Diamond grinding concrete slab before gluing hardwood floor

Old 07-25-19, 08:08 PM
Thread Starter
Join Date: Jul 2014
Posts: 17
Upvotes: 0
Received 0 Upvotes on 0 Posts
Diamond grinding concrete slab before gluing hardwood floor

About 2 years ago, I installed solid bamboo hardwood floors in the living room. The substrate was the concrete slab, and I installed it using the glue-down method. Prior to gluing, I rented a diamond blade floor grinder from Lowe's and ground down the entire surface. I had read that if the concrete was too smooth or mirror-like, the glue may not stick as well and that it needed to be ground down to expose the porous inner core. Ultimately, the project turned out beautifully. I have had absolutely no issues.

BUT... I'm wondering if the grinding is really 100% necessary. I am about to embark on a similar project in the bedroom. I will be using the same Bostick SingleApp glue. This time, I am using engineered (rather than solid) bamboo flooring. The pieces are "click" fit. The exact product is here:


The substrate is the same concrete slab as in the living room. It is perfectly level. There are no high spots that need to be ground down or low spots that need to be filled. If I did grind down the surface, it would be for the same reason as last time - to scrape off the glossy coat and exposure a porous surface for gluing. I'm just wondering if that's really necessary. There is definitely some drywall overspray that I need to scrape off near the walls, but I'm hoping that's about all the prep work needed.

I figure that:
1) The flooring is engineered hardwood, so very stable and not prone to warp.
2) The flooring is click fit, so that each piece effectively holds the surrounding pieces in place.
3) The room is the bedroom, which gets daily traffic, but nothing heavy.
4) I live in central Texas, humidity is usually not an issue.

Considering all of these, I feel that there is a fairly good chance that the wood won't warp or deform much after laying. And as such, I feel that grinding down the entire surface in an attempt to get the best possible "stick" may be overkill. The house was built in 2008 (I moved in in 2014), and the office already had hardwood floors installed, possibly during the initial build. After doing enough renovations on other parts of the house, I'm going to say it is HIGHLY unlikely that ANY prep work was done prior to laying the flooring in the office, and it seems to be holding up just fine.

I wanted to attach a few pictures just in case it helps. The first is the room in general, the second is the drywall overspray that I am removing, and the third shows a small section that I ground down to test. In this third picture, the lower left shows the ground-down porous surface, and the upper right shows the grossy-ish slab without grinding.

Anyway, I suppose the main reason I'm asking is because I just want someone to agree with me that grinding is overkill in this situation. But I would love to hear either way!

Name:  f1.jpg
Views: 382
Size:  65.8 KB

Name:  f2.jpg
Views: 375
Size:  88.4 KB

Name:  f3.JPG
Views: 384
Size:  60.8 KB

Last edited by PJmax; 07-25-19 at 08:20 PM. Reason: resized pictures
Old 07-26-19, 03:20 PM
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 27,789
Received 2,186 Upvotes on 1,956 Posts
I've only ground when the floor needed leveling or if there was something like paint, sealer or oil to remove. Other than that if the concrete is smooth and clean I glue without grinding.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: