Showing posts with label core drilling. Show all posts
Showing posts with label core drilling. Show all posts

Sunday, 1 March 2015

Installing a fence on top of a limestone wall

Arguably, one of the tidiest looking Colorbond fence installations sits upon limestone blocks. Why the tidiest? Because instead of the Colorbond posts being concreted into a hole in the dirt, a neat, round hole is core drilled straight into the limestone blocks for the fence posts to sit in, then filled up with concrete nice and cleanly.

If there is a height difference in the soil between properties, that is if one house pad sits up higher than the other, installing a limestone retaining wall on the boundary will mean the fence can sit squarely on the boundary, with equal amounts of limestone block on either side.



Above: Prior to installing the large limestone blocks, an old asbestos fence was removed as well as some limestone garden edging. A tree stump had to be removed, and a string line set up to see what else might be in the way. The timber screening put in place further down the fenceline was to add height and privacy for both neighbours, since previously the fence sat lower (not on top of the retaining).

Above: Once all obstacles along the stringline are removed, the dingo can be brought in to lift the blocks into place (these big blocks weigh 240kg each!).
Above: One course of large, one metre limestone blocks have been installed to make up the height difference between neighbouring properties, ready for the installation of a new Colorbond fence.
Above: All of the Colorbond fence post holes are core drilled into the limestone blocks.

Above: The completed Colorbond fence with infill panels now installed, sitting atop the limestone blocks.

When installing a Colorbond fence and a limestone wall separately, be aware that any steel used to reinforce the limestone may present an issue in core drilling the holes for the Colorbond fence posts. New drill bits for a core driller can be costly, so talk to your fence installer prior to giving the go ahead on the limestone installation. Using larger limestone blocks can prevent the need for reinforcement.






Core drilling limestone blocks for colorbond fence installation

Where possible, core drilling limestone blocks is the preferred choice of most reputable fencing contractors.
Core drilling for a colorbond fence installation is generally considered the most aesthetically pleasing finish. When installed to a neat, level limestone block wall, the fence rails will sit flat on the surface exposing little to no gaps. The clean lines of the fence will compliment the wall and the wall will in turn compliment the fence.

Many people are not aware of how easy it is to install a fence with this type of installation method, although, as is the case with any building work, the correct equipment and knowledge is key to a successful fence installation.
Unlike installing with a post and panel type retaining system, the limestone block retaining wall can be installed to align the centre of the block with the centre of the surveyed boundary. When using a 1m x 350mm x350mm limestone block as a base for your fence installation, you can run the boundary with a 175mm centre (when installing a common fence), meaning the block will hug the boundary and will be exposed on just under approximately the 175mm boundary line taking into consideration the bottom rail dimensions. When installing on a Limestone block it is advised that the fence be installed in the centre of the block. This will not only look pleasing to the eye but will more importantly provide the fence base with the best structural support.       

The procedure is displayed and described in order of the pictures you see here from a recent Perth Trade Centre fence installation.

On this particular installation we were working with an existing natural limestone wall and screening an unsightly pre-installed picket fence that was installed on the outside facing wall.


The top of the wall is aligned, marked and core drilled using a core drill machine. It is very important to make sure the measurements are absolutely perfect. This is considered the most important part of the job.


The core is then removed leaving a hole that will accommodate the base of the fence post.

The bottom rail must be in line with the hole and boundary dimensions, also taking into consideration the size of the post.

The post is then lowered into the hole attaching to the rail joining from one panel to the next.