shop drainage

by **grumpyvette** » June 28th, 2011, 1:47 pm

most problems youll have with a shop can be AVOIDED with careful planing,and doing some research BEFORE starting construction, the foundation pad size, height and sorounding slope has a huge effect on your shop drainage and how solid the slab will be supported a few things that should be mentioned is that the shop floor should be at least A MINIMUM OF 24"-48" higher than any surrounding area, and 48"-60" is a far more reasonable minimum pad height if you want the shop floor to remain dry under all conditions where water from a hard rain might collect and the area around the shop should be sloped away to speed drainage, 48" is really the safe minimum in most areas, but some building departments don,t require more than 24"-36", now you might not have hurricanes in your area but a hard rain and wind can do a good deal of damage if the drainage for the shops marginal. french drains can be installed in problem areas to speed drainage, but having the shop floor higher than the surrounding area is the best plan as water tends to run down hill. and its best to have the main shop doors not face the prevailing wind direction, or up hill
IF you intend to install a bathroom check building code requirements, in many cases youll need to have 50-200 feet from a property line
when they pour most shop floors you have the option of having it dead level or slightly sloped to the doors to make clean-up and drainage easy, or to install floor drains in the shop floor with pipes to drain water out of the shop, just take the time to plan carefully because those pipes could be allowing water from a hard rain storm,to drain into your shop is placed incorrectly
a great reminder for anyone planing a garage to have a pad built thats at least 24" taller than the surrounding area before pouring a garage floor pad, yes that usually requires a good deal of fill and having it firmly compacted to build the pad but its also going to mean a dry shop during hard rain storms, and in Florida where we get hurricanes thats MANDATORY if you want to keep the cars and tools dry as is selecting dade county approved doors designed to withstand 150 mph winds and sloping the area around the shop for decent drainage.
water runs to the lowest local area and pools after a hard rain, its your job to plan the shop site so its not located in the area water pools and to have decent drainage and a floor height thats high enough to avoid water intrusion under normal or even some rare conditions
, obviously you'll need to check building codes and your site plan but in most areas thats the MINIMUM mandatory pad height.
I had my shops pad built on a 48" tall pad with a 5:1 slope for drainage, again your deed restrictions and building codes will effect what you can do, but planing ahead always beats making corrections later
your going to be way ahead if the pad height the floors poured on is significantly higher than the surrounding area.

read the linked info
viewtopic.php?f=27&t=5007

viewtopic.php?f=27&t=116

http://forum.grumpysperformance.com/viewtopic.php?f=27&t=116

http://forum.grumpysperformance.com/viewtopic.php?f=28&t=5

http://forum.grumpysperformance.com/viewtopic.php?f=27&t=98

http://www.helphive.com/advice-center/2 ... ch-drains/

http://www.catskillhouse.us/blog/making-a-french-drain/

http://en.wikipedia.org/wiki/French_drain

by **grumpyvette** » August 29th, 2011, 9:50 am

just some info, one of my friends built a really nice shop and he built it up on a 4 foot high pad so that should have provided excellent drainage and no water intrusion, its a really nice shop and he had zero problems until he got a little spare cash and decided to have a 30 foot wide and 40 foot long concrete pad built in front of his shop so he could park cars and do welding out side in the open air,the problem started with the design, and its as built in that application.
the result was that his dead level outside pad with no drain allows wind and rain to flood the shop floor, hes now having to cut the pad to install a covered. grated drain channel, which has added a good deal of UN-necessary extra expense
most problems youll have with a shop can be AVOIDED with careful planing,and doing some research BEFORE starting construction,
,(1) he failed to build in a covered drain gutter along the front of the pad/shop to allow storm driven rain water to drain off the pad before it could flow into the shop

a drain slot like this ALWAYS needs to be placed and located between the shop floor and edge of the slab so water draining into it drains reliably when a slab is poured in front of a shop, to prevent water intrusion

(2) he failed to slope the pad about 2.5" of slope per 10 feet of slab surface minimum, sloping the slab very slightly to allow storm driven rain water to flow away from the shop, (its currently a dead level pad, and wind and rain cause problems)

(3) he failed to have the level of the upper edge of the sloped slab, thats sloped away from the shop,to be at about 1.25"-to-1.5" lower than the shop floor

1

Determine specifications. Driveways for one-car garages should be at least 10 feet wide. A two-car driveway should be 16 to 24 feet. The slab's thickness depends on the vehicles that will roll on it. A good measure is at least four inches for cars and at least six inches for heavy trucks. If the soil is soft or drainage is poor, add another one or two inches.
2

Design the slabs. For six-inch slabs, use a shovel to dig at least eight inches deep to accommodate for a four-inch gravel bed and raising the slab two inches above the grade. To prevent water from flowing into a garage, the slabs butting against the garage floor should be about one inch below that of the garage floor. For a six-inch slab, use 2 x 6 wood borders to create the forms.
3

Slope away the rain. The land should slope gently from garage to street, at least one-quarter inch per foot. A rise greater than one and three-quarter inches per foot will cause most cars to scrape the rear bumper on the driveway. If the slope is reversed, from street to garage, install a drain and drainage channel where the driveway meets the garage to divert water.
4

Build the slabs. Pour the concrete, smooth it with a wood float and cut the isolation joint with a trowel. Set isolation joints where the drive meets the garage, walkways and the street. Control joints should be no more than 10 feet apart. A longitudinal control joint should be included down the middle of the driveway. Cut control joints at least one-quarter of slab depth.
5

Curve entryways. To create a curved apron from sidewalk to street, set stakes at the edge of the sidewalk, about 15 feet from either side of the driveway. Hammer a nail into the top of each stake and attach a 15-foot string to the nail. Use the string as a radius to place additional stakes in the desired curved pattern. Dig 10 inches deep between the curves and extend the excavation nine inches beyond the stakes. Build slab forms with 2 x 2 boards, lay the gravel base, pour the concrete, smooth it and install isolation joints.

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