Expert: Bruce E. Johnson - 3/29/2009

Question
QUESTION: I am building 12 in. concrete block walls to support steel beams which will
support a raised (about 8 ft), poured concrete patio floor.  Underneath the
patio floor will not be finished, i.e, no slab, just dirt/gravel.  In one of the
block walls, I want to install a 32 in. door for access under the patio.  The
door opening will begin after the fourth course of block.  The block walls will
be finished with a concrete parging and painted.  I'd like for the door
frame/brick moulding to be a few inches inset from the exterior wall.  I plan
to use a reinforced concrete lintel block for aesthetics.  The door I plan to
install is a standard exterior steel door pre-hung with wood jambs.  Can you
explain the details of building the block wall opening and installing the door
into the opening.  For example, how large should the opening be? Should I
frame the opening with lumber or attached the jamb directly to the block?  
How is the base plate attached to the block?  How is the jamb work sealed?
etc.

ANSWER: Hi Bill, the opening for your door project is based on your brick mould.  Calculate two times the width of the brick mould to account for each side of the door casing(depending on the brick mould but  for example 2x 2 1/2"= 5").  Then add a half inch for the jamb reveal (2x 1/4"). Then add your door width 32".  So in this case your rough opening would be 37 1/2" however you also add 1/4" each side for squaring and plumbing the frame in the opening.  So your rough opening would be 38".  Now, your door width 32" plus the jamb should equal 34" which leaves 4" which will need to be "bucked out" with a pressure treated 2x6 on each side of the rough opening (I use tapcon concrete screws for this).  Use solid shims etc. to square the door frame in the opening. Make sure to keep your door frame as centered in the opening as much as possible so that your brick mold works.  

Your height should equal the rough opening size needed for the door, generally 6-8 + 1 1/2 or 6-9 1/2,  however, with the brick mould you need to take the brick mould in consideration so you add the brick mould width to 1/4" and then add the door height.  If you need special room for your threshold you need to add that also. The top of the door will get a pressure treated "buck" also.  The top course of your block at the bottom of the door is filled solid with concrete and you can tapcon your threshold to that.

So once your block opening is complete:  Put a bead of caulking behind the pressure treated buck as you tapcon them to the masonry.  Install your door frame (as centered as possible in the opening), shim as neccessary and then screw it to the bucks.  I prefer to do all my shimming on the hinge side specifically close to the hinge locations and on the latch side, similar as the hinge side and definately close to the latch location...Anyhow after the frame is installed you can attach your brick mould if it doesn't come preinstalled.  Once you have your brick mould installed you push a foam backing rod between the brick mould and the masonry.  Pack it in far enough that  you can get a good 1/4" deep bead of good urethane caulk around the moulding..That's about it in a nutshell.

If your door comes with the brick mould  and threshold already installed, physically measure the outside dimensions of the brick mould and add one quarter inch to 3/8"  for each side and a quarter to a half inch for the height.   I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com

---------- FOLLOW-UP ----------

QUESTION: Thank you for the reply.   I do have one follow up question.  What is a foam
backing rod?  Thanks!

Answer
Hi again Bill, foam backer rod can be found in the weather stripping section of Home Depot or other similar stores.  It comes is various thickness from 3/8 up to 1".  It is made from foam and looks like rope only foamy and pliable.  Using a putty knife or even a butter knife you push the foam rod into large cracks or joints that are going to be caulked.  Because it is foam, when it is forced into the crack it stays there.  You push it far enough below the surface so that you can get a nice 1/4" of depth on your caulking.  Using the backing rod saves on caulking and helps keep large beads of caulking from falling behind the work surface into the void. I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com