Damp concrete floor

M

marsaday

I have a kitchen where the lino has come up today and underneath is all damp.

I boarded out the solid floor last march with 5mm ply and put down a lino.

I am pretty sure this is not due to human beings, but rather the solid floor is damp. I bought the house to renovate and rent out so dont know if there was a previous problem. They had vinyl tiles stuck down before with a black tar i think. I took up these tiles and laid the ply (screwed into the floor) and then finished with lino.

I need to solve this problem. Any ideas on how to do this.

Do i need to dig up the whole concrete floor ?

Can i screed a special waterproof solution on top.

My final finish is to be the vinyl which you glue down and it looks like wood.

The area in between the units is very damp and the washing machine was here. I dont think this had a leak.

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M

marsaday

I have done a bit of reading and it seems i can buy a tanking slurry product and this will seal the concrete.

Any ideas what product i could get ?

How do you go about putting down a new floor on top of this sealant ? I assume you can drill through and screw and plug ply like i have done already?
 

ree

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To do the job properly, you must lift all the ply and expose the whole concrete floor. All units and appliances will have to be cleared out to give a free space.
Any corner cutting, and the damp will return.

Do you have a membrane below the slab? i doubt it.

Carefully examine all interior plaster and skirting in the kitchen - look for signs of damp.

Is the external ground level lower than the kitchen FFL - by how much?

The black stuff below the vinyl tiles was probably bitumen or asphalt. Its probably best to remove all traces - if possible!

There are lots of Tanking "Liquids" for damp concrete floors - read the tech spec v. carefully or call the tech dept. for a heads up on suitability for your floor situation.
There are SLC's that would suit over a tanking application.
 
M

marsaday

What is SLC ?

I dont know if there is a membrane below ?

The external ground level is very close to the internal finished floor level.
 
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ree

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self levelling compound

Then perhaps remove a skirting board and look for one.

Moisture could be coming across a solid wall or a blocked cavity wall. Best building detail is for the solid floor to be 150mm above the ground level.

Its your call as to whether you should screw and plug thro your tanking?
 
M

marsaday

Spoke to dryzone today and their painted damp membrane looks like what i need. They do a tougher 2 coat resin, but because i am laying laminate ion top i only need the lighter product.
 
M

marsaday

Does anyone have any knowledge on these epoxy resins for floors ? You can get a slurry one which you mix from powder or there are paintable ones straight from the tub ?

What is better ?
 
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Are you 100% sure there's nothing leaking under the floor, and was it damp last March before you screwed anything down?
 
M

marsaday

I am 100% sure as i can be that there is no leak under ground.

The heating system did go through this concrete floor, but i ripped out the whole system and put in a new plastic pipe network and boiler. So nothing was laid under the concrete.

The stop tap in the corner is leaking and i need to get this changed (cut into old lead and then fit adapter for 15mm).

There is no hot / cold water under the floor.

I have decided to go with the F Ball resin system.
 
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I would ensure the lead is not leaking under the floor, it's not unheard of. My fear is, should you seal the floor and there is a leak then that water may be trapped and will look for another way out.....
 
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Was there a thick layer of bitumen that was acting as a damp proof? If there was and it was damaged / part removed when the floor was done ....
 
M

marsaday

Yes there is bitumen down and it has come away in many places when i scrapped off the old vinyl tiles.

I have dug down around the lead pipe today and no leaks.

I also have my solution which is to really clean up the floor and remove as much bitumen as possible. Then i use a Ball product called 1200 and this is a nice thin screed to prepare the floor for a sealant. This goes off pretty quick and so the next day i will apply F76 which is a one coat epoxy resin.

Pretty chuffed i have sorted all this out. Should solve all the problems i think.

I have also stripped off some plaster up to 90cm in height today and applied an eggshell membrane i had left over from a tanking job yrs ago. This is why the lead pipe has been exposed as i have dug out a small drainage channel for this membrane to run into. Will back fill with gravel and then finish off with cement. Saved myself £350 on this bit alone as that was a quote i had from someone
 

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