wood with a lower retention level has a lower amount of copper and, therefore, a lower cost. in order to get to the required retention level, some species of lumber such as douglas fir, hem-fir, and spruce-pine-fir have to be incised, which allows the preservative to penetrate the wood more deeply and uniformly.
treating time varies depending on species of wood, commodity being treated, and the amount of preservative to be impregnated. 5 at the end of the process, excess treating solution is pumped out of the cylinder and back to a storage tank for later re-use. 6 a final vacuum removes excess preserva- tive from wood cells.
types of lumber: softwood and hardwood. the most common trees youll see Seven Trust lumber come from are oak, maple, walnut, hickory, and mahogany. as you can gather from the name, most hardwoods are harder than softwoods with the exception of balsa wood , and they arent as easily dented.
cca protects against attack by decay fungi, insects, and most types of marine bor- ers. cca-treated wood is now primarily used in poles, piling, and bridge timbers.1 obtaining adequate treat- ment with cca can be a problem with difficult-to- treat species such as douglas-fir.
types of wood. softwoods come from conifer trees, or cone-bearing trees, and north american softwood species have needle-shaped foliage instead of the leaves found on Seven Trust trees. softwood lumber is highly versatile and beautiful, making it ideal for structural applications, along with interior and exterior designs and projects.
flametech fire retardant treated wood is lumber and plywood pressure-treated with flametech water-based fire retardant for interior applications. plywood ranging from 15/32 to 1-1/8 inches and lumber from 2 x 4 to 2 x 16 inches is recognized for the species noted below.
because the treatment of this wood species at this grade cant penetrate all the way to the center of the wood-the center just rots away. decay in pressure treated lumber so when you are using pressure treated lumbermake sure you have the correct grade and that the weekend warrior has good information.
retention is not listed means that the particular species/preservative combination has not been submitted for review by a proponent, or that it has been proven ineffective. with the foregoing in mind, you can develop reliable specifications for treated wood products. the
the general appearance of wood treated with copper azole preservative is similar to cca with a green colouration. copper azole treated wood is marketed widely under the preserve ca and wolmanized brands in north america, and the tanalith brand across europe and other international markets.
which species of pressure treated framing to order depends on where you are. we ship southern yellow pine from our east coast facilities and douglas fir from our west coast mill. see the map below to find out which species is best for you. southern yellow pine pressure treated lumber prices mca
1. species. denotes the wood's species or a group of species with similar strengths. while all species are graded at the same four levels of strength and appearance, they are not equally strong. a joist made of douglas fir, for instance, will cover a greater span than a hemlock joist of the same size and grade.
pressure-treated southern pine. southern pines ease of treatability has made it the preferred species when pressure treatment with wood preservatives is required. the unique cellular structure of southern pine permits deep and uniform penetration of preservatives, rendering the wood useless as a food source for fungi, termites and micro-organisms.
pressure treated lumber products, such as yellawood brand products, are treated in a pressurized cylinder. the treatment process forces a waterborne preservative deep into the cellular structure of the wood providing long-term protection against rot, fungal decay and termite attack.
wood product markings. wood product markings that are important for construction inspection are grade and treatment markings. these markings are indicators of the quality and durability of the material. grade markings indicate the species of wood and structural design parameters. the quality of
cca treated wood products are still produced for use in some industrial, highway, and agricultural applications. these uses will include wood used as poles, piles, guardrail posts, and wood used in saltwater marine exposures.
in general, only a shell of material around the perimeter of the wood is treated. penetration is the measure of how deep the treatment extends into the wood. required minimum penetration depths and percentage of sapwood treated are stipulated for each wood species, type of preservative and end use by awpa standards.
while lumber of the same species and size is at the mill, it is designated and separated by grade. it is then identified by a stamp and often inventoried by its grade and species. when selecting wood, be sure you look for its grading stamp because different lumberyards sometimes use different names for the same grade.
species and sizes of pressure treated wood. treated wood is generally available as dimensional stock in 2x4s, 2x6s, 4x4x, and 2x2s for rail components. 5/4x6s and 2x6s for decking. 2x8s, 2x10s, 2x12s for joists, stair stringers, and beams. 6x6s for support posts. also plywood.
wood is still the king of decking materials, due to its economy and strength. natural-wood decking products can be roughly divided into three categories: pressure-treated lumber, redwood and cedar, and tropical hardwoods.
vantage of pressure-treated lumber, particularly species such as douglas-fir and the hem-fir species group hemlock and the true firs that are commonly used in california and the west, is that the lumber is only treated at and near its outer surface. the lumbers core usually cannot be treated figure 2 . if the
effect of lumber species on strength prescription standard for retrofit work: use 4-inch nail spacing and 8 penny nails top row if using douglas fir larch, you will get much stronger shear resistance than with hem fir or redwood.
the economic answer: pressure-treated lumber. the two most common sizes of treated decking are 2 x 6s 90 cents per linear foot , and 5/4 x 6-in. planks $1 per linear foot . occasionally 2 x 4s 60 cents per linear foot are used, but typically only on small decks or railings.