Shed/office flooring

[Eaks77]

In the process of converting my shed into an office. It's coming along nicely! This post isn't about it being off-grid or how it'll be heated, there are other posts about that. But because everyone has been so helpful within this forum, I thought I'd seek for some flooring advice.

As you can see, the flooring is one of the last tasks. The shed does not have a concrete foundation and is sitting on top of a couple 4"x4" that run lengthwise. Throughout the seasons, the floor tends to warp and shift. How should I do my flooring?
- While plank flooring (vinyl/laminate) would be ideal, I've been told it'll difficult (if not impossible) to install due to the unlevel surface and warpage.
- Someone told me to lay down 3/4" 4x8' pieces of plywood down first to get a level surface. While I should be able to get this plywood and some plank flooring under the door (the only restriction), I have concerns with the way it'll sit on top of the warped subfloor. As of right now, the middle of the floor is the heighest point and if I place plywood on top, wouldn't it teeter? haha
- Another thought I had was getting some 1/4" MDF wall panels (that actually looks like flooring) and place it on top of the current floor. It'll be way easier to install and will likely warp with the subfloor. I understand the wear of the floor is questionable and will be susceptible to water.
- The only other area I'm lost is the underlayment. I want/need something that'll be an excellent thermal layer.. suggestions?

 

[Hedges]

My house had D (or E or F?) grade plywood subfloor under carpet, which would have telegraphed through any vinyl. So I put down bamboo (which has now worn through the finish in places.)

Maybe I should have put down 1/4" "A" faced plywood followed by vinyl.
My sister used linoleum, for a natural materials rather than petroleum outgassing.

Rental condo on slab, I filled the giant divets where tack strip nails had been, and paid to have resilient vinyl rolls put down. Seams only in doorways. Way to expensive, but holds up to abuse better.

Not sure about your warped issue. How bad? Is it moving?
Rolls might form to uneven surface better than planks.
Wonder if anything compliant under plywood could help.

I prefer plywood to MDF, particle board, and fiber bonded planks with a photograph of hardwood on top.
But the lowest maintenance flooring I've had which held up the best was vinyl in a mobile home. Only failures were where square slashed openings for floor vents continued to split due to shrinkage (should have been round corners), and where I pulled a glowing Pyrex bread pan from the broiler and it went Ping! and pieces melted into the floor (I got my toes out of the way before it hit.) No, I don't follow instructions even if I do read them.

 

[MattiFin]

IF your flooring was stable I’d add 4 to 6 inches of XPS insulation, top it with 3/4” subflooring (OSB or plywood) and put laminate on top of that. Vinyl laminate if you suspect that you are going to drag water/snow inside your hut.

 

[Eaks77]

IF your flooring was stable I’d add 4 to 6 inches of XPS insulation, top it with 3/4” subflooring (OSB or plywood) and put laminate on top of that. Vinyl laminate if you suspect that you are going to drag water/snow inside your hut.

Unfortunately, woudln't consider it "Stable" as it warps/shifts throughout the year. Also, I don't have 4-6" of space. I have maybe 1" tops between the bottom of the door and the current subfloor

 

[Hedges]

vinyl laminate?
Depending on size, you might get roll vinyl remnant cheap.
Our installers didn't want to do coved edges just flat. I did cove in my sister's bathroom, using concave round wood pieces. Took me an entire day, but it was clean.

1/2" foam board, 1/4" to 1/2" plywood, sheet vinyl?

 

[MattiFin]

vinyl laminate?
Depending on size, you might get roll vinyl remnant cheap.
Our installers didn't want to do coved edges just flat. I did cove in my sister's bathroom, using concave round wood pieces. Took me an entire day, but it was clean.

1/2" foam board, 1/4" to 1/2" plywood, sheet vinyl?

Dunno what it is called in US. Vinyl plank? (instead of vinyl sheet you got fairly rigid vinyl/composite planks that are installed same way as laminate flooring)
1/2" foam board would be crazy COLD in Canada. Especially so if you have shed that is open from underneath and -40 air can circulate under your 1/2" insulation. ?

I was afraid that OP doesn't have space for proper insulation. Is there same situation with ceiling ie. no insulation?

 

[Eaks77]

Dunno what it is called in US. Vinyl plank? (instead of vinyl sheet you got fairly rigid vinyl/composite planks that are installed same way as laminate flooring)
1/2" foam board would be crazy COLD in Canada. Especially so if you have shed that is open from underneath and -40 air can circulate under your 1/2" insulation. ?

I was afraid that OP doesn't have space for proper insulation. Is there same situation with ceiling ie. no insulation?

Ceiling is fully insulated with R14 Rockwool.

I'm getting confused by the suggestions... if I understand correctly, 1/2" foam board then 1/2" plywood? How would that cope with the continous warping of the original subfloor?

 

[Hedges]

Nothing we can do about warping, if you mean dynamic movement with the seasons.
If static and not flat, something that fills to planarize might work.
I was suggesting what little insulation could be added, given restriction on total thickness. Plywood was to distribute your weight so as to not crush the insulation.
Sheet vinyl could conform to an undulated shape, if planks won't fit right.

 

[MattiFin]

If your floor currently has no insulation at all I'd say 2" XPS would be a bare minimum unless you want to have your toes frozen indoors.
Or 1" to 1.5" PIR foam.

 

[circus]

What's wrong with a low berber carpeting? Cheap, easy, fast, tough, warm, quiet and looks good enough. My brother installed hardwood laminate in his living room the same time I installed berber in mine claiming hardwood more durable (not). You wouldn't even need any seams.

 

[Q-Dog]

That OSB subfloor you have currently is NOT correct for a situation that close to the ground. It absorbs moisture, and over time it swells and falls apart. And if you cover it with vinyl it will take twice as long to dry out after it absorbs any moisture because the moisture can't pass through the vinyl to get out.

I don't know where you are, but in my area I would want pressure treated for any wood that sits closer than 16" to the ground. I would likely pull it all up and replace it with treated plywood.

 

[Eaks77]

That OSB subfloor you have currently is NOT correct for a situation that close to the ground. It absorbs moisture, and over time it swells and falls apart. And if you cover it with vinyl it will take twice as long to dry out after it absorbs any moisture because the moisture can't pass through the vinyl to get out.

I don't know where you are, but in my area I would want pressure treated for any wood that sits closer than 16" to the ground. I would likely pull it all up and replace it with treated plywood.

Thanks for the suggestions! I agree, OSB is not ideal, but redoing is not an option.

I think i'm going to install some Dricore Subfloor while leveling it with some shimes or inserts underneath it and then either carpet or plank flooring

 

[MattiFin]

Thanks for the suggestions! I agree, OSB is not ideal, but redoing is not an option.

I think i'm going to install some Dricore Subfloor while leveling it with some shimes or inserts underneath it and then either carpet or plank flooring

Go for carpet. Your floor is going to be really cold but at least it feels slightly less freezing with carpet.

 

[Supervstech]

Can you seal out the moisture under the building? I’m guessing the 4x4’s are sitting on blocks… get some visqueen 6Mill, and seal out the moisture?

 

[Rednecktek]

Step 1: Get a BIG box of screws
Step 2: Apply screws everywhere you can to secure the flooring to the 4x4's and anything else available
Step 3: Lay in 1/2" ACX or PT plywood over the current floor
Step 4: Repeat Step 1
Step 5: Carpet/Lino/Vinyl/Bear skins/whatever

I'm assuming that ripping up the current floor isn't an option? Since it doesn't sound like you have access to get underneath, ripping up the floor and installing some floor joists to screw new subfloor down isn't an option?

 

[Eaks77]

@Supervstech unfortunately, sealing the underside is not realistic right now. Not much room under there.. maybe 4". I might be able to drape some poly from one end to the other, but I wouldn't consider it sealed.

@Rednecktek thank you for the suggestions. Any thoughts on just using this ?

If I were to use a vapour barrier, where would I put it? In between the flooring (planks or carpet) and the Dricore Subfloor, or somewhere else in between?

 

[Rednecktek]

You could but I think that the 4ft x 8ft sheathing would be cheaper and more effective. The goal is to secure the krap out of all the boards so that if 1 floor board tries to twist/warp/creak/dance, it has to fight a ton of screws AND the 4x4's AND the top layer. That'll help hold everything in place better than the warping trying to move a 2ft square board.

If you're just worried about insulation, you can go with those or get some thin sheet foam and sandwich it between the subfloor layers. That way you're not over the door threshold height.

 

[Eaks77]

@Rednecktek now I completely understand why I would need a crap load of screws and what you were trying to do. However, if I screwed everything in as it stands, I'd still have an uneven floor that's less likely to shift/warp. If I was able to get the shed and floor level, than your process would be awesome! Right? :S Unfortunately, I won't be able to shift the foundation of the shed. You're absolutely right, the 2x2's are more likely to shift and warp, but I think I need to embrace that and hope for the best haha.

 

[eXodus]

If you're just worried about insulation, you can go with those or get some thin sheet foam and sandwich it between the subfloor layers.

you can actually get Zip-R Sheeting which hast the foam board already attached to the plywood/OSB,

That's current industry practice to sandwich the foam board between layers of the exterior.

If I were to use a vapour barrier, where would I put it?

Zip-R also has a integrated Vapor barrier. - just screw it down - and tape the seams.

You can get it in a various thickness.

 

[Rednecktek]

If you're just going for level, and can't rip up the floor (pesky walls, am I right?) to put in more bracing, there's always the liquid subfloor leveler that they use when they install linoleum. It's basically a really thin mortar/cement/plasticine stuff that the guys would pour out on the floor and level with a trowel before screwing down sheathing. The goop got everything level and the sheathing kept it that way.