Red Concrete floor??

[Joe87]

Hi all,

 

 We are looking at getting hard floors put down in our front room/dining area. We've had someone over to get floor samples/ideas, when i told him about the red floor under the carpet that we have. He said that after ww2 they were running low on concrete and so started using a different type of material which is hell for hard floors because of vapour being released. A carpet allows the moisture through, but hard floors could potentially eventually get damp and pop up because the moisture can not pass through it. He told me all this before i told him the house was built in 1947 which falls in line with what he had to say.

 

Im not questioning him at all and i trust what hes saying. Hes gone through alot of effort to find out as much as he can about the floor for us. Hes basically said we could have the hard floors but there is a chance that in the future suddenly we have floor boards springing up from damp, so he wanted us to have all the information so we could make an informed decision.

 

I wanted to see if anyone on here had any experience with this stuff (composite floor i think he said??) and if so what did you do about it or what do you know about it? Im tempted to drill a few holes to see how deep it is (From parts of it cracked on the edge i think about a cm deep...atleast on the edges) and if it would be possible to dig it out and have concrete filled in with new vapour barrier etc. Obviously all this is added cost to a job which is already pricey.

 

Anyone have any ideas or experience with this stuff? It only seems to be in the dining room although under the front room area there are tiles so i couldnt say what is under them until i get them up. Although it does look like the red concrete or whatever it is is slightly higher then the tiles as youll see from the images. So maybe it was poured after the front room was done?!

 

Thanks for any help

 

Joe

 

[Onoff]

Red ash from blast furnace slag. Wife's uncle & cousin are builders up in Stoke and he's mentioned it. More common in areas that historically had such works.

 

Some reaction happens when it gets wet even years on.

 

As an aside I believe German engineers used similar ash in constructing the Channel Island defences (again because of shortages). Found it made really strong concrete. Says something that they're still up and in such good nick!

 

 

[Ian]

@Joe87 there are surface applied liquid dpm products available that you could use on top of that floor which would get rid of the issue of rising moisture affecting the new timber floor. There are also dimpled underlay mats that disperse any moisture to the edges of the room but I have less experience of those.

[nod]

37 minutes ago, Onoff said:

Red ash from blast furnace slag. Wife's uncle & cousin are builders up in Stoke and he's mentioned it. More common in areas that historically had such works.

 

Some reaction happens when it gets wet even years on.

 

As an aside I believe German engineers used similar ash in constructing the Channel Island defences (again because of shortages). Found it made really strong concrete. Says something that they're still up and in such good nick!

 

 

Great information there Onoff 

I’ve seen this before and assumed it was painted at some stage 

[Joe87]

1 hour ago, Ian said:

@Joe87 there are surface applied liquid dpm products available that you could use on top of that floor which would get rid of the issue of rising moisture affecting the new timber floor. There are also dimpled underlay mats that disperse any moisture to the edges of the room but I have less experience of those.

 

I'll be really happy if it's as simple as that! I really don't want to be digging out the floor. You may have made my day. I'll look more into what you've suggested. 

 

1 hour ago, Onoff said:

Red ash from blast furnace slag. Wife's uncle & cousin are builders up in Stoke and he's mentioned it. More common in areas that historically had such works.

 

Some reaction happens when it gets wet even years on.

 

As an aside I believe German engineers used similar ash in constructing the Channel Island defences (again because of shortages). Found it made really strong concrete. Says something that they're still up and in such good nick!

 

 

 

Thanks for the information. I found it really hard to find anything about it online. I knew someone here would know something about it :D. Thanks

[Ian]

8 minutes ago, Joe87 said:

 

I'll be really happy if it's as simple as that! I really don't want to be digging out the floor. You may have made my day. I'll look more into what you've suggested. 

The best liquid dpm products are epoxy based. There are lots of different manufacturers but here’s an example from Tremco:

https://www.tremco-europe.com/en_GB/product/es300-surface-dpm/

you’ll need to check with the manufacturers technical department that it’s okay to use with the type of concrete that @Onoff identified for you.

Edited July 15, 2020 by Ian

[scottishjohn]

my only worry would be not the expoxy coating in it self --

but if the floor does absorb moixture from underneath then I would worry that the expoxy might become unbonded 

then it could crack --then moisture could come through 

If iwere goign to put down expensive hard wood flooring ,then i think Iwould be thinking about ripping it up --putting ina proper vapour barraier and relaying it 

cos there iwll be no barrier at the edge of floor to brick wall --so again another  place for it to crack the epoxy and leak 

 do some more hunting beofre you make a decsion and will one of the expoxy makers warranty it will be a real impervious water barrier ?

and this si a quote from thier application spec

  

 

Remove all surface dust, etc., by industrial vacuum cleaning. Machine scarifying or shot blasting will be necessary for removal of incompatible curing agents, admixtures or other stubborn surface contamination. Shot blasting is also recommended on lightly polished surfaces.

 

 so now you got to get a sand blaster!!

It could work fine -your call

 

 

Edited July 15, 2020 by scottishjohn

[Onoff]

I'm confused...I'd heard of this as i said but never read up on it until now. Depending on what you read the red ash was used UNDER "normal" concrete as a hardcore/filler. I took it that it was mixed in with the concrete. Tbh I reckon both scenarios might have happened. Your photos look like red floor paint at first glance.....is it red all the way through?

[scottishjohn]

I looked atthat tremco site and reading it -there seems lots of loop holes for them to jump through if it don,t work 

like --a consistant +18c when it curing  and surface must be dry and then in another part they say it can be used on a floor with 97% RH iwould never call that dry 

 

you need to talk to them 

Edited July 15, 2020 by scottishjohn

[Ian]

1 minute ago, scottishjohn said:

I looked atthat tremco site and reading it -there seems lots of loop holes for them to jump thorugh if it don,t work 

like --a consistant +18c when it curing  and surface must be dry and then in another part they say it can be used on a floor with 97% RH iwould never call that dry 

 

you need to talk to them 

Yes, you need to talk to them but I’ve specified lots of it from different manufacturers over the last 30 years or so with no failures.

By dry’ they mean no standing surface water.

Surface preparation of the concrete is very important

[scottishjohn]

9 minutes ago, Ian said:

By dry’ they mean no standing surface water.

i,m not trying to be picky --but thats NOT what it says --so in advent of a problem you know what thier definiton of dry will be --maybe you can get them to confirm that it can be used on a floor with 97RH  --I know I seem pedantic --but ive been here before with makers of other products-find out up front is my suggestion 

and yes iam quite sure most times it will be fine --but it s a supposed cure for a problem you don,t really want in the first place 

-dig it and fit a proper dpm below and up the brick work 

 maybe time to think about UFH  at same time?

Edited July 15, 2020 by scottishjohn

[Joe87]

11 hours ago, scottishjohn said:

i,m not trying to be picky --but thats NOT what it says --so in advent of a problem you know what thier definiton of dry will be --maybe you can get them to confirm that it can be used on a floor with 97RH  --I know I seem pedantic --but ive been here before with makers of other products-find out up front is my suggestion 

and yes iam quite sure most times it will be fine --but it s a supposed cure for a problem you don,t really want in the first place 

-dig it and fit a proper dpm below and up the brick work 

 maybe time to think about UFH  at same time?

 

I plan to drill some holes to see how deep this stuff goes, but if I did go about digging it out what would I need to do. Obviously get all the red concrete out but then do I lay the vapour barrier and have concrete poured over the top again to give a level surface? 

 

Thanks everyone for the help so far. I am wondering if it would be best in the long term to dig it out. 

[Joe87]

Ive had a bit more of a research and i think it might be a magnasite floor? It may not be the red ash as first thought? Still looking into it but it may be only a case of about 1-2 cm that will need to come out. Like i said i need to look into it a bit more. No job ever seems to be easy in this house. No matter what we get done something is there to cost more money and time!

[Onoff]

If you end up digging your floor up you might consider digging a bit deeper then building it back up with a good layer of insulation (like 160mm) and maybe even some UFH pipes?