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Building Homes or Extensions/Enlarging crawl space opening

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Expert: - 12/2/2009


Question

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The crawl space under my house is 6' high at the lowest place (by the door).  The door opening is rough 4'-0" by 5'-6" and I would like to expand the opening by one foot or two feet so that I can store my riding lawn mower.  

The foundation wall is constructed of studs sitting on 5 or 6 courses on 8" cmu sitting on concrete footings which you probably know.  

To enlarge the opening I would have to cut 3 or 4 course of cmu and rebuild the opening on one side.

What are your thought about the structural integrity of doing this and would I have to reinforce the girder/header?  Can I cut the opening using a rental concrete saw?

I live in the Piedmont area of NC.

Answer

BASEMENT/ STEM WALL OP
Hi Josh, I don't see a problem doing what you want to do.  I'm not sure what kind of header your existing door opening has if any.  From your drawing it looks like your floor joists are being supported over the door opening by the rim joist or perimeter joist that your joists butt into.  If this is the case you may want to double up the rim joist and turn it into a beam.  This can be done a couple of ways.  You can support your joists with temporary shoring, remove the amount of stud wall you want to remove plus 3" on each side, use a sawzall to cut 1 3/4" off the ends of your joists, slip an additional 2x12 or whatever size your rim joist is, into place, add two cripple studs on each side, nail the rim joists together and add joist hangers to the joists, remove the temp shoring and then cut the concrete block with a rented 14" cut saw.  If you have a header over the opening now and it is a minimum of double 2x6 (for up to a 6' span)  double 2x8 (for up to an eight foot span) etc.  Then you can cut out your wood wall and install a new, properly sized header over the opening.  I am attaching a simple drawing to illustrate.  I hope this information helps, feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com

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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