There are a lot of myths out there, some founded on reality, some on bad guessing.  Using the wrong product on the outside of a log home can make or break the log home.   

    A few years ago, we looked at using the water based primers and sealers simply because 20+ years ago the federal government and environmentalists determined that oil based products were bad for the environment.  Restrictions were then applied to oil based products which changed the formulations of a lot of those products.    This forced the water based products to really improve - and they did a great job.  They developed products that were easier to apply and lasted longer than oil based products.  However, through the years, the tables have turned a bit, and now the oil based products are coming back because of the way they put their products together it is a better product that lasts longer, and is easier to apply. 
    
     Water based products are still good - the problem that we have is when we apply the product, it has a dull finish, not glossy like you can get from an oil based product.  A year after application, people wish for a new coat to be applied to improve the visual aesthetics.  In actuality, it is functionally effective and does not need to be redone.  If they do go ahead, they are now putting a water based product on a water resistant surface.  After application, in a very short period of time will begin to flake off and look even more unappealing. 

     So what we recommend is an oil based product.  It is a glossier product, and over time imperfections appear that indicate that reapplications are necessary, such as graying of the upper hemisphere of the log where the sun hits and the water sets.  The length of time this takes depends on the exposure.   The North and East sides of the home finish will last a lot longer than the South and West sides that receive much more sun, wind and rain.  Typically 3-5 years after first application sealers need to be reapplied on the South and West side, where the North and East will probably last 5-8 years before the next application is necessary.  Re-applying can change the appearance of your logs, typically the more applications, the darker the finish. 

     Another factor to consider is the color of the stain/sealer.  Typically the darker the pigment of the finish, the longer the sealer will last, and conversely the lighter the finish, the less time you will get out of it. 

     Lastly, because the surfaces will not wear evenly, for example the area under the eaves will also last longer than the areas exposed to the elements, reapplying sealant requires some preliminary work.  It may require some power washing and soda blasting or sanding on these areas to take off the old finish .   I never recommend sand blasting - it is too harsh.  The sanding actually makes the logs look better for the next application of sealer because it accents of the hand crafted work on the logs when the home was built.

Insects
     We have carpenter ants indigenous to this area that if not handled properly in the construction stage have the potential to become a problem.  During construction, if the problem arises, we have an exterminator out and then scheduled annually in Sept/Oct and have the foundation treated.  As far as bugs in the trees themselves, occasionally after the first year a bug that was in the log when it was cut will hatch and come out.  It happens - but it will only happen one time because they do not lay more eggs and re hatch the next year.  That does not happen. 
    
     When we build a house we seal every conceivable crack or space that external insects could find their way into the house.  We will monitor the house and inspect it quarterly the next 12-16 months and then we will reseal it all again.