Wrapping Porch Beams w/ Primed Pine – What Fastners? (Cent Florida)
Hey guys. I recently added on to an existing porch by adding a gabled roof in the middle of the porch to emphasize the front entrance. I’m complete with the framing and roofing but now I need to cover all the PT beams and post. The original builder used pine to wrap all everything and it lasted 60 years so I am going to do the same (was going to use PVC but the wife wants it painted black).
My question is – how should I fasten the primed pine to the beams? My plan was to use construction adhesive and brad nails until it was all set and then use exterior screws and fill the holes. Do I even need the screws with the adhesive? Is there a better way to screw and plug maybe?
I planned on leaving a 3/4″ air space below the beams to the bottom wrap. I planned on a glued and brad nailed bottom piece with a small reveal, no miter. All will be painted.
Any pointers or wisdom? The house is located in Orlando. The beams will stay dry but may get some blowing rain on the columns.
Replies
If the PT lumber in Florida is anything like most of the Midwest I would let it set for a year before you do anything to it if you can. The lumber usually arrives so wet that it takes a full season cycle to dry out. As an example, when we install our more economical deck package with treated lumber for decking we install the decking as tight as possible (no spacing). Within a years time the gap is usually 1/4” (sometimes 3/8”). PT shrinks a ton! They do sell dried versions, but they are more expensive and a special order, so majority of PT is the standard stuff here. I’m assuming you have standard type installed as well.
As far as wrapping. You can paint the PVC black, but would avoid doing so if it’s in full sun. I had issues with navy blue painted pvc trim a few years back. In full sun the dark color retained the heat to a point that the PVC started to get soft. Once the PVC cooled again it had deformed terribly.
Pine is fine if a lot of water will not be getting to it. I would prime all sides and cuts with 2 coats of oil primer. If you use a latex primer make sure to get a good quality primer especially if there are knots in the pine. The knots will bleed through the paint if not primed properly.
For the construction of the pine wrap I would basically build a box with the pine using exterior rated wood glue. I would use a few finish nails and clamps to construct the pine box. I would also install spacer boards on the PT post (1/2” or 3/4”) to create an air gap between post and pine. You will nail pine wrap to post at spacers. You want the pine wrap to move somewhat independently from the PT post, so oversize the wrap slightly 1/8” to 1/4” to fit a little loose on the spacers. You basically want the box to hang off of post.
I've done similar work on a house at the Oregon coast - colder, but also wet like Orlando.
Use only stainless fasteners - rusting itself is an issue, but also the stains don't look nice.
When I wrap anything, I leave a small air gap. I would glue and nail 1/4" wood strips (1/8" is probably fine) to the posts, then the outer pine to those. You have this idea with the 3/4 space at the bottom, but I'd apply it everywhere. I'd use a polyurethane adhesive and stainless trim screws with small heads. You can paint them to match the black posts.