Garage floor Help

[henry8]

Hello
Doing a self build with a basement garage of 50 sqm on a concrete raft ,the walls are concrete as well joined into the floor and no dpm was installed at time due to concern about slipping
The raft is 350mm thick with reinforcement and has been down for about two years ,it seems ok and is dry
I want to have a good cosmetic finish and boy have i been around the houses ,first i was going to put a screed of sand and cement 70mm bonded to the concrete ,i was advissed against this by the architect who thought it would not take cars and crack ,i then went on the self levelling route ardex k301 which was expensive before actually buying cempolay ultra and sending back as it does not cope with no dpm and if moisture comes up well we know what will happen ,lastly i am looking at laying a dpm on the concrete and then placing 80mm of new concrete and powerfloating it to give a good finish .I will put in some joints engineer is ok with this and had some details from cemex
Any thought and advice welcome ,never again will i be involved in a self build
Thanks

 

[theoldun]

Cempolay ultra is basically a diy product for levelling of floors prior to covering.
There are two or three ways to go.
Google Resin Screeds. Have a read what they say, explain to them what you want and ask for a quotation. They can get a scuff free screed capable of taking weight of car down to 10/20mm thick.
If price is outside of budget, consider 2 coats of Ikopro Synthaprufe Original. First coat across the floor second coat opposite way, blast second coat with sharp sand when still tacky. Two coats round bottom of walls up to say 50mm above what ever finished floor level will be.
Would suggest you do not go power float route unless you have had previous experience. You will need a design ready mixed concrete mix, that will want laying very first thing in morning, hopefully, warmish day.
Mid day, hopefully hand trowel all perimeters and get first pan over, possibly another pan one hour later.
One hour later, polish all perimeters and get first set of blades over. Another hour, blades again, another hour, final finish with blades.
Saying all that, you may get finished in 3 hours or it may be 10 hours. All depends on mix and drying.
Sand and cement screed 80mm thick reinforced with PPF will take a car but the top will chip up and scuff very easy. If you want to go the screed route then you want a 60mm grano screed, but finding someone these days who can do a grano is another story.
If you go power concrete, expansion round all perimeter, follow any expansion in existing slab and consider mid section expansion. Guidance only. old un.

 

[noseall]

Why the need for expansion joints on a non-exposed (zero sunlight) slab?

 

[henry8]

I think i might look at a dpm from ardex and then bite the bullet with ardex k301 , it does seem easier than the conrete way and am worried about cracking ,anyone know where you can get a reasonable price for thi stuff

 

[theoldun]

Noseall. Always understood definition of basement to be the lowest story of a building, below the main floor and wholly or partly below ground level.
This basement floor could be 1 metre below ground level, with open up and over garage doors facing south with possible full sunlight on 50% slab for 6 hours a day.
As we do not know, we have tried to cover the worst possible scenario with regard to initial shrinkage and drying out and possible future thermal expansion.
Are we wrong? old un.

 

[henry8]

Hi re the expansion joints ,the concrete company advised me to put them due to the size of the floor as in their opinion it would crack ,we talked about saw cut and also using perimeter edge expansion
Thanks

 

[noseall]

Hi re the expansion joints ,the concrete company advised me to put them due to the size of the floor as in their opinion it would crack ,we talked about saw cut and also using perimeter edge expansion
Thanks

So, is the ambient temperature in the basement subject to large fluctuations or is there sunlight upon the slab at any time of the day?

 

[henry8]

Hi
It is a basement under the ground on three sides apart from the front where there are two garage doors which when open would face the south however thgey would be closed most of the time ,o it would be complete darkness
Thanks

 

[henry8]

Ok
I have had a price of about £500 to do it in concrete ,i am looking at about £600 to do it K301 Ardex , i am told that if i do it in ardex there is no need to put a dpc just use a breathable paint
I think the ardex has got the least potential for problems and will be quicker to carry on works

 

[alittlerespect]

Hi

You need to be wary that the concrete may be moisture resistant, but it will definitely not be vapour resistant, and the structure basically needs to breathe if you are going to avoid problems. If vapour gets trapped behind an impermeable membrane/paint film it can cause all sorts of problems.
If you want a good finish use a lime based (renovation) plaster which is breatheable to some extent and then apply an emulsion paint to finish (mist coat and 2 finishing coats)

Regards