"Ceiling" Material for Underside of Deck

April 3, 2006 10:45 AM

I have a deck with a patio underneath. I have created a guttering system between the deck joists that keeps the patio dry, but it isn't much to look at. I would like to install a "ceiling" attached to the underside of the joists. One major challenge is that the joists are 24" centers, so sagging is a major concern. Ideally, this material would: -Provide a reasonably finished look -Be available in white -Not add tremendous weight to the overall structure -Be water resistant in case my guttering springs a leak -Be in the neighborhood of $1-3/sq foot. My only idea so far is the soffit treatment they use in vinyl siding applications. Any other ideas are most welcome!
posted by jbradley to home & garden (8 comments total)

One possibility is that corrugated plastic sheeting you sometimes see used as the roof of say a shed. It will be around your price, is pretty lightweight, and will definitely be avaiable in white. Reasonably finished? Yes, I think so.

In case you're not sure what I'm talking about here's a link, but you'll obviously need to do some further shopping..."corrugated roofing" will get you some search results. But you can probably order this from your local roofing supply, like home depot, lowe's, or the mom and pop if you have one.
posted by poppo at 11:02 AM on April 3, 2006

The KC Star newspaper ran an "ask a builder" column just last Sunday, in which the builder made reference to a new, plastic porch ceiling material, meant to mimic the look of the beadboard porch ceilings common on victorian porches. Here it is.
posted by LarryC at 11:35 AM on April 3, 2006

I was going to suggest the corrugated plastic -- could be the cheapest option.

If you're reasonably confident of your plumbing skills, you could use outdoor fabric attached to the joists. The fabric itself doesn't mold or mildew, and it breathes for better ventilation. I've bought from this place before; I know they have plain white, plus tons of colors and patterns.
posted by vetiver at 11:44 AM on April 3, 2006

Fiber-cement products (Hardipanel or Hardisoffit), lauan, or exterior grade plywood are common alternatives to vinyl for sheathing the underside of a *waterproof* deck. But you don't have a waterproof deck.

Unless you're confident that your gutter system will always catch 100% of every drop of water that comes through your open deck, I would strongly advise against attaching any type of sheet goods directly to the underside of the deck joists. You'll trap water against the joists, leading to rot and failure. Even with treated or decay resistant (redwood, cedar) joists. I've seen joists with dinner plate sized holes in them, resulting from exactly what you're talking about doing.

Vetiver's outdoor fabric might be a solution. You might could also use some type of spacer to separate the porch ceiling from the joists.

The best solution, which will be above your price point, would be to remove the open deck boards and rebuild a waterproof deck. Here in the South, materials would run $3/sq.ft. and up, and the project would be something a reasonably competent homeowner could accomplish.
posted by lost_cause at 12:37 PM on April 3, 2006

If you are concerned about trapping water against the bottom edge of your joists (which is a good thought, lost_cause) you could run sleepers/furring strips perpendicular to your joists first, and then run your finish material perpendicular to those.
posted by misterbrandt at 12:57 PM on April 3, 2006

Definitely needs ventilation in there, to keep down moisture.

Lost_cause: what materials are used for a waterproof deck? I have a 100 year old 2 story porch, with tongue & groove floor that is in bad shape on the second floor. I was thinking of using a rubber membrane on it when I fix the floor. What else would work?
posted by jjj606 at 3:46 PM on April 3, 2006

jjj606, a waterproof deck consists of three basic elements: subfloor, water barrier, and finished floor. For a traditional T&G look, I install a treated plywood subfloor, builders felt (aka roofing felt, tar paper), then tongue and groove flooring. This system is really just water resistant and most appropriate if the porch is covered. But it can work well for restorations.

For something truly waterproof, go with a plywood subfloor, rubber membrane, then attach your flooring to sleepers simply laid on the rubber. There are no mechanical fasteners penetrating the membrane to connect the decking to the rough framing; the deck is simply held in place by gravity. I've only done this with regular deckboards, but I don't see why you couldn't also use T&G.

Finally, you can tile. I can usually find decent tile for under $2/sq.ft., making it a really affordable solution, cheaper than the previous two systems. Plus you get an extra waterproof layer. Install plywood subfloor, fiber-cement backerboard (don't forget to lay it in thinset and tape and mud the seams), and tile (also in thinset, no mastic). My local roofing supplier, who sells rubber roofing, but not backer or tile, swears that this is the best long-term sollution with the fewest problems.

I'm lucky enough to live in an area with mild weather - if you're somewhere subject to high winds or heavy freeze/thaw, check with your local building permit office, because one or more of these may not work for you. For example, the gravity deck and hurricane wind probably isn't so much a good combination. Good luck.
posted by lost_cause at 8:11 PM on April 3, 2006

Sorry to derail the original question. Thanks, lost_cause.
posted by jjj606 at 9:16 PM on April 3, 2006