Retaining Wall Backfill

For a terraced look in the backyard or for claiming more land if you are living on a slope a well-constructed retaining wall can add more living and growing space. Theses are basically “earth dams” which need a strong support to hold back the dirt.

In the past many of these used to fail after years because most of them used to be made of wood. ven pressure-treated wood only has a limited lifespan in normal soil conditions. However, cement was no better because it would crack in a freeze-thaw situation in wetter climates.

The new cinder-block- or pressurized concrete block- systems work better because each block can move with expansion and contraction. There is no cracking or falling over. This is in part to do with the wall being angled back. This means that a 1″ lip on the top front of the block pushes the next course back so if the blocks are 10″ high then for a 60″ height the wall angles back 6″.

A big part of a retaining wall system is the material directly behind the wall. Since water also causes a lot of pressure against a retaining wall there has to be a way to get it out before the pressure becomes too great. Before the wall is built a 4″ perforated pipe should be put down on the bank side and this should drain water away so should be slightly angles lower.

The next step is to get 1″ crushed rock behind the wall to aid in the drainage. So the wall should not be built directly into the bank but should have a space behind for the drainage rock. However, this buffer can get clogged from the dirt behind as the silt seeps in with the water. So landscapers use a fabric to strain the water and keep the silt back. This is spread over the bank before the crushed rock is put in against the wall itself. if you want a flower bed on top of the wall then the fabric can be put down between the rock and the topsoil.

For walls over 6′ usually 2 walls are built, the top one one staggered behind the first one.

Buying Softwood for Projects

Shopping for wood is never the same every time. The methods change with the type of wood you are looking for. For example, if you are buying plywood you would not use the same methods as you would 2′ X 4′ studs or stair railings. However there are many things that they have in common. Construction boards are usually everything from 1″ X 3″ strapping to 2″ X 12″ boards and depends on the use.

1. Grades: Boards usually loose a 1/2″ during the milling and drying process so a 2″ X 4″ plank is actually 1 1/2″ X 3 1/2″. “Dressed lumber” is usually planed smooth whereas “Rough” shows the saw marks and is not usually used in construction. “Construction” and “standard” grade wood is usually free of bark and is the proper dimensions the full length of the board whereas “utility” will show some rounded areas and bark because it came from the edge of the board. Utility is not a bad board, especially a straight one, because it’s really cheap and can be used behind walls.

2. Linear vs. Board Feet: Board feet is the cubic amount of board whereas linear is the length. For example a standard 2″ X 4″ X 8′ stud has 5.3 board feet and and 8 linear feet.

The best way to buy them is to pick them out yourself from a pile. Some lumber yards frown on this but to get good boards you have to sort through them. After boards are milled and kiln dried they may warp and twist and this may not show up until the packing bands are taken off. With the pressure gone the wood may try to find its original shape along the grain and twist. Therefore, look down each board to see if it is straight because these ones do not cost any more than the warped ones. A slight “crown” is okay.

Pressure-treated wood is more expensive but you should still pick through the piles. If ordering large quantities for a deck most suppliers will take back the twisted pieces afterward.

Look for bargains in the flyers. They are usually in the spring and fall.

Pressure Treated Wood

We all marvel at the amazing new products for decking that have come out in the past dozen years. They are all meant to be low-or-no maintenance for the homeowner so they can enjoy their deck instead of have to paint it every year or so. Because real wood rots after years of use, even the decks which are well-maintained. So the invention of the pressure-treated wood process has put wood back outside with great results.

Pressure-treated (sometimes called preservative-treated) wood is formulated in a process where chemicals are forced into the wood. This is done in a special chamber which uses both pressure and vacuum forces. Although a very effective method for preserving wood the chemicals do not go that far down into the wood because the cell walls of the wood are dense. So for cutting you have to soak the ends in chemical or you will have raw wood exposed. This wood is graded on the amount of chemical retention it possesses which is based on the length of time spent in the treatment tank.

Most wood uses in construction used to be treated with chromated copper arsenate (CCA). However, because of its toxicity the industry, in January 2004 the US and Canada shifted away from CCA for residential purposes in . Taking the place of CCA are amine copper quat (ACQ) and copper azole (CA). However, CCA is still used for exterior purposes and non-residential applications: shakes and shingles, wood foundations, utility poles, etc. Ammoniacal copper zinc arsenate (ACZA), another toxic treatment, is more limited in its uses but suited for wood going into water.

Breaking down the chemicals in CCA,, copper is used as the fungicide and arsenic kills insects and mold-related species. The chromium compound is a base for the mixture and provides resistance to ultra-violet rays. Rather than a coating the CCA penetrates the wood in a water solution causing a reaction with the wood fibers to form non-water soluable bond called a “fixation.” In fact the CSA standards are explicit that fixation has to be complete before shipping the wood.

Amine copper quat (ACQ) was developed in Canada and is now available in the USA, Europe and Japan . It uses copper for the primary anti-fungal agent and a quaternary ammonium compound (quat) for the secondary. Quats have many other uses as well: cleaning pipes in food processing areas and breweries, antiseptics in hospitals and eyewashes. Copper azole (CA) contains an organic compound as its secondary fungal agent. Other copper compounds such as acid copper chromate and copper citrate are also being used but not as much as the first two.

Borates are also been used as they are almost environmentally inert but they do not work well in wet areas. However, unlike the others borate will continue to penetrate the wood long after the initial treatment for a much deeper penetration. In fact, it is possible to achieve penetration with borate throughout the entire piece. Borates are also commonly used in non-pressure methods of wood treatment.

After a year of weathering the wood is in a position to take a stain and can be finished just like ordinary wood.

Dry Off

Wood is organic and therefore it will rot. Even cedar and pressure-treated wood will break down over time in the wrong conditions. Why? Because just like humans wood does not like to be wet all the time. It’s okay to be soaked once and while but there has to be a way for the wood to dry. Because organisms go where the penetrating water goes and die when the wood dries. If the wood stays wet then they multiply and begin eating away at the wood.

The first thing when building a deck, fence or shed is to check the drainage area and grade where the deck will be built to make sure it slopes away from the foundation of the home. The supports should be set off the ground with with a deck block or on a cement post. If the wood is sitting at ground level on a cement pad the ground it should have a French drain around it so the water will have some place to go. This should then be drained off the property.

When building a deck the ledger board which is attached to the house should have a flashing over the joint between it and the house to avoid water getting into the joint. The flashing would go up under the siding.

Wood fencing, because of its design, leaves a lot of places where water can sit. Build your with a design that allows the least surface area to hold water. Many deck raining systems cover the balusters with a board to prevent water from seeping in from the top. The cracks and seams are completely covered and if water blows up from underneath gravity helps water get out.

You are never going to stop water from getting in. By its very nature it will be sucked up into any cracks despite gravity. The main idea idea is to have a way for water to get out.