How To Install Landscape Timbers On A Slope

Installing landscape timbers on a slope can be a daunting task, but with a little preparation it can be accomplished relatively easily.

Completing landscape projects on sloped terrain can be generally challenging since it is more prone to soil erosion and shifting of the ground due to the slope.

Landscaping timbers can be used to form retaining walls, containing the soil and giving your landscaping project a neat and polished appearance.

Be sure to check with your local building authority if a permit is needed before you start the work. It is always better to get the red tape out of the way first. There is nothing worse than having to pull the wall down later because you didn’t cross all the ts and dot all the ‘i’s with the relevant authorities from the start. 

1 Planning

Whether installing landscape timbers on sloping ground is difficult or simple, the process will require an accurate plan. The plan should include identifying the requirements for the area and how best to secure the timbers in place.

Begin construction of your wall by driving wooden stakes to mark the corners and tying string between the stakes to mark the top and bottom borders.

2 Dig A Trench

First, you will need to dig a trench for the timbers to sit in. The depth of the trench will depend on how steep the slope is. For a slope that is less than 10 degrees, the trench should be about 8 inches deep. For steeper slopes, the trench should be deeper – 12 to 16 inches is ideal.

3 Fill

Where the timbers will sit needs to have a base of gravel or sand to assist with drainage and to provide a firm base for the timber to sit on. It will greatly assist in maintaining the longengevity of the timber if it is resting on gravel or sand, and not bear dirt. Evenly cover the bottom of the trench with at least 1 inch of sand or gravel.

4 Cut Timbers To Fit

Make sure that the first row of timbers are set end to end, and that the length is just right for the trench. Use the chainsaw to cut the pieces so they fit tightly into the trench.

5 Cut Second Row Of Timbers

Lay the second row of timbers on the first row. Stagger the seams above the first row of timbers when laying the second row. Every subsequent row should be pitched into the slope by 1/4 inch from the row below it. Between the first and second rows, drive galvanized spikes to secure the wall. It’s easier to work with the wood if it’s predrilled.

6 Deadman And Header Pieces

For the dead men and header pieces, dig perpendicular ditches into the sloped hillside. By jutting into the hillside, these short pieces of wood will help to solidify the wall further. Each 6 to 8 foot section of the wall should have a deadman piece.

Install the deadman and header pieces in the prepared perpendicular ditches and level them.

7 Rinse And Repeat 

Repeat the steps 4 to 6 to continue building up the wall.

8 Backfill

Use sand or gravel to backfill to the second row.

9 Backfill With Soil

Backfill the trench so as to cover the entire top area with soil, taking care to tamp as you go.

10. You’re done. Maybe time for a beer??

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