the ones still standing represent the best of the best in the construction knowledge and industry of the time, combined with varying levels of luck and overkill to cover elements and forces that were unknown or unquantifiable at the time. Trust me, someone spent a lot of time and effort and experience "engineering" the ones that lasted, even if their methods were just wide-scale trial and error.

If you are going to do something similar to what they did, you have to be as good or better than the best available at that time, because the stuff built by average quality builders are either not still standing or barely hanging on because they got lucky in never facing standard design load forces. You will have to take into account that your loading and differential movement will be different than theirs because you will have items they did not have and you will be using building techniques that they did not use. Your mortar/concrete will have different properties than theirs did as well. So will your lumber.

Not impossible, but not simple either.

 

[Yankee Chronicler]

Methods and systems that in the prescriptive code have also failed. The question should be which have failed more by percentage.

That's a question for the people who write and who adopt the codes, it's not a question I have to ask or answer as a building official.

R101.3 Purpose. The purpose of this code is to establish minimum
requirements to provide a reasonable level of safety,
health and general welfare through affordability, structural
strength, means of egress, stability, sanitation, light and ventilation,
energy conservation and safety to life and property from
fire and other hazards and to provide a reasonable level of
safety to fire fighters and emergency responders during emergency
operations.

I suspect the reason rubble stone foundations are not in the code has more to do with the home building businesses than it's suitability and safety.

Or the difficulty in quantifying and codifying a traditional, ad hoc construction method. But ... rubble stone foundations ARE in the code.

 

[Paul Sweet]

Good foundation drainage is even more critical in rubble stone foundations to keep the soil pressure below 30 PSF per foot. I recommend a perforated PVC footing drain discharging to grade in 2 or more locations and stone backfill.

 

[bill1952]

Good foundation drainage is even more critical in rubble stone foundations to keep the soil pressure below 30 PSF per foot. I recommend a perforated PVC footing drain discharging to grade in 2 or more locations and stone backfill.

I assume this would be for a foundation wall with habitable space on one side? I'm not sure what the OP intends. I like the rubble stone foundation for slab on ground buildings, no or minimal unbalanced fill, but drainage is still required for frost protection.

Do you think a mortared rubble stone wall is more susceptible to water intrusion than cmu or concrete?

Rubble stone seems to have so many variations from dry lay to mortared to formed - formed walls with concrete and rubble stone and even foam.

 

[Yankee Chronicler]

Rubble stone seems to have so many variations from dry lay to mortared to formed - formed walls with concrete and rubble stone and even foam.

You raise a good point. The IRC has a provision for rubble stone foundations, but it doesn't have a definition of what a "rubble stone" foundation is. I think it refers to a dry-laid construction made up of un-cut field stones. The question indicated using "cement" to fill gaps between the stones. I interpreted "cement" to mean mortar, not concrete, so IMHO what the question is actually asking about is stone masonry, not rubble stone.

 

[bill1952]

I can't guess what the code's intent is, but pretty sure rubble stone masonry can be mortared or dry lay, but always uncut stones

And ashlar masonry is cut stones, also mortared or not.

At least that what the Internet seems to suggest.