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How to get concrete ready for sealing/staining/painting/overlay?

Lumberhack
Junior Contributor

How to get concrete ready for sealing/staining/painting/overlay?

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Hi y’all,

 

I’ve been lurking on here for awhile now, but am finally being driven from the shadows by a diy that I began a week ago.

 

I live in a first floor apartment in Sydney, built approx 1975-80. I’ve just pulled up the gross, manky carpet in the empty bedroom in favour of the concrete underneath. My aim is to seal/finish/paint/overlay the concrete in this room as a trial and if it’s (mostly) successful , I’ll get rid of ALL the gross, manky carpet (seriously, it’s yuuuuck).

 

Removing the carpet was the easy part as no adhesive had been used. However, I have a few concerns about the state of the concrete and am unsure of what next my steps should be!

 

SO FAR:

I believe the concrete is unsealed, as it’s rough, porous and absorbs water. I did a simple MVT test (see picture of coles bag duct taped to floor) and waited 3 days but there were no signs of condensation and the area that had been taped off wasn’t a darker colour. However there is a dark patch in the middle of the floor that is definitely moisture and it was there when I removed the carpet.

 

After repeated cleans, there were other darker areas like this as well although they’ve since dried out. I held the wet/dry vac over the main darker part for 30 seconds and it left a circle of lighter (drier) concrete when I removed it. (See pictures).

 

CLEANING PROCESS:

I used Clean n Easy Concrete & Driveway Cleaner (1L to 10L water) with a coarse broom and scrubbing brush and have done 2 passes with this (after letting it sit a while). I then used a metal scraper to remove as much of the paint, dirt and dark lumps of concrete as I could.

I mopped the floor with fresh water, used a wet vac to soak up the excess and have had a pedestal fan blowing on the floor (& the window open) for several hours. I just checked and it seems to be dry in there, except for that original dark spot 🤨

 

CURRENT STATUS...

I don’t want to keep using water in there in case I’m making things worse, plus I think the remaining paint would come off quite well with a Josco Abrasive Nylon Cup Brush or similar drill attachment (suggestions very welcome!)

 

REMAINING TASKS

- Fill tack holes, divots and low spots with Builders Quickset Concrete & sand (once set)

- scrape & smooth back dark, hard, raised patches of concrete (not sure what these are called, but pic in gallery)

- remove paint and stains with Joyco drill brush attachment

- hand sand entire surface so it’s smooth, uniform and ready for either sealing/paint/polish/top layer.

 

I haven’t decided coz I don’t know what I’ll be working with yet! 🤷‍♀️

 

Just before  writing this, I was deep in the archives of the Hive-mind that is Bunnings Workshop 😃I figure I should take care of this concrete creature before jumping headfirst in to a kitchen reno, right? But WOW everyone! So many amazing diy’s here!!

 

Regardless of how my con-creature turns out, I’m looking forward to learning some stuff!!

 

Peace 🛠

MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: How to get concrete ready for sealing/staining/painting/overlay

Welcome to the Bunnings Workshop community @Lumberhack. It's fantastic to have you join us and many thanks for sharing your project.

 

That sounds like a really interesting project and I trust you'll get many questions from interested members. Can I ask if you have considered a product similar to Lanko 20kg 133 Pro Level Floor Leveller? A skim coat of a couple of millimetres thick over the current surface would fill all the holes and low spots and provide a self levelled surface ready for you to start the polishing process on or paint over.

 

If you did want to fill all the defects by hand I would suggest Timbermate Concremate Expanding Cement instead of Builders Quickset Concrete as it will adhere better to the surface.

 

In case you were looking for alternatives to polishing/painting I thought I would mention that we have a fantastic range of easy to install Hybrid Vinyl Planks.

 

We look forward to hearing more about your project and following along will the process. Please let us know if you need any assistance or had questions. We're here to help.

 

Mitchell

 

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Lumberhack
Junior Contributor

Re: How to get concrete ready for sealing/staining/painting/overlay

 

Thanks for the warm welcome @MitchellMc!

 

The Lanko floor leveller will definitely save a lot of time & effort, thank you 🙏 I’m hoping to be able to afford vinyl/alternative flooring later down the track but sadly it’s not in the budget at the moment.

 

I have a few follow up questions, if that’s okay?

 

1. Will I be able to apply vinyl/other flooring over the Lanko in the future?

 

2. Do I need to prepare the current concrete in anyway before applying the Lanko?

 

3. There are expansion joints between the floor and wall. Should I caulk these before applying Lanko, or after?

 

And most importantly:

 

4. The original dark (damp?) spot is still there. Applying the wet vac to a small section exclusively for 10 straight minutes hasn’t made a difference (pics below). I’m worried it’s MVT because this area of the carpet (prior to pulling it up) had a circular laminated piece of art work sitting on it, creating conditions similar to the those of of an MVT test (taping a piece of plastic over an area without sunlight for a few days). It was probably there for about 3-4 months all together (being used as a ‘rug’ by previous flatmate).


Maybe it’s better to start a new post to trouble shoot this damp spot/MVT issue?

 

Any & all suggestions or insights are gratefully received!

 

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: How to get concrete ready for sealing/staining/painting/overlay

@Lumberhack,

 

The Lanko product would be perfect for all types of flooring over the top of it. Some types of flooring require an underlay but the Hybrid vinyl planks do not. 

 

If there are any large patches of paint on the concrete you could scratch them up with some type of abrasive wire wheel so the surface is keyed. Apart from that, there are no special preparation requirements.

 

I would fill the expansion joints with Sikaflex 11FC which is a flexible adhesive/filler. I'd suggest doing this before as if the expansion joints are not filled the Lanko product will run down into them.

 

I've made contact with Davco and they suggested using their K11 floor membrane prior to applying the floor-leveller. This product will stop the rising damp and seal the slab. The product can be ordered through the special orders desk at your local store.

 

Mitchell

 

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Lumberhack
Junior Contributor

Re: How to get concrete ready for sealing/staining/painting/overlay

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This is great advice! Thank you very much for such wonderful help. I have one more question & then I should be good to go:

 

Re ‘scratching up paint patches with abrasive wire wheel so the surface is keyed’...

 

Is it only the areas with paint patches that wouldn’t be keyed? There’s a few areas that have what looks like scaling, except that it’s raised (pics below). Should I attempt to scratch these up with the abrasive wire wheel as well, or can the Davco floor membrane be applied over them as they are?

 

Thanks again for your help with this! I’m feeling much more confident than I was this morning!😌

 

 

 

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: How to get concrete ready for sealing/staining/painting/overlay

@Lumberhack,

 

Everything in those pictures is fine to go straight over with the membrane. The little dots of paint are fine, but if there are large intact pieces of paint it would be worth scuffing them up. The membrane will adhere perfectly well to this and the floor leveller will even these areas out afterwards.

 

Please remember to let us know whenever you need a hand or if you have more questions.

 

Mitchell

 

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Lumberhack
Junior Contributor

Re: How to get concrete ready for sealing/staining/painting/overlay

Fantastic! Thanks @MitchellMc!!

 

Would you mind sending a link to the Davco K11 floor membrane? I just googled it and have come up with ‘Davco K11 Flex’ or ‘Lanko K11 CWA’, but I couldn’t find an exact match. 🤨😅🙏

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: How to get concrete ready for sealing/staining/painting/overlay

@Lumberhack,

 

I apologise for the confusion.

 

It's the Davco Lanko K11 CWA Part A + B that you would need to order. The flex is an overseas version. Davco is now owned by Sika Australia so we'll be ordering through them. Please make sure you specify that you need the Part A + Part B when ordering in-store. 

 

When it comes time to order, please let me know if you would like me to make contact with the store to confirm they are ordering the correct product.

 

Mitchell

 

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Lumberhack
Junior Contributor

Re: How to get concrete ready for sealing/staining/painting/overlay

Perfect! Thank you so much for this @MitchellMc! I’ll definitely reach out when it’s time to order to make sure it’s all correct!

 

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Lumberhack
Junior Contributor

Re: How to get concrete ready for sealing/staining/painting/overlay

Hi @MitchellMc (& everyone)


I think I’m ready to ‘get the stuff and attempt the thing’🤞

 

The room measurements are 

374.9 (L) x 253.4 (W)

 

Based on these measurements, my Bunnings shopping list is:


-
Sika 300ml Grey Silaflex 11FC Plus Polyurethane Adhesive Sealant 

Qty = 1

Lanko 20kg 133 Pro Level Floor Leveller

Qty = 2


Davco Lanko K11 CWA Part A + B

Qty = ?

@MitchellMc as discussed, would you be able to contact the store to confirm they are ordering the correct product & amount? My local store is Alexandria NSW 😊

 

Masterfinish 600mm Squeegee

Qty = 1

I watched this video and chose this as the closest match to what was used. Is this ok?

 

Paint Partner 230mm 3 Piece Roller Kit

Qty = 1 

(for applying primer)


Handy Pail 20L White Plastic Pail With Lid

Qty = 2

(for mixing primer and concrete - after cleaning them of course!)

 

Craftright 120mm SDS+ Paddle Mixing Rotary Bit

Qty = 1

(I have this Ryobi Rotary Hammer Drill that i believe it will attach to?)

 

STEPS:

1. Scrape off any large, intact pieces of paint

2. Vacuum thoroughly (for the 1000th time)

3. Caulk expansion joint (perimeter of room) with Sikaflex. Wait for recommended time

4. Vacuum again

5. Mix and apply Davco Lanko K11 CWA (mix in 20L buckets, pour into paint tray and apply with paint roller)

6. Wash buckets for use with Lanko 133. Wait recommended time for K11. 
7. Mix Lanko 133 in (cleaned) 20L buckets as directed

8. Pour Lanko 133 as directed and distribute evenly with squeegee

9. Let dry recommended time & pray

 

Im so grateful for your help in getting me to this stage! As always, any advice or suggestions are very welcome. Finance-wise, if there’s anywhere I could cut costs without sacrificing the results (cheaper tools maybe?) I would love to know about it!

 

If the floor turns out well I’ll be so happy and will have the confidence to do the rest of my apartment (and FINALLY get rid of this gross carpet!) 😃🤞

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