I'm about half way done with my house. I'm doing a glue down engineered hickory hardwood.

I'm not sure if I have a problem or not. I've been working on my house in sections over the past couple months, basically I'm done with the master bedroom, hallway and halfway in the kitchen. Recently while inspecting the kitchen and entry floor, I've noticed little gaps on the long side in some of the strips, i'd say about 20%... I don't have this problem in the bedroom or hallway. I can't see it being an acclimation problem because if anything, the boxes for the kitchen have over a month of sitting in the house vs the bedroom. The only thing that I've done differently is I stopped using wedges. Instead I been tightening with straps/clamps because it allows me to go faster. Perhaps I should use the wedges again. I'm almost certain none of the gaps were there when I was installing as I'm pretty anal about my installation. The brand is not sold here, but it's not inexpensive.

I'm thinking that it's moved slightly while drying. Unless I'm not thinking of something else, would this make sense? Also, I've been filling the gaps with a color fill for hardwood, is this correct? Looking at the picture, how bad does this gap look? I hate imperfections, esp after spending so much time on this!

Where do you live Ronnald, and what glue are you using? It could be seasonal gapping. Did you just enter a cold spell and using the furnace a lot? Check the RH levels.

Fillers are best left until the floor goes through a few season changes, it may close back up in a few months.

Hi Jerry, I live in Sacramento, I'm using Bostiks Best and MVP. Yes, there was a cold spell going on, but wouldn't the bedrooms and hallway do the same?

My experience:
I installed quite a bit of bamboo back in November. I'm in Utah. It was cool outside so I was using a heater, but I allowed my bamboo to acclimatize for at least a full week. Some was probably sitting out for 3 weeks.
I continued to install (and buy new bamboo) throughout other areas of the house, through the present time (mid January)

NOW we are in the midst of a bitter cold spell. The air indoors is BONE DRY. I noticed that the areas I installed back in November were starting to gap. Not big gaps (largest just barely approaching business card width), but enough that I didn'ty want it to continue.

I went and bought a cheap humidifier and left it running 2 days. Most of the gaps have disappeared. This has to be absolutely the worst time of year for indoor humidity.

Hickory is a fairly unstable specie, it will move fast if it gets too dry in there as noted. Get a humidifier for when the heat runs constantly.

Hi guys and thanks for the replies. A few things I still don't understand.

First, if it's because of lack of humidity, why are the other rooms okay? Second, if I get a humidifier, do I use it for a few days and then ??

Well, today I'm more convinced it's a wedge issue, so I'm back to using them.



Wedges work great, but my slab is very hard. I have to drill and use anchors.

A couple of things.
1) When gluing flooring directly to concrete, I install with the groove out, not the tongue. This allows me to angle the board and engage the T&G without sliding it in the adhesive. Best has a tremedous memory and when you try to put a board down and slide it into place, Best wants to push it back to where you first set it down. This could contribute to your minor gaps.
2) I use blue masking tape as I install. This acts like a "clamp" but much easier and faster than messing with the strap clamps. In fact, some brands of engineered floors describe this method of keeping their glued down floors tight as they are being installed.
3) You should only need to wedge at the end of your install day. In fact, I do not wedge except against a wall. So I work till I get to a wall, pry that floor up tight and wedge it. Then let the adhesive set overnight. In the meantine, I can pull tape and clean the floor.

So, I think your gaps are more installation technique than temp related since by wedging, you are not getting them again.

NEW TIP


Steve Olsen from CA has had success wedging with hot melt glue. Apparently with that technique it it easier and less labor intensive. I've been trying to get some pics but to no avail.

I wonder if there's a way to get some hot melt glue under the last row after each area is installed? A dab here and there just to keep the installation tight?

Hi Gary,

I tried the blue masking tape at first, but small gaps still appeared, and I used quite a bit of it too. I'm not sure if this is a result of the glue I'm using or ??? Isn't Bostik's Best suppose to be good stuff? I would still get minute gaps using the tape, thus I switched to the wedges.

Yes, I do only wedge the last row, but since I'm working solo, I can only complete about a 12 rows or so depending on the length. Of course with the glue down, I have to make sure no glue oozes out of the last row underneith.


Ken, hot glue? I would think the hot glue wouldn't have any sticking power to the concrete.

Oh, Gary regarding the tongue side out. I did start on the grove side out. Once I got into this room that is pictured, the tongue is out, due to my continuous layout.

These glue downs sure take a lot of time. Half the battle, at least for me is removing glue. I do find that Bostik's glue removal is superior to mineral spirits.

That's what I thought initially. Apparently it does work..on clean concrete. If Steve O says it works I take his word for it. He seems to be a perfectionist with everything he does.