Building Homes or Extensions/Addition foundation

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Expert: - 7/29/2010


Question
I am designing a addition. The house has a full basement.
The owner want the addition built on a concrete slab.
What type of footing and foundation will I need?
Owner want "monolithic" How do I do attach the slab to
the existing foundation wall? Will I need footings?

Answer

mono slab tie in
Hi John, a monolithic slab foundation has the footings built right into the slab so you pour your footings and slab at the same time.  I am attaching a simple sketch.  As far as attaching the addition slab to the house foundation?  I have done it both ways, attached and not attached.  If you are worried about soil conditions and the new addition settling over time then you should attach the slab to the existing foundation.  This is normally done by drilling 3/4" holes into the basement foundation and ,using two part anchor epoxy, epoxy dowels made from #5 reinforcing rebar.  Generally speaking the dowels are inserted into the existing foundation one half the depth of the foundation wall thickness.  In other words if the existing wall is 8" thick then your dowels are embedded 4" into it.  This doweling effect keeps the slab from settling should it have a tendency to do so.  But good ground compaction prior to pouring your concrete is more important.  If the ground is properly compacted and then the dowels are added you will have a superior connection.  I hope this information helps, please feel free to write again regarding this or othe matters, sincerely bruce e johnson  
    Questioner's Rating
    Rating(1-10)Knowledgeability = 10Clarity of Response = 10Politeness = 10
    CommentBruce, I can not thank you enough. You have solved my problem. If there is anything I can ever do for you, please do not hestitate to ask. John jcpolitte@aol.com


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Bruce E. Johnson

Expertise

I can answer any construction related question in regards to carpentry, concrete, drywall, masonry, structural elements of any type of building, residential or commercial. Interior or exterior.

Experience

Custom Commercial and residential buildings. Churches, theaters, schools and auditoriums. Most recently I am working with the Catholic Church on several design build committees. I have a website related to scheduling and project supervision. Although my expertise is more related to multimillion dollar commercial, educational and theatrical projects my generous credentials in residential and remodelling construction make me a viable source of information regarding all forms of building questions.

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