Concrete subfloor prep

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Greetings all! First post, like many on here I’m after some advice, guidance and clarification as I’ve read so many differing routes to take it’s all becoming a bit of a mind f…..well, you get the picture!

In a moment of madness I purchased a reclaimed Jarrah wood parquet floor which I intend to fit into the lounge / dining room in my place. Over the past couple of months this has been painstakingly cleaned and scrapped. My question is on how to best prepare the subfloor for this. Should I have just taken the easy route and bought engineered jarrah floor? Well, where would the fun be in that?!

My bungalow was built in the late 60’s (believed to be 1968 / 69) and originally had a finger block parquet floor in this room. It also had all the water pipes and central heating pipes imbedded in the concrete.

When I moved in I discovered that the original parquet had been removed and replaced with a cheap laminate and then had a thick underlay and carpet laid over the top. (The previous occupant was very elderly and I think she got cold with just the laminate down as the old heating system wasn’t really up to much)

My suspicion was that one of the old underfloor pipes had burst and damaged the floor, hence its removal. Some of the bungalow had pipes fed from under the floor whilst the main room had pipe work running down the walls. (I have re-plumbed the whole property so now none of the old underfloor pipework is in use.)

Now that the room has been completely cleared I am almost certain that this happened as there is an area where it is clear that the surface screed has been dug up and replaced. It is also directly between 2 old pipes that came out of the floor….the plot thickens!

Now to the crux of my question. Where the old parquet was removed there is a residue of the old bitumen adhesive that was used to fix it down. As I am now well aware, this can cause problems when prepping the surface for anything new. The property does have a DPM (a bitumen type, discovered when cutting a channel for new drain installation.) but I am unsure whether this was damaged / repaired in the lounge when the pipe incident occurred. Also there is a crack in floor (only 1mm wide) that runs across the room where I think the place has settled over the years. After much reading and researching I am thinking of doing the following:

Fill the crack – Not sure what to use for this, does it even need worrying about?

Level off the repaired concrete bit in the floor with a grinder (it’s a little lumpy)

Apply a layer of ARDITEX NA over the whole floor, approx 3 – 4mm thick.

Apply ARDEX DPM 1 C as a precaution that the DPM may be damaged (although there are no signs of damp anywhere, I’d rather not take chances and knacker my new floor)

Prime the DPM with ARDEX P4

Apply second layer of SLC (more ARDITEX NA?)

Glue down parquet blocks with suitable bitumen residue friendly adhesive such as Lecol 5500 or SikaBond 5500S

Is this an acceptable plan of attack or are there other options I should consider? Should I try and fill the crack with something before the first coat of Arditex NA? Are the products I intend to use suitable? (I think they are, from what I have read!)If anyone has any suggestions or alternatives on what I’m thinking, I’m all ears!

Thanks for reading, looking forward to your inputs.
 
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That would be right mate what you want to do but Ardex NA isn't strong enough for a solid wood floor.
You need a screeding compound with at least a Compressive Strength of 25 newtons
You should of gone engineered really. But now you have already got the wood I would do the same but with differnt screed
 
Thanks dazlight, that's much appreciated. I take it you mean Arditex NA the base coat then use something different on the dpm layer for fixing the floor too. Is there anything in particular you or other readers would suggest?
 
No mate. You can't put a harder screed about a softer one.

So
Remove the old adhesive / bitumen off the sub floor.
Then apply dom to the floor. If it's not smooth I'd use
F ball stopgap green bag with 114 liquid
 
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Ah I see. Bugger. The old adhesive is basically all off, it's just the residue that's impregnated the screed and the only thing I've found that might be suitable (so I've read anyway) is the Arditex NA. My concern would be that the DPM might not adhere properly with this.

I am fortunate in that the other rooms connecting to this room are at least an inch higher than the screed level is at the moment, so building up the subfloor isn't an issue threshold wise. In view of this could I lay a plywood subfloor down over an Arditex NA / ARDEX DPM 1 C and fix the wood blocks to that? Or is this just a daft idea from the start.....
 
Hmm....just had a read of the F ball stopgap green bag data sheet and it states the following:

Non-absorbent surfaces - Priming of non-absorbent subfloors such as minimal
adhesive residues, terrazzo and quarry tiles is not essential when using STOPGAP 114 Liquid. Sound flooring grade asphalt and STOPGAP waterproof surface membranes must be primed with neat STOPGAP P131 to ensure that good adhesion is obtained between the underlayment and substrate.

So with that in mind could I do what I initially outlined but use f. ball products instead i.e. green bag SLC, Stopgap F76 DPM and Stopgap P131 primer?
 
Yes you could as its stronger then Na. Na would be the best but not for solid wood.
You can use F77 instead of 76 as well.
 
Thanks so much for your input dazlight, it's really appreciated. Pity you are not closer to my neck of the woods, as I'd get a quote from you guys to pour this stuff. I've done small areas of SLC before but this room is little over 30 square metres, should be interesting!

Done some reading on F76 & 77 and there doesn't seem to be much difference between the 2 for the type of application I require (I'm not installing underfloor heating for example). Is there any particular preference to one or the other?

Also, as a bit of belt and braces would it pay me to prime the surface with the residue with P131 before the first coat of Green Bag?
 
No you can't prime under a liquid DPM. In fact f ball say you can very thin 7-1 but I'd go more 12-1 water to prime

Don't think you will need to though.
F77 is new an can go up to highter RH reading them 76.

So
Remove as much adhesive as possible
Prime weak or none
Green bag
F77
Green bag.

Years ago I always did

Same but with 2 coats f75
 
Good post guys. How did you get on engminded? I am just in the process of removing 'crunchy' thermoplastic Marley tiles with bitumen adhesive beneath and replacing with a vinyl plank. I've had a professional asbestos company is to take a sample - both the tile and adhesive came back as positive so it's all to come up. The plan is to go with Arditex NA with aggregate, Ardex DPM 1C, Arditex NA + aggregate. The spec sheets advise no priming is required for either.

One thing I would like to understand is how to estimate the required volume of smoothing compound and aggregate? I am thinking of supplying the materials and getting a fitter in to do the rest. The current sub floor is quite uneven and I would estimate has a discrepancy of approximately 15 - 20mm in places over the 31 square metre area.
 
That's a lot out mate. I would do base coat trying to level the floor 1st. 1 unit does about 5m2 at 3mm
So a room 31m2 you would use 7-8 units. For the 2nd coat.
1st coat more if some building up is needed.

I'd say buy
20 units na
2 x 10kg dpm1c
 
That's a lot out mate. I would do base coat trying to level the floor 1st. 1 unit does about 5m2 at 3mm
So a room 31m2 you would use 7-8 units. For the 2nd coat.
1st coat more if some building up is needed.

I'd say buy
20 units na
2 x 10kg dpm1c

Thanks for that daz...

I have continued with this project on the flooringforum - hope it's ok to mention that on here.
 
Anyone got a kilo or two of Lecol 5500 or SikaBond 5500S going spare? Got a patching job of 1.5m2 and balking at having to buy 16kg! Can't find smaller cans.
 

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