The main room will be in pine tongue and groove. However, my concern is for the choice I made for the bedrooms. As occasional heating may cause moisture transfer, I bought 1/8-inch mahogany backed wall panelling, based on the advice I received. This is to be installed directly to the studs. I was told to avoid drywall and 1/4-inch wall panelling due to moisture absorption.
Since I purchased this I have been told this is not a good choice and have received conflicting opinions about installing it. Some say strapping is required and others say nailing every six inches is all that is required.
Did I make the right choice? What are the positives and negatives of the available choices? How do I correctly install the 1/8-inch panelling?
--Lawrence Roberecki, e-mail
ANSWER -- I'm not sure if I can offer the definitive answer you seek, but I have hundreds of hours of experience in installing all kinds of panelling and wallcoverings, so my advice should help with your choice of materials. I have also installed several different types of wallcoverings in many cabins and cottages, including my own, and I have seen which types are affected by the high humidity in lake country. This is an excellent question and you should be commended on your research prior to spending a substantial amount of time and money on materials that may not work well.
Surprisingly, drywall does not seem to be affected as much as you would think in humid conditions. I have had similar reservations about this, but have seen well-painted and sealed drywall perform well in lakefront summer homes. Turning the heat off in the winter does not appear to considerably affect the drywall itself, but often the drywall tape and compound may crack with drastic changes in temperature. Drywall may not be the best choice for this reason, as well as its need for regular painting.
In my opinion, you can never go wrong with real wood panelling, as long it is properly dried and acclimatized to the local conditions. Pine, in particular, has a tendency to shrink considerably as it dries out, and may cause problems if not properly cured prior to use. Ensure that the material is either kiln dried or air dried for a substantial length of time. The tongue and groove panelling should also be stored in the partially finished cabin for a few weeks, to acclimatize to the humid conditions. If the material if too dry, it may absorb moisture from the air after installation, and buckle.
The choice of mahogany-backed sheets of panelling for lake country is the right one. Plywood panelling has much less chance of warping than composite panelling made of fibreboard or particleboard, regardless of thickness. The plywood panels are very light, easy to cut, even with a utility knife, and installation with finish nails is fine. The panels are durable, but are more subject to holes from mechanical damage than thicker panels. Often, a backing layer of drywall or OSB is installed for this reason but is not essential on interior walls. Strapping is also an option, but is used mainly on exterior walls.
Eighth-inch-thick panels are not durable enough for installation without backing on exterior insulated walls. They will buckle between the studs from the expansion of the friction-fit fibreglass insulation. Drywall, OSB, plywood, or strapping is necessary to hold the fibreglass insulation in place. This should be installed immediately over the polyethylene vapour barrier, taking care not to poke holes in the vapour barrier except over the exterior wall studs. This sheathing or strapping will also strengthen the thin wall covering and prevent unwanted damage.
Fibreboard composition panelling is also acceptable for use in lake country, but must be of sufficient thickness and type to resist moisture absorption and bowing or buckling. Some types work well and other very poorly, and more expensive panels are often thicker and better quality. Almost all 4 x 8 solid panels are designed to be nailed directly to wooden studs, using the appropriate finish nails. Nails should be ringed, ardox or fluted to grab the thin panels and resist popping through. These can be purchased pre-coloured to match the panelling or covered with coloured putty after installation. Panel adhesive is also a good idea for use with thin panels. This can be applied over the bare wood studs, sub-panelling or strapping with a caulking gun before nailing up the finished panels.
Ari Marantz is owner/inspector of Trained Eye Home Inspection Ltd. and is the PR Rep. for the Canadian Association of Home & Property Inspectors- Manitoba (www.cahi.mb.ca). Questions can be e-mailed or sent to: Ask The Inspector, P. O. Box 69021, #110-2025 Corydon Ave.,Winnipeg, MB. R3P 2G9. Ari can be reached at (204) 291-5358.