Part 2 – Demolition and construction of the landing
This post is the second in a series that describes the construction of an elegant but practical front entry, providing you with how you can turn your front walkway landscape idea into reality. Let’s start with a look at the old stairs and landing area on the left to compare with what was created on the right.
Before we could begin the walkway landing construction, we had to remove the existing landing. Normally excavation would take care of the job but in this case due to the ledge that the home was built on, the concrete of the old landing was fused to the ledge, forming a huge rock and requiring hydraulic equipment to break it up.
Some people think demolition is easy but we first need to determine if the current landing has a foundation and if so, is it attached to the house foundation. In this case the landing was not attached as this house was built before the build code was updated to require that landings be attached. If there is an attached landing, the contractor needs to carefully separate it from the home so as not to do damage to the foundation. Keep in mind that depending on your town, an inspection by the building department may be required at certain phases of this work.
Now that we are cleared to excavate the old landing, we need to completely excavate the soil around and below the old landing, looking for virgin material. The reason for this is virgin material will pack tighter and eliminate possible settling of the new landing.
Creating the landing foundation
The landing will require new concrete footings at a minimum of 4 feet below grade. However, depending on the soil types we discover, the concrete footings may need to be deeper. In a project like this, we are looking for non-organic soil, preferably gravel as the foundation for the landing area. If these soils don’t exist, we will need to excavate more materials and add crushed rock and compact in lifts, to bring the ground back up to starting grade.
The bottom of the hole needs to be level and dug out by 1 to 1.5 feet larger on all sides than the finished size of the new landing. Once the crushed stone base or virgin ground gravel base is level and compacted, footing construction can begin.
Walkway landing construction begins
Footings are constructed with poured concrete, leveled to ensure the base of the landing is solid. To begin the construction of the concrete footing, a wood form is built in hole after careful measurements are taken. The importance of having the footing square and level cannot be over emphasized. Once forms are built and secured in the hole, concrete can be poured and leveled to the height of the form. Top of concrete shall be screeded level with the top of the form and keyed to accept a concrete modular unit (CMU) which will be built on top of the cement footing.
The CMUs are constructed on the cured footing using mortar, forming the framework for the landing, with their outside dimensions being the same as the proposed finished landing. The CMU are built up to or just below the finish grade height of the landscaping, as these are raw looking and we don’t want it to be visible. The CMUs are pinned to the house foundation using rebar pins that are drilled into the concrete house foundation, ensuring no movement or separation from the house.
After the CMU framework is completed and cured, it can be backfilled. Before we backfill, we spray a concrete sealer on the below grade foundation for extra longevity, then backfill with crushed stone on the inside and existing site soils on the outside. Backfilling is done in 8 inch lifts, that is the soil and aggregate fill is compacted with a plate compactor machine every 8 inches to ensure no settling later. Water is used to aid in soil compaction.
The finishing touch
After the backfilling the substructure is complete, the landing construction work can begin. The materials chosen for this job include Brussels Dimensional Stone by Unilock. The antiqued or weathered appearance of Brussels Dimensional Stone is a great alternative to expensive natural stone products. These blocks will form the outside of the landing and stair risers to give it a finished appearance. While the framework is being constructed using the Brussels Stone, the inside is backfilled with crushed stone and mortar. Once the overall height and stair landing layout is complete, the inside is filled with crushed stone to within 4 to 6 inches of the top layer of Brussels Stone. The remaining area is poured concrete with rebar pins locking the three sides together along with concrete wire mesh.
The final phase of building the landing is to install the stair tread and landing materials. The material chosen is bluestone, an attractive and durable material that comes in many complementary patterns and colors. The bluestones are cut onsite for the perfect fit. Once all the stones are set and perfectly placed on the mortar bed, the joints are grouted. The completed landing will now need to cure. Later it will be acid washed and sealed for longevity.
The key to a solid, long lasting quality landing is paying attention to the preparation of the foundation and ensuring it is level and stable before building the landing. Many landscape construction contractors make it look nice on the outside, but it is what’s inside that counts.