Trained Eye

 
 
 

Exhaust Fans in Log Home

Question:

My hubby and I just bought a 2900 sq ft handcrafted log home out in the country and are moving at the end of the month. On the main floor all the interior walls are log, whereas on the 2nd level there is some drywall and panelling on the walls and ceilings. Our main floor bathroom is quite a large room with vanity, sink, toilet and shower stall. Also, at the end of the room, right by the window, is a 4 person hot tub. The original owners never installed a bathroom fan and we are a bit concerned about this, especially with all the steam coming from the hot tub and shower when they are on. Should we get one installed and how would it be installed thru the logs?

In the open kitchen we have an electric cook top on the island counter and there is no range hood or kitchen fan in here, either. The ceilings on this level, with an open living room and dining room area, are all 9 ft high. We are just wondering how we could install a fan in the kitchen area and is it necessary? The original owners have seemed to live here for the past 16 yrs, just fine. What do you suggest?

Answer:

I am happy to hear from new homeowners who have decided to buy a home that is unique and different from the norm. Log home construction has been done successfully for hundreds of years with many original homes lasting for generations. I have seen several in recent years that combine modern technology and building practices with old style log construction. The results can be stunning, but may have unique problems or concerns due to the shrinkage of the natural wood that have to be accounted for.

One of the differences between the natural wood walls and those in modern wood frame construction, is the air-vapour barrier. Logs or timbers, when used for exterior walls have inherent insulating properties, due to the thickness of the material. The walls are rarely covered with sheathing, insulation, or vapour barrier and are allowed to naturally gain and lose moisture. Preservatives or finishes are sometimes used on the logs to protect the surface and may restrict moisture penetration. Chinking or caulking is also used between the logs to fill gaps and further prevent air movement. Air and moisture movement is very important to the comfort and health of a building and its occupants.

Most new homes are very “tight” in relation to air-moisture movement from interior to exterior and visa versa. Because of this fact, normal moisture produced in a home from bathing, cooking, etc. must be expelled to the outside to prevent damage to interior components. Also, fresh air must be brought in to the building for combustion appliances and general health of the occupants. Bathroom and kitchen exhaust fans, windows and doors, and fresh air intakes on furnaces and other ventilation equipment accomplish these tasks.

Log homes are not as air and moisture tight as newer conventionally built ones, but still require adequate ventilation. The doors and windows may still be well sealed and caulked and prevent air movement. The wooden walls, however, are not as susceptible to damage due to high humidity as drywall or other sheathing. For this reason, you may find that the windows and doors already in the home provide adequate ventilation. This will only be true if the windows are high quality and are opened year round, primarily in the bathroom. If Mr. And Mrs. Krulicki don’t mind cooking or taking a hot tub with the window open when it’s –20 C outside, then they may be fine. This is likely the reason that no apparent problems have been encountered thus far.

Having said this, it is rarely detrimental to add extra ventilation in the way of exhaust fans, especially in bathrooms with jet tubs. The installation of the fan should not be that difficult, but the venting may trickier. It may be possible to run ducting through the bathroom or kitchen ceiling, behind the 2 nd floor walls, and connected to a vent hood on the exterior wall or roof. If any mould or mildew is seen forming on the bathroom walls or ceiling, then a visit and quotation from a qualified contractor is recommended.

 

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