Expert: Bruce E. Johnson - 10/26/2008

Question
QUESTION: am constructing a basic cement block building and have purchased a metal door
with metal jambs and adjustable width extension flanges (7.5"-8"). What would
be the best way to install-2x8 PT on sides and bond beams above?? Novice at
this so more details in layman terms would be much appreciated.Thanks

ANSWER: Hi david, If your door requires the 2x8 furring around the opening to attach your jambs to then really all you need is some 2x8 pressure treated wood, cut it to fit the opening top and sides and then tapcon the PT to the masonry.  A tapcon is a concrete screw that comes with its own drill bit in the box.  Drill through the wood and into the concrete and then screw the tapcon into the hole.  For 2x8 PT you need at least a 2 3/4" tapcon, preferably a 3" and with a 1/4" shaft size.  Do one of these every 12" in a zig zag pattern up the wood and stay at least  1 1/2" in from the edge. Prior to final installation of the 2x8 I always put a couple of good beads of caulking between the wood and the masonry so when the board is screwed into place.

If your door jamb is made to be installed during the masonry stage, then you brace the jamb in place, making sure that is stays square and plumb and then using masonry ties you mortar the door in place as you build the wall around it.

I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com

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

QUESTION: Thanks alot for the quick reply. Not sure about the top of the door though
and how the header or lintel works.

Is using bond beam blocks with a few pieces of rebar concreted in the best
way to go and if so do are these bond beam blocks mortared to the top of
the pressure treated 2x8 above the door?

 How far over on each side of the door do I continue them before resuming
regular block?

And what is the minimum number of courses of block necessary over the
door. The roof of this building will be poured concrete, covered with a foot
or so of dirt (this is going to be a root cellar built into a hillside for storing
fruit and produce from our garden)

One more question about using horizontal wire every other course and
vertical rebar at each corner and on either side of the door-is this necessary
given that there will be lateral pressure on three sides from the hillside after
I backfill behind the walls and vertical pressure from the concrete roof and
dirt above??

Thanks again!!

ANSWER: Hi again david, I'm sorry I thought you were only inquiring about the
installation of the door.  I didn't realize that you needed masonry help also.  Normally there is at least two courses of masonry above a door or window opening.  Oftentimes it is more than that but in an 8' tall wall you have 16" over the top of a standard 6'8" door.  A two course bond beam or 16" tie beam is used to top off a masonry building.  I use precast lintels over my doorways.  They come in lengths which can be cut to fit.  Usually a minimum of 4" of bearing is required on each side of the doorway masonry.  If you are going to build a masonry header out of concrete block then you will need to build some shoring to support the header masonry until the concrete has been pourted.  Header masonry is called a U-block, which has the top half of the webbing removed and the ends are open so that you can lay rebar into the U part of the block which will be grouted later to make the header solid concrete.  The shoring is removed after the concrete has cured.

Wire wall reinforcement( HJR 'horizontal joint reinforcement) is required every other course and should continue around the corners. You can purchase "L" shaped HJR for the corners.  Vertical steel reinforcement is also required.  Corners and on each side of the door and window openings and one every 48" in the length of the walls is recommended also along all walls whether or not they are retaining earth.

Don't forget to waterproof the exterior walls and provide for a footing drain around the perimeter to ensure that your cellar remains free of moisture.  I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com

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

QUESTION: Thanks again for a very quick and helpful reply! Just to make sure I have this
right-since the last two courses above the door are bond beam, the 4"
overlap of the door is not an issue as this would be part of one of the
continuous bond beam courses used to top off a masonry building. As for
shoring the part of the bond beam up above the doorway while it cures,
would the 2x8 bucks and header take care of this or is another post in the
middle of the 3' span necessary? And are the bond beam blocks mortared to
the header?

Also you spoke of cement in the bond beams and then grout-are they
different and if so which should be used-I would prefer cement since I have
all the "fixings" and a mixer on site.

Finally, you mentioned waterproofing the exterior walls, what do you
recommend for this?

Thanks so much, without your help I would truly be in the dark as none of
the books I have been relying on have this kind of detail in them!!

Answer
Hi again david, There is a difference between the shoring and the Furring for the door installation.  Now you probably could use the 2x8 header for the shoring and leave it in place after the masonry is complete, that is up to you.  When I say grout I mean a small aggregate concrete that has a high cement ratio and can be wet down enough so that it flows into the fill cells and beam blocks and completely fills them up.  It is not mortar but is concrete made with pea gravel and sand.  AS far as waterproofing goes, I recommend a good roofing mastic or foundation waterproofing mastic if available in your area.  I like the kind that is brushable or thin enough to apply with a fat paint roller.  Put on several coats before backfilling against the walls.  I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com