Reinforcing new shed floor

[Lady BlackThumb]

Hi all, I finally bit the bullet and got myself a new wooden Loxley potting shed, built on a concrete base. The floor of the wooden shed itself is set on a row of wooden joist/beams so there is about 4cm gap between the floor and the concrete. (Eyeballing it).

It's been raining a lot, so all the wood of the shed feels a bit moist even on the inside, and the floors (12mm tongue and groove) feel just a hair "bouncy" when I lean hard on the parts between the beams underneath.

I was thinking of buying some thick 1cm plywood to lay on top of this floor to reinforce it (plus a lick of floor paint), would this be a bad idea? I have no clue about sheds, but in theory I suppose if the timbers got a bit damp from rainy weather, it wouldn't be able to dry off as easily if there was a layer of plywood on top?

Thoughts from you folks?

[AntC]

Prolonged exposure to moisture is not good for a garden shed and I am surprised that your new shed feels damp inside. It sound to me that the concrete base might not be perfectly level which would account for the slightly spongy feeling on the floor and it is imperative that when it rains, no water can get under the shed and soak into the joists. This is all stuff that I am sure you are aware of but I can't think of much else to say!

You will always get a bit of "give" on a 12mm floor between the joists but I definitely wouldn't lay plywood on top of the new floor until you have sorted out the damp problem. Do you have a rain gutter on the shed?

[nickdub]

The general idea in any construction like this is to keep the wood part as dry as possible.

So as to the floor, ideally you would want to put something impermeable under the beams to give additional support by spreading the load on to the concrete base - eg 4 cm thick floor tiles or broken pieces of paving stones - you want to avoid any wicking of wet from below to make the wood in contact with whatever it is damp. I'd stick a few stones under the beams and see if this helps solidify the structure.

Obviously when the wood dries out in the Summer it might be a good idea to treat it in some way - e.g. ranch paint.

[veggiechicken]

Is it one of these?
https://www.sheds.co.uk/garden-sheds...eft-sided.html
The image shows the floor bearers.

Useful info about sheds at https://www.secrets-of-shed-building...hed_floor.html

[Lady BlackThumb]

@veggiechicken, yes its the 6x8 version of that shed.

@nickdub @antC I'll need to double check the levelness of the concrete base, but I'm pretty sure it's level, From the sounds of it I should get around to installing some gutters, as I don't think I'll be able to lift the shed now that it's built to add anymore things between the wooden bearers and the concrete.

On the otherhand, I'm crossing my fingers and hoping that the shed feeling dampish on the inside is due to the fact that it was lying unassembled (and being rained on) in my garden for a month due to the shed company cocking up their delivery of parts and sending out of The Men Who Build Sheds, and i went into the new shed and identified the dampness literally the morning after installation.

[Lady BlackThumb]

I Just went out to check, and the shed interior seems damp-ish BUT drier (and the floors/ base are level) than it was before. So chances are it was because it was lying around soaking up all the rain before it was assembled. Fingers crossed.

On a side note, the minute i can I'll be putting a coat of paint on it. It's mega frustrating that this is happening now when the weather is not conducive to painting. (impatient gardener!)

[AntC]

What you also need to do is check that water dripping off the side of the shed isn't running under the floor. I painted my shed within the last 10 days so it is possible but make sure the wood is completely dry. I was lucky the sun shone for three days!

I do envy you that potting shed!

[nickdub]

Easy enough to lift the beams individually by simply putting a car jack under the beam next to where you want to add the support (obviously you'd need to take the floor panel up first) or if that isn't practical just jack up one corner, chock that with some wood, do what needs to be done, jack up again to release the chock - 10 mins tops :-)

As for levelling the base precisely, I wouldn't bother - if its open to the wind and rain you'll get water blowing in whatever you do - in fact a slightly convex finish is preferable to a flat one imo since at least the water will naturally drain away again.

[Lady BlackThumb]

@antC it was the closest compromise I could find to a Greenhouse + storage shed for my tiny garden. XD I'm looking forward to having proper growing adventures with it in the new year!

[Lady BlackThumb]

Well don't I feel like a silly parsnip now. I kept the little window on my potting shed open all night and that has pretty much solved 95% of the condensation issues that caused all the wood around the window areas to be soggy. :P