it really depends a lot on the height of the retaining wall. im not sure how much the posts would increase the support of the wall. in the past i have used a combination of the t pieces you mention, staggering the front of the wall and constructing the wall in steps staggered back.
it's best to have the same depth of post in the ground as is above the ground., i.e. for a 1m high retaining wall, the posts will be 1m into the ground. also appreciate that it's also the diameter of the concrete post footings that contribute to the strength of the finished wall.
a three foot high retaining wall will, then, have posts recessed below ground three feet. this is pretty rough logic but its a place to start. on flat ground, a retaining wall need not be so deeply footed but, if you want that wall to last, its not that much more work to bury those posts nice and deep.
how deep do post holes need to be for a retaining wall? use a post hole borer to dig 300mm diameter holes so that the total depth is as deep as the wall is high. angle the borer to allow for the slope of the poles 1:10 so the posts lean 100mm for every 1m of height .
when the wall is built with a back slope it just finishes up a bit more vertical. set the posts a minimum of 5mm below the planned finished height. its safer with the hard steel edges below the softer timber. spend some time making sure the tops of the posts are level as any mistakes really show up.
once the posts are cut, then lay them aside, and dig the holes you need on each side of the retaining wall area. they should be 18 inches deep. set the posts inside each hole and then pour quick dry concrete into the hole to hold the posts strht. use 2x4 braces to keep the 4x4's completely strht.
use the 4 pound sledge to hammer 60d wall tie nails through the top of the post into the course below. install the wall tie nails every 16 inches. install full length posts to complete the course cutting only the end post.
how-to-build guide low retaining walls what you can build using this guide this guide shows you how to build a timber retaining wall up to 1.2 m high consisting of posts embedded in the ground and horizontal rails. it includes drainage behind the wall to prevent the build-up of water which could overload it.
mark out post holes along string line as per your plan. dig holes to depth. if your retaining wall is over 1m you will need to angle your posts. angle the hole to allow posts to lean back towards the area being retained at a ratio of 1:10 so the posts lean 100mm for every 1m of height .
that depends on where you are and the local building codes, but it definately has to be below the frost line, assuming it's a 'wet' wall. if the wall is laid up without mortar it's only got to be about 8' deep, but that limits the height that the wall can be. a dry wall usually shouldn't be more than 2 or 3 feet above ground.
the following is a look at what retaining walls are and how to tell if you need one, as well as a discussion of some retaining wall design options to beautify your house landscaping. the functions of a retaining wall. retaining walls are often found in places where extra support is needed to prevent the earth from moving downhill with erosion.
i'm building a concrete sleeper retaining wall that will retain earth just under 1.2m high. the neighbour requested to install an additional sleeper high at their cost so the overall height is 1.4 meters high therefore the depth of the hole will need to be 1.4m down.
how deep do you put posts in for a retaining wall? use a post hole borer to dig 300mm diameter holes so that the total depth is as deep as the wall is high. angle the borer to allow for the slope of the poles 1:10 so the posts lean 100mm for every 1m of height .
diy retaining walls made of interlocking blocks how to build a retaining wall highly recommended for short walls no more than 3 feet tall, the idea is to fill the cavity behind the wall with earth to create pressure that will push these blocks forward and hold the joints firmly with the underlying blocks.
determine the planned wall's height and width. the footing dimensions will largely be determined by the size of the wall. a poured concrete footing for concrete, block or brick walls should be at least twice as wide as the planned wall. the footing should be at least as thick vertically as the wall's planned width.
i'm in the middle of building my retaining wall. i'm using 200x75mm for the posts and 200x50x2400 for the wales. i've put the posts every 1200mm. the depth of the holes varies from 600mm to 800mm deep. the smaller holes are where the augur had heaps of trouble in the rock, but as its in rock i doubt they'll move.
this wall is unusual in that it doesn't rely on dead weight or deep pilings to keep from caving in or shifting. instead, it gets its soundness from the inherent strength of a rigid triangle assembly and the dirt that's piled behind it. the very earth that's the enemy of most retaining walls actually works with this design to give it strength.
double the wall height to 8 feet, and you would need a wall that's eight times stronger to do the same job. with forces like these in play, you should limit your retaining wall efforts to walls under 4 feet tall 3 feet for mortarless stone .
the size of the pit is determined by the surcharge behind you wall and the length of your wall and your area or zone. make sure each of your walls are no more than 3' or you shall be eligible for permit fines if they find out. one wall no more than 4'. check your codes.
sleeper retaining walls 101. for example if your wall is going to be 800mm high, the holes for your posts should be 500mm deep. time now to concrete your posts into position. sleeper retaining wall posts come in two varieties steel galvanised h beams or a vertical sleepers. using sleepers as your posts costs about a third of the price of h beams.
smaller retaining walls, less than four feet, can be easily planned and created without worrying too much about structure. larger walls above that height may need an engineer's touch. also be sure to check with local codes before starting one more than four feet tall.
to maintain a safe load on the retaining wall, the wall should lean into the hill a minimum of 1 inch for every 12 inches of height. this helps with drainage when the soils get saturated. you may also be able to redesign the grade of your slope before placing the retaining wall.
section 1809.5 of ibc 2009 deals with frost depth and leaves most of the requirements up to the local jurisdiction. you may want to look in this section to see if you can work your way out of the requirements for a landscaping retaining wall it's up to your interpretation . as far as other types of walls, see the post above.
answers. for a one brick thick wall that 211 to 220mmm wide the trench will need to be 450mm wide. as for the depth of the concrete 100 to 150mm will be sufficient. you will need to make provision for any ground water at the back of the will to escape use short lengths of plastic rain water pipe at not more than 600mm centres.
setting posts using temporary bridging. with your level string-line in place, you can now measure down to the edge of the hole. lets say its 4-feet from the level string line to the hole. add 3-feet for the hole depth and you know you need a 7-foot tall post. cut the post to length.
not how deep the footing itself should be i'm thinking i'll go with a 1' footingfeel free to comment on that , but rather how deep into the ground do i need to dig my trench in order to set the footing? i know that for gravity walls on sloped yards i need to measure 5' out of where i plan my wall to be and dig the difference.