Glueing wood to concrete


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Hi, I'm working on a staircase, I am comissioned to wrap (?) a staircase with oak. But since it has 9 flying steps and I have to put wood on all 5 faces, i wouldn't want to finish it there, it would be very hard. So i'm planning on building a box that is a little bit bigger than the step so I can finish it in my shop and then install it. But I have to be able to glue it down, so it won't slip.

And i'm thinking of using 2 part epoxy glue, because they told me I should just put glue con the four corners and in the centerpart, so... it won't be very expensive. Another choice is the sikabond T-53, this is especially for wood floors to concrete, the thing is, I can't really find it, I just found the sikabond construction adhesive and it's more like a multi porpuse elastic poliurethane adhesive, I mean it's not especially for wood and I don't really know how much will it hold the wood in place, plus, this would be more pricy.

What do you think? Can I use epoxy glue and have good results?.

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A buddy at work is doing somewhat the same thing. Just a stair tread, but the idea is the same. Because the wood will want to be able to move and will regardless of how you attach it, I'd use an adhesive like liquid nails and only do a glob on both side in the middle of the tread. That way the would can still move.

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I've used Liquid Nails like Vic suggested to stick wood to concrete and it definitely holds tight. If people have been walking on the concrete directly, it might be glazed over and won't be the best surface for the glue. You can get concrete etching solutions that work pretty quickly and would take off that glazing so the glue sticks better. I used a water-based product to etch, but it is difficult to get outside the American southwest. Try a water-based one, though, as the fumes were infinitely better than some of the straight acids.

I'm sure you will, but seal all sides of the oak including the side that gets glued down or seasonal moisture will make a mess of your work especially that it is attached to concrete. Heck, Liquid Nail is water-based and can cause problems when you glue-down unsealed wood.

Post pictures when you get it installed :)

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Yes I think I'll use that. The funny part, is that I bought a cylinder of liquid nails ( actually "No mas clavos" wich means no more nails, and I think it's the same) like a year ago, and never used it. And I spent around 4 hours searching on the web about glues for wood to concrete and finding somebody who actually sold them, and liquid nails never crossed my mind. I think I should KNOW all the things I have in my shop. haha, thanks for your advice. And I'll sure post some pictures. The problem is, I can't really upload them, i've been having trouble with that, on the first post my intention was to show you the boxes but the images did't upload, it said error IO or 10. That's also the reason why I haven't uploaded the pictures I had on "my page" back on the other forum, to my gallery.

Well, thank you very much, hope it goes right!

P.D: I wanted to multiQuote your replies, but I don't think it worked.

Walter Wolf

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I've used Liquid Nails like Vic suggested to stick wood to concrete and it definitely holds tight. If people have been walking on the concrete directly, it might be glazed over and won't be the best surface for the glue. You can get concrete etching solutions that work pretty quickly and would take off that glazing so the glue sticks better. I used a water-based product to etch, but it is difficult to get outside the American southwest. Try a water-based one, though, as the fumes were infinitely better than some of the straight acids.

I'm sure you will, but seal all sides of the oak including the side that gets glued down or seasonal moisture will make a mess of your work especially that it is attached to concrete. Heck, Liquid Nail is water-based and can cause problems when you glue-down unsealed wood.

Post pictures when you get it installed :)

I went to home depot and found liquid nails even cheaper than the "no mas clavos" and actually bought a Beats The Nails from DAP, they were both cheaper and if you have used it for the same purpose I rather just use liquid nails. But, I bought the heavy duty liquid nails, is it okay with this?

Thanks

Walter Wolf

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Definitely should work out okay with the heavy duty. Just remember to etch the glazing off the concrete steps so the glue has a better adhesion. If you don't want a chemical stripper like the concrete etchants, use a coarse sand paper like P60 or P80 on a disc sander to scuff up the surface

So Liquid Nail is thick so spreading it is, uhm, fun. Wipe the concrete with a damp sponge before you start to get rid of the dust and give the LN a better surface to grip. When you apply it, I'd trowel it around with a notched trowel (1/4" or 3/16"). The reason is that if you just squirt out a bead of it then apply the stair box, the LN doesn't spread around; you'll eventually have those beads cured so the step is only adhered in those areas; worse, the areas between the beads will act like a mini drum when people walk on it. With an even distribution of the LN, you'll get a much better adhesion and avoid any drum issues.

Sorry for the long reply... B)

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Definitely should work out okay with the heavy duty. Just remember to etch the glazing off the concrete steps so the glue has a better adhesion. If you don't want a chemical stripper like the concrete etchants, use a coarse sand paper like P60 or P80 on a disc sander to scuff up the surface

So Liquid Nail is thick so spreading it is, uhm, fun. Wipe the concrete with a damp sponge before you start to get rid of the dust and give the LN a better surface to grip. When you apply it, I'd trowel it around with a notched trowel (1/4" or 3/16"). The reason is that if you just squirt out a bead of it then apply the stair box, the LN doesn't spread around; you'll eventually have those beads cured so the step is only adhered in those areas; worse, the areas between the beads will act like a mini drum when people walk on it. With an even distribution of the LN, you'll get a much better adhesion and avoid any drum issues.

Sorry for the long reply... B)

Unless you live in an extremely dry area like Paul, I'd be hesitant to use it on the whole tread. I'd only apply it to the the back edge and a couple place at the center edges. Wood moves quite differently than the concrete and depending on the humidity variations, gluing the entire tread could cause some serious problems. Just my opinion.

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ok so if the box is slightly bigger than the step, then I think I can still press it down so the LN will spread, I think. Do you still recommend me to trowel it?. If I visualize it correctly, for me to trowel the LN it would have to be like a big amount of LN around it or not?

Now, I do live in a dry area, it's very hot here in my city, and there's nearly no rain, but I still want the wood to move and everything so it won't crack. So what should I do? Put 2 beads of LN along the steps, and then a little bit on the edge that is touching the wall?.

I don't know what etching is, i've never done it. But I know what you mean with the glaze, and I was planning on using p60 grit sand paper. Will this be ok?

Thanks, you're really helping me out!

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No, it won't spread out like you're thinking. At least I don't think so. ;)

What I suggest it a "dry fit" so to speak. Get a tube of LN and a scrap peice of wood. If you have never used LN before you are in for a treat. :) Get yourself adapted to how it acts, try to spread it around. It won't behave like a caulk, much more sticky and thicker... The last thing you'll want is to put down too much LN, it will squeeze out of the cracks and make a huge mess. Good Luck.!

BTW, I'd trowel it down if it where me. Much more even, level coverage.

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When I've used LN (before I had a clue), trying to squeeze it down was futile. Troweling it down is the best way. Definitely, try troweling it on some scrap ply and glue other scrap to it. You'll need a lot of pressure when troweling, but it's the best way for an even consistent spread.

I thought your stair tread boxes would completely enclose the concrete step so squeeze-out would be hidden inside. If not, keep some acetone handy to wipe it off and a putty knife to take the bulk of it. Don't step on a blob; don't ask how I know...

LN is not rigid so the movement issues are moot. You'll find other handy trivia at the Liquid Nails FAQ.

Naturally, you'll want to finish all surfaces anyway; you wouldn't want the part glued to the concrete to be unfinished. For one, moisture from curing LN is an issue and second concrete loves holding moisture to wood (it's the architectural version of rock-paper-scissors).

Lastly, the etching I'm talking about it where you use a concrete etchant. Basically it is an acid that dissolves the smooth top layer of the concrete making it look rough and porous, which is great for bonding. It will also remove the 'glazing' of dirts and oils that will affect the bond. But, there's a smell to it. If you already plan on the P60, you are set to go. Wear a mask.

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Hi, here is the link for some pics of the stairs and the boxes I'm talking about, the 5th face is missing, but I will be using it, and actually there will be some changes, the sides are not going to be 3/4" thick they will be 1/4" instead, so it's not that big and the flying steps can be appreciated as that, if not it just looks like a normal staircase without a hand rail.

So basically I make a zig zag bead, and then trowel it?, to trowel means to spread the glue around right?

And yes, i'm planning on finishing both sides.

Now, you are saying that I should do it on a piece of ply, you say that, so I can practice right?

thanks, i hope you can see the pictures.

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Hi, here is the link for some pics of the stairs and the boxes I'm talking about, the 5th face is missing, but I will be using it, and actually there will be some changes, the sides are not going to be 3/4" thick they will be 1/4" instead, so it's not that big and the flying steps can be appreciated as that, if not it just looks like a normal staircase without a hand rail.

Looks to be a very interesting project!

So basically I make a zig zag bead, and then trowel it?, to trowel means to spread the glue around right?

Here's a trowel:

RA183QGelRubberHandleNotchedTrowel.gif

Usually, apply the glue kinda evenly then give one pass with the trowel so it turns the glue into strips of glue (the strips are formed by the glue coming out of the notches). When you press the stair down, the idea is that the glue strips will flatten into the voids between the strips making for a very even layer. That's what you want. Don't go spreading all over the place; you would like to ideally do one pass to get glue strips going side to side. Don't crisscross them making a tic-tac-toe board. This is a picture of thin-set mortar troweled, but gives the idea of what you are after:

wkr208_3fi_lead.jpg

(you can't believe how hard it is to find a picture of a properly troweled floor... about half of them zig-zag all over the place!) You want the glue strips even; don't worry if there's a break here and there as you have plenty of adhesive and other adhesive will flow into the area when you press on it.

Now, you are saying that I should do it on a piece of ply, you say that, so I can practice right?

Yes, practice it. Spreading thin-set mortar for tiles spreads pretty nicely. Liquid Nail is much stiffer and stickier. You'll want to try it out. There might be a flooring glue (that you'd trowel) expressly made for concrete to wood. I have some, but it's a long drive :) It's also more expensive than Liquid Nail, but then you'll go through a ton of that stuff. The flooring glue is made to be troweled whereas LN is not normally troweled.

If you have more questions, post them. If you get stuck and need a demo, maybe I could video Skype you.

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Hi, yeah I asked to my wood supplier for a wood to concrete glue and they offered me a glue that is called bostik I think, but they would just sell me a bucket and I certainly don't need that much glue haha plus it would be expensive even if I decided to keep the left over. Anyway, tomorrow I'll get a trowel and practice on scrap. I actually tested my 3 options: no mas clavos, beat the nails and liquid nails. I glued down yesterday with no mas clavos (in some places it's from a brand named Pattex) a piece of wood to my shop floor just to see how would it hold up, i was very skepticall, but today, it amazed me! I couldn't get it of. And today I glued another 2 pieces with the other 2 glues and I did noticed that it is much different it's harder to spread. But it's okay, I think i'll stay with liquid nails because you have already used it for the same purpose and got good results, plus it's cheaper.

If time lets me (I'm going back to school tomorrow), tomorrow i'll practice that and show you a picture, just to know if i'm doing it well. But i do have the idea now.

Thank you very much for your help. I will pay you with a very nice project and some pictures haha.

P.S: I always call that wood white oak, but I realized it comes from a different tree which is, quercus ilex or holm oak... So the wood is holm oak or what? haha I think it looks like white oak but I don't really know, they actually say it's from the u.s

Walter Wolf

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I never would have thought of gluing the wood directly to the concrete... I would have gone the furring strips set with the powder actuated nails. (Any excuse to buy firearms, in some books...)

So I'm glad i stumbled on this...

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