Construction Adhesive for Baseboard on Cinderblock Walls?

[dkerfoot]

I just installed bamboo flooring in a basement room (engineered, floating install) and am trying to install baseboard against the painted cinderblock walls. Part of the problem is that the cinderblock is far from being a flat, square surface. So, the 7 foot long baseboard sections need to flex a bit to come close to remaining flush to the wall.

I tried Loctite powergrab first but it wasn't strong enough. When I removed the weights I was using to clamp it to the wall after 24 hours, one end of the baseboard popped off the wall

It is cold here (Michigan) and even though the room is heated, I figured it may be that the cinderblok is just too cold. So, next I tried some heavy duty construction adhesive that is supposed to even work on wet or frozen lumber. It is supposed to work down to 40 degrees F. After 24 hours it was still a gooey mess.

Any suggestions? Am I crazy for considering Sumo or Gorilla glue?

[thrytis]

Wall base adhesive will attach rubber cove molding to cinder block walls. I don't know though if it would work with wood or not or provide enough stick for something that stiff.

[iceman61]

In this situation, I think I would counterbore the baseboard, use tapcon screws, & plug behind the counterbored screws with some wood dowels.

[Tequila]

How much flex are we talking about? If it's a lot, you may want to consider doing a two part baseboard. You can take flat 3/4" stock and either scribe it to fit the wall or use fasteners (like iceman suggested). Then cover the fasteners with the the smaller moulding.

[cabinetman]

In this situation, I think I would counterbore the baseboard, use tapcon screws, & plug behind the counterbored screws with some wood dowels.

I've had to use Tapcons on base to block. For painted base, it's an easy fill/sand/paint. For finished clear/stained woodwork, facegrain plugs are an out. I've had some unusual luck with Liquid Nail adhesive. If used properly, it may hold if the wall is fairly flat. I run beads, press into place, to get a transfer, then pull it away and let it flash off for about five minutes, then press back.

If the wall is really wavy, you don't want to mount the base so tight as to take on the wave. That would be very noticeable.
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[JSUPreston]

I've gotten to where when I am doing something like this and it is to be painted, I'll use that PVC based trim that I've seen at the BORG. They also make some that is an engineered wood fiber of some sort. Can't remember any of the names off the top of my head. I like them because they do have a lot of flex and are lightweight.

[Uncle Cracker]

I've had some luck with Tapcon-ing the base first flush to the "high" spots of the wall, then using Tapcons to pull the "low" spots to within about 3/16" of the wall, and caulking the gap shut and painting the caulk to match the wall (not the base). This serves to largely reduce the wavy look of an uneven base.

[dkerfoot]

Just for clarification, the floor is fairly flat and where it isn't I am not overly concerned about following the minor curves. The issue is that the wall the baseboard is mounting to isn't flat. I'd say there is about 1/4" of total flex needed. Part of the issue is that the baseboard I am using is solid strand woven bamboo and is very heavy and quite springy.

Strand woven bamboo is really nasty to drill and I am not optimistic that it would plug well. Particularly because it is coated with a clear aluminum oxide coating that is strong, but when scratched, leaves a white "edge" that can't be removed. The only thing i have found that works is to sand the entire piece and then poly. (Ain't gonna do that!)

The other potential issue is that I have carefully water-sealed the wall using hydraulic cement to replace the inner mortar and Dry-Loc paint on the inside. I am very reluctant to be drilling holes in it especially at the very bottom.

So for now - I see adhesive of some sort as the only option. Any adhesive suggestions?

I appreciate the thought of letting the Liquid Nails "flash" for 5 minutes first. That may be the issue why it was so gooey after 24 hours.

By the way, the flooring and the baseboards were part of a payoff by a customer who went bankrupt. I am using it because I have it.

[Tequila]

How about making some relief cuts in the back to help make the baseboard more flexible?

[Uncle Cracker]

Just for clarification, the floor is fairly flat and where it isn't I am not overly concerned about following the minor curves. The issue is that the wall the baseboard is mounting to isn't flat. I'd say there is about 1/4" of total flex needed. Part of the issue is that the baseboard I am using is solid strand woven bamboo and is very heavy and quite springy.

Ah, won't take a screw, then? By "high" and "low" spots, I was referring to the wall, not the floor, by the way, with "high" being the places where the wall juts out most into the room, and "low" being where it juts out the least. You could still straighten the base a little by scabbing thin boards behind the low spots, thus relieving the bend stress on the base, and using liquid nails instead of screws. Then caulk the gaps in the top edge and paint as earlier suggested. This will conceal the curvature of the wall. Have you given any thought to a two-part epoxy if the liquid nails won't hold? How about contact cement?

[windmill]

I used liquid nails to attach my baseboard to the cinderblock wall in the basement. This was ordinary pine baseboard, primed and painted. It's not very cold here in NC, but it was winter when I did the install.

It could be simply a matter of a bad tube of adhesive, in which case it will never cure all the way. Check the expiration date. I'd try a small section first with a fresh tube. Also, how much are you using? I usually run two beads (alternating sine patterns) as wide as a pencil and half as thick.

If the wall is really wavy, you may want to cut a section in half and use a scarf joint. Not quite as pretty, but better than the whole thing flexing off.

[chopnhack]

As I understand the product your trying to install is the prefinished pce of bamboo that matches the floor and you dont want to mar it. Have you considered mounting perhaps a 1x6 to the wall with a 1/4 cove top as an accent and then you can easily mount the finished product to the 1x6? Its a lot of extra work, but then you can pin nail the bamboo to the "other"baseboard pretty easily.
Just a thought.

[dkerfoot]

Just wanted to update this thread to reflect what I ended up doing.

Thanks for the suggestion on relief cuts Tequila. I didn't think it would help at first because the baseboards have roundovers on top that prevent me from doing a relief cut all the way through. But I found that doing three or four near the flex point through the bottom back corner (the bottom edge that abuts the wall) did provide a bit more flex. Nothing magic, but it all helps.

I ended up deciding to use 5 minute epoxy. I am sure whoever decides to remove it someday will curse me for it, but it certainly did the trick.

Funny how it is taking me about 4 times as long to put up the baseboard as it did to install the whole floor!