How to install Fence Posts

by Lawrence Winterburn

The most common flaw in all deck and fence projects is poor footings”

Here in Ontario we use footings 4-5’ in depth. A good rule of thumb is to bury 1/3 of the final height of the fence. This will usually give sufficient lateral strength.

·         If you are contemplating a solid fence (sound barrier), or a fence higher than 6’-0” consider increasing the post size to 4” x 6” or 6” x 6” posts due to possible wind damage.  If working with cedar, consider using  treated lumber which is about 25% stronger than red cedar. You can always face with Cedar after.  Again for solid or oversized fences increase the size of the posts or decrease the size of sections or both.

*“Call your local building department first and obtain their specifications before initiating any project”

proper fence footings

Our standard footing shown utilizes a  post set in concrete 4’ deep.

The upper 2’ of the footing is backfilled with limestone screenings or fine crushed stone.

The corner posts are set first and a string line is cast ½ “ from the side of the post to allow the in line posts to be set accurately.


Why a Two Part Footing Works

Two part footings... why they work better.

*Illustration shows how compression over time locks the concrete in place

1)       Screenings compact or settle- allowing the surrounding soil to expand. The concrete will not compact. Over time the soil will encroach over the concrete thus locking the footing in place.

2)       When pressure caused by the expansion of freezing soil or swelling clay based soil (as it absorbs moisture), is transferred to the screenings they will give way allowing the ground to rise and fall independently of the footing.

3)       Screenings will drain effectively and also allow for evaporation keeping the footing relatively dry.

4)       Limestone screenings will prevent growth of vegetation, which retains moisture and causes wood rot.

5)       A footing is only as solid as the ground around it. The screenings will conform to the contour of the ground and adapt to seasonal changes or those caused by extreme winds etc. The post will be noticeably more stable than traditional concrete to grade footings.


Deck blocks are a floating footing, They are free to rise and fall with the effects of frost. They  are suitable on stable ground. Where the ground has been excavated i.e.:  within 3’ of a foundation or where grade has been elevated by adding soil they are not recommended. (If you are intent on using these add a round patio stone beneath it for additional stability. Never connect a floating deck to a foundation.

Fence spikes are never recommended. A seriously inferior product. They will not withstand the pressure exerted by wind on a fence and have shown to be inadequate under the pressure of a deck.


Why do footings lift ?

why do footings lift?

The source of the problem—concrete to ground level. Since the top of the hole is larger than the base, a lip for frost to catch is formed. 

As the concrete is lifted by frost, soil falls into the base which causes the footing to remain—A little higher every year. 

Concrete retains moisture—If using cedar or untreated lumber consider sealing or treating with preservative the portion of the post that comes in contact with the ground or concrete.

* Always call for utility locates prior to digging.