Is it OK to Use Pine Outdoors?
I use a variety of woods for outdoor projects but often get asked if it is OK to use pine or laminated pine for outdoor use.
I have used all types of different woods for outdoor projects but mostly Meranti, Saligna and Pine. The guys and gals attending the DIY Divas workshops often ask me if it is OK to use pine for outdoor projects and the answer is yes, but only as long as you follow a few guidelines that I discuss below.
Can you use Laminated Pine for Outdoor Projects?
When it comes to laminated pine, this is a different material than PAR pine. Laminated pine is manufactured by splicing together long planks and then gluing together the lengthened planks which are glued together to create the width. When you buy a piece of laminated pine shelving at your hardware store, you will clearly be able to see how the planks are glued together and this is where the problem comes in.
When planks are laminated or glued together to make a wider product, the glue used in this process is not a waterproof glue. It's just your ordinary wood glue.
When used for outdoor projects, taking into consideration that pine - or any other wood for that matter - expands and contracts according to the ambient environment, as it expands and contracts, and particularly if it gets wet, this process weakens the joints between the planks and these will eventually split apart.
However, you can overcome this by regularly applying an exterior sealer or wood treatment product. But even with the application of such a product, laminated pine should not be used outdoors where it can get wet.
Can you use PAR Pine for Outdoor Projects?
PAR pine, while basically the same material, is not in any way laminated. PAR pine, which by the way stands for Planed All Round, is the actual size of the timber and no joining method is used to create the planks that you buy at a hardware store. PAR pine comes in different widths - up to 94mm side - and lengths of 1800mm, 2400mm and 3000mm.
You can use PAR pine to make outdoor projects, with the understanding that any project is finished with the application of a suitable exterior sealer or other finishing product. Furthermore, this project should be re-applied on an annual basis so that it continues to offer maximum protection to your pine projects.
How to use pine for a project that is wider than the standard width of a plank
There will be times when you want to make a project using pine that is wider than the standard PAR pine plank size and this is where a few tools will come in handy.
• Clamp and glue together
The easiest method for joining planks together, although not the best, is to glue and clamp the planks together, making sure to use a waterproof glue. There will still be expansion and contraction of the wood and this could cause the joins to split later on, but with the application of a quality exterior product this may not happen if the piece is kept dry, say on a covered balcony or patio.
• Use a Biscuit Joiner
The biscuit joiner method is definitely stronger than simply using glue and clamps, but even this method is not as strong as the method using a Kreg Pocket-Hole Jig. A biscuit joiner cuts a slot on the mating edges into which waterproof wood glue is applied, followed by wood biscuits. As the biscuits absorb the wood glue they swell and lock the pieces together.
• Use a Kreg Pocket-Hole Jig
Joining planks using a Kreg Pocket-Hole Jig is the most effective method for joining planks together. Using waterproof wood glue and pocket-hole joints and screws, even the natural expansion and contraction of the pine will not split apart the joins. Yearly application of an exterior-grade finishing such as sealer or oil will further protect the laminated pine and prevent future damage.
Pine used for outdoor projects and left untreated will not age well. They will cup, bow, warp and twist.
Yes, you can use pine for outdoor projects on condition that you apply an exterior-grade sealer or treatment. Yes, you can use laminated pine for outdoor projects, but only for those where the project won't be subjected to rain and again, only with regular application of a suitable exterior-grade treatment.