Top Mark Property Improvements > Natural Stone Retaining Walls
Natural Stone Retaining Walls
Armour stone retaining walls are a very popular way of adding timeless beauty and functionality to your garden, especially if your garden has different elevations. Armour stone is natural stone and is quarried mainly by two different methods: drilling or blasting the rock face 8, peeling off layers of stone with an excavator.
Traditionally, armour stone is quarried by drilling and blasting, so its final size, shape and quantity could not be guaranteed. These types of Armour stones are great as accent pieces but are not recommended for retaining wall construction as they cannot be stacked effectively. For retaining wall construction, Armour stones that are of uniform height with smooth surfaces are the best. Usually, stones that are about 12,14″ in height, and weigh in excess of a tonne, are best suited for retaining wall construction. We obtain our Armour stones directly from the quarry and each stone is handpicked at the quarry to ensure that they are the best suited for retaining wall construction.
Stand alone Armour stone retaining walls can be categorized as Gravity retaining walls: they use their sheer weight to retain the soil behind them. Armour stone retaining walls do not interlock and each stone is held in place by gravity and friction. Since these walls are somewhat flexible they can absorb movements without undermining the structural integrity of the retaining wall. Depending on the site conditions and soil characteristics, Geo-Grid may be incorporated into the retaining wall design to stabilize the Backfill and to act as a Tie-Back.
Dry-stacked gravity walls are somewhat flexible and do not require a rigid footing in frost areas. However, a solid Foundation constructed with mechanically compacted gravel is an absolute must. Proper Drainage to dissipate the ground water in behind the retaining wall, and drainage material to minimize hydrostatic pressure, will help prevent the retaining wall from suffering premature structural failure.
Dry-stacked gravity walls are somewhat flexible and do not require a rigid footing in frost areas. However, a solid Foundation constructed with mechanically compacted gravel is an absolute must. Proper Drainage to dissipate the ground water in behind the retaining wall, and drainage material to minimize hydrostatic pressure, will help prevent the retaining wall from suffering premature structural failure.
Sandy Dix Garden Wall
The original garden retaining wall was a 3 tiered wooden retaining wall made of 6 x6 pressure treated timber. The wood had been installed for a few decades and was extensively rotten. It had lost much of its aesthetic appeal and was infested with insects and mold, as well as being unsafe.
The replacement wall was made of an Ontario natural stone quarried in the Owen Sound area. The stone known as Eramosa, or ‘Tiger Stripe’ was dry-stacked, using a combination of 8 inch high and 4 inch high pieces. Each tier of the wall was ‘bookended’ with a large piece of Armour Stone in order to provide visual appeal while saving material cost.
Stone was laid on a bed of ¾ inch gravel and dry-stacked. Gravel was placed behind the wall for drainage. A 12 inch x 2 inch Natural Stone Eramosa coping glued atop each layer of wall.
Jancy King Wall
This home in Toronto’s High Park district originally had an informal tiered rockery-style retaining wall. The homeowners wanted a more formal look to create a tiered planter-style wall. The original stairs were solid concrete, and had cracked and were unsafe.
The replacement wall was made of dry-stacked 8 inch high Eramosa natural stone from the Owen Sound area of Southern Ontario. The wall was laid on a base of ¾ inch gravel, and back filled using ¾ inch clear gravel. Non-woven filter fabric was used to separate the sandy soil from the clean gravel. Flexible 4 inch socked weeping tile was used behind the wall for drainage. Geo-grid mesh was used as tie-back material every 24 inches in height for structural support.The two sets of stairs were both made of rough finished (bush-hammered) Eramosa treads, individually set on a concrete base. Top coping of entire wall was natural Eramosa stone for visual appeal.
