Installing the rain screen and window trim

Spent the day screwing on trim and nailing up rain screen battens.

Rain screen is essentially 3/8″ x 2″ strips of pressure-treated plywood that we nailed over the house wrap with 2” 8d galvanized ring nails. idea behind this relatively new construction technique is to create an air space for water to escape and air to circulate in case the siding or flashing fails. It adds bulk and weight to a tiny house build but considering the lack of eaves at the sides I think it makes a lot of sense.

The door and corner trim is set directly onto the house wrap although we haven’t bedded it in sealant yet so we can replace it later if we decide it doesn’t look quite right. These trim pieces run continuously to the bottom of the roof sheathing and are slightly notched toward the top to hold the facia boards.

I built the window boxes separately on a table. They are screwed at the corners, with a 6 degree bevel top and bottom to drain water. The inside of the boxes is exactly an eighth of an inch larger than the outside of the window casing giving me a 16th inch gap all the way around which will get caulked at the sides but not at the top so the window cap flashing can drain. We set the boxes on top of the rain screen rather than onto the housewrap to the hassle of a second cap flashing on top of them that would have to be integrated with the housewrap. These thin but proud (sticking out) boxes are Liz’s idea, it’s not something I would’ve thought of on my own but seeing it in place I think it looks really nice.

For our trim and our siding we are using GRK fin/trim screws. I’ve always used stainless trim screws in the past but we both think that the gold color of the GRK’s will complement the look we’re aiming for.

– Brian

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