View Full Version : Getting a smooth underlayment for Linoleum flooring

Dec 12, 2005, 12:37 PM
Hello again!
I am planning to install linoleum flooring in my kitchen, for that super retro look. :) The installation instructions stress that the underlayment must be as SMOOTH as possible. Any indentations or imperfections will show through the linoleum.

My underlayment is plywood, CDX (underlayment grade). It is pretty smooth... I had to fill a couple of small surface knots with wood filler, but mostly it's a good surface.

BUT! Installation instructions for the plywood specify that a 1/8" gap be left between all panels, for expansion.

Now, isn't that gap going to show through my linoleum? What can I do about that? Can I FILL the gaps with wood filler? I would think not, since that pretty much defeats the purpose they serve, right?

Is it possible that the gap they specify is meant for outdoor sheathing uses only? (the instructions stamped on every piece of plywood do not say one way or the other) Would the fact that they're indoors, in a relatively controlled climate, mean I could fill those gaps and not worry about some kind of terrible expansion ruining the whole thing?

Any advice is greatly appreciated, as always!

Cheers, james

Dec 12, 2005, 01:39 PM
I don't think it makes much difference. I am slowly replacing all the original tile floors in my 1970 house with seamless vinyl. I have carefully screwed the plywood down to the joists or at least the layer under it with drywall type screws. Downstairs, I drove all the old nails out. Just did a bathroom upstairs with no access to the bottom. I settled for sinking them well with a nail set. I then smoothed everything up with floor leveler, cement like stuff sold by Armstrong. In some cases I slopped it into the gaps, and in other places didn't. Some of the jobs are over 5 years old and still look good.

Some people insist you must use Luan, but I think it is just more expense and work. It also leaves a ridge. I see places where you can see edge lines and nail heads, and I wonder how they were done.

Dec 12, 2005, 01:41 PM
We do a lot of this type of work. We use lauan and all but butt each piece up against each other. We only leave "a hair" between them... and it does not show through - or give us any problems with expansion or contraction.

Dec 12, 2005, 02:32 PM
I have an installation guide for the linoleum I bought, which made a mention of lauan plywood. I don't remember what it said though so I'll check it again tonight.

If I decide to do that, what type of fastener do you use? Staples? If I do it, I'll get the thin stuff (1/8" I think) so I don't have too much of a ridge from the kitchen to the dining room (which is even now).

And just to be clear: is it a "bad" idea to use wood filler on my current seams? In other words, of these options:

1. Do nothing, just lay linoleum onto current plywood
2. Fill gaps with wood filler and sand smooth
3. apply another layer of thin luan plywood to smooth everything out

Which would you guys choose?

I should mention something I forgot to originally post: I'm laying linoleum TILES, not sheets. This may have a bearing on your answer; obviously it'd be bad if seams between tiles fall near seams of the plywood...

Thanks a bunch guys,


Dec 12, 2005, 03:10 PM
We also use luan plywood. The smooth surface works well w/ the peel & stick tiles and like rickj said the joints won't show if butted tight. If by chance you have any high seams, hit them with a sander.
Use an air stapler w/ to fasten the sheets to the subfloor. (You can rent one if you don't have one) Install the sheets perpendicular to the main subfloor sheets and make sure you also stagger the luan sheets. Staple 3" along seams & 6" in the field. To cut the sheets, a "T" square w/ a sharp utility blade works well. You may need to make 4 or 5 passes to cut through the sheet but the cut will be straight. Just be careful if you use this cutting method.

Dec 12, 2005, 06:55 PM
The old tile I took up was laid over the cracks between the plywood sheets. I removed it not because of any problems with the joints, but because it was 30 years old, cracked and coming loose in places. Laying tile or vinyl directly over plywood is standard practice in new construction. Laying Luan is more quick than waiting for wood filler or floor leveler to dry if you already have an air stapler and are passing the cost of the materials on to somebody else. The most important thing, luan or no luan is to have the floor firmly fastened down. It sounds like you have already done what you need to do with the wood filler. You may need to use cement for the tile. I have never applied peel and stick tile over the old black cutback adhesive and don't think they would work well.

Dec 13, 2005, 10:54 AM
The tile I'm using is not peel n stick. In fact, it's not even "common" linoleum... It's called Marmoleum, made by a company called Forbo. It is an "environmentally friendly" material in that it's made with all natural, renewable ingredients. Check out some info at www.environmentalhomecenter.com.

Anyway, I checked the installation guide last night and it states, in bold letters, NOT to use lauan as underlayment for this product. It says the chemicals used in the manufacture of lauan can cause "color failure", whatever that means.

I'd be tempted to do it anyway because, like you said, it gives a nice smooth surface and you can butt the sheets right up against each other. But, if an installation guide goes so far as to put something in bold, I guess I should listen. :)

I guess my choice of material, once again, has added complication to an otherwise simple project!

I'm going to use filler, just on the largest of the gaps (instead of a nice uniform 1/8" on each side, I ended up wide on one and narrow on the other), then give it a good sanding, and that'll be that.

I appreciate you all's advice! At least I know more info for next time! And that's what a first house is for, right? :D

Dec 13, 2005, 11:24 AM
You'll be just fine with the plywood.

The truth is, most tile manufacturers recommend against lauan yet most installers use it.

Go figure.

Dec 13, 2005, 01:36 PM
Yeah, follow the directions exactly. On another site, I finally suggested the guy replaced the dry wall to get rid of the sticky mess his environmentally friendly Bio Shield linseed oil paint left. Somebody did it ''their way'' and the stuff never dried. I figure stripper would have worked, but redoing the drywall would be easier and safer.

Dec 14, 2005, 06:17 AM
I was watching a home improvement show the other day called Holmes on Homes. Basically, it follows a contractor (Mike Holmes) who goes to home to correct issues caused by shoddy work done by other contractors. It is seen on one of the Discovery Channels.

What Mike was doing on that show was repairing a floor issue caused by improper preparation. He ripped up the flooring and put down new subflooring. What he strongly recommended was to screw the subfloor into the joists. And to use as thick a subflooring as you can. This is especially important when doing tile work requiring grout.

The subfloor he ripped up was held down with about 300 nails. Mike estimated that he used 3000 (yes thousand) screws. Granted in this case the joists were undersized (2x8 where 2x10 would be required now) and he wanted to stiffen up the floor by making sure that the subfloor was stronger.

He implied that nails wouldn't be strong enough as they may pop loose. Perhaps using a ring shank nail may be enough as they are technically a screw.

Mike didn't put down a 1/4 luan layer as he used an isolation membrane to protect the tile from cracking. But, I have come across other sites which do put down a luan layer. Maybe this can be stapled down without any problems.

But, for my projects, where I am tiling, I will be screwing down both layers of subfloor. Whether it be a 1/4 luan or cement board before I put down any tile.

One of the home improvement big box stores (Menards) in my area carry a 4x4 sheet of plywood called plyfloor. It is marked with x's to indicate a fastening pattern and is not luan. It is not luan.

As for putting in filler between the sheets of plywood, I wouldn't recommend it. Most hardwood flooring installers don't recommend using filler as wood expands and it would pop out the filler.

Good luck, and I hope this helps a bit.


Dec 14, 2005, 03:35 PM
I see another strong vote for screwing down good whatever you use. Not sure what the membrane he mentioned is. I wanted to mention that if you are using a natural oil based product and apply it over nasty old black adhesive, it could bleed through it. Maybe the membrane is something that will stop that.

I haven't had problems with th eblack bleeding through either the vinyl floors, or the one poured epoxy I did.

Dec 16, 2005, 04:48 PM
As always, thanks for all the input. When I put down the CDX plywood, I used both ring-shank nails and 3 1/2" gold screws. I didnt' want that sucker to ever move! It's installed over top of the old subfloor, which is 3/4" thick lap boards, laid diagonally to the joists. This gives me a total subfloor thickness of 1 1/2", which I'm confident will be sufficient.

I'm going to skip using lauan plywood for 3 reasons:

1. The instructions say to :)
2. More expense
3. Would cause a greater transition between the dining room and kitchen floors, which might look weird, plus be prone to damage from foot traffic...

The linoleum tiles are supposed to be delivered after Christmas, so I have some time to continue sanding the floor smooth where I filled the small knots and covered over my screws.

I'll leave small gaps for expansion, and then plan my tile placement accordingly so there are no seams near these gaps. Hopefully it'll work out!

Thanks again, j

Dec 16, 2005, 07:20 PM
If you put down new plywood, that eliminates any problem with old adhesive. Like I say, I have taken up tile over gaps and not seen any problem. Interesting thing was a floor done in the 50's, the Pastor's study at my church. The underpayment was a fairly soft material, I think maybe called soft board, softer than hardboard. After about 50 years, it still looked good over the gaps. I quietly let the old tile go in the trash without ever pointing out it may have contained asbestos and been hazardous waste. We carpeted over the soft board, no problem.

Aside from the thickness, what is the difference between luan and plywood? Does luan have some oil in it that would be a problem?

Dec 17, 2005, 05:52 AM
Instructions from forbo website.

Like other resilient flooring, linoleum telegraphs the shape of whatever’s underneath. Glue tiles to existing vinyl only if it is a single layer, relatively smooth and not cushioned.

Otherwise, prep the floor:

Option 1: Install underlayment (special plywood with all voids plugged, one surface sanded and edges milled to interlock). Forbo recommends dispersion-type staples; nails can pop up. Fasten every 4 to 6 inches in the field and every 2 to 3 inches along seams. Sand seams flat.

Option 2: If the old flooring is in relatively good shape and not too cushioned, fill gaps with a floor-leveling compound made with Portland cement and a liquid latex binder. Do not use gypsum-based fillers; they may harbor mildew and interfere with the linoleum adhesive.


When I have installed flooring I have always filled the gaps or any depression (from the screws that I used to secure the underlayment). I have used floor leveler for this purpose. The floors always come out smooth.

The width of the gap and whether to fill it may depend on the thickness of the new tile being put down. If it is of a thicker material than the smaller gaps may not transfer through the tile. If one uses a thinner tile then the smaller gaps may have a tendency to appear.

Nov 3, 2009, 05:27 PM
The finer your gaps are will reflect how fine a job you end up with. I have had past troubles with plywood firmly butted against each other leading to noise issues. Consider this especially in middle flooring situations