"Tarpaper" is used as an underlayment under your shingles because it will help keep moisture out of your house. If you put that stuff on you soil it will do the same thing and it will also keep necessary air exchange of the soil from happening and you will then have an anaerobic soil where disease pathogens could grow better (many disease pathogens really like anaerobic conditions). I would not use "tarpaper" in my garden.

Why cover the grass? It's providing root structure and someplace for rain to go and not become run off. I just built my raised beds and put down straw/cardboard/straw on my paths to keep them from becoming mud. This fall I plan on removing all of that and composting it, while I plant a cover crop of clover and comfry that should hold up to light traffic and remain for my path, also providing root structure/OM for to improve drainage.

Of course I have very poor drainage to begin w/. You could have entirely different reasons, but as kimmsr stated I wouldn't use it either.

I instinctively feel tar paper is a nasty no-no

Trust your instincts. ;)

Dave

OK--the NAYS have it! Off to the landfill (gulp) with the tar paper and down will go the cardboard-newspaper/woodchip mulch that I have used successfully in countless situations in a number of gardens over the last 40 years. "If it ain't broke, don't fix it!"
Thanks, all. RD

Beyond the impervious nature of it that was mentioned above, I would add that the "tar" in tar paper is asphalt which is loaded with carcinogenic polycyclic aromatic hydrocarbons (PAHs). Not particularly dangerous up on the roof but not something you should put in the garden.

Leftover building materials, I offer on Craigslist or Freecycle. It's surprising what people will take sometimes. Your scraps would be great for a doghouse, for example.

I think it would be horrible to use as a mulch. Tar equals no air and water exchange.

Darn, I was hoping it could be used- that last statement no air and water exchange sealed its date for me.

I'm looking for something to put down between septic Rows that will carry water away. The water will be from my container garden built above septic field.

Any ideas?

That thick red paper used under floors is also treated to be water resistant. It has an Alum-rosin sizing, and may also have a polyurethane coating.

To carry water away? A french drain?

I'm not clear on what the goal is here. Are you trying to carry away water from the septic drainfield or from the container garden?

Container garden and any excess when it rains. I'm wanting to build a garden space that sits above drainfield. It will need to have its water diverted away from drainfield area.

That's where tar paper would have come in. I would have placed it on the 3 foot paths between the septic lines.

There is a natural slope in the yard and I will use that to bring water to opposite side of yard and create a catchment area- maybe, or use it, the water, in some other way.

I'm no expert on septic tanks but it seems like there shouldn't be an awful lot of excess water coming out of the containers, compared to the amount of water used and discharged by an average house. Are you sure it's really necessary to convey all your drainage away?

I have slight slope so I'm thinking of just using the land and letting it carry it just past the drain field area. Just to be safe.