Flooring questions

[Pat Barry]

I have a cabin that was built in 1930 or so. It has log 'joists', abut 4 inch dia, on 24 in centers. The lengthwise span of these joists is about 8 ft each. Each joist is supported at both ends with a much larger log, approx 8 inch diameter. The log structure seems pretty good from what I can tell. The original flooring on this is 3/4" pine T&G planks, approx 4 to 6 inch width. Anyway, someone installed some Pergo over the top of it and didn't fix the problem with the floor which is some softness in a few places due to the 24 in span, possible damage to the floorboards (moisture issues in the past). What I'm planning to do is to remove the Pergo, and install some underlayment. What I'd like is advice on the underlayment. Should I go with 3/4" plywood or is the 23/32 OSB a suitable choice?

Second question, this is a kitchen area and the base cabinets were installed over the Pergo. Should I remove the base cabinets (this will be a big job I think) or is it OK to remove the Pergo up to the base cabinets and butt the new underlayment right up to the base cabinets?

Third question, is the underlayment even necessary if I install 3/4 finished flooring over the existing flooring (removing the prego of course, but same question about dealing with the base cabinets?

I also have to deal with some transisitons to bedroom and bathroom - is it acceptable to have a small stepdown in these areas or should I be working to keep everything on one level?

[Tom M King]

I'd have to see it, but I'd guess that 3/4 flooring would take care of it on top of the original floor, unless there is some spot that there is worry about stepping through now. I'd do something not to have height transitions from one room to the other, even if there is a slight slant to a small width of it. I've done that a number of times. Again, hard to say on the cabinet question. There should be good support under the ends of the flooring there. If when you take the Pergo up, you can move the original floor boards to amount to anything with a foot, I'd take them up and go under.

[Pat Barry]

I'd have to see it, but I'd guess that 3/4 flooring would take care of it on top of the original floor, unless there is some spot that there is worry about stepping through now. I'd do something not to have height transitions from one room to the other, even if there is a slight slant to a small width of it. I've done that a number of times. Again, hard to say on the cabinet question. There should be good support under the ends of the flooring there. If when you take the Pergo up, you can move the original floor boards to amount to anything with a foot, I'd take them up and go under.
Tom could you clarify these two points you made:
"I'd do something not to have height transitions from one room to the other, even if there is a slight slant to a small width of it. I've done that a number of times." DO you mean making the transisiton slope in the doorways?
"you can move the original floor boards to amount to anything with a foot, I'd take them up and go under." Do you mean that if it feels soft near the base cabinets you would remove the bases and do the floor and then re-install?

[Scott T Smith]

If it were me, I would:
1 - leave the pergo under the cabinets. There is no reason to remove.
2 - level the floor across the entire cabin. This can be achieved by placing thin spacers as needed underneath the plywood. For spacers, I would consider 1/4" plywood (if that was the correct size), linoleum, etc.
3 - I would install some supports under the floor joists in the soft areas. Typically cement blocks and pressure treated lumber will work fine. If needed, you can put a beam underneath them mid-span and support it with blocks, etc.

[rudy de haas]

Hi:

I've had to do something similar..so I rather think the answer is the classic "it depends"

1) OSB vs plywood depends on annual variation in humidity - the more variation you get, the stronger the argument for good quality plywood because OSB (contrary to many mfg claims) swells/shrinks more. (but don't use chinese made junk plywoods, pay for the usa label)

2) whether you should remove the pergo under the cabinets depends on how wide their base of support is. The more beams it crosses (and if they look ok friom underneath) the less you should worry about replacing the pergo layer. Also, if the pergo was added later, it may or may not extend completely under them.

3) 3/4" hardwood flooring will support a huge amount of weight without flexing - but only if your average piece lenght crosses several beams. You can buy (at extra $, of course) wood guaranteed to be of some minimum length like 6 feet. Your choice of wood will be affected by local variations in humidity, but almost any hardwood will give you to the strength needed to justify skipping the plywood layer.

However.. getting the floor flat across all rooms is tricky, and made much much much easier if you use plywood (even 3/8") as a substrate. Home depot et al
sell rolls of 1/8" cork that has a vapour barrier on one side: putting it plastic side up on your plywood makes putting the hardwood in much easier too.

[Tom M King]

Tom could you clarify these two points you made:
"I'd do something not to have height transitions from one room to the other, even if there is a slight slant to a small width of it. I've done that a number of times." DO you mean making the transisiton slope in the doorways? shim it
"you can move the original floor boards to amount to anything with a foot, I'd take them up and go under." Do you mean that if it feels soft near the base cabinets you would remove the bases and do the floor and then re-install? yes, if the floor is soft after taking the pergo up with the cabinets in place, do something to make the floor sturdy again

[Peter Quinn]

3/4" plywood over 24" OC framing is pretty much the maximum span in the charts I looked at. Do you like a bouncy floor? I'd be looking at 7/8"-1" ply for a substrate, real joy to install but easier to live with. Guess it depends on the budget and how you like the floor to feel? If the cabs aren't sinking I wouldn't worry about them, particularly if they run perpendicular to the framing. I don't count on flooring to add structure, it also adds dead load, and you can't count on joints landing over framing, the stiffening effect is diminished when joints land in the middle of the span, requires some real careful planning and staggering of joints....better off to create a solid subfloor.

[scott vroom]

I'd avoid unsupported sub-flooring edges, which it sounds like what you'll get by not running it beneath the cabs. If you're unable to add support from beneath for those edges then I'd remove the cabs and run the subfloor to the wall. Do it once do it right.

I'd also avoid tiling over that floor structure due to excessive deflection (or plan to add additional joist support). It sounds like you're planning hardwood planks, though.....should be fine for that.

I've installed lots of flooring that elevated above adjoining room flooring; transition pieces can be custom milled to a wider width to smooth the transition. I've never had a complaint.

[Pat Barry]

I've installed lots of flooring that elevated above adjoining room flooring; transition pieces can be custom milled to a wider width to smooth the transition. I've never had a complaint.
Is there a code or rule for how much of a transistion height difference is considered excessive? For example, 3/4 " flooring - I would think, no problem to have a small transistional slope of maybe 6 in width (door jambs). Would 1 1/2" be excessive in that same distance?

[Pat Barry]

3/4" plywood over 24" OC framing is pretty much the maximum span in the charts I looked at. Do you like a bouncy floor? I'd be looking at 7/8"-1" ply for a substrate, real joy to install but easier to live with. Guess it depends on the budget and how you like the floor to feel? If the cabs aren't sinking I wouldn't worry about them, particularly if they run perpendicular to the framing. I don't count on flooring to add structure, it also adds dead load, and you can't count on joints landing over framing, the stiffening effect is diminished when joints land in the middle of the span, requires some real careful planning and staggering of joints....better off to create a solid subfloor.
I am thinking that 3/4" would be overkill over the top of the existing 3/4" pine subfloor but I am not seeing T&G plywood in other than 3/4" thickness and T&G sounds like the best choice. Would plain old plywood be OK or is T&G the only good way to go?

[scott vroom]

I am thinking that 3/4" would be overkill over the top of the existing 3/4" pine subfloor but I am not seeing T&G plywood in other than 3/4" thickness and T&G sounds like the best choice. Would plain old plywood be OK or is T&G the only good way to go?

If you already have 3/4" T&G pine subfloor then no need to overlay with additional T&G. You can install your 3/4" wood flooring planks directly onto the pine T&G subfloor, but with 24" joist centers and 3/4 pine subfloor I'd want to add at least 1/2" exterior glue ply perpendicular to the joist direction and screwed to the pine. It won't reduce joist deflection but will stiffen the subfloor between the joists. If installing 1/2" ply raises the overall floor height too high then just install the 3/4" hardwood planks onto the existing pine subfloor perpendicular to the joist direction. It's an improvement from what is in all likelihood a thinner laminate floor.

In any case, your subfloor joist structure is not suitable for tile or stone...too much deflection.

[scott vroom]

Is there a code or rule for how much of a transistion height difference is considered excessive? For example, 3/4 " flooring - I would think, no problem to have a small transistional slope of maybe 6 in width (door jambs). Would 1 1/2" be excessive in that same distance?

You can check with your local code compliance officer, but as a practical matter I wouldn't exceed 5/8" (allows for a 5/8" rabbet from a 3/4" transition piece, leaving an 1/8" overlay on the higher side). You didn't mention the height of the flooring in the adjacent rooms. What is that measurement?

[Pat Barry]

You can check with your local code compliance officer, but as a practical matter I wouldn't exceed 5/8" (allows for a 5/8" rabbet from a 3/4" transition piece, leaving an 1/8" overlay on the higher side). You didn't mention the height of the flooring in the adjacent rooms. What is that measurement?
Thanks Scott, the adjacent rooms are currently at the same level as the Pergo floor, within about 1/8 inch. room is a bedroom, one other is a bathroom.

[Pat Barry]

Here is an update on my floor problem. I started to remove the Pergo and was instantly amazed at the crappy installation. The guy who did this job used thin strips of lath, cardboard, and sometimes Pergo scraps to attempt to level out the floor. He had those strips on about 16 inch centers, perpendicular to the Pergo, with little or no regard tot the seams in the Pergo he was overlaying. Believe me, you need more support than that for Pergo. LOL. Honestly, thats the best news I have. The downside is that the floor, in the area he was trying to fix is not level. It slopes approx 1/4 to 3/8 per 2 ft. Consequntly, the one end (7 ft) has about a 1 1/2 inch difference. Obviously there has been some settling (this low spot is in a corner of the house). More good news is that the sub floor is basically pretty solid. Maybe a few spots where a board or two needs replacement, but basically good. Now I need to decide how to get the floor fixed. I am not certain that I even need to fix the nonlevelness in this stuation. A little non planarity may not be a problem. What do you folks think?

[keith micinski]

It's a log cabin so a solid but un-level floor seems perfectly acceptable. As far as removing the cabinetry to get the pergo out that seems like a silly waste of time and could possibly cause more problems. Cheap Cabinetry doesn't like to be installed and then uninstalled and then installed again. Even good cabinetry doesn't like it all that much. I honestly don't know of what benefit it would be to get the pergo out from underneath of it. Are you even sure it goes underneath the cabinets to begin with?

[Pat Barry]

It's a log cabin so a solid but un-level floor seems perfectly acceptable. As far as removing the cabinetry to get the pergo out that seems like a silly waste of time and could possibly cause more problems. Cheap Cabinetry doesn't like to be installed and then uninstalled and then installed again. Even good cabinetry doesn't like it all that much. I honestly don't know of what benefit it would be to get the pergo out from underneath of it. Are you even sure it goes underneath the cabinets to begin with?
Yes, it does go under. In order to assess the floor I described above I did remove one isolated cabinet. Just two screws in the back into the 'stud' logs was all that was holding it so it came out easy. Still, I'm not looking forward to the bigger cabinet set (L shape) with sink, etc in the main kitchen. I'd really like to remove the Pergo up to the cabinets and then trim out the floor under the cabinets. Right now the toe kick space is about 4 1/2" tall so there is room to work.

[Matt Meiser]

Cabinetry isn't supposed to be installed over a floating floor (or so I was told when we found that had been done in our new house.) The plan was for the installers to cut it at the toekicks and leave it but the installers found they could grab onto it and pull out the pieces that ran under the cabinets, then use scraps and shims to support the cabinets which let them install the new flooring up to the cabinets as they normally would. Granted, ours was 12x12 "tile" squares.

Before the flooring installers came we removed the toekick face. They were careful to keep a tight gap at the front of the structural part of the toekick, then we reinstalled the face and didn't have to use any shoe.

[Pat Barry]

Cabinetry isn't supposed to be installed over a floating floor (or so I was told when we found that had been done in our new house.) The plan was for the installers to cut it at the toekicks and leave it but the installers found they could grab onto it and pull out the pieces that ran under the cabinets, then use scraps and shims to support the cabinets which let them install the new flooring up to the cabinets as they normally would. Granted, ours was 12x12 "tile" squares.

Before the flooring installers came we removed the toekick face. They were careful to keep a tight gap at the front of the structural part of the toekick, then we reinstalled the face and didn't have to use any shoe.
Great idea, Thanks Matt. I will look at that

[keith micinski]

Cabinetry over floating floor is not an issue at all. As you pointed out you were able to pull it out by hand. It will still be able to move with cabinetry on top. I know the rule is not to do it but I do it all of the time and have never had a problem with it and never will. Most floating floors at this point are made out of some sort of an mdf or ply base and move way less then a solid wood product would. I get the feeling this came about because in the past people always installed the cabinets first and it sounds good to say that the cabinets won't allow movement but it's not true. Also a lot of people think it's a waste of material to put under cabinets but having had to cut around cabinets a few times for flooring, whatever material I am wasting I am getting back 2 or 3 fold in time savings and I get a much better surface to set cabinetry on.

[Scott T Smith]

Why don't you take some jacks and start by making the cabin level? It's not hard to do.

I did this several years ago to an old Sears kit house that was built in 1939. It had settled so bad, the floor dropped 4-1/2" in 12'.

All you need is a laser level, a tape measure and a 20 ton hydraulic bottle jack.

[Pat Barry]

Why don't you take some jacks and start by making the cabin level? It's not hard to do.

I did this several years ago to an old Sears kit house that was built in 1939. It had settled so bad, the floor dropped 4-1/2" in 12'.

All you need is a laser level, a tape measure and a 20 ton hydraulic bottle jack.
That sounds easy. I worry that raising up the corner might create new issues. I am not sure how long ago the settling did happen and not quite sure that just jacking it up will fix the problem, but I will look at this idea further.

[Pat Barry]

I dod agree that I don't need a perfectly level floor but someone mentioned the idea of using a self leveling epoxy to pour onto the existing subfloor and build up the low est areas. Does anyone have experience with this sort of thing and can recommend a product, things to watch out for, tips, etc?

[Steve Peterson]

I didn't see anyone mention it, but isn't Pergo a bit out of place in a log cabin? It should have something like tongue and groove planks. 3/4" plywood (or thicker) would be OK as an underlayment.

Steve

[Pat Barry]

I didn't see anyone mention it, but isn't Pergo a bit out of place in a log cabin? It should have something like tongue and groove planks. 3/4" plywood (or thicker) would be OK as an underlayment.Steve
Yes - the Pergo was certainly not the right material but it did work ok except for the lousy attempt at using it to cover non-level subfloor. It is going away though, in favor of solid wood floor or possibly an engineered hardwood.