How to Seal Pine Tongue-and-Groove Air Infiltration

Sealing the Surface of the Wood

• 1

  Clean the wood by power washing or hand washing. Allow it to dry for at least two days. Sand off any old polyurethane or paint and remove the debris and dust by sweeping or with a high-velocity blower.

• 2

  Apply paint or polyurethane to the boards with a roller or paintbrush, paying special attention to the ends -- cuts across the wood on the ends will require more paint or varnish to seal. Unless the manufacturer recommends a single application, apply a moderate coat.

• 3

  Apply a second coat of the paint or polyurethane after the first coat dries. Allow it to thoroughly dry. Paint and polyurethane are finished drying when the product is no longer tacky and does not smear (consider a test application on a "dummy" piece of wood that you can touch later to see if the paint is dry). With interior polyurethane, applying three to four coats and sanding between them with a fine sandpaper is often the best way to obtain a transparent finish showcasing the wood grain.

• 4

  Use a product such as linseed oil for oil treatment. Rub it into the surface of the wood with a rag. Apply the oil liberally and wait for the surface of the wood to soak it up. Apply a second coat and wait for the wood to dry.

Sealing Large Gaps and Cracks

• 5

  Fill large gaps and cracks with expanding foam if they are in a non-visible location (behind trim, for example). Most expanding foams will at least double in volume -- leave plenty of room for the foam to expand. Apply more foam if a single application did not seal the gap. If the gap is very large, and not visible, cut a piece of scrap wood to fit and nail it in as a backer for the foam.

• 6

  Cut out pieces of the boards if there are large gaps in an exposed surface. Cut down the middle of the board in the section you are patching (as well as across the ends) with the reciprocating saw -- cutting down the middle will allow you to pull the board out by making space to separate the tongue-and-groove joint. Make square cuts across the end of the sections you are replacing at the halfway point of a stud or joist (if you have to patch multiple pieces of material, stagger the cross cuts).

• 7

  Cut pieces out of matching pine tongue-and-groove stock to the length of the gaps from the pieces you removed. Cut away the "tongue" and the bottom protrusion from the "groove" side on the new pieces with a table saw. Lay the pieces in place and nail them with finish nails where the boards cross the joists.

• 8

  Seal the material by applying paint or polyurethane as described above.