Concrete base for sawmill

solodan · October 21, 2007, 10:57:04 PM

I have thought about building an elevated deck on a slight grade, and then digging a 3 sided pit and leaving an access on the downhill side, then using that heavy duty expanded metal decking you see at ski resorts, so the saw dust can fall through into the pit. The pit would still have to be cleaned out every so often, but not as often as sawing on grade. ??? maybe I could conveyor the sawdust out to a sawdust burner. ???

kelLOGg · September 16, 2021, 07:32:43 AM

Did something dumb 10 years go when I put RR crossties for the base of the mill. Now they are rotting. I am considering 3 options:

1. dig up the rotting ties and replace with concrete
2. drill 12" (approx) dia holes where the legs are and fill with concrete
3. excavate a bed and fill with concrete for the entire mill to rest on. (about 29' long)
I will have a concrete company do the work due to the amt of concrete involved. Access is limited to the ends of the shed due to the rollway on one side and trees on the other. I want to keep cost down but minimize the labor I have to do. I am leaning to option 1 but I want FFer's comments

doc henderson · September 16, 2021, 07:52:19 AM

cheapest and easiest might be the hole in the ground with concrete. you can throw in the cardboard sono tube if your soil will not hold. could even do the quick-rete bags if you want it fast and simple. a small pad of concrete (2x2) under the tires may help them last, or they can be taken off and stored inside. I only tow/move mine about once a year.

VB-Milling · September 16, 2021, 08:45:06 AM

How are option 1 and option 2 different? Not sure I'm understanding. It seems to me if you go with option 1, you are 90% of the way to option 2. Maybe I'm missing something. ???

kelLOGg · September 16, 2021, 09:34:01 AM

In option 1 the rotting ties are about 4 or 5 ft long and span the width of the mill (plus about a foot on each side)
In option 2 a 12" dia hole would be drilled where the legs contact the ground and then filled with concrete. Drilling would go through the rotting ties and down maybe 18" to 24".

WDH · September 16, 2021, 09:37:52 AM

You deserve a nice set up. You have worked hard. I would pour the pad and enjoy how much better that will make things for you.

doc henderson · September 16, 2021, 12:13:28 PM

I agree the pad is the best/nicest option. if that does not fit your budget, you can do the sono tube footings, and pour a slab over them later. i think if the mill is all that will roll on the slab, then a 4 inch reinforced slab should be enough.

doc henderson · September 16, 2021, 12:17:07 PM

a 5 x30 foot 4 inch slab is under 2 yards of concrete. that costs about 210 bucks here. I would add wire mesh or even the roll wire that is 5 feet wide. i still like having the footing under where the most pressure will be under the feet. if you hire it done, it will add to the cost, but be a better finish if you are unfamiliar with concrete placement.

VB-Milling · September 16, 2021, 03:17:38 PM

I would also agree the pad is the best option. Hired out, it could be formed and poured in a day and its done.

If you're like me (stubborn and cheap), it can be formed and poured in sections with welded wire fabric as doc said and rebar doweling between pours. The sections give you built in control joints so nothing needs to be cut afterwards.

I broke my patio up this way into 7 pours over a few weekends. Each pour was roughly 100 sqft. Totaled about 360 80lb bags mixed in a drum mixer. My wife and I did it with occasional help from a friend. Mostly helping to dump bags into the mixer.

If you did two pours, each 5 x15ft, I think it could be very manageable. If you're not familiar with concrete finishing, I wouldn't worry about it. You could mix it a little dry to avoid pooling water, screed the top with a straight 2x4 and give it a throwaway push broom finish.

kelLOGg · September 16, 2021, 03:36:16 PM

Thanks for the encouragement to pour a pad. I am seriously considering it. And thanks to WDH for the kind supporting comments.

So, 4" thick with wire and rebar is the recommendation?

Magicman · September 16, 2021, 05:15:04 PM

There would be no way to control any shift in position with multiple support pads. Yes, pour a single pad with a moisture barrier beneath the wire.

Ventryjr · September 16, 2021, 08:51:13 PM

I did concrete piers with railroad ties crossing them. Then hemlock 8x8s on top. Haven't been thru winter yet. So we will see. The idea is the posts are below the frost line so they won't move.

doc henderson · September 16, 2021, 08:55:40 PM

most walks and driveways are 4 inch. if you were going to drive a dump truck loaded on it then I would go 6 inches. just increase the concrete cost by 50%. the labor would be the same as you only finish the top. if you pour a pad, still best to put some circular footing under the pressure points down to the frost depth.

PoginyHill · September 17, 2021, 07:22:14 AM

A pad of any thickness would do better with a 2-3"+ base of crushed rock or gravel compacted. If it's a wet area, add a daylight drain if your slope allows to keep water from collecting under the slab.

kelLOGg · September 18, 2021, 06:53:19 AM

Still planning. Is it a good idea to install any support system (pad, piers, e.g.) under the sawmill trailer tires? Seems to me that since they are soft and flexible they don't provide firm support when sawing, so why bother? Omitting such support would make the forms for pouring concrete a little simpler.

doc henderson · September 18, 2021, 07:15:26 AM

it is always dangerous asking for advice with things like pouring concrete. even my buddy Eddie who has done it for 40 years, will waffle on certain "rules" for no apparent reason. so the piers could be a mixed blessing. can transmit forces on the pad down to solid ground below the frost line, and make everything more solid. If the whole pas settles, the concrete may crack there. If you have a 3,000 pound log on a 1,000 pound mill, that is 2 tons, and divided that into the square inches of surface on the pad. many jack have what seems to be a 2 x 4 inch foot (prob. more) if there are 6 of these jacks supporting the mill, then 6 x 8 is all the weight on 48 sq. inches or 83 pounds per sq. inch. you could also put a chunk of wood under each jack say 12 x 12 and now you spread out the forces and reduce to 4.6 pounds per sq. inch. if you will be dropping and scooting large logs, this will impart some dynamic forces as well in addition to the static force. you have all kinds of options. you can form a slab that is 4 inches in the interior, with a 6 inch thick edge for a foot reinforced with rebar like a beam or mass footing. a simple 4 inch slab with some wire roll mesh in it is much better than what you currently have. I have what you have at this point. If you have well compacted soil, you can dig the holes for the footings, and pour it all in one pour. it is only time and money. ;)

doc henderson · September 18, 2021, 07:20:12 AM

On the tires, unless they are suspended off the ground, then they are sharing part of the weight. my jacks and tires are all in line, I am liking the thicker edge with rebar along the edge better and better, I think that is what I would do.

2308500 · September 18, 2021, 10:01:39 PM

4 piers dug down 3 feet below grade and 6 inch pad with rebar and wire mesh. overkill.....maybe...maybe not

thecfarm · September 19, 2021, 05:23:59 AM

overkill? you will never know. ;)
overkill has made me feel better about a build many times. ;D

kelLOGg · October 24, 2021, 07:12:38 AM

It is finally done. 4 x 27 with 2 x 4 for the tires and 4" thick. Packed gravel beneath all - but no rebar. My concrete guy said it wasn't necessary. Hope he's right. Good bunch of guys to watch work. I told them it was the first time I had watched people work. While it cures I will be getting my 1st cataract surgery.

TimW · October 24, 2021, 02:28:24 PM

No rebar? I think your concrete guy is wrong. Guess you won't be handling any huge logs. I do hope I am wrong.
hugs, Brandi

kelLOGg · October 24, 2021, 03:47:19 PM

32" dia is the max. Usually less than 16'. Fingers crossed. I guess what I failed to emphasize to him is that logs "fall" several inches when they are turned.

230Dforme · October 24, 2021, 04:14:24 PM

They didn't want to unload, carry, cut
or tie the rebar

doc henderson · October 24, 2021, 04:22:51 PM

no option now but to wait and see. I only use the plastic fiber when nothing else will work. keep us in the loop! thanks. I used it in my pool floor under vinyl and in the 1.5 inch slab over plywood and trusses in my shop with floor heat, and it has done well.

I would put some relief cuts as it is long and skinny and will crack, even if you had put mesh and rebar in it.

TimW · October 24, 2021, 11:53:20 PM

Quote from: kelLOGg on October 24, 2021, 03:47:19 PM
32" dia is the max. Usually less than 16'. Fingers crossed. I guess what I failed to emphasize to him is that logs "fall" several inches when they are turned.

Oh, okay. Not too big. When I load a huge 36 incher 20 feet 3 inches with the loader arms, if it rolls too fast on the bunks to the back stops, my whole mill moves, then settles back down with a thunk. Think water shifting back and forth in a dog's water bowl.
All bets are off if you accidently drop a log while sitting it down on the bunks.
hugs, Brandi