Addition and Garage

So here is the thing.  This house has a basement.  I know that is not usually remarkable but in an area called Tidewater, it turns out that maybe 10 houses in the whole city have basements and none of them have a basement floor elevation of 1.2 feet above sea level!  That means that when the extra high tides or the storm surge from a nor’easter come along, the water table is a couple of feet above the floor level.  And of course, the basement leaks.  When I first moved in I valiantly chiseled out all the cracks and joints with an air hammer and filled with hydraulic cement.  Yes, I reversed keyed the joints.  It held for about 5 years and then the inevitable laws of physics came into play.  Hence, I need a garage!

I also have come to a decision on the interior remodel which will result in all first floor living with no need to climb stairs in the normal day to day.  There is a wonderful large room at the rear of the house which will become the master bedroom but, there are no closets.  Hence, I need a small addition!

Since building these two things involves the same trades in the same sequence, Concrete slab and footings, concrete block walls, wooden rafters, roof and floors.  I determined to build them at the same time.  So far, this has worked out for the good.

I elected to have a monolithic slab poured for the garage.  That meant that the block wall construction could start when the slab was cured and no return trip for the concrete truck to finish the floor.  We dug and poured the slab first and then dug and poured the addition footings.  This allowed the concrete truck to back all the way into the back yard for the slab and eliminated the need for a pump truck.  After the concrete was laid for the slab then the footings on the side of the house could be dug and poured.  If we had dug the footings before the slab was poured, then the truck would not have been able to get into the back yard without collapsing the footing forms.

As readers know by now, this house is a bunker with with 12″ concrete walls.  Therefor I could not consider any other construction method than masonry.  For a number of reasons, cost being one major one, I decided on concrete block, or concrete masonry unit (CMU) construction.  This will be similar to the original construction and when stuccoed, will be indistinguishable from the original walls.

I can not emphasize enough the necessity of engaging a professional engineer in a situation like this.  I serve as my own architect, since I know clearly the details of design that I want but a project of this size, and common sense, requires that a professional provide advise to ensure safe and quality construction.  Before embarking on the whole project I had a professional civil engineer inspect the entire house to insure that the structure was sound and worthy of the large investment in the remodel.  In addition, there are several load bearing walls, heavy masonry walls at that, that are involved. Besides, the city made me do it.

By that I mean that when I went to discuss my project with the city planning department, it became clear that the location of my house required extra effort.  The first hurdle was to clear the requirements of the Chesapeake Bay Preservation Act.  I got very lucky there since my entire lot was deemed to be outside of the preservation area.  It is in the conservation area but that does not require any unusual approvals.  Fifty feet closer to the inlet and just the plans and approvals for construction would have easily added $10,000 to my expenses!

I still wasn’t out of the woods however.  Because my house is near two large bodies of water (Chesapeake Bay and Lynnhaven Inlet) it puts me in a high wind risk zone.  This means that the walls of any construction must be certified to withstand the high winds of nor’easters and hurricanes.  This means that the plans for construction must be inspected and sealed by a professional engineer.

I was fortunate enough to have already found a very good engineer (Wes Lewis) that had provided the inspection of my house in the beginning.  If you know what you want, in detail, then having an engineer work with a draftsman to do your drawings is a very economical approach.  My engineer included his services to inspect the building during construction with a letter required by the city certifying that it had been built properly.  If you are not completely clear on your design and are not comfortable with dealing with the inevitable adjustments and compromises that arise during construction, then I advise that you engage the services of an architect in addition to an engineer.

The pictures below  show the backyard before the garage started and then the digging and construction of the form.  My concrete contractor ( Cornerstone SiteWorks ) has a lot of experience with cell tower foundations which are usually monolithic slabs.  They also had a fierce attention to detail.

You can see how tight the space is for the truck.  You can also see some of the details like the compacted gravel in the middle which is first covered with a plastic vapor barrier followed by welded wire mesh.  As they pour and spread the concrete they pull the mesh up into the concrete.  The trenches around the perimeter have rebar in the bottom.  These are set on concrete block, not brick, and also pulled up as the concrete is poured.  Finally, the slab is troweled smooth, raked around the perimeter to make a good bond with the block and covered with plastic to slow the cure.  After curing for a few days, they came back and sawed two groves perpendicular to each other across the slab.  All large slabs tend to crack.  The cuts provide a place for the crack to occur.  Later the grooves will be filed level with caulk before the floor is painted.

The following pictures show the construction of the footings for the addition.  I am adding 7’4″ to the side of the house.  There was already a bump out there so I just extended it.  This will contain his and her’s closets for the master bedroom.

This is the foundation for the CMU walls that will be built here.  The window shown on the side of the house will be turned into a 4′ doorway with two pocket doors on either side.  This is a non trivial thing since the concrete wall above the door must be properly supported when the door is built.  I will cover that in detail later on.

In preparation for the giant hole to the outside coming to the wall of the bedroom, I constructed a temporary wall.  I made this from 2x4s set 48″ on center and sheathed with 1/2″ foam board.  This is cheap, quick and light.  The seams were taped to stop air infiltration and dust.  This is far superior to hanging plastic and one of the panels was turned into a hinged door which makes moving things like scaffold and materials in and out an easy thing.  Notice that I had to redirect a heating duct because I didn’t want to heat the great outdoors.

The next phase brought my favorite masons back to the job.  This time, in addition to the famous Julio and Marice, Chuck brought his two sons, Andrew and Evan and his brother Jerry to the job.  The first thing they did was to lay out block, conveniently delivered by Lowes on the footings and the garage slab.  This was to be accurate in the placement of vertical reinforcement bars (rebar).  There are two ways to do this.  You can set the rebar while the concrete is wet or you can drill and epoxy the rebar after the concrete has cured.  Many masons will say that they can just drill the holes and drive the rebar into the holes.  This is not acceptable!  The vertical rebar performs two functions.  It stiffens the wall because concrete grout is poured into the block voids around the rebar which creates a reinforced column.  On my wall this is every 40″.  Second the rebar ties the bond beam at the top of the wall to the foundation AND the roof is tied to the bond beam.  Hurricane anyone?  This keeps the roof from being lifted off in high winds.  The bond beam at the top of the wall is a special CMU that has a single horizontal U shaped cavity.  This makes a trough at the top of the wall that has two pieces of rebar in it and is filled with concrete grout.  That is how you make a strong, wind resistant block wall.

It is important to be particular when epoxying the bar in place.  The holes must be cleaned with compressed air and some products require brushing as well.  Then the hole is filled with epoxy and the rod is then inserted.  The epoxy has at lease 5000 psi strength which likely exceeds the strength of the concrete.   The following pictures show the details of the process.  My mason preferred this method because it allows for precise setting of the rebar.  I guess he doesn’t trust concrete guys to space the rebar properly.

Laying the block started in ernest.  These guys are a well oiled machine designed to lay block in the most efficient way possible.  They used a method called knock out block.  This allowed them to place long lengths of vertical rebar and then the knock outs allow them to lay the block without lifting the block all the way to the top of the rebar before setting in place.  It worked well but it involves a lot of cutting for corners and special circumstances.  A lot of dust and rubble generated.  Notice that rebar spacers are used to insure that the rebar stays centered  in the void.  I also had them add fiberglas insulation to the voids as they built the wall.  It’s cheap and makes the space a little more livable.

Then came the SNOW!  I had 2′ drifts in my yard.  There is a slab out there somewhere.

Chuck and crew were great.  The day after the snow they came and cleared the foundations of snow.  Then when the sun came out and it warmed up enough to work, the foundations and blocks were dry and ready to go.  In one day they had the first 5′ of wall all the way around the garage.  they also stuccoed the addition foundation they had laid previously.  The SBC material is a very good vapor barrier and sealant for foundations.  Superior to parging with cement.  Then the cold hit.

It is not a good idea to lay concrete or brick or block at temperatures below 40 degrees F.  So called “antifreeze” used by masons are actually cure accelerants and do not prevent freezing.  If the mortar has cured before freezing then it is not a problem.  Our solution was a giant tent.  We put a giant tarp over the addition and used salamander heaters to warm the enclosure.  It wasn’t hot but it was comfortable to work without heavy coats.  One night we had to run the heaters all night just to insure full cure.  Another thing I forgot to mention is clean outs.  As a mason lays block a lot of mortar fall down the voids in the block.  If that void contains rebar the stuff that accumulates at the bottom must be cleaned out.  Also the mortar that intrudes into the block void as the block is laid should be cleaned and drops to the bottom as well.  A trick my masons used was to place a layer of sand at the bottom around the rebar.  Then all droppings can be easily cleaned out.  They then use a shop vac to clean the bottom.  The hole is then sealed and the void is filled with grout.  The grout recipe is  another interesting thing.  Grout is just concrete that is soupy.  However, if you take a standard concrete mix and add water to make it flow it makes the grout weak.  In order to maintain the cement to water ratio it is necessary to add more cement to a grout.  This will maintain the strength.  My engineer is not a fan of premixed concrete products.  He says that he tested many in his lab (he is a former professor at a local university) and found it hard to get the yield strength to the advertised  level.  He prefers mixing your own.  Therefore I have a large pile of sand, a large pile of gravel and many bags of portland cement.  We created a mix using an online tool and then adjusted by doing slump tests (look it up) to verify the specified mix.   It has been my intent that if the master of concrete that originally built my house looks down from heaven (all masons go to heaven) and sees what we are doing, he will approve.  You can see all of the things I talked about in the following pictures.

Now about the opening from the bedroom to the closet.  This presented a problem.  The original construction used bond beams above the windows.  Since we were removing a window and making the opening wider than the original opening, we needed to add more support.  We would be removing the support from the ends of the original bond beam.  We did this in two stages.  In the first stage we removed the window and the block below it down to the poured foundation.  This exposed the ends of the floor joists which we have to match up with in the new floor.  Then we used a large diamond saw to cut two slots on each side of the top of each wall and extended those slots 8″ beyond our final opening size.  Then we inserted large angle iron lentil beams into the slots.  We used mortar in mortar bags to fill any spaces between the beams and overhanging block.  Then we used the saw to cut and remove the block below to make the final finished opening.  Now we can safely frame within the opening to make the pocket doors and finished opening to the closet.  I know, it seems a lot to do for a closet.  We also had another lintel to place.  My design calls for a glass block window in the closet.  In fact, the concept is that the closet consists of a 4×6 foot anteroom with the closets on either side.  The window is in the center directly across from the door.  We needed to place a lintel above the window opening.  In this case the lintel beams are placed with the tall parts in the center of the wall and block laid above is then supported.  Finally, to finish the walls, we had to lay the block up above the beams that support the old overhang.  This was accomplished by jacks supporting the rake of the overhang and the beams were cut away allowing room for the finished bond beam to be laid all the way to the old wall.  we were fortunate in that the original construction included a void just below the beams for the overhang.  we were able to carry the rebar in the bond beams and the grout into the old wall to further tie the new structure to the old.   Finally, we have a crawl space access door so we also put a small bond beam above that door.

So to bring us completely up to date, 8 Feb 2014, We have finished the block walls for the addition.  Below you can see from the the master bedroom the inside of the closet area, the peak of the roof and the window.  Now its time for the masons to get on the garage and the carpenter to get on the roof of the addition!