Tar paper over deck joists

Jul 27, 2008 6 Replies

When I repaired a deck, I decided to put a strip of 15lb tar paper over the joists before attaching the deck boards. The tar paper was about 1/2" past the edge of the joist, and then lightly folded down to form a drip edge. My theory is that the tar paper will tend to run rainwater away from the joists, and drip it slightly away from them, extending their life. Any opinions out there?


We used strips of shingles at the cottage. Worked well.

Rather than roofing felt, try to find some of the newer plastic roofing underlayments, like PermaFelt. Much thinner, tougher, longer lasting than tarpaper. Most roofing supply companies have it, some box stores. Problem is getting a small quantity as roll sells for $90. Try scrounging a dozen feet or so from a roofing company from left over rolls. HTH

Joe

I've never heard about using tar paper over deck joists. Wouldn't that create a situation if the wet wood underneath could not dry out? My deck is 17 years old and still holding strong without any rot and no tar paper, but I ally Cabot Decking stain every 3-4 years.

On 7/29/2008 8:08 AM Phisherman spake thus:

Yep. Sounds like a solution in search of a problem to me.

The rest of the joist is still exposed. The only area not available for evaporation is the top edge. Joist rot may be less of a problem in dryer climates than here in Seattle.

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required