Plastered floor!!!!!!!

[Albopalbo]

In the kitchen of the house I've just bought, all the tiles by the doorway were broken. When I was lifting all of them to re-tile (we're getting a new kitchen too) the concrete just fell away, and underneath is what I suspect to be plaster! Now it is STILL DAMP also and I have a few questions-

1. Is it still damp because it wasn't allowed to go off or because water has been getting in and it's a possible sign of another problem?
2. How do I put it right before I tile?

Thanks

 

[Richard C]

Unless it's been laid in the last couple of weeks, it won’t be damp because plaster wasn’t allowed to go off; if that's what it is. Unless you’ve put water down there or had an appliance/pipe leak you have damp getting in there somehow; you will have to sort out where it's comming from before tiling or it won't last long. You could have a breach in the floor damp membrane, possibly there is no integrity between the floor & wall damp membranes or water is getting past the doors cill/frame. Looking at the photo, there appears to be a definite strip in front of what looks like French Doors, Has there need any sort of extension? has the wall been knocked through in order to retro-fit the doors? What’s outside? A few extra pics, a couple from further away might help.

You will also have to get rid of the plaster if that’s indeed what it is & all that tile adhesive is going to have to come off as well. Read the tiling sticky & the Tiling Forum archive before preparing/proceeding with your tiling, it may prevent you making expensive mistakes.

 

[Nige F]

Classic retro fitted window - the cavity wall has lost it`s damp proof membrane = usual window fitters bodge dig it all out and lay some damp membrane / aquaseal and brige the cavity with some slate

 

[Richard C]

Classic retro fitted window - the cavity wall has lost it`s damp proof membrane = usual window fitters bodge dig it all out and lay some damp membrane / aquaseal and brige the cavity with some slate

My thoughts as well but wanted to get a bit more info before jumping in; my guess is it’s a new door opening or there was once just a window there; hopefully we’ll see once the OP responds.

 

[Albopalbo]

It is a door the previous owner has fitted. He's done 2 other also!

Thanks for the info, where do I lay the membrane? up under and touching the door? Or on the bottom of the hole? Do I need to dig out the entire length of the door? And once dug out how do I fill it? Any special sort of concrete? and will it bond OK to the dusty dirty hole?

Thanks again.

 

[Richard C]

It is a door the previous owner has fitted. He's done 2 other also!

Thought as much; basically it’s as Nige F said; unfortunately the chances are the other 2 doors are just as bodged & non compliant.
Before I go any further, can you just confirm if was there a door there originally or is it a new opening or an opening extended from an original window. Is there any sign of damp in the reveals or in the adjacent walls?

 

[Albopalbo]

It is a door the previous owner has fitted. He's done 2 other also!

Thought as much; basically it’s as Nige F said; unfortunately the chances are the other 2 doors are just as bodged & non compliant.
Before I go any further, can you just confirm if was there a door there originally or is it a new opening or an opening extended from an original window. Is there any sign of damp in the reveals or in the adjacent walls?

I'm afraid I don't know mate. I suspect there was SOMETHING there before - either a door or window, but couldn't tell you for sure. It's a repossession so can't even ask the original owners.

 

[Richard C]

OK. You need to dig all that crap out full length of the door so you can see what you’ve got there; you should be able to see where the damp membrane in the original floor ends & may uncover the original cavity & below DPC brick/blockwork if it’s a cut opening. You need to extend the damp proof membrane in the floor (a liquid membrane may be the easiest) up to & over the brickwork to meet the inner/outer cavity wall DPC which should be present under the door; if not lay some slate across the cavity as per Nige F. It’s important you check for breaching of the cavity underneath the door cill; this could be cement (or plaster), bricks or anything that was laid across the cavity to support the door frame. The floor damp membrane must form an integral damp barrier with the inner & outer wall DPC/slate. Once you’ve done all that, use a screed mix to cover it all up & float it off level.

If it was a new cut opening, plastic cavity closers should have been fitted to the cavity before plastering to prevent cold spots & damp bridging between the inner & outer brick walls on the reveals. If the guy has just lumped a strip of plasterboard up there & not least stuck a lump of DPC on there, you could get damp occurring in the reveals & on the adjacent walls

 

[Albopalbo]

Thanks for your reply, I have had a dig out and this is what I found -

There a layer of bricks under there after the cavity. The damp stops when you get past the bricks.Do I need to lay some DPC horizontally, fom the concrete, over the bricks and cavity to meet the door?

 

[Nige F]

yes, I also knew thats what you`d find . I fixed mine by adhering some wide plastic DPC to the bottom of the plastic door frame with some Neutral Curing silicone leaving it to hang down slightly over the cavity - then lay on the bricks inside the room . Leave to go off - Then get some SBR and Self levelling screed powder - Mix that and slurry under and over the DPC laying on the bricks Let that go off - You`ll then have a slightly drooping DPC across the cavity- with the edges fixed to the door and to the bricks . Then cover the lot with a thicker Screed mix with a bit of sand to bulk it . Takes time - wouldn`t be cost effective for a builder to do . BUT it worked for me ( tho` you might just get away with slate if you`ve got the depth of screed over it )

 

[Albopalbo]

Thanks Nige. If I did that tugh, there wuldn't be anything under the DPC that covers the cavity. Wouldn't the tiles crack that are laid over it as there's no support for them for the last 2 inches? Or does the screed mix over the top of it for a rigid "shelf"?

 

[Nige F]

you`ve got less than 50mm to bridge - it would become rigid - but having said that , I had vinyl flooring down on mine . I wouldn`t think there could be much that would impact the floor in that vulnerable 50mm - But if you have adequate depth , then go with the slate - real slate not cement/fibre ones and bed that in with SBR/ Latex slurry - That will be more rigid . In any case when doing any floor /wall tiling , Always get a box of spares - you will never find replacements , even after 1 year they disappear off the face of the earth - dunno why, but it always happens

 

[Albopalbo]

OK, so I've cleared all the rubbish out of there. This is the plan - is it OK? The depth of the concrete to the brick is only 10mm. I'm concerned with such a thin layer of SLC resting on DPC is will crack?

Also, do I just leave the cavity like that - with nothing in it?

 

[Richard C]

Sorry for delay only just found this one; I would use a liquid membrane over the brick with a self levelling screed over that. If you’re taking the door frame out or can get enough access underneath the frame, I would be inclined to stick a cavity closer in the base for additional strength, even if it means a little trimming to get it in; lay it over the liquid membrane & then a self levelling screed over the lot.