Concrete Slab

[Muddy Funker]

Hi guys. 

Need some collective advice re the above. 

A while ago I converted a garage that's part of an steading type outbuilding into a nice little boxing gym. 

Sadly I noticed small puddles of water appearing on the floor that I'd painted with Leyland floor paint. It's definitely not coming from above so was thinking it must be wicking up though concrete and settling on surface. 

Now I've only recently found the time to tackle this and I've started by ripping out the floor and I want to start again. 

I've taken up the old concrete that ranges from a few mils to a few inches thick. Under this is a variety of different sized stones set into sand, some quite large. I'm guessing this is a fairly standard way of doing a floor in an old outbuilding. 

I was expecting more water but there's been just a few wet stones and general dampness, no water pipes ect. 

Appreciate this is a bit long winded just wanted to set the scene. 

The questions I have are. 

What to do next that's the easiest most cost effective way to put in new floor. I've got a damp proof membrane I'll obviously put down. 

Will I need to whacker plate some sand down first before membrane, if so how deep? 

Will i need to use rebar? I've paced out floor and it's around 3m wide by 5m long so not big. 

Is this something I can do myself with the hiring of mixer and whacker ect? 

I've done the easy bit, though back breaking now need a plan for the next part. 

Some pics included including a couple when it was just finished and in use. 

I'll be adding some more ventilation also. 

Many thanks 👍🏻

https://photos.app.goo.gl/dvHAr89rhkHy6WPP6

https://photos.app.goo.gl/hV5Yb9kpUnKeRcJH6

https://photos.app.goo.gl/nrDWuZ7c3w5xotbv9

https://photos.app.goo.gl/oFrh8cF9PBR6CC4K8

https://photos.app.goo.gl/PHdmzhGCNY2wZDzm9

 

 

 

Edited September 21, 2019 by Muddy Funker
Typos

[silver pigeon69]

Hi,

Did you have any heating in the room?

Are the walls, roof/ceiling insulated?

Did you notice any condensation on the walls/ceiling/ windows(if any)?

Floor specs:

Measure down from what you would like as your finished floor height, 400-450mm(depending on concrete depth you decide? 100mm should be fine.). That's 150mm of hardcore, whacker down, 50mm sand, whacker again, DPM, 100mm kingspan, then 100-150mm concrete. Place your mesh/rebar, lifted 50mm off the insulation(you can buy spacers). 

 

As its an outbuilding/separate garage(different r-values to living space and not heated?) you can buy cheap polystyrene insulation instead of Kingspan, if you want?

Make sure dpm comes up the wall higher than the finished slab level. Trim it when concrete is dry.

You will need (for 3m x 5m room) approx 1.5m3 at 100mm depth and 2.25m3 at 150mm depth of concrete, quite a lot to mix. If you can drive to it, i would get it premixed.

Good plan with the ventilation.

One problem you may find, is that once the floor is done, the condensation moves to the next cold spot, the walls/ceiling?

 

[KB1]

You haven't been leaking some kind of 'fluid' whilst looking at the Arnie photo too much have you🤪?   PS. Seeing as your a boxer, I most definitely wouldn't say that to your face🥴

Anyway………   you don't need re-bar on a floor that size, unless your going to move heavy equipment around..

The advice above is good, and this should help you….

 

[figgy]

Silver pigeon 69 gives you the correct way.

If you just want a concrete floor for a gym or outdoor workshop barn. Make sure you have 100mm minimum from your finished floor height. If the sub floor under is hardcore or gravel etc wack it down with a plate, spread of sand to fully level off visqueen down and up round all sides. Cut weld mesh to fit and sit on stones to keep up off bottom and pour concrete.  I've done and others too where I've pulled the mesh up into the wet concrete or laid it on top and trodden it in to about halfway.  All this info is not the best way of doing it but is cheaper and easy. 

[Saltings]

2 hours ago, figgy said:

 Silver pigeon 69 gives you the correct way.

If you just want a concrete floor for a gym or outdoor workshop barn. Make sure you have 100mm minimum from your finished floor height. If the sub floor under is hardcore or gravel etc wack it down with a plate, spread of sand to fully level off visqueen down and up round all sides. Cut weld mesh to fit and sit on stones to keep up off bottom and pour concrete.  I've done and others too where I've pulled the mesh up into the wet concrete or laid it on top and trodden it in to about halfway.  All this info is not the best way of doing it but is cheaper and easy. 

I am assuming an already built structure within walls  so    , what he said ,     as a gym not a dwelling does not need insulation but does need (visqueen plastic 1000g or more) membrane turned up the walls for waterproofing  ,(would advise weld mesh R193) at app  £30 a sheet  inv vat  or less (do it properly so you can never say I wish I spent the xtra £60 /£80 ) to do it right first time , set your self up some screed rails (scaffolding tube or 2x2 timber  ) level  on top of the mesh to get a finished  level floor  ,( all layers of sub base being level everything else falls into place ) and after concrete is poured and still  pliable  remove the rails  and fill voids to the concrete level ,    you can hire a skip float (basically a long trowel on a long handle to finish ) or a really light tamper and trowel as you go for a smooth finish  , or  tamper through out with the intent of using a self leveling compound for  smooth finish  surface  in the future,   (the better your prep work the better the end result)  also the cheapest in the long run,   if in a sandy area , no need for a whacker just use watering hose  wet the area down watch the sand tighten up (old school)  and works   if struggling to get levels a simple water level from screwfix / toolstation or an other , about a tenner mark ,   your finished floor level marks  1m above,   on the walls with a chalk line ,  you can always measure down to check where you are re levels you just need a DIP stick a(1m ) long   (water levels don't lie for a £10 or more  and go round corners voids etc I still use them after 40 yrs +until this day where others need a light of sight a water level does not  LIE     keel it simple  stupid (KISS) 

Edited September 22, 2019 by Saltings

[Muddy Funker]

Thanks for the brilliant answers above I think that's all the information I need. 

Some more info, the garage is not insulated or heated. The walls are thick stone that I just painted over. Ceiling I did a bit of a crude plasterboard job. 

None of the walls are actually external if that makes sense. Each of them has another internal space beyond them. The only thing facing the elements is the garage door. 

The walls have been wet to the touch but only once. Soon after painting had dried so I'm not sure if was something in the paint coming to the surface. 

Doesn't seem to have happened since putting some vents in garage door. So with that said would it be worth including a tanking slurry in this or no need? 

KB1 you've got to have arnie overseeing things in a gym 💪😂

Thanks again for the great help.