M-F. 8AM-5PM | SAT. 8am-12pm
 685 Berne Rd. Columbia Falls, MT 59912
 (406) 892-4208

You Should Know

RBM Wood Moisture Content

If there is a single, unique detail that sets RBM Lumber apart from other wood products manufacturers and lends itself to our success it is our attention to moisture content. Of course, we pride ourselves on our customer service, overall product quality and fair pricing as well but we believe moisture content, MC, is the most important aspect of a wood product to insure a quality product. Wood products are used either inside or outside – it’s that simple. In this part of the country wood inside a heated structure is going to acclimate at about 6% MC. Outside it will typically vary from 8 to 10% MC up to 16% MC depending on the time of year, location, and how large the piece is. At RBM our products are dried for either interior or exterior use. This is important because if you use an exterior product inside it will shrink and possibly twist, bow or check as it dries out. The only time wood moves – shrinks, expands, warps, checks, twists, etc. – is when it is losing or gaining moisture. If you use an interior product outside it will expand as it acclimates and depending on the product may pop off the structure. If you ask a vendor if their wood product is dry and they say yes it is kiln dried, which sounds very official, it really has no significance what-so-ever because industry the specification for #2 and #3 one inch boards, at least in western soft woods, is 19%. To us that is still green. At 19% MC a 1x8 with a 3/8” tongue and groove will shrink enough to completely separate the tongue groove by the time it reaches 6% MC. The question you really need to ask is “what is the moisture content in the product?” because dry could mean 6% or 20% or any other number. To ask this question though you need to know what moisture you need. It is doubtful that very many wood products vendors can answer either question – what is the MC or what MC is ideal for your application. At RBM we make a great effort to make sure the moisture content is correct for the product you need and its application.

It is also important for you to know that most wood products need some level of maintenance depending on the product and its application. Wood floors typically will need refinishing from time to time depending on the owner’s desire. The location of exterior products will have a large impact on the need for maintenance. Southern and western exposures get the hottest sun which is as hard on wood as rain and snow so they may need refinishing sooner than the north and east exposures. Porch roofs and overhangs like soffits help greatly to protect your wood from the elements and using finishing products engineered for exterior use is important.  Also, we highly recommend finishing the back side of products like exterior siding, trim and decking to help protect it from moisture that gets in behind the product. Be aware that it is natural for continual shrinking and expanding to occur in any exterior wood product.

When you shop at RBM for the first time you can expect to be asked dozens of questions. Please don’t take offense to this because it comes from our commitment to ensure you get the best product suited for your project. We may even tell you that somebody else’s product may be better suited for your application than ours. Our goal is not to sell you a product but rather to make sure that you are completely happy with the end results of your project. The truth is, we don’t have salespeople at RBM – we have people who educate you about our products and the products sell themselves.


RMB Lumber Montana Wood Products and Lumber Mill


RBM Lumber Columbia Falls MT | Montana Lumber Products