Plywood thickness under sump

crabbydan · 07/31/2018, 11:13 AM

I have a 5 foot wide Steel stand. I plan to put plywood on the bottom section where the sump goes. The stand has a left cross beam a middle cross beam and a right cross beam with a 2.5 foot gap between them. I also have the back wall and front wall cross beams the plywood will lay on. I have 1/2 inch plywood in stock at home. My question is how do I know if this is strong enough to hold a 40 to 45 gallon sump?

I hope I described this enough to understand what I am asking?

Any advice? Yes to be safe I can go out and buy a 3/4 inch sheet of ply wood but since I have the 1/2 inch laying around i'm thinking why not use it?

lowtek · 07/31/2018, 01:42 PM

Hello, Well since I'm using 1/4" ply under my 44x20x16 sump, I think 1/2 is more than enough. Just try to get the cross beams as flush as you can to the rest of frame to eliminate any bowing/flexing from the ply and I'd say you're good. Also I would cushion the sump too. I'm using those silicone non slip tool box drawer liners to cusion mine and its been good since February.

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thegrun · 07/31/2018, 06:53 PM

Personally l would not go any thinner than 3/4”. Two layers of 1/2” for a total of 1” would be ideal. If you get any sagging at all it places a tremendous amount of pressure on the sump and you risk a major disaster. The price of a piece of plywood is a small cost considering the risk.

lowtek · 07/31/2018, 07:24 PM

Quote:

Originally Posted by thegrun

Personally l would not go any thinner than 3/4”. Two layers of 1/2” for a total of 1” would be ideal. If you get any sagging at all it places a tremendous amount of pressure on the sump and you risk a major disaster. The price of a piece of plywood is a small cost considering the risk.

Very true if there were no cross members. But you are right better safe than sorry. Then again a 1 foot gap between cross members makes for a quite strong platform

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thegrun · 07/31/2018, 09:02 PM

Quote:

Originally Posted by lowtek

Very true if there were no cross members. But you are right better safe than sorry. Then again a 1 foot gap between cross members makes for a quite strong platform

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If I’m reading his post correctly (and I certainly may not be) there is a 2-1/2’ gap, but either way I would go with at least 3/4” plywood.

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lowtek · 07/31/2018, 09:23 PM

Quote:

Originally Posted by thegrun

If I’m reading his post correctly (and I certainly may not be) there is a 2-1/2’ gap, but either way I would go with at least 3/4” plywood.

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Sorry I forgot to mention to the OP that I would add a cross member between each 2.5 gap which will help stop sagging otherwise 3/4 ply might be in order. On my stand I spaced my cross members a little over a foot apart. Flush with frame on both top and bottom with 1/4" ply and no problems. My son was playing around on it before I added my sump even. I did however use 3/4 ply under my 60x32x22" DT. As long as both ends and middle of sump is resting where the cross members are I dont believe you will get sagging issues. I'm no expert by any stretch but my system hasnt collapsed yet. Knock on wood. Hopefully i was of a little help. Good luck

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crabbydan · 08/01/2018, 12:32 AM

Good advice. The sump is acrylic no bottom trim also the stand only has the one cross brace in the middle and is complete so just going to get the 3/4 plywood which I then do 2 coats killz and 2 coats epoxy appliance paint.

07/31/2018, 11:13 AM	#1
crabbydan Registered Member Join Date: Dec 2014 Location: Phoenix, AZ Posts: 267	Plywood thickness under sump I have a 5 foot wide Steel stand. I plan to put plywood on the bottom section where the sump goes. The stand has a left cross beam a middle cross beam and a right cross beam with a 2.5 foot gap between them. I also have the back wall and front wall cross beams the plywood will lay on. I have 1/2 inch plywood in stock at home. My question is how do I know if this is strong enough to hold a 40 to 45 gallon sump? I hope I described this enough to understand what I am asking? Any advice? Yes to be safe I can go out and buy a 3/4 inch sheet of ply wood but since I have the 1/2 inch laying around i'm thinking why not use it?

07/31/2018, 01:42 PM	#2
lowtek Registered Member Join Date: Apr 2015 Location: Pacific Northwest Posts: 111	Hello, Well since I'm using 1/4" ply under my 44x20x16 sump, I think 1/2 is more than enough. Just try to get the cross beams as flush as you can to the rest of frame to eliminate any bowing/flexing from the ply and I'd say you're good. Also I would cushion the sump too. I'm using those silicone non slip tool box drawer liners to cusion mine and its been good since February. Sent from my SM-G935P using Tapatalk

07/31/2018, 06:53 PM	#3
thegrun Registered Member Join Date: Dec 2008 Location: Garden Grove, Ca Posts: 17,023	Personally l would not go any thinner than 3/4”. Two layers of 1/2” for a total of 1” would be ideal. If you get any sagging at all it places a tremendous amount of pressure on the sump and you risk a major disaster. The price of a piece of plywood is a small cost considering the risk.

08/01/2018, 12:32 AM	#7
crabbydan Registered Member Join Date: Dec 2014 Location: Phoenix, AZ Posts: 267	Good advice. The sump is acrylic no bottom trim also the stand only has the one cross brace in the middle and is complete so just going to get the 3/4 plywood which I then do 2 coats killz and 2 coats epoxy appliance paint.