Can Heat Treated wood be used to build decks and fences?
The wood shown in this picture is a No 2 grade, KD-HT (Kiln-Dried, Heat Treated), S-P-F (Spruce-Pine-Fir). From our research, there are many conflicting stories online (forums, posts, articles, etc.) about whether or not this can be used for exterior projects such as decks and fences.
The International Standards for Phytosanitary Measures Guidelines were implemented for Regulating Wood Packaging Material In International Trade to eliminate the spread of pests across the CANADA-US borders. That’s basically what the Heat Treatment is all about. It has nothing to do with the wood being pressure treated (PT) at all. However, some KD-HT wood at your local lumber yard might have a tag on the end of the lumber that specifies PT. It’s usually stapled to the wood and isn’t a requirement to be on the actual stamp.
That being said, it’s hard to know if the wood you are looking at is pressure treated or not. For example, Home Depot sells both KD-HT pressure treated and non-pressure treated grade 2 lumber. Typically, pressure treated wood will look at little different with a slightly greener or browner tint; however, some untreated wood also comes with a stamp that may say something like w/CE (which stands for with Colour Enhancement) so it’s truly a case of buyer beware. Lastly, pressure treated wood should be marked with CCA or ACQ from what we read.
Now all this being said, the heat treated lumber does offer protection against rot and wither, and as a result, expanded use opportunities.
So, the question remains… is the #2 KD-HT, SPF acceptable to use for a deck? From what we’ve researched, the answer is yes. As long as it’s weatherproofed with a sealer of some sort.
For BEST results, the ideal decking wood is by far the pressure treated stuff or KDAT (kiln dried after treatment).