What Is the CHEAPEST way to level a concrete floor and add DPM?

[propertydev83]

Been trying to figure this out. Saw a few more ideas online now and am more unsure so thought best to ask here.

I want to level the downstairs concrete floors as they are all at different levels throughout, very rough and uneven, and there isn't a full and proper DPM so want to add that. I would prefer to avoid raising the finished floor level too much but I could go to a maximum of 100mm.

The lowest points of the existing concrete are about 2 inches below the highest.

What's the best options?

Thanks!

 

[mikeey84]

There is a sticky in the flooring forum that discusses the best way to do this

 

[propertydev83]

There is a sticky in the flooring forum that discusses the best way to do this

I looked at the one about adding a surface DPM and one about self levelling concrete. Wouldn't those approaches be very expensive? I'm assuming the levelling compounds are expensive and I have quite a difference in levels. I'm also quite happy to raise the floor a bit if it makes it cheaper, just keeping it to a minimum. I also already have DPM sheets which can be used if possible as opposed to purchasing liquid DPM.

I was thinking concrete or screed to level it all off. DPM sheet. And screed over. I'm just not sure if this would be cheaper or how thinly this could be done??

 

[mikeey84]

2 inches at the lowest point is a bit thin to use screed, let alone sheet DPM I reckon.

I've seen 50mm being the thinnest you can go for bonded screed, and I don't know if you can do a bonded screed over sheet DPM.

 

[propertydev83]

2 inches at the lowest point is a bit thin to use screed, let alone sheet DPM I reckon.

I've seen 50mm being the thinnest you can go for bonded screed, and I don't know if you can do a bonded screed over sheet DPM.

Concrete over the top of everything now should be ok though as it is bonded? I'd probably be looking at 1 m3 volume of whatevers used. Does anyone know how much it would cost for the same amount of a self levelling compound?

As for the DPM and top layer... I don't know the exact options there are / cost of those options.

I could stand to gain up to 100mm max height from the currently highest points.

I'd prefer what option is cheapest overall, provided it creates a solid damp proof floor., within 100mm of gained floor height.

Approx. 1 m3 of material needed to level off.

Total floor area is 40 sqm.

 

[mikeey84]

Well if you have 100mm to play with, ignore my previous comments.

Sheet DPM should work, then cheapest I imagine would be self mixed followed by ready mix concrete.

However it will take a fair bit of prep to make sure you get it level. You may need to use self leveling afterwards to get it perfectly flat

 

[propertydev83]

Well if you have 100mm to play with, ignore my previous comments.

Sheet DPM should work, then cheapest I imagine would be self mixed followed by ready mix concrete.

However it will take a fair bit of prep to make sure you get it level. You may need to use self leveling afterwards to get it perfectly flat

Would this definitely be cheaper than the other options? And how thin could concrete go above the dpm to keep cost and floor height down?

Although I imagine the other materials would be more expensive per volume, if a thinner layer can be used then the cost difference would change... Hence my difficulty deciding which way to go.

I could work out what's cheapest if I'm aware of exactly how much of what is needed for the options that are viable, i.e. how thin can the layer over the dpm be and how does the choice between liquid or sheet dpm affect this.

At the moment I'm guessing concrete to level off is cheapest. Then I'm guessing sheet dpm is cheaper to cover the area but may mean that a thicker layer is needed above, increasing cost. And so I don't know if it would in fact be cheaper to use liquid dpm and allow a thinner layer above, decreasing cost... ?!?

Or is there even a way to not have a layer above the DPM without this causing a problem. Then I could just level with concrete and apply the DPM and that's it? The final floor finish/coverings are going to be laminate flooring and ceramic tiles.

 

[^woody^]

Does it need a DPM?

You can't level 2" to 0 with concrete, or screed.

 

[Deluks]

Cheapest and expensive are relative terms. It will cost whatever isn't costs, scrimping could cost you more in the long run.

I'm surprised that insulation hasn't entered the conversation, a tiled solid concrete floor can get pretty chilly on the toes.

 

[propertydev83]

I wouldn't be able to enjoy the life I do if I didn't make sure I'm always doing and getting things for the best price. I don't have deep pockets. It's not about cutting corners or doing things cheaply but just doing the math to determine the best options rather than throwing unnecessary hard earned money away. I've done it my whole life and won't stop now. But I can't do the math to work out volumes of materials without first knowing exactly what each option is? Once i know the required type of materials for each option I can work it out myself.

*******

In a nutshell it's just answering how thin can self levelling compound be if I used that to level off?

If concrete is used to level off, it would need to still probably be done to 50mm above the currently highest point, right?

How does liquid or sheet DPM change options for the layer above it? And what options are there for the layer above, and how thin can they be?

Doesn't seem easy to get conclusive answers to those questions, which is why I'm here.

 

[^woody^]

By that logic, the cheapest thing to do would be to rent, get the landlord to do all the work for free and invest surplus cash in commodities and IT start-ups.

 

[propertydev83]

By that logic, the cheapest thing to do would be to rent, get the landlord to do all the work for free and invest surplus cash in commodities and IT start-ups.

Missing the points but I won't bother with discussing this irrelevance any more, and wait for helpful replies.

 

[Ivor Windybottom]

I suspect the actual answer so far is "don't know", but sadly some here revert to stupid sarcasm if this is their position.

I'm happy to say I don't know. But I'm watching this thread with interest as we have exactly the same scenario so would be interested to hear from those who actually know how to do it. My unqualified thinking out loud discussion starting point would be to look at epoxy DPM systems. You probably need a liquid screed either above or below it (again, don't know what's best).

I wonder whether the screed could be built up in layers where the deeper fill is needed, i.e. fill the deeper parts first, then a complete screed over the whole lot after.

My approach will be that I'll probably do the DPM myself and get someone else to do the screed. It's one of those skilled things like plastering that you can't learn from an online guide and a couple of youtube videos. I did my old garage floor and it was good enough for a garage but not to interior standards. It's only "self-levelling" to a degree - it's perfectly capable of making a nice smooth hump or slope, also with a good few air bubbles in my case.

 

[Notch7]

How does liquid or sheet DPM change options for the layer above it? And what options are there for the layer above, and how thin can they be?

Doesn't seem easy to get conclusive answers to those questions, which is why I'm here

Ok starting with the basics, there are 3 screed situations

(thicknesses quoted for cementitious screed)

1) bonded: this is screed straight over concrete (min 25mm to 40mm)
2) unbonded: this is screed put over a membrane, liquid or sheet sitting on concrete (min 50mm)
3) floating screed: this is screed over insulation (min 65mm or so)


I would recommend you get a laser level if you are screeding

 

[propertydev83]

Thanks that's really helpful. I just need to do some working out now and refer to the thread mentioned earlier aswell. But I'll leave that til after the holiday I think!

Merry Xmas!