Hey there, time traveller!
This article was published 8/8/2014 (1020 days ago), so information in it may no longer be current.
As soon as the weather allows, we will be preparing to refinish our front-porch deck, starting with a good sanding. We have asked several paint distributors what to use on our deck. Two years ago, we sanded and finished our back deck with a white stain. The deck faces south, so it bears the brunt of all of our beautiful sunshine in the summer. It has not held up as we would have hoped. Our covered porch faces north and we want the deck floor to be grey in colour with white risers. Do you recommend a stain, porch paint or something else entirely?
Looking forward to your reply.
Paul and Wendy MacNair
Finishing horizontal decks and porches can be a challenge, due to the constant human traffic that wears away on surface finishes. Choosing a product that will last more than a year or two can be difficult, but your situation may be helped by the location and design of your porch.
Applying a finish to an older wood deck or porch is always a tricky situation because there are numerous products out there making many different claims. My own experience is the boasts of years of durability in any finish to be applied to an exterior horizontal surface are all to be taken with a grain of salt. Having said that, using products with less solids and suggest a more "natural" look to the wood may be the better choice. That is because they normally cover up less of the wood grain and don't have as much material to stick to the bottom of the many shoes that will tread upon the surface. The drawback with these finishes is they may not give you your desired look, unless applied to a newly installed wood deck.
The most commonly used finish for deck surfaces is likely an alkyd semi-transparent stain. This is often chosen because it combines the good absorptive properties of an oil-based stain, with the light tint of a semi-transparent finish. These stains often contain an added preservative, which may help prevent rot in the wood even after the colour fades. They will also contain ultraviolet (UV) protection, which is normally better the heavier the tint component. So, I would recommend looking for a product that has all these qualities and enough of a grey colour to satisfy your aesthetic desires.
Too many times, homeowners opt for finishes that will cover all of the imperfections of older wood by choosing a solid colour stain. This is a bad decision, as the extra materials in the solid finish will only wear faster from numerous feet and be more noticeable in the highest traffic areas. That type of finish may be quite suitable for vertical surfaces such as fences, but will not work on most decks. Also, opting for a latex-based finish may seem like a better idea from an environmental and easy cleanup standpoint, but it will not penetrate deep enough to provide good protection from moisture damage. Because that type of finish mainly sits on the surface of the wood, it will also wear off in no time flat. For those same reasons, choosing a paint finish, rather than a stain, will accelerate the deteriorated look of the entire surface.
The main benefit your front porch has over the rear deck is not the direction it faces, but the fact it is covered. The roof covering over this area will help prolong the life of any finish you choose for two reasons. First, the overhang of the roof will keep the majority of precipitation from directly falling on the decking. While not the most destructive force to the finish itself, heavy rains, snow and ice can penetrate the wood and cause the finish to peel, flake, or simply lose its adherence. As the wood ages, and rot begins to take hold, keeping a nice-looking finish becomes even more difficult. Sanding or pressure washing the surface of the old wood is a good idea, to allow damaged wood on the surface to be removed, ensuring better adhesion of the new stain.
The second major benefit of the roof over your porch is prevention of UV rays from damaging the finish. The strong UV rays in direct sunlight may be the most severe variable in the deterioration of flat decking. This strong light source can cause untreated wood to quickly grey in colour, while drying out any moisture within the wood. The excessive drying can allow the wood to check or crack, opening the surface and allowing penetration of damaging water, moss and insects. Having a covering on the porch should prevent the majority of the sun's damaging UV rays from creating that problem. It will help prevent the finish from deteriorating, while preventing damage to the underlying wood surface.
While your question is a very common and excellent one that is posed to anyone working at a home centre or paint store on a daily basis, you have one benefit over most other individuals. The north-facing direction of your porch, combined with the roof covering, will minimize two of the three most problematic items for decks, UV from the sun and precipitation. The third variable of foot traffic cannot be avoided, no matter what direction your deck faces, but still must be taken into consideration. For that reason, using a high-quality alkyd semi-transparent stain finish should be your best bet. Exterior stains are an item where spending more should ensure you get a better quality, longer lasting product, so don't bother looking at the bargain brands when shopping.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the President of the Canadian Association of Home & Property Inspectors -- Manitoba (www.cahpi.mb.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at www.trainedeye.ca.