Concrete Kiln Pad

[Larry]

The first solar kiln I built 29 years ago was supported by the butt end of old poles.



I sold the farm a few years ago and the new owners were using it as some kind of green house.

I used 6" fiberglass batts for insulation in the floor.  I didn't have much crawlspace so I put the batts in from the top, than the floor followed by the rest of the kiln.  It was a pita keeping the batts dry from frequent showers while I got the rest built.

I just now got to thinking and that solar kiln held almost the exact same amount of wood as my new L53.  Never had any trouble with the floor.

[Don P]

15 psi x 144 si/sf=2160 lbs per square foot capacity on the 15 psi foam. You probably don't need the high density. I typically assume the soil is only good for 2000 psf.

[firefighter ontheside]

I'm thinking 11' wide inside and 7' or 8' deep inside.  It wouldn't hurt my feelings if I never mill another 10' log, but I hate to limit myself especially if someone wanted to pay for kiln service.

[Tom K]

15 psi x 144 si/sf=2160 lbs per square foot capacity on the 15 psi foam. You probably don't need the high density. I typically assume the soil is only good for 2000 psf.

HERE, presumptive allowable bearing capacity is 2000 psf, most of out soils are good for 2500-3500 psf. Regardless, I wouldn't put 15 psi under a slab as it's just not good practice, and not recommended by the foam manufacturers. 25 psi foam isn't really anything special and is available at most if not all big box stores.

I was more mentioning the foam rating so FF could run the numbers and figure out he probably didn't need a frame if he did over slab insulation.

FF, why the hate for 10'+ logs? In the shop I would much rather have 10-12' lumber then 8'. I'll be following along to see what design you end up going with.

[blackhawk]

For reference, the concrete pad for my kiln was 14' x 9'.  I did a monolithic slab with 18" deep footers around the perimeter.  I poured in September 2022 and had around $1000 in the foundation.  This includes concrete, gravel, 6 mil plastic, and rebar.  I did all the labor myself.  

On the foam, I used 25 psi and would not use anything less.  In my area, there wasn't a choice anyway as 25 psi foam is all that is stocked.

[firefighter ontheside]

I found these on FB and thought they were interesting and perhaps useful for something.  


 

[firefighter ontheside]

also found this


 

[KenMac]

also found this

This looks like walk-in cooler or freezer wall panels and may or may not be good in heated spaces. I did think I was wrong once, but was mistaken..............

[firefighter ontheside]

  @Tom K I cut a lot of live edge stuff.  10' long 8/4 slabs are so heavy.  I broke my tractor loader on a very large 10' log.  It just doesn't seem that 10' logs are great for me.  That being said, I have decided to go ahead and build the kiln to allow 10' lumber.

[Stephen1]

If you going to build 11' you might as well go for a 13' so you can load 12' lumber, or slabs. 
I get lots of call for 12' very few for 16' 

[firefighter ontheside]

I can only mill 10' 6" long at max.

[Don P]

Remember door swing/thickness and being out of level so you are going though the door diagonal to the door a bit. And I can't nail the landing the way I used to, in my fondest memory. Just make sure you can wiggle in. I wish we had gone 22'  :D

[GAB]

I can only mill 10' 6" long at max.

Bed extensions, last I heard, are still available.
GAB

[Larry]

It wouldn't hurt my feelings if I never mill another 10' log, but I hate to limit myself especially if someone wanted to pay for kiln service.

I feel the same way for a variety of reasons.  About all I saw is hardwood grade lumber.  It is always easier to get high grade (FAS) out of 8' logs especially if I buck the tree.  With only one length of log it is easier to fit the load in the kiln and block the empty space on the sides.  It's easier to surface shorter boards in my smallish shop.  Makes measuring and storage easier when time to sell boards.  Most of all shorter boards are LIGHTER which is pretty important when jointing and planing....and the boards get heavier every year!

I did make my kiln 12' wide but would have been most happy with 11'.  The last two loads through it were 10/4 live edge walnut and 8/4 grade walnut all 10' plus long.  I can only lift one end of the live edge stuff.
 

[Tom K]

 @Tom K I cut a lot of live edge stuff.  10' long 8/4 slabs are so heavy.  I broke my tractor loader on a very large 10' log.  It just doesn't seem that 10' logs are great for me.  That being said, I have decided to go ahead and build the kiln to allow 10' lumber.

Thanks for the reply. That makes a lot of sense if you deal with a lot of live edge and 8/4 stuff.

Most of what I cut is 4/4 hardwood that I plan to keep in the 8-12' range, and for my own use. I always get frustrated in the shop when I need a whack of 30-32" or 48" pieces and 8' boards don't work well allowing for some waste.

Those 3" IMP panels in your first link would make some decent walls. Being that thick you would not need any intermediate support. Depending on the manufacturer they should have a R value around R-25 with an EPS core. While not right, I have seen those used as roof panels as well with just caulking the panel joints.

[K-Guy]

I'm probably repeating myself but this is very important.

Whatever insulation you are looking at, remember to check the heat rating on it. Some insulation is only good for cooling and breaks down at higher temperatures.

[firefighter ontheside]

Thanks Stan and others.  I will definitely confirm the temp rating before I buy something.  I would think anything that could be used in a roof will be fairly high rated to be able to take the summer heat.  A lot of the used foam stuff I see is stuff that has come out of commercial roof systems.

[scsmith42]

I'm probably repeating myself but this is very important.

Whatever insulation you are looking at, remember to check the heat rating on it. Some insulation is only good for cooling and breaks down at higher temperatures.

Yes, but...... how much heat will insulation see below a concrete pad?  
I can see where temp rating for the walls and ceiling inside a kiln would be critical, but seems to me that the slab will be a giant thermal heat sink and the insulation under the slab will not see that high of a temp.

[Tom K]

Yes, thanks for the reminder again Stan. We do use these panels a lot in cooler buildings, and we have also used them as bulkheads above oven lines. Without knowing the manufacturer it's going to be hard to nail down a solid temp rating. I would think the IMP's would be able to hold up much better to the heat then a prefab cooler panel. I doubt those are, but some IMP's are also fire rated.

[Tom K]

I'm probably repeating myself but this is very important.

Whatever insulation you are looking at, remember to check the heat rating on it. Some insulation is only good for cooling and breaks down at higher temperatures.

Yes, but...... how much heat will insulation see below a concrete pad?  
I can see where temp rating for the walls and ceiling inside a kiln would be critical, but seems to me that the slab will be a giant thermal heat sink and the insulation under the slab will not see that high of a temp.

These other types of insulation would not be used below grade, or at least I hope not. I was assuming FF was looking at different options for walls/roof, which is where Stan's comment is applicable.

Under slab really needs to be XPS, which the IPM's or other sandwich panels are not.

Unless I'm not following along right, which could also be a possibility.....

[K-Guy]

how much heat will insulation see below a concrete pad

I'm talking about insulated panels or insulation out of coolers mainly that might be used for wall and ceiling insulation. For the pad you are probably correct.

[firefighter ontheside]

My L53 has shipped, but I do not have a tracking number yet.  I assume it will be here early next week.

[firefighter ontheside]

Well, the L53 will be here tomorrow it seems.  I've been trying to get the tracking number from Nyle, but they were having trouble finding it.  Got a call from the shipper today.  It will be here tomorrow.

[Larry]

My Nyle came on a lift gate truck.  We didn't use it, I just meant the driver on the road and pushed the pallet off the truck into the back of my pickup.  Its not all that heavy.

[firefighter ontheside]

Yeah, the shipper said its on a pallet and weighs about 150lbs and that the driver would need help offloading it.  I will probably just take the tractor down to the road and pick it up with the forks.  I need to boxblade my driveway anyway from the recent rains we've had.  Maybe the truck will show up while I'm out doing that.