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Question DetailsAsked on 11/7/2016

Where can I find a 16" diameter, cast iron, round grate for a garage floor drain?

This is to replace an existing 60-year old rusted and cracked grate.
This appears to be a rare item. The biggest grate I found after a long Internet search is about 14" in diameter.
Must be strong enough to carry about 1/4 of the weight of a compact car. (I.e. 1 out of 4 tires resting at the center of the grate, while the other 3 rest on the garage floor.)

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5 Answers

Voted Best Answer

US Foundry has 14-1/4, 15, 16-1/4 round grates - catalog page here, watch out to check for whether they are flat or domed, and if traffic rated (H10 or larger number [which relates to vehicle load, not drain size, and may have an HS prefix with larger numbers for more modern highway semi trailer loads] is probably the rating you need). For your vehicle weight, even a golfcourse or parking lot drain grate would be fine - does not have to be highway rated -

Also found 15" rounds listed in Zurn ( and some similar (but not exact 16") sizes at Neenah Foundry ( Grainger Industrial (a dealer, not a manufacturer) and listed 14-18 inch range ones in a category search, but I could not get their listing pages to come up on my computer - or the web was too busy on election night maybe.

I would still say find the local dealer in heavy construction drainage products who sells manholes, street drains, large irrigation drains, etc and let THEM do the legwork for you - though still going to be about $200-300 range probably for that size in case iron.

One other alternative that would be cheaper - especially if you are up to a bit of DIY work - go to junkyard and buy a piece of scrap steel large enough - 1/4" thick might take a light car (I am too lazy to dig out my ASCI manual and calculate the load capacity for an edge supported round disc) but I would go with 1/2" to be on safe side, take to a welding shop to have him torch it into a rough round and drill or blow a half dozen or so holes in it with a torch equally spaced in a roughly circular pattern about halfway in from the edge, then spend some time with a hand grinder rounding it off smoother and knocking the rough spots off. Or if you don't care about looks, just hammer the slag off and the sharp spots down. Probably about $30 or so for a chunk of steel plate (in fact welding shop might well have scrap in stock that could be used directly), probably about $5-8/hole o about that to drill or blow rough holes through it, maybe $50-100 or so to torch cut the rough circle - if you are lucky they will have a circle cutting jig and cut it pretty much perfectly round (with rough edges at the same price. (Note the previous estimate I gave you was for a machine shop doing it - so using a laser or water jet cutter to cut a smooth perfect circle and drill perfect holes - what I am talking about here is how cousin Bubba would do it.

Another possibility - get an old street drain or access manhole steel (not cast) bar grate (so a lot less metal to cut than a solid plate) at junkyard and have welding shop cut it into round shape concentric around center, or do it yourself if you have metal bar cutting ability using a cutoff blade in a skil saw or a chop saw or such. Will not hold HS-20 or HS-25 tractor-trailer load it was probably originally designed for, but as long as the bars are standard 2" or smaller spacing with crossbars every 4 inches or so, and the bars are at least an inch deep will probably hold your car weight fine. No guarantees not seeing the exact grate and the hole it covers, but that is what I would do it if I had your situation and did not care too much about looks.

Another possibility if this does not get wet real often - or maybe if it does even. Get an old scrap of marine 1" plywood and use it, with a few drain holes cut in it, or maybe just a few notches cut around the edges to allow drainage. Around $100-140/sheet for whole new sheets (which would keep you in drain covers for awhile at about 18-20 covers per sheet, and I would expect 3-10 years life depending on how often it gets wet and on whether you paint the edges and top with a good waterproof paint first - do NOT paint the bottom surface, so it can dry out if water get through scratches and ceracks in the paint). A boatyard might sell you a scrap much cheaper.

One other thought on the hole sizes - obviously the larger the holes the more you can lose down the drain, though you could use some hardware cloth or heavy duty filter fabric or such over the top to catch dropped items. There are also strainers that will fit in 3 or 4 inch drain pipe, if that is what is under the grate.

Answered 3 years ago by LCD


In that size, you are not talking about a drain grate - you are probably talking a manhole cover. Contact local commercial plumbing supply wholesaler, or drainage product wholesalers. You would need to know the outside diameter, the thickness of the existing recess at the outside rim (how thick the grate needs to be) and the design wheel loading you want, but should be no problem for cars/SUV/pickup loadings (and I would pick one suitable for large SUV or pickup for possible personal vehicle model changes in the future or for resale purposes).

Made by many companies in cast iron - for weight loading you are looking at possibly a fiberglass one might work too if you are concerned with rust. US Foundry, Neenah Foundry, McNichols, Garrycraft, Deeter, Travis Perkins among many others make this approximate size of street gratings and draining manhole covers. Industrial supply companies like Grainger Industrial Products and International Industrial Supply and such also carry or can get such items - again, exact sizing is the issue. You could also google for grating and manhole suppliers in Sweet's Building and Construction Materials Directory or Thomas Register and then contact those companies with your exact dimensions to see what they have to match.

Note - unless you intend to watertight seal the perimeter (not usual for your application) leave 1/4" clearance in diameter to allow for washing or blowing out grit and sand and such to be able to lift it back up - get too close on tolerance and it will friction lock in with the grit and such. Also, make sure the drain rim dimension is uniform - not larger one way than another due to sloppy installation.

Other alternatives - have a metal working shop make up a replacement grate from standard bar grating (a likely solution), matching what you have now, with appropriate perimeter thickness buildup if needed to get thickness right. Or ditto, with buildup as necessary to avoid significant recess, from plate steel with drainage holes or slots torched/machined or drilled in it. Of course, that sort of custom thing would cost more for the product itself, but if what you need has to be shipped from out of town custom manufacture might be cheaper.

One other alternative - though would be a fluke if it fit exactly right - would be a lighting can cover from a commercial electrical supplier. The drive-on rated steel lids for wiring "cans" - in ground small manholes basically, in which street light and traffic signal wiring is run and connected. Then if you find right size take to a machine shop / metalworking shop to have drain holes cut/drilled in it.

Answered 3 years ago by LCD


Dear LCD,

Thanks for your response and your thoughtful recommendations. However, the manhole covers I see on the market are all solid and would not accomplish the draining function of a grate. I guess I could buy a fiberglass-plastic composite manhole cover and drill holes in it, but short of this difficult approach, which may ruin the cover's load-bearing capacity, do you have any specific suggestions (manufacturer, web page...)?

Answered 3 years ago by MoA


Ignore the ,,,'s - Angies List's computer is stripping out paragraph breaks AGAIN !,,,,,,I did a quick check through a few catalogs - several of the manufacturers I gave you do manufacture around 16" (plus or minus depending on their drain adapter dimensions) grates for use in streets (driveable), though I admit 16" is rarer - jumps from 15" to 18" with many manufacturers.
,,,,,,And I should have said storm drain grates, not manhole covers - sorry. Though many street manhole covers for sewer and storm drain access have about a 1" diameter hole which will drain in minor amounts of water - and you could drill a few more holes for more drainage if you wanted, being sure to avoid drilling out ribs and staying away from edges. ,,,,,,Probably simplest way to find a new grate - call your city or state street department wastewater utility or commercial plumbing supplier and ask who in your area sells manhole and storm drain grates and covers and call them and see what they can do for you. Be sure the vendor knows you will be driving on it. ,,,,,,One other possibility - since this had to be surplus put in by some homeowner because it was what he could get for free - unless your house is built on top of a public sewer or you should think about getting a boat intead of a car if that size drain may actually be needed. Anyway - depending on what size the drain pipe below this drain is, if a standard 3 or 4 inch drain pipe, maybe wrap a layer of cardboard (like the backing from a pad of paper or a cereal box) around a standard 3-6 inch drain grate (to provide removal and installation clearance) that will fit down well on top of the drain housing around the pipe, put self-adhesive weatherstrip around the bottom rim to prevent grout intrusion into the drain, tape over the grate slots to prevent fall-in of grout, then set and weight it in place and use a dry-mix (not flowable) patching grout to fill in the rest of the 16" depression with grout - sloping as needed to drain to the new smaller grate. A $10 bag of patching grout is a lot cheaper than a $200-400 drain grate. Before doingthis, make sure the drain grate has a chamfered edge - file or grind it so that the outside diameter tapers from full diameter at the top to a bit less at the bottom so it can easily be lifted up or popped out with a screwdriver and does not get locked in by grit and sand around it.,,,,,,One other possibility - I called my go-to steel supply yard and they quoted $380 for a 16" (or close to that dimension, as you specify) 1/2" plain steel plate with eight 1/4" holes drilled through it in a circle - so going to a steelyard that sells to the public, or a machine shop that does work other than automotive might yield you a similar quote. That would weigh about 28 pounds - might or might not need shimming or grout buildup to bring it close of floor level if you care, and cost is in the range of or not more than twice a manhole cover size.,,,,,,======,,,,,,NEWS FLASH - found something I did not know - storm drains and utility manholes cannot be 16" diameter by code - that size is reserved for FUEL tank access hatches - so google 16" manhole cover (though you would have to drill holes) and you can find a lot of tank suppliers who sell 16" covers - though whether it would sit in your opening without rocking or clanking you don't know, but if not thicker (so it would stickk up above the floor) you could always rubber cement some rubber strip or weatherstripping under the edge to limit that. "Service station and fueling supply" or "petroleum storage tanks" would be the google phrases to find local vendors of service station and storage tank supplies.

Answered 3 years ago by LCD


Dear LCD,

Tanks again - especially for making a phone call and getting an estimate on machining a part. You are right, $380 or more is too much.

Your grout idea can work if modified for the actual drain opening configuration and dimensions. But I don't want to take your time with more detail.

One last (I promise) question: In which catalog did you see the 15" round grate? (You wrote that sizes jump form 15" to 18", and that 16" is not allowed for storm drains.) 15" diameter will work. So far, the largest I have found commercially is 14-1/4".


Answered 3 years ago by MoA



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Answered 3 years ago by Member Services

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