Air-Dried (AD) Or Kiln-Dried (KD) Hardwood Decking:

Since there is no protection against direct sunlight when using Ipe outdoors, the closeness to excess moisture implies that an air-dried Ipe is the ideal wood.

There is no doubt concerning the use of Ipe for decking is the most common use. When Ipe is used for decking it has E4E (eased 4 Edges) and is S4S (smoothed four sides), this has to be performed on the four sides and four edges of Ipe respectively to curb splintering and sharp edges for the decking use. Based on the manner with which our clients want to use Ipe for decking, we are sometimes required to groove for clip fasteners. However, in most cases, such tasks are what we do on wood before shipment.

For decking use, we pretty much always default to air-dried Ipe wood which is close to 18% moisture content prior to milling in South America as deck boards. And for exterior use, it is precisely what you will need for quality and durable decking board. To prevent the effect of various weather conditions such as the sun, temperature changes, or rain hitting hard on your board, it is best advised to use the gently dried material with high moisture content.

Although we deal in kiln-dried and roughly sawed Ipe lumber (mostly used in timbers for larger size boards), there is always a low demand for these types compared to air-dried. They are mostly kiln-dried to about 6-8% moisture content, and either sold as a roughly sawed material or milled. Such products are entirely different and are best used for interior projects. While the species are the same, they are released with a distinct humidity level that is different and typically used for different applications. Due to a different type of treatment, air-dried won’t work for indoor use (it will cause splintering). However, you can use kiln-dried for outdoor use.

We certainly sell kiln-dried Ipe decking. But when used for decking, it is a kind of humorous because both the air-dried Ipe and the kiln-dried Ipe are similar materials. Regardless of which one you purchase you will need to review our installation instructions with the most important part being the acclimation of the wood to your specific environment. With this knowledge, you can save some money as AD is a little less expensive than KD. When you choose between the two products as they are both excellent choices for dry or humid weather.

History of AD Ipe and KD Ipe

It used to be that all woods were always air-dried. But currently, the rate of production is alarming, and the seasoning process for lumber is at a faster rate. Hence, the process of kiln-drying has now included decking products for exterior use. The most important point to note here is that in contrast to the lumber used for interior work, Ipe is not kiln-dried to 6-8% moisture content; instead, it is kiln-dried to 10-18% moisture content. Why? Because such a level is enough for eliminating the water without expelling the bound water or solidifying the wood’s cell walls, which consequently makes the wood harder and withstand any change.

While a wood which can withstand change looks like an excellent material, it can be a nightmare — the reason being that you can hardly go against moisture change in the outside environment, particularly a deck which stands as the cruelest place for wood. On the other hand, the most prudent choice is a flexible board which can work hand-in-hand with weather changes such as high moisture during the raining season or high sun which can dry a wood.

One cogent point to consider is the intensity of sunshine being received by the deck. A deck can be substantially heated by day-long, direct sunshine, which will expel every moisture out, and result into warping. However, you can win this situation by putting down a drier board first, then focus on ventilation, and gap spacing. But, a question still stands, which is: how to lay down a drier board if the two allegedly distinct materials have the same moisture content. The solution is to leave it for some time on the project. Allow the boards to acclimatize. In a case where your deck is moving down the desert during the summer, naturally, the weather will reduce the moisture content of the decking to a stable point. As long as it is at a stable point with the immediate environment, the decking will concede and recede moisture as the season changes. In a case like this, gap-spacing selection and focusing to stabilize the airflow will assist your course significantly more than lower moisture content.

For this reason, air-dried decking is commonly found since it is mostly believed that high moisture content is closer to a stable point in almost every part of the USA. For those staying in dry climates or under open southern exposed decks, you will hear people (even knowledgeable contractors) say that kiln-dried decking should be used. However, this is simply not true they are the exact same thing.

Calling AD and KD “The Same Thing”?

Calling the two kinds of material the same thing is a fault of the lumber industry. Kiln-dried lumber usually has 6-8% moisture content, and as mentioned earlier, roughly sawed Ipe is usually moved at this level too. To differentiate between the 6-8% Ipe and the decking product with higher moisture content, naturally, we call the decking as “air-dried.” Hence, it is pertinent to apologize on behalf of the Lumber industry for the misconception. However, don’t get carried away as lumber terms will remain confusing and possibly, overwhelming.

At Ipe Woods USA, we move a large amount of Ipe in different sizes meant for either decking boards, posts, balusters or joists. Also, we run both the air-dried Ipe decking and the kiln-dried Ipe decking.

If you are having a difficult time in your subsequent project concerning decking material in an extreme climate, just attempt to request a kiln-dried decking from a supplier. Then, ask your supplier about the moisture content you will be getting from the board. Without a doubt, for as long as possible, both the kiln-dried and the air-dried decking will remain in similar and overlapping range.