# Anyone have experience gluing engineered hardwood to gypcrete?



## RhodesHardwood (Jun 28, 2010)

We have a large condo project booked that is going to require us to glue 5/8" unfinished engineered to gypcrete in a multi-unit condo building. The plans call for us to seal the gypcrete with a product called Specco S-55. The gypcrete guy and contractor claim that this helps the gypcrete not suck all the moisture out of the glue and that this helps it glue to it better.. I have reached out to Bostik and Taylor to see what they have to say about this but I haven't got much help.. The contractor is on me about getting a contract to him but I want to be sure that this sealer isn't going to create issues. This is a great job so I hate to pass on it, but I also don't want major issues coming up because of it. 

If anyone has any experience please help. Thanks!!


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## donerightwyo (Oct 10, 2011)

We did a job with a pre-finished Shaw plank. The job was about 4000sq ft. The Gypcrete was Maxxon with the Maxxon sealer applied. Then verify moisture content was good. I spent many hours getting the shaw rep to commit to being able to put it over the gypcrete. It specifically said in the instructions not to. We have had no issues with the floor. 

I would make sure and use the gypcrete's sealer so as not to void their warranty.


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## RhodesHardwood (Jun 28, 2010)

Thanks for the reply. Ya unfortunately they want us to seal the gypcrete with the sealer I mentioned.. I did just find that Taylor (the adhesive manufacturer I planned to use) actually makes a gypcrete sealer and it is also acrylic latex based like the other product they mentioned. So think I might see if they are open to using it.. I did specify the psi strength of the gypcrete to that will not be an issue.. My only dilemma is making sure that I'm not going to run into issues with bonding.. Either way I appreciate the reply, and it's good to know that someone has had some success with this.


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## ccoffer (Jan 30, 2005)

Have you "reached out" to whoever specified the product you seem squeamish about using?


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## RhodesHardwood (Jun 28, 2010)

Thanks for the reply. Yes I've been in discussion about this job for about 30-40 days. I have spoke with the architect, gypcrete guy, the contractor etc.. They are all insisting that we use this. I've done a fair amount of research tonight and it seems that it's at least somewhat common to seal the gypcrete.. From what I am gathering it seems that not sealing it will cause the gypcrete to suck too much moisture from the adhesive and that can potentially cause issues..


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## Metro M & L (Jun 3, 2009)

Ive laid approximatley 8000 feet of solid bamboo over gypcrete with ms plus. No primer. No call back. Floor needs to be flat and thats about it. Ive been doing these installs for the last 30 months. The gypcrete is 20 years old so its perfectly dry; a newly poured slab will require much more caution.


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## MIKE ANTONETTI (Jul 17, 2012)

*Anyone Have Experience Gluing Engineered Hardwood To Gypcrete?*

I haven't looked up the specco product nor any hardwood on gypcrete.
But we installed LVP to Gypcrete. We used Ardex primer 81 or 51 can't remember # but the effect it seemed to have was not a "sealer", it seemed to strengthen by penetrating down creating vertical 3 dimensional bond.
You know weakness is right below the product(primer) applied, so when it soaks in it creates a better bond than on a flat plane


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## RhodesHardwood (Jun 28, 2010)

Metro M & L said:


> Ive laid approximatley 8000 feet of solid bamboo over gypcrete with ms plus. No primer. No call back. Floor needs to be flat and thats about it. Ive been doing these installs for the last 30 months. The gypcrete is 20 years old so its perfectly dry; a newly poured slab will require much more caution.


Thanks for the reply. The gypcrete guy says it takes 7 days to cure, we will have 3-4 weeks between it being done and the floors. I plan to start monitoring the moisture content after the gypcrete has been poured for 2 weeks. I have also specified that we need the gypcrete to be at 3500psi. I'm going to record the moisture content, take pictures, level/grind as needed before applying the primer/sealer.. Just worried about the bond.. I guess the word sealer just scares me..


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## RhodesHardwood (Jun 28, 2010)

MIKE ANTONETTI said:


> I haven't looked up the specco product nor any hardwood on gypcrete.
> But we installed LVP to Gypcrete. We used Ardex primer 81 or 51 can't remember # but the effect it seemed to have was not a "sealer", it seemed to strengthen by penetrating down creating vertical 3 dimensional bond.
> You know weakness is right below the product(primer) applied, so when it soaks in it creates a better bond than on a flat plane



Thanks for the reply. Ya I've read a lot about Ardex and it seems to be a preferred product for this. Also, in doing more research it seems that you are absolutely right about it actually creating a better bond. Like I mentioned in my reply to Metro, I think the word sealer just had me worried because in most other cases for glue downs sealer is a bad thing..


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## PrecisionFloors (Jan 24, 2006)

Metro M & L said:


> Ive laid approximatley 8000 feet of solid bamboo over gypcrete with ms plus. No primer. No call back. Floor needs to be flat and thats about it. Ive been doing these installs for the last 30 months. The gypcrete is 20 years old so its perfectly dry; a newly poured slab will require much more caution.


You're braver than I. That crap won't stick to broom finished 30 year old above grade concrete worth a damn. I'd never trust it over gypcrete. I hate that glue.


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## elementbldrs (Sep 26, 2010)

Have a fall back plan if the gyp doesn't dry in the time frame you need. Dehumidifiers and heaters as a t&m clause. Bit me for $18,000 on a job, couldn't get my moisture numbers down.


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## donerightwyo (Oct 10, 2011)

We sanded the gypcrete the next day with a floor sander to flatten in out. 

So I think your sealer that you are going to use looks reputable, just make sure the glue company is good with their product going over the sealer.

Is there heat in the floor?


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## RhodesHardwood (Jun 28, 2010)

elementbldrs said:


> Have a fall back plan if the gyp doesn't dry in the time frame you need. Dehumidifiers and heaters as a t&m clause. Bit me for $18,000 on a job, couldn't get my moisture numbers down.


Thanks for the reply. The contractor has large commercial dehumidifiers they plan to use for this and I triple checked that this bill isn't on me. I think we have 2 weeks between the gyp being poured and the start of the install.. In general do you think this is enough time? I know their are many variables ie; temp, humidity, air movement, thickness of gyp etc.. Thanks for the reply!


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## RhodesHardwood (Jun 28, 2010)

donerightwyo said:


> We sanded the gypcrete the next day with a floor sander to flatten in out.
> 
> So I think your sealer that you are going to use looks reputable, just make sure the glue company is good with their product going over the sealer.
> 
> Is there heat in the floor?



Ya I planned to buff the gypcrete with a 60 or 80 hard plate sand paper if needed to level it out.. Contractor tells me we should have little prep, as he uses these gyp guys regularly.. But you know how that goes.. I'm waiting to hear back from the adhesive company on compatibility..


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## MIKE ANTONETTI (Jul 17, 2012)

One thing that concerns me personally, and I've heard a tech rep confirm is when you sand a surface your actually forcing dust into the slab and leaving on surface. Then he said shotblasting is preferred method in certain situations. 
I've been grinding for quite a while now and the residue is annoying, say when I walk from slab to top of hardwood you see footprints. I have a good vac system while grinding and afterward but doesn't ever get film gone. I always wanted something to spray on surface like a densifier to lock dust and slab together and of course compatible with adhesive/s


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## elementbldrs (Sep 26, 2010)

We ran 15 commercial dehumidifiers a floor (8,000 sq ft compartmentalized to 10 condos) for 7-15 days at 2-3 1/2" gyp poured, this was after 2 weeks of drying due to moisture not coming down to acceptable levels.

I really think it depends on the variables as you stated. Just warning that the bill goes up fast.


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## RhodesHardwood (Jun 28, 2010)

elementbldrs said:


> We ran 15 commercial dehumidifiers a floor (8,000 sq ft compartmentalized to 10 condos) for 7-15 days at 2-3 1/2" gyp poured, this was after 2 weeks of drying due to moisture not coming down to acceptable levels.
> 
> I really think it depends on the variables as you stated. Just warning that the bill goes up fast.



I appreciate the heads up. I emailed the contractor again making triple sure that they plan to handle everything associated with dehumidifiers if needed and he assured me they would provide them, pick them up etc.. Hopefully we don't have this kind of hold up because it would throw off our schedule horribly.. Guess I'll plan for an extra couple of weeks just in case.. Then if it don't hold us up I'll take a couple week break.


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## MIKE ANTONETTI (Jul 17, 2012)

There's wood adhesives that don't care how much moisture is in slab, the trowel applies a layer of adhesive and the notch and they say this acts as the barrier. Trying to get water out of slab is time consuming.


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## RhodesHardwood (Jun 28, 2010)

MIKE ANTONETTI said:


> There's wood adhesives that don't care how much moisture is in slab, the trowel applies a layer of adhesive and the notch and they say this acts as the barrier. Trying to get water out of slab is time consuming.


Ya I plan to use Taylor adhesive.. I've only used their stuff once before as we don't do many glue downs, but apparently the adhesive acts as a moisture barrier too at the right spread ratio.. So I plan to do the thicker spread to be safe.. I wouldn't be so concerned but its 6,000sf so I want to make sure everything is perfect so nothing can come back on me as it would put a huge financial hurting on me if it did.


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## MIKE ANTONETTI (Jul 17, 2012)

I agree, we try to get everything with minimum risk, following or close to guidelines makes life less stressful. Wiggle room is good. 
Not that I believe all of the claims on products, the one for thinset where it says it will bridge cracks up to 1/8", and some people say the products for the barrier doesn't work, so maybe not if your at the high mark, but say the dehumidifiers remove a lot of water and the barrier may be just enough to avoid a moisture problem, then it's worth the extra effort. Wagner has a good site for info as well for moisture situations. When you have multiple products they tend to blame one another.


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## Metro M & L (Jun 3, 2009)

RhodesHardwood said:


> Ya I plan to use Taylor adhesive.. I've only used their stuff once before as we don't do many glue downs, but apparently the adhesive acts as a moisture barrier too at the right spread ratio.. So I plan to do the thicker spread to be safe.. I wouldn't be so concerned but its 6,000sf so I want to make sure everything is perfect so nothing can come back on me as it would put a huge financial hurting on me if it did.


I found with ms plus that the cost using the xtra notched trowell was a dollar a foot for the glue alone. Not sure what exact product youre considering. Also, the taylor trowel extension included with the bucket is a joke, spend the ten bucks for the dedicated trowell.


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## MIKE ANTONETTI (Jul 17, 2012)

Good number, so applying extra adhesive saves on labor/cost adding the barrier separately.
The trowels worked ok for me, they say to replace after every bucket due to the lift notches wearing out spreading less adhesive.


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## RhodesHardwood (Jun 28, 2010)

Metro M & L said:


> I found with ms plus that the cost using the xtra notched trowell was a dollar a foot for the glue alone. Not sure what exact product youre considering. Also, the taylor trowel extension included with the bucket is a joke, spend the ten bucks for the dedicated trowell.



Ya I hadn't figured the math on the spread vs the cost per sqft on that.. But I priced the adhesive at $6k on 5200sf so I think I did ok there.. Ya I planned to get a few good trowels.. I think my supplier said, 3/16X1/4X1/2 v trowel.. Thanks!


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